path: root/em-format/em-format.c

/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) version 3.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the program; if not, see <http://www.gnu.org/licenses/>
 *
 *
 * Authors:
 *      Michael Zucchi <notzed@ximian.com>
 *      Jeffrey Stedfast <fejj@ximian.com>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <string.h>

#include <gio/gio.h>
#include <glib/gi18n-lib.h>

#include "em-format.h"
#include "e-util/e-util.h"
#include "shell/e-shell.h"
#include "shell/e-shell-settings.h"

#define EM_FORMAT_GET_PRIVATE(obj) \
    (G_TYPE_INSTANCE_GET_PRIVATE \
    ((obj), EM_TYPE_FORMAT, EMFormatPrivate))

#define d(x)

typedef struct _EMFormatCache EMFormatCache;

struct _EMFormatPrivate {
    guint redraw_idle_id;
};

/* Used to cache various data/info for redraws
   The validity stuff could be cached at a higher level but this is easier
   This absolutely relies on the partid being _globally unique_
   This is still kind of yucky, we should maintian a full tree of all this data,
   along with/as part of the puri tree */
struct _EMFormatCache {
    CamelCipherValidity *valid; /* validity copy */
    CamelMimePart *secured; /* encrypted subpart */

    guint state:2;      /* inline state */

    gchar partid[1];
};

#define INLINE_UNSET (0)
#define INLINE_ON (1)
#define INLINE_OFF (2)

static void emf_builtin_init (EMFormatClass *);

enum {
    EMF_COMPLETE,
    EMF_LAST_SIGNAL
};

static gpointer parent_class;
static guint signals[EMF_LAST_SIGNAL];

static void
emf_free_cache (EMFormatCache *efc)
{
    if (efc->valid)
        camel_cipher_validity_free (efc->valid);
    if (efc->secured)
        g_object_unref (efc->secured);
    g_free (efc);
}

static EMFormatCache *
emf_insert_cache (EMFormat *emf, const gchar *partid)
{
    EMFormatCache *new;

    new = g_malloc0 (sizeof (*new)+strlen (partid));
    strcpy (new->partid, partid);
    g_hash_table_insert (emf->inline_table, new->partid, new);

    return new;
}

static void
emf_clone_inlines (gpointer key, gpointer val, gpointer data)
{
    EMFormatCache *emfc = val, *new;

    new = emf_insert_cache ((EMFormat *)data, emfc->partid);
    new->state = emfc->state;
    if (emfc->valid)
        new->valid = camel_cipher_validity_clone (emfc->valid);
    if (emfc->secured)
        g_object_ref ((new->secured = emfc->secured));
}

static gboolean
emf_clear_puri_node (GNode *node)
{
    GQueue *queue = node->data;
    EMFormatPURI *pn;

    while ((pn = g_queue_pop_head (queue)) != NULL) {
        if (pn->free != NULL)
            pn->free (pn);
        g_free (pn->uri);
        g_free (pn->cid);
        g_free (pn->part_id);
        if (pn->part != NULL)
            g_object_unref (pn->part);
        g_free (pn);
    }

    g_queue_free (queue);

    return FALSE;
}

static void
emf_finalize (GObject *object)
{
    EMFormat *emf = EM_FORMAT (object);

    if (emf->priv->redraw_idle_id > 0)
        g_source_remove (emf->priv->redraw_idle_id);

    if (emf->session)
        g_object_unref (emf->session);

    if (emf->message)
        g_object_unref (emf->message);

    g_hash_table_destroy (emf->inline_table);

    em_format_clear_headers (emf);
    camel_cipher_validity_free (emf->valid);
    g_free (emf->charset);
    g_free (emf->default_charset);
    g_string_free (emf->part_id, TRUE);
    g_free (emf->uid);

    if (emf->pending_uri_table != NULL)
        g_hash_table_destroy (emf->pending_uri_table);

    if (emf->pending_uri_tree != NULL) {
        g_node_traverse (
            emf->pending_uri_tree,
            G_IN_ORDER, G_TRAVERSE_ALL, -1,
            (GNodeTraverseFunc) emf_clear_puri_node, NULL);
        g_node_destroy (emf->pending_uri_tree);
    }

    /* FIXME: check pending jobs */

    /* Chain up to parent's finalize() method. */
    G_OBJECT_CLASS (parent_class)->finalize (object);
}

static const EMFormatHandler *
emf_find_handler (EMFormat *emf,
                  const gchar *mime_type)
{
    EMFormatClass *emfc = (EMFormatClass *)G_OBJECT_GET_CLASS (emf);

    return g_hash_table_lookup (emfc->type_handlers, mime_type);
}

static void
emf_format_clone (EMFormat *emf,
                  CamelFolder *folder,
                  const gchar *uid,
                  CamelMimeMessage *msg,
                  EMFormat *emfsource,
                  GCancellable *cancellable)
{
    /* Cancel any pending redraws. */
    if (emf->priv->redraw_idle_id > 0) {
        g_source_remove (emf->priv->redraw_idle_id);
        emf->priv->redraw_idle_id = 0;
    }

    em_format_clear_puri_tree (emf);

    if (emf != emfsource) {
        g_hash_table_remove_all (emf->inline_table);
        if (emfsource) {
            GList *link;

            /* We clone the current state here */
            g_hash_table_foreach (emfsource->inline_table, emf_clone_inlines, emf);
            emf->mode = emfsource->mode;
            g_free (emf->charset);
            emf->charset = g_strdup (emfsource->charset);
            g_free (emf->default_charset);
            emf->default_charset = g_strdup (emfsource->default_charset);

            em_format_clear_headers (emf);

            link = g_queue_peek_head_link (&emfsource->header_list);
            while (link != NULL) {
                struct _EMFormatHeader *h = link->data;
                em_format_add_header (emf, h->name, h->flags);
                link = g_list_next (link);
            }
        }
    }

    /* what a mess */
    if (folder != emf->folder) {
        if (emf->folder)
            g_object_unref (emf->folder);
        if (folder)
            g_object_ref (folder);
        emf->folder = folder;
    }

    if (uid != emf->uid) {
        g_free (emf->uid);
        emf->uid = g_strdup (uid);
    }

    if (msg != emf->message) {
        if (emf->message)
            g_object_unref (emf->message);
        if (msg)
            g_object_ref (msg);
        emf->message = msg;
    }

    g_string_truncate (emf->part_id, 0);
    if (folder != NULL)
        /* TODO build some string based on the folder name/location? */
        g_string_append_printf(emf->part_id, ".%p", (gpointer) folder);
    if (uid != NULL)
        g_string_append_printf(emf->part_id, ".%s", uid);
}

static void
emf_format_secure (EMFormat *emf,
                   CamelStream *stream,
                   CamelMimePart *part,
                   CamelCipherValidity *valid,
                   GCancellable *cancellable)
{
    CamelCipherValidity *save = emf->valid_parent;
    gint len;

    /* Note that this also requires support from higher up in the class chain
        - validity needs to be cleared when you start output
        - also needs to be cleared (but saved) whenever you start a new message. */

    if (emf->valid == NULL) {
        emf->valid = valid;
    } else {
        camel_dlist_addtail (&emf->valid_parent->children, (CamelDListNode *)valid);
        camel_cipher_validity_envelope (emf->valid_parent, valid);
    }

    emf->valid_parent = valid;

    len = emf->part_id->len;
    g_string_append_printf(emf->part_id, ".secured");
    em_format_part (emf, stream, part, cancellable);
    g_string_truncate (emf->part_id, len);

    emf->valid_parent = save;
}

static gboolean
emf_busy (EMFormat *emf)
{
    return FALSE;
}

static gboolean
emf_is_inline (EMFormat *emf,
               const gchar *part_id,
               CamelMimePart *mime_part,
               const EMFormatHandler *handle)
{
    EMFormatCache *emfc;
    const gchar *disposition;

    if (handle == NULL)
        return FALSE;

    emfc = g_hash_table_lookup (emf->inline_table, part_id);
    if (emfc && emfc->state != INLINE_UNSET)
        return emfc->state & 1;

    /* Some types need to override the disposition.
     * e.g. application/x-pkcs7-mime */
    if (handle->flags & EM_FORMAT_HANDLER_INLINE_DISPOSITION)
        return TRUE;

    disposition = camel_mime_part_get_disposition (mime_part);
    if (disposition != NULL)
        return g_ascii_strcasecmp (disposition, "inline") == 0;

    /* Otherwise, use the default for this handler type. */
    return (handle->flags & EM_FORMAT_HANDLER_INLINE) != 0;
}

static void
emf_base_init (EMFormatClass *class)
{
    class->type_handlers = g_hash_table_new (g_str_hash, g_str_equal);
    emf_builtin_init (class);
}

static void
emf_class_init (EMFormatClass *class)
{
    GObjectClass *object_class;

    parent_class = g_type_class_peek_parent (class);
    g_type_class_add_private (class, sizeof (EMFormatPrivate));

    object_class = G_OBJECT_CLASS (class);
    object_class->finalize = emf_finalize;

    class->find_handler = emf_find_handler;
    class->format_clone = emf_format_clone;
    class->format_secure = emf_format_secure;
    class->busy = emf_busy;
    class->is_inline = emf_is_inline;

    signals[EMF_COMPLETE] = g_signal_new (
        "complete",
        G_OBJECT_CLASS_TYPE (class),
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (EMFormatClass, complete),
        NULL, NULL,
        g_cclosure_marshal_VOID__VOID,
        G_TYPE_NONE, 0);
}

static void
emf_init (EMFormat *emf)
{
    EShell *shell;
    EShellSettings *shell_settings;

    emf->priv = EM_FORMAT_GET_PRIVATE (emf);

    emf->inline_table = g_hash_table_new_full (
        g_str_hash, g_str_equal,
        (GDestroyNotify) NULL,
        (GDestroyNotify) emf_free_cache);
    emf->composer = FALSE;
    emf->print = FALSE;
    g_queue_init (&emf->header_list);
    em_format_default_headers (emf);
    emf->part_id = g_string_new("");
    emf->validity_found = 0;

    shell = e_shell_get_default ();
    shell_settings = e_shell_get_shell_settings (shell);

    emf->session = e_shell_settings_get_pointer (shell_settings, "mail-session");
    g_return_if_fail (emf->session != NULL);

    g_object_ref (emf->session);
}

GType
em_format_get_type (void)
{
    static GType type = 0;

    if (G_UNLIKELY (type == 0)) {
        static const GTypeInfo type_info = {
            sizeof (EMFormatClass),
            (GBaseInitFunc) emf_base_init,
            (GBaseFinalizeFunc) NULL,
            (GClassInitFunc) emf_class_init,
            (GClassFinalizeFunc) NULL,
            NULL,  /* class_data */
            sizeof (EMFormat),
            0,     /* n_preallocs */
            (GInstanceInitFunc) emf_init,
            NULL   /* value_table */
        };

        type = g_type_register_static (
            G_TYPE_OBJECT, "EMFormat", &type_info, 0);
    }

    return type;
}

/**
 * em_format_class_add_handler:
 * @emfc: EMFormatClass
 * @info: Callback information.
 *
 * Add a mime type handler to this class.  This is only used by
 * implementing classes.  The @info.old pointer will automatically be
 * setup to point to the old hanlder if one was already set.  This can
 * be used for overrides a fallback.
 *
 * When a mime type described by @info is encountered, the callback will
 * be invoked.  Note that @info may be extended by sub-classes if
 * they require additional context information.
 *
 * Use a mime type of "foo/ *" to insert a fallback handler for type "foo".
 **/
void
em_format_class_add_handler (EMFormatClass *emfc,
                             EMFormatHandler *info)
{
    info->old = g_hash_table_lookup (emfc->type_handlers, info->mime_type);
    g_hash_table_insert (emfc->type_handlers, (gpointer) info->mime_type, info);
}

struct _class_handlers {
    EMFormatClass *old;
    EMFormatClass *new;
};

static void
merge_missing (gpointer key, gpointer value, gpointer userdata)
{
    struct _class_handlers *classes = (struct _class_handlers *) userdata;
    EMFormatHandler *info;

    info = g_hash_table_lookup (classes->new->type_handlers, key);
    if (!info) {
        /* Might be from a plugin */
        g_hash_table_insert (classes->new->type_handlers, key, value);
    }

}

void
em_format_merge_handler (EMFormat *new, EMFormat *old)
{
    EMFormatClass *oldc = (EMFormatClass *)G_OBJECT_GET_CLASS (old);
    EMFormatClass *newc = (EMFormatClass *)G_OBJECT_GET_CLASS (new);
    struct _class_handlers fclasses;

    fclasses.old = oldc;
    fclasses.new = newc;

    g_hash_table_foreach (oldc->type_handlers, merge_missing, &fclasses);

}

/**
 * em_format_class_remove_handler:
 * @emfc:
 * @info:
 *
 * Remove a handler.  @info must be a value which was previously
 * added.
 **/
void
em_format_class_remove_handler (EMFormatClass *emfc,
                                EMFormatHandler *info)
{
    EMFormatHandler *current;

    /* TODO: thread issues? */

    current = g_hash_table_lookup (emfc->type_handlers, info->mime_type);
    if (current == info) {
        current = info->old;
        if (current)
            g_hash_table_insert (emfc->type_handlers, (gpointer) current->mime_type, current);
        else
            g_hash_table_remove (emfc->type_handlers, info->mime_type);
    } else {
        while (current && current->old != info)
            current = current->old;
        g_return_if_fail (current != NULL);
        current->old = info->old;
    }
}

/**
 * em_format_find_handler:
 * @emf:
 * @mime_type:
 *
 * Find a format handler by @mime_type.
 *
 * Return value: NULL if no handler is available.
 **/
const EMFormatHandler *
em_format_find_handler (EMFormat *emf,
                        const gchar *mime_type)
{
    EMFormatClass *class;

    g_return_val_if_fail (EM_IS_FORMAT (emf), NULL);
    g_return_val_if_fail (mime_type != NULL, NULL);

    class = EM_FORMAT_GET_CLASS (emf);
    g_return_val_if_fail (class->find_handler != NULL, NULL);

    return class->find_handler (emf, mime_type);
}

/**
 * em_format_fallback_handler:
 * @emf:
 * @mime_type:
 *
 * Try to find a format handler based on the major type of the @mime_type.
 *
 * The subtype is replaced with "*" and a lookup performed.
 *
 * Return value:
 **/
const EMFormatHandler *
em_format_fallback_handler (EMFormat *emf,
                            const gchar *mime_type)
{
    gchar *mime, *s;

    s = strchr (mime_type, '/');
    if (s == NULL)
        mime = (gchar *)mime_type;
    else {
        gsize len = (s-mime_type)+1;

        mime = g_alloca (len+2);
        strncpy (mime, mime_type, len);
        strcpy(mime+len, "*");
    }

    return em_format_find_handler (emf, mime);
}

/**
 * em_format_add_puri:
 * @emf:
 * @size:
 * @cid: Override the autogenerated content id.
 * @part:
 * @func:
 *
 * Add a pending-uri handler.  When formatting parts that reference
 * other parts, a pending-uri (PURI) can be used to track the reference.
 *
 * @size is used to allocate the structure, so that it can be directly
 * subclassed by implementors.
 *
 * @cid can be used to override the key used to retreive the PURI, if NULL,
 * then the content-location and the content-id of the @part are stored
 * as lookup keys for the part.
 *
 * FIXME: This may need a free callback.
 *
 * Return value: A new PURI, with a referenced copy of @part, and the cid
 * always set.  The uri will be set if one is available.  Clashes
 * are resolved by forgetting the old PURI in the global index.
 **/
EMFormatPURI *
em_format_add_puri (EMFormat *emf,
                    gsize size,
                    const gchar *cid,
                    CamelMimePart *part,
                    EMFormatPURIFunc func)
{
    EMFormatPURI *puri;
    const gchar *tmp;

    d(printf("adding puri for part: %s\n", emf->part_id->str));

    if (size < sizeof (*puri)) {
        g_warning (
            "size (%" G_GSIZE_FORMAT
            ") less than size of puri\n", size);
        size = sizeof (*puri);
    }

    puri = g_malloc0 (size);

    puri->format = emf;
    puri->func = func;
    puri->use_count = 0;
    puri->cid = g_strdup (cid);
    puri->part_id = g_strdup (emf->part_id->str);

    if (part) {
        g_object_ref (part);
        puri->part = part;
    }

    if (part != NULL && cid == NULL) {
        tmp = camel_mime_part_get_content_id (part);
        if (tmp)
            puri->cid = g_strdup_printf("cid:%s", tmp);
        else
            puri->cid = g_strdup_printf("em-no-cid:%s", emf->part_id->str);

        d(printf("built cid '%s'\n", puri->cid));

        /* Not quite same as old behaviour, it also put in the
         * relative uri and a fallback for no parent uri. */
        tmp = camel_mime_part_get_content_location (part);
        puri->uri = NULL;
        if (tmp == NULL) {
            /* No location, don't set a uri at all,
             * html parts do this themselves. */
        } else {
            if (strchr (tmp, ':') == NULL && emf->base != NULL) {
                CamelURL *uri;

                uri = camel_url_new_with_base (emf->base, tmp);
                puri->uri = camel_url_to_string (uri, 0);
                camel_url_free (uri);
            } else {
                puri->uri = g_strdup (tmp);
            }
        }
    }

    g_return_val_if_fail (puri->cid != NULL, NULL);
    g_return_val_if_fail (emf->pending_uri_level != NULL, NULL);
    g_return_val_if_fail (emf->pending_uri_table != NULL, NULL);

    g_queue_push_tail (emf->pending_uri_level->data, puri);

    if (puri->uri)
        g_hash_table_insert (emf->pending_uri_table, puri->uri, puri);
    g_hash_table_insert (emf->pending_uri_table, puri->cid, puri);

    return puri;
}

/**
 * em_format_push_level:
 * @emf:
 *
 * This is used to build a heirarchy of visible PURI objects based on
 * the structure of the message.  Used by multipart/alternative formatter.
 *
 * FIXME: This could probably also take a uri so it can automaticall update
 * the base location.
 **/
void
em_format_push_level (EMFormat *emf)
{
    GNode *node;

    g_return_if_fail (EM_IS_FORMAT (emf));

    node = g_node_new (g_queue_new ());

    if (emf->pending_uri_tree == NULL)
        emf->pending_uri_tree = node;
    else
        g_node_append (emf->pending_uri_tree, node);

    emf->pending_uri_level = node;
}

/**
 * em_format_pull_level:
 * @emf:
 *
 * Drop a level of visibility back to the parent.  Note that
 * no PURI values are actually freed.
 **/
void
em_format_pull_level (EMFormat *emf)
{
    g_return_if_fail (EM_IS_FORMAT (emf));
    g_return_if_fail (emf->pending_uri_level != NULL);

    emf->pending_uri_level = emf->pending_uri_level->parent;
}

/**
 * em_format_find_visible_puri:
 * @emf:
 * @uri:
 *
 * Search for a PURI based on the visibility defined by :push_level()
 * and :pull_level().
 *
 * Return value:
 **/
EMFormatPURI *
em_format_find_visible_puri (EMFormat *emf,
                             const gchar *uri)
{
    GNode *node;

    g_return_val_if_fail (EM_IS_FORMAT (emf), NULL);
    g_return_val_if_fail (uri != NULL, NULL);

    node = emf->pending_uri_level;

    while (node != NULL) {
        GQueue *queue = node->data;
        GList *link;

        link = g_queue_peek_head_link (queue);

        while (link != NULL) {
            EMFormatPURI *pw = link->data;

            if (g_strcmp0 (pw->uri, uri) == 0)
                return pw;

            if (g_strcmp0 (pw->cid, uri) == 0)
                return pw;

            link = g_list_next (link);
        }

        node = node->parent;
    }

    return NULL;
}

/**
 * em_format_find_puri:
 * @emf:
 * @uri:
 *
 * Search for a PURI based on a uri.  Both the content-id
 * and content-location are checked.
 *
 * Return value:
 **/
EMFormatPURI *
em_format_find_puri (EMFormat *emf,
                     const gchar *uri)
{
    g_return_val_if_fail (EM_IS_FORMAT (emf), NULL);
    g_return_val_if_fail (uri != NULL, NULL);

    g_return_val_if_fail (emf->pending_uri_table != NULL, NULL);

    return g_hash_table_lookup (emf->pending_uri_table, uri);
}

/**
 * em_format_clear_puri_tree:
 * @emf:
 *
 * For use by implementors to clear out the message structure
 * data.
 **/
void
em_format_clear_puri_tree (EMFormat *emf)
{
    if (emf->pending_uri_table == NULL)
        emf->pending_uri_table =
            g_hash_table_new (g_str_hash, g_str_equal);

    else {
        g_hash_table_remove_all (emf->pending_uri_table);

        g_node_traverse (
            emf->pending_uri_tree,
            G_IN_ORDER, G_TRAVERSE_ALL, -1,
            (GNodeTraverseFunc) emf_clear_puri_node, NULL);
        g_node_destroy (emf->pending_uri_tree);

        emf->pending_uri_tree = NULL;
        emf->pending_uri_level = NULL;
    }

    em_format_push_level (emf);
}

/* use mime_type == NULL  to force showing as application/octet-stream */
void
em_format_part_as (EMFormat *emf,
                   CamelStream *stream,
                   CamelMimePart *part,
                   const gchar *mime_type,
                   GCancellable *cancellable)
{
    const EMFormatHandler *handle = NULL;
    const gchar *snoop_save = emf->snoop_mime_type, *tmp;
    CamelURL *base_save = emf->base, *base = NULL;
    gchar *basestr = NULL;

    d(printf("format_part_as()\n"));

    emf->snoop_mime_type = NULL;

    /* RFC 2110, we keep track of content-base, and absolute content-location headers
       This is actually only required for html, but, *shrug* */
    tmp = camel_medium_get_header((CamelMedium *)part, "Content-Base");
    if (tmp == NULL) {
        tmp = camel_mime_part_get_content_location (part);
        if (tmp && strchr (tmp, ':') == NULL)
            tmp = NULL;
    } else {
        tmp = basestr = camel_header_location_decode (tmp);
    }
    d(printf("content-base is '%s'\n", tmp?tmp:"<unset>"));
    if (tmp
        && (base = camel_url_new (tmp, NULL))) {
        emf->base = base;
        d(printf("Setting content base '%s'\n", tmp));
    }
    g_free (basestr);

    if (mime_type != NULL) {
        gboolean is_fallback = FALSE;
        if (g_ascii_strcasecmp(mime_type, "application/octet-stream") == 0) {
            emf->snoop_mime_type = mime_type = em_format_snoop_type (part);
            if (mime_type == NULL)
                mime_type = "application/octet-stream";
        }

        handle = em_format_find_handler (emf, mime_type);
        if (handle == NULL) {
            handle = em_format_fallback_handler (emf, mime_type);
            is_fallback = TRUE;
        }

        if (handle != NULL
            && !em_format_is_attachment (emf, part)) {
            d(printf("running handler for type '%s'\n", mime_type));
            handle->handler (
                emf, stream, part, handle,
                cancellable, is_fallback);
            goto finish;
        }
        d(printf("this type is an attachment? '%s'\n", mime_type));
    } else {
        mime_type = "application/octet-stream";
    }

    EM_FORMAT_GET_CLASS (emf)->format_attachment (
        emf, stream, part, mime_type, handle, cancellable);

finish:
    emf->base = base_save;
    emf->snoop_mime_type = snoop_save;

    if (base)
        camel_url_free (base);
}

void
em_format_part (EMFormat *emf,
                CamelStream *stream,
                CamelMimePart *mime_part,
                GCancellable *cancellable)
{
    gchar *mime_type;
    CamelDataWrapper *dw;

    dw = camel_medium_get_content (CAMEL_MEDIUM (mime_part));
    mime_type = camel_data_wrapper_get_mime_type (dw);
    if (mime_type != NULL) {
        camel_strdown (mime_type);
        em_format_part_as (
            emf, stream, mime_part, mime_type, cancellable);
        g_free (mime_type);
    } else
        em_format_part_as (
            emf, stream, mime_part, "text/plain", cancellable);
}

/**
 * em_format_format_clone:
 * @emf: an #EMFormat
 * @folder: a #CamelFolder or %NULL
 * @uid: Message UID or %NULL
 * @msg: a #CamelMimeMessage or %NULL
 * @emfsource: Used as a basis for user-altered layout, e.g. inline viewed
 * attachments.
 * @cancellable: a #GCancellable, or %NULL
 *
 * Format a message @msg.  If @emfsource is non NULL, then the status of
 * inlined expansion and so forth is copied direction from @emfsource.
 *
 * By passing the same value for @emf and @emfsource, you can perform
 * a display refresh, or it can be used to generate an identical layout,
 * e.g. to print what the user has shown inline.
 **/
void
em_format_format_clone (EMFormat *emf,
                        CamelFolder *folder,
                        const gchar *uid,
                        CamelMimeMessage *message,
                        EMFormat *source,
                        GCancellable *cancellable)
{
    EMFormatClass *class;

    g_return_if_fail (EM_IS_FORMAT (emf));
    g_return_if_fail (folder == NULL || CAMEL_IS_FOLDER (folder));
    g_return_if_fail (message == NULL || CAMEL_IS_MIME_MESSAGE (message));
    g_return_if_fail (source == NULL || EM_IS_FORMAT (source));

    class = EM_FORMAT_GET_CLASS (emf);
    g_return_if_fail (class->format_clone != NULL);

    class->format_clone (emf, folder, uid, message, source, cancellable);
}

void
em_format_format (EMFormat *emf,
                  CamelFolder *folder,
                  const gchar *uid,
                  CamelMimeMessage *message,
                  GCancellable *cancellable)
{
    /* em_format_format_clone() will check the arguments. */
    em_format_format_clone (emf, folder, uid, message, NULL, cancellable);
}

static gboolean
format_redraw_idle_cb (EMFormat *emf)
{
    emf->priv->redraw_idle_id = 0;

    /* FIXME Not passing a GCancellable here. */
    em_format_format_clone (
        emf, emf->folder, emf->uid, emf->message, emf, NULL);

    return FALSE;
}

void
em_format_queue_redraw (EMFormat *emf)
{
    g_return_if_fail (EM_IS_FORMAT (emf));

    if (emf->priv->redraw_idle_id == 0)
        emf->priv->redraw_idle_id = g_idle_add (
            (GSourceFunc) format_redraw_idle_cb, emf);
}

/**
 * em_format_set_mode:
 * @emf:
 * @type:
 *
 * Set display mode, EM_FORMAT_MODE_SOURCE, EM_FORMAT_MODE_ALLHEADERS,
 * or EM_FORMAT_MODE_NORMAL.
 **/
void
em_format_set_mode (EMFormat *emf,
                    EMFormatMode mode)
{
    g_return_if_fail (EM_IS_FORMAT (emf));

    if (emf->mode == mode)
        return;

    emf->mode = mode;

    /* force redraw if type changed afterwards */
    if (emf->message != NULL)
        em_format_queue_redraw (emf);
}

/**
 * em_format_set_charset:
 * @emf:
 * @charset:
 *
 * set override charset on formatter.  message will be redisplayed if
 * required.
 **/
void
em_format_set_charset (EMFormat *emf,
                       const gchar *charset)
{
    if ((emf->charset && charset && g_ascii_strcasecmp (emf->charset, charset) == 0)
        || (emf->charset == NULL && charset == NULL)
        || (emf->charset == charset))
        return;

    g_free (emf->charset);
    emf->charset = g_strdup (charset);

    if (emf->message)
        em_format_queue_redraw (emf);
}

/**
 * em_format_set_default_charset:
 * @emf:
 * @charset:
 *
 * Set the fallback, default system charset to use when no other charsets
 * are present.  Message will be redisplayed if required (and sometimes
 * redisplayed when it isn't).
 **/
void
em_format_set_default_charset (EMFormat *emf,
                               const gchar *charset)
{
    if ((emf->default_charset && charset &&
        g_ascii_strcasecmp (emf->default_charset, charset) == 0)
        || (emf->default_charset == NULL && charset == NULL)
        || (emf->default_charset == charset))
        return;

    g_free (emf->default_charset);
    emf->default_charset = g_strdup (charset);

    if (emf->message && emf->charset == NULL)
        em_format_queue_redraw (emf);
}

/**
 * em_format_clear_headers:
 * @emf:
 *
 * Clear the list of headers to be displayed.  This will force all headers to
 * be shown.
 **/
void
em_format_clear_headers (EMFormat *emf)
{
    EMFormatHeader *eh;

    while ((eh = g_queue_pop_head (&emf->header_list)) != NULL)
        g_free (eh);
}

/* note: also copied in em-mailer-prefs.c */
static const struct {
    const gchar *name;
    guint32 flags;
} default_headers[] = {
    { N_("From"), EM_FORMAT_HEADER_BOLD },
    { N_("Reply-To"), EM_FORMAT_HEADER_BOLD },
    { N_("To"), EM_FORMAT_HEADER_BOLD },
    { N_("Cc"), EM_FORMAT_HEADER_BOLD },
    { N_("Bcc"), EM_FORMAT_HEADER_BOLD },
    { N_("Subject"), EM_FORMAT_HEADER_BOLD },
    { N_("Date"), EM_FORMAT_HEADER_BOLD },
    { N_("Newsgroups"), EM_FORMAT_HEADER_BOLD },
    { N_("Face"), 0 },
};

/**
 * em_format_default_headers:
 * @emf:
 *
 * Set the headers to show to the default list.
 *
 * From, Reply-To, To, Cc, Bcc, Subject and Date.
 **/
void
em_format_default_headers (EMFormat *emf)
{
    gint ii;

    em_format_clear_headers (emf);

    for (ii = 0; ii < G_N_ELEMENTS (default_headers); ii++)
        em_format_add_header (
            emf, default_headers[ii].name,
            default_headers[ii].flags);
}

/**
 * em_format_add_header:
 * @emf:
 * @name: The name of the header, as it will appear during output.
 * @flags: EM_FORMAT_HEAD_* defines to control display attributes.
 *
 * Add a specific header to show.  If any headers are set, they will
 * be displayed in the order set by this function.  Certain known
 * headers included in this list will be shown using special
 * formatting routines.
 **/
void
em_format_add_header (EMFormat *emf,
                      const gchar *name,
                      guint32 flags)
{
    EMFormatHeader *h;

    h = g_malloc (sizeof (*h) + strlen (name));
    h->flags = flags;
    strcpy (h->name, name);
    g_queue_push_tail (&emf->header_list, h);
}

/**
 * em_format_is_attachment:
 * @emf:
 * @part: Part to check.
 *
 * Returns true if the part is an attachment.
 *
 * A part is not considered an attachment if it is a
 * multipart, or a text part with no filename.  It is used
 * to determine if an attachment header should be displayed for
 * the part.
 *
 * Content-Disposition is not checked.
 *
 * Return value: TRUE/FALSE
 **/
gint
em_format_is_attachment (EMFormat *emf,
                         CamelMimePart *part)
{
    /*CamelContentType *ct = camel_mime_part_get_content_type(part);*/
    CamelDataWrapper *dw = camel_medium_get_content ((CamelMedium *)part);

    if (!dw)
        return 0;

    /*printf("checking is attachment %s/%s\n", ct->type, ct->subtype);*/
    return !(camel_content_type_is (dw->mime_type, "multipart", "*")
         || camel_content_type_is(dw->mime_type, "application", "x-pkcs7-mime")
         || camel_content_type_is(dw->mime_type, "application", "pkcs7-mime")
         || camel_content_type_is(dw->mime_type, "application", "x-inlinepgp-signed")
         || camel_content_type_is(dw->mime_type, "application", "x-inlinepgp-encrypted")
         || camel_content_type_is(dw->mime_type, "x-evolution", "evolution-rss-feed")
         || camel_content_type_is(dw->mime_type, "text", "calendar")
         || camel_content_type_is(dw->mime_type, "text", "x-calendar")
         || (camel_content_type_is (dw->mime_type, "text", "*")
             && camel_mime_part_get_filename (part) == NULL));
}

/**
 * em_format_is_inline:
 * @emf:
 * @part:
 * @part_id: format->part_id part id of this part.
 * @handle: handler for this part
 *
 * Returns true if the part should be displayed inline.  Any part with
 * a Content-Disposition of inline, or if the @handle has a default
 * inline set, will be shown inline.
 *
 * :set_inline() called on the same part will override any calculated
 * value.
 *
 * Return value:
 **/
gboolean
em_format_is_inline (EMFormat *emf,
                     const gchar *part_id,
                     CamelMimePart *mime_part,
                     const EMFormatHandler *handle)
{
    EMFormatClass *class;

    g_return_val_if_fail (EM_IS_FORMAT (emf), FALSE);
    g_return_val_if_fail (part_id != NULL, FALSE);
    g_return_val_if_fail (CAMEL_IS_MIME_PART (mime_part), FALSE);

    class = EM_FORMAT_GET_CLASS (emf);
    g_return_val_if_fail (class->is_inline != NULL, FALSE);

    return class->is_inline (emf, part_id, mime_part, handle);
}

/**
 * em_format_set_inline:
 * @emf:
 * @part_id: id of part
 * @state:
 *
 * Force the attachment @part to be expanded or hidden explictly to match
 * @state.  This is used only to record the change for a redraw or
 * cloned layout render and does not force a redraw.
 **/
void
em_format_set_inline (EMFormat *emf,
                      const gchar *part_id,
                      gint state)
{
    EMFormatCache *emfc;

    g_return_if_fail (EM_IS_FORMAT (emf));
    g_return_if_fail (part_id != NULL);

    emfc = g_hash_table_lookup (emf->inline_table, part_id);
    if (emfc == NULL) {
        emfc = emf_insert_cache (emf, part_id);
    } else if (emfc->state != INLINE_UNSET && (emfc->state & 1) == state)
        return;

    emfc->state = state?INLINE_ON:INLINE_OFF;

    if (emf->message)
        em_format_queue_redraw (emf);
}

void
em_format_format_attachment (EMFormat *emf,
                             CamelStream *stream,
                             CamelMimePart *mime_part,
                             const gchar *mime_type,
                             const EMFormatHandler *info,
                             GCancellable *cancellable)
{
    EMFormatClass *class;

    g_return_if_fail (EM_IS_FORMAT (emf));
    g_return_if_fail (CAMEL_IS_STREAM (stream));
    g_return_if_fail (CAMEL_IS_MIME_PART (mime_part));
    g_return_if_fail (mime_type != NULL);
    g_return_if_fail (info != NULL);

    class = EM_FORMAT_GET_CLASS (emf);
    g_return_if_fail (class->format_attachment != NULL);

    class->format_attachment (
        emf, stream, mime_part, mime_type, info, cancellable);
}

void
em_format_format_error (EMFormat *emf,
                        CamelStream *stream,
                        const gchar *format,
                        ...)
{
    EMFormatClass *class;
    gchar *errmsg;
    va_list ap;

    g_return_if_fail (EM_IS_FORMAT (emf));
    g_return_if_fail (CAMEL_IS_STREAM (stream));
    g_return_if_fail (format != NULL);

    class = EM_FORMAT_GET_CLASS (emf);
    g_return_if_fail (class->format_error != NULL);

    va_start (ap, format);
    errmsg = g_strdup_vprintf (format, ap);
    class->format_error (emf, stream, errmsg);
    g_free (errmsg);
    va_end (ap);
}

void
em_format_format_secure (EMFormat *emf,
                         CamelStream *stream,
                         CamelMimePart *mime_part,
                         CamelCipherValidity *valid,
                         GCancellable *cancellable)
{
    EMFormatClass *class;

    g_return_if_fail (EM_IS_FORMAT (emf));
    g_return_if_fail (CAMEL_IS_STREAM (stream));
    g_return_if_fail (CAMEL_IS_MIME_PART (mime_part));
    g_return_if_fail (valid != NULL);

    class = EM_FORMAT_GET_CLASS (emf);
    g_return_if_fail (class->format_secure != NULL);

    class->format_secure (emf, stream, mime_part, valid, cancellable);

    if (emf->valid_parent == NULL && emf->valid != NULL) {
        camel_cipher_validity_free (emf->valid);
        emf->valid = NULL;
    }
}

void
em_format_format_source (EMFormat *emf,
                         CamelStream *stream,
                         CamelMimePart *mime_part,
                         GCancellable *cancellable)
{
    EMFormatClass *class;

    g_return_if_fail (EM_IS_FORMAT (emf));
    g_return_if_fail (CAMEL_IS_STREAM (stream));
    g_return_if_fail (CAMEL_IS_MIME_PART (mime_part));

    class = EM_FORMAT_GET_CLASS (emf);
    g_return_if_fail (class->format_source != NULL);

    class->format_source (emf, stream, mime_part, cancellable);
}

gboolean
em_format_busy (EMFormat *emf)
{
    EMFormatClass *class;

    g_return_val_if_fail (EM_IS_FORMAT (emf), FALSE);

    class = EM_FORMAT_GET_CLASS (emf);
    g_return_val_if_fail (class->busy != NULL, FALSE);

    return class->busy (emf);
}

/* should this be virtual? */
void
em_format_format_content (EMFormat *emf,
                          CamelStream *stream,
                          CamelMimePart *part,
                          GCancellable *cancellable)
{
    CamelDataWrapper *dw = camel_medium_get_content ((CamelMedium *)part);

    if (camel_content_type_is (dw->mime_type, "text", "*"))
        em_format_format_text (
            emf, stream, (CamelDataWrapper *)part, cancellable);
    else
        camel_data_wrapper_decode_to_stream_sync (
            dw, stream, cancellable, NULL);
}

/**
 * em_format_format_content:
 * @emf:
 * @stream: Where to write the converted text
 * @part: Part whose container is to be formatted
 * @cancellable: optional #GCancellable object, or %NULL
 *
 * Decode/output a part's content to @stream.
 **/
void
em_format_format_text (EMFormat *emf,
                       CamelStream *stream,
                       CamelDataWrapper *dw,
                       GCancellable *cancellable)
{
    CamelStream *filter_stream;
    CamelMimeFilter *filter;
    const gchar *charset = NULL;
    CamelMimeFilterWindows *windows = NULL;
    CamelStream *mem_stream = NULL;
    const gchar *key;
    gsize size;
    gsize max;
    GConfClient *gconf;

    if (emf->charset) {
        charset = emf->charset;
    } else if (dw->mime_type
           && (charset = camel_content_type_param (dw->mime_type, "charset"))
           && g_ascii_strncasecmp(charset, "iso-8859-", 9) == 0) {
        CamelStream *null;

        /* Since a few Windows mailers like to claim they sent
         * out iso-8859-# encoded text when they really sent
         * out windows-cp125#, do some simple sanity checking
         * before we move on... */

        null = camel_stream_null_new ();
        filter_stream = camel_stream_filter_new (null);
        g_object_unref (null);

        windows = (CamelMimeFilterWindows *)camel_mime_filter_windows_new (charset);
        camel_stream_filter_add (
            CAMEL_STREAM_FILTER (filter_stream),
            CAMEL_MIME_FILTER (windows));

        camel_data_wrapper_decode_to_stream_sync (
            dw, (CamelStream *)filter_stream, cancellable, NULL);
        camel_stream_flush ((CamelStream *)filter_stream, cancellable, NULL);
        g_object_unref (filter_stream);

        charset = camel_mime_filter_windows_real_charset (windows);
    } else if (charset == NULL) {
        charset = emf->default_charset;
    }

    mem_stream = (CamelStream *)camel_stream_mem_new ();
    filter_stream = camel_stream_filter_new (mem_stream);

    if ((filter = camel_mime_filter_charset_new (charset, "UTF-8"))) {
        camel_stream_filter_add (
            CAMEL_STREAM_FILTER (filter_stream),
            CAMEL_MIME_FILTER (filter));
        g_object_unref (filter);
    }

    max = -1;

    gconf = gconf_client_get_default ();
    key = "/apps/evolution/mail/display/force_message_limit";
    if (gconf_client_get_bool (gconf, key, NULL)) {
        key = "/apps/evolution/mail/display/message_text_part_limit";
        max = gconf_client_get_int (gconf, key, NULL);
        if (max == 0)
            max = -1;
    }
    g_object_unref (gconf);

    size = camel_data_wrapper_decode_to_stream_sync (
        emf->mode == EM_FORMAT_MODE_SOURCE ?
            (CamelDataWrapper *) dw :
            camel_medium_get_content ((CamelMedium *)dw),
        (CamelStream *)filter_stream, cancellable, NULL);
    camel_stream_flush ((CamelStream *)filter_stream, cancellable, NULL);
    g_object_unref (filter_stream);
    camel_stream_reset (mem_stream, NULL);

    if (max == -1 || size == -1 || size < (max * 1024) || emf->composer) {
        camel_stream_write_to_stream (mem_stream, (CamelStream *)stream, cancellable, NULL);
        camel_stream_flush ((CamelStream *)stream, cancellable, NULL);
    } else {
        EM_FORMAT_GET_CLASS (emf)->format_optional (
            emf, stream, (CamelMimePart *)dw,
            mem_stream, cancellable);
    }

    if (windows)
        g_object_unref (windows);

    g_object_unref (mem_stream);
}

/**
 * em_format_describe_part:
 * @part:
 * @mimetype:
 *
 * Generate a simple textual description of a part, @mime_type represents the
 * the content.
 *
 * Return value:
 **/
gchar *
em_format_describe_part (CamelMimePart *part,
                         const gchar *mime_type)
{
    GString *stext;
    const gchar *filename, *description;
    gchar *content_type, *desc;

    stext = g_string_new("");
    content_type = g_content_type_from_mime_type (mime_type);
    desc = g_content_type_get_description (content_type ? content_type : mime_type);
    g_free (content_type);
    g_string_append_printf (stext, _("%s attachment"), desc ? desc : mime_type);
    g_free (desc);

    filename = camel_mime_part_get_filename (part);
    description = camel_mime_part_get_description (part);

    if (filename != NULL && *filename != '\0') {
        gchar *basename = g_path_get_basename (filename);
        g_string_append_printf (stext, " (%s)", basename);
        g_free (basename);
    }

    if (description != NULL && *description != '\0' &&
        g_strcmp0 (filename, description) != 0)
        g_string_append_printf (stext, ", \"%s\"", description);

    return g_string_free (stext, FALSE);
}

static void
add_validity_found (EMFormat *emf,
                    CamelCipherValidity *valid)
{
    g_return_if_fail (emf != NULL);

    if (!valid)
        return;

    if (valid->sign.status != CAMEL_CIPHER_VALIDITY_SIGN_NONE)
        emf->validity_found |= EM_FORMAT_VALIDITY_FOUND_SIGNED;

    if (valid->encrypt.status != CAMEL_CIPHER_VALIDITY_ENCRYPT_NONE)
        emf->validity_found |= EM_FORMAT_VALIDITY_FOUND_ENCRYPTED;
}

/* ********************************************************************** */

static void
preserve_charset_in_content_type (CamelMimePart *ipart, CamelMimePart *opart)
{
    CamelContentType *ict;

    g_return_if_fail (ipart != NULL);
    g_return_if_fail (opart != NULL);

    ict = camel_data_wrapper_get_mime_type_field (camel_medium_get_content (CAMEL_MEDIUM (ipart)));
    if (!ict || !camel_content_type_param (ict, "charset") || !*camel_content_type_param (ict, "charset"))
        return;

    camel_content_type_set_param (camel_data_wrapper_get_mime_type_field (camel_medium_get_content (CAMEL_MEDIUM (opart))),
        "charset", camel_content_type_param (ict, "charset"));
}

#ifdef ENABLE_SMIME
static void
emf_application_xpkcs7mime (EMFormat *emf,
                            CamelStream *stream,
                            CamelMimePart *part,
                            const EMFormatHandler *info,
                            GCancellable *cancellable,
                            gboolean is_fallback)
{
    CamelCipherContext *context;
    CamelMimePart *opart;
    CamelCipherValidity *valid;
    EMFormatCache *emfc;
    GError *local_error = NULL;

    /* should this perhaps run off a key of ".secured" ? */
    emfc = g_hash_table_lookup (emf->inline_table, emf->part_id->str);
    if (emfc && emfc->valid) {
        em_format_format_secure (
            emf, stream, emfc->secured,
            camel_cipher_validity_clone (emfc->valid),
            cancellable);
        return;
    }

    context = camel_smime_context_new (emf->session);

    emf->validity_found |=
        EM_FORMAT_VALIDITY_FOUND_ENCRYPTED |
        EM_FORMAT_VALIDITY_FOUND_SMIME;

    opart = camel_mime_part_new ();
    valid = camel_cipher_context_decrypt_sync (
        context, part, opart, cancellable, &local_error);
    preserve_charset_in_content_type (part, opart);
    if (valid == NULL) {
        em_format_format_error (
            emf, stream, "%s",
            local_error->message ? local_error->message :
            _("Could not parse S/MIME message: Unknown error"));
        g_clear_error (&local_error);

        em_format_part_as (emf, stream, part, NULL, cancellable);
    } else {
        if (emfc == NULL)
            emfc = emf_insert_cache (emf, emf->part_id->str);

        emfc->valid = camel_cipher_validity_clone (valid);
        g_object_ref ((emfc->secured = opart));

        add_validity_found (emf, valid);
        em_format_format_secure (
            emf, stream, opart, valid, cancellable);
    }

    g_object_unref (opart);
    g_object_unref (context);
}
#endif

/* RFC 1740 */
static void
emf_multipart_appledouble (EMFormat *emf,
                           CamelStream *stream,
                           CamelMimePart *part,
                           const EMFormatHandler *info,
                           GCancellable *cancellable,
                           gboolean is_fallback)
{
    CamelMultipart *mp = (CamelMultipart *)camel_medium_get_content ((CamelMedium *)part);
    CamelMimePart *mime_part;
    gint len;

    if (!CAMEL_IS_MULTIPART (mp)) {
        em_format_format_source (emf, stream, part, cancellable);
        return;
    }

    mime_part = camel_multipart_get_part (mp, 1);
    if (mime_part) {
        /* try the data fork for something useful, doubtful but who knows */
        len = emf->part_id->len;
        g_string_append_printf(emf->part_id, ".appledouble.1");
        em_format_part (emf, stream, mime_part, cancellable);
        g_string_truncate (emf->part_id, len);
    } else
        em_format_format_source (emf, stream, part, cancellable);

}

/* RFC ??? */
static void
emf_multipart_mixed (EMFormat *emf,
                     CamelStream *stream,
                     CamelMimePart *part,
                     const EMFormatHandler *info,
                     GCancellable *cancellable,
                     gboolean is_fallback)
{
    CamelMultipart *mp = (CamelMultipart *)camel_medium_get_content ((CamelMedium *)part);
    gint i, nparts, len;

    if (!CAMEL_IS_MULTIPART (mp)) {
        em_format_format_source (emf, stream, part, cancellable);
        return;
    }

    len = emf->part_id->len;
    nparts = camel_multipart_get_number (mp);
    for (i = 0; i < nparts; i++) {
        part = camel_multipart_get_part (mp, i);
        g_string_append_printf(emf->part_id, ".mixed.%d", i);
        em_format_part (emf, stream, part, cancellable);
        g_string_truncate (emf->part_id, len);
    }
}

/* RFC 1740 */
static void
emf_multipart_alternative (EMFormat *emf,
                           CamelStream *stream,
                           CamelMimePart *part,
                           const EMFormatHandler *info,
                           GCancellable *cancellable,
                           gboolean is_fallback)
{
    CamelMultipart *mp = (CamelMultipart *)camel_medium_get_content ((CamelMedium *)part);
    gint i, nparts, bestid = 0;
    CamelMimePart *best = NULL;

    if (!CAMEL_IS_MULTIPART (mp)) {
        em_format_format_source (emf, stream, part, cancellable);
        return;
    }

    /* as per rfc, find the last part we know how to display */
    nparts = camel_multipart_get_number (mp);
    for (i = 0; i < nparts; i++) {
        CamelDataWrapper *data_wrapper;
        CamelContentType *type;
        CamelStream *null_stream;
        gchar *mime_type;
        gsize content_size;

        /* is it correct to use the passed in *part here? */
        part = camel_multipart_get_part (mp, i);

        if (part == NULL)
            continue;

        /* This may block even though the stream does not.
         * XXX Pretty inefficient way to test if the MIME part
         *     is empty.  Surely there's a quicker way? */
        null_stream = camel_stream_null_new ();
        data_wrapper = camel_medium_get_content (CAMEL_MEDIUM (part));
        camel_data_wrapper_decode_to_stream_sync (
            data_wrapper, null_stream, cancellable, NULL);
        content_size = CAMEL_STREAM_NULL (null_stream)->written;
        g_object_unref (null_stream);

        if (content_size == 0)
            continue;

        type = camel_mime_part_get_content_type (part);
        mime_type = camel_content_type_simple (type);

        camel_strdown (mime_type);

        /*if (want_plain && !strcmp (mime_type, "text/plain"))
          return part;*/

        if (!em_format_is_attachment (emf, part) &&
            (em_format_find_handler (emf, mime_type)
            || (best == NULL && em_format_fallback_handler (emf, mime_type)))) {
            best = part;
            bestid = i;
        }

        g_free (mime_type);
    }

    if (best) {
        gint len = emf->part_id->len;

        g_string_append_printf(emf->part_id, ".alternative.%d", bestid);
        em_format_part (emf, stream, best, cancellable);
        g_string_truncate (emf->part_id, len);
    } else
        emf_multipart_mixed (
            emf, stream, part, info, cancellable, is_fallback);
}

static void
emf_multipart_encrypted (EMFormat *emf,
                         CamelStream *stream,
                         CamelMimePart *part,
                         const EMFormatHandler *info,
                         GCancellable *cancellable,
                         gboolean is_fallback)
{
    CamelCipherContext *context;
    const gchar *protocol;
    CamelMimePart *opart;
    CamelCipherValidity *valid;
    CamelMultipartEncrypted *mpe;
    EMFormatCache *emfc;
    GError *local_error = NULL;

    /* should this perhaps run off a key of ".secured" ? */
    emfc = g_hash_table_lookup (emf->inline_table, emf->part_id->str);
    if (emfc && emfc->valid) {
        em_format_format_secure (
            emf, stream, emfc->secured,
            camel_cipher_validity_clone (emfc->valid),
            cancellable);
        return;
    }

    mpe = (CamelMultipartEncrypted*)camel_medium_get_content ((CamelMedium *)part);
    if (!CAMEL_IS_MULTIPART_ENCRYPTED (mpe)) {
        em_format_format_error (
            emf, stream, _("Could not parse MIME message. "
            "Displaying as source."));
        em_format_format_source (emf, stream, part, cancellable);
        return;
    }

    /* Currently we only handle RFC2015-style PGP encryption. */
    protocol = camel_content_type_param(((CamelDataWrapper *)mpe)->mime_type, "protocol");
    if (!protocol || g_ascii_strcasecmp (protocol, "application/pgp-encrypted") != 0) {
        em_format_format_error (
            emf, stream, _("Unsupported encryption "
            "type for multipart/encrypted"));
        em_format_part_as (
            emf, stream, part,
            "multipart/mixed", cancellable);
        return;
    }

    emf->validity_found |=
        EM_FORMAT_VALIDITY_FOUND_ENCRYPTED |
        EM_FORMAT_VALIDITY_FOUND_PGP;

    context = camel_gpg_context_new (emf->session);
    opart = camel_mime_part_new ();
    valid = camel_cipher_context_decrypt_sync (
        context, part, opart, cancellable, &local_error);
    preserve_charset_in_content_type (part, opart);
    if (valid == NULL) {
        em_format_format_error (
            emf, stream, local_error->message ?
            _("Could not parse PGP/MIME message") :
            _("Could not parse PGP/MIME message: Unknown error"));
        if (local_error->message != NULL)
            em_format_format_error (
                emf, stream, "%s", local_error->message);
        g_clear_error (&local_error);

        em_format_part_as (
            emf, stream, part,
            "multipart/mixed", cancellable);
    } else {
        if (emfc == NULL)
            emfc = emf_insert_cache (emf, emf->part_id->str);

        emfc->valid = camel_cipher_validity_clone (valid);
        g_object_ref ((emfc->secured = opart));

        add_validity_found (emf, valid);
        em_format_format_secure (
            emf, stream, opart, valid, cancellable);
    }

    /* TODO: Make sure when we finalize this part, it is zero'd out */
    g_object_unref (opart);
    g_object_unref (context);
}

static void
emf_write_related (EMFormat *emf,
                   CamelStream *stream,
                   EMFormatPURI *puri,
                   GCancellable *cancellable)
{
    em_format_format_content (emf, stream, puri->part, cancellable);
    camel_stream_close (stream, cancellable, NULL);
}

/* RFC 2387 */
static void
emf_multipart_related (EMFormat *emf,
                       CamelStream *stream,
                       CamelMimePart *part,
                       const EMFormatHandler *info,
                       GCancellable *cancellable,
                       gboolean is_fallback)
{
    CamelMultipart *mp = (CamelMultipart *)camel_medium_get_content ((CamelMedium *)part);
    CamelMimePart *body_part, *display_part = NULL;
    CamelContentType *content_type;
    const gchar *start;
    gint i, nparts, partidlen, displayid = 0;
    gchar *oldpartid;
    GList *link;

    if (!CAMEL_IS_MULTIPART (mp)) {
        em_format_format_source (emf, stream, part, cancellable);
        return;
    }

    /* FIXME: put this stuff in a shared function */
    nparts = camel_multipart_get_number (mp);
    content_type = camel_mime_part_get_content_type (part);
    start = camel_content_type_param (content_type, "start");
    if (start && strlen (start)>2) {
        gint len;
        const gchar *cid;

        /* strip <>'s */
        len = strlen (start) - 2;
        start++;

        for (i=0; i<nparts; i++) {
            body_part = camel_multipart_get_part (mp, i);
            cid = camel_mime_part_get_content_id (body_part);

            if (cid && !strncmp (cid, start, len) && strlen (cid) == len) {
                display_part = body_part;
                displayid = i;
                break;
            }
        }
    } else {
        display_part = camel_multipart_get_part (mp, 0);
    }

    if (display_part == NULL) {
        emf_multipart_mixed (
            emf, stream, part, info, cancellable, is_fallback);
        return;
    }

    em_format_push_level (emf);

    oldpartid = g_strdup (emf->part_id->str);
    partidlen = emf->part_id->len;

    /* queue up the parts for possible inclusion */
    for (i = 0; i < nparts; i++) {
        body_part = camel_multipart_get_part (mp, i);
        if (body_part != display_part) {
            EMFormatPURI *puri;

            /* set the partid since add_puri uses it */
            g_string_append_printf(emf->part_id, ".related.%d", i);
            puri = em_format_add_puri (
                emf, sizeof (EMFormatPURI), NULL,
                body_part, emf_write_related);
            g_string_truncate (emf->part_id, partidlen);
            d(printf(" part '%s' '%s' added\n", puri->uri?puri->uri:"", puri->cid));
        }
    }

    g_string_append_printf(emf->part_id, ".related.%d", displayid);
    em_format_part (emf, stream, display_part, cancellable);
    g_string_truncate (emf->part_id, partidlen);
    camel_stream_flush (stream, NULL, NULL);

    link = g_queue_peek_head_link (emf->pending_uri_level->data);

    while (link && link->next != NULL) {
        EMFormatPURI *puri = link->data;

        if (puri->use_count == 0) {
            if (puri->func == emf_write_related) {
                g_string_printf(emf->part_id, "%s", puri->part_id);
                em_format_part (
                    emf, stream, puri->part, cancellable);
            }
        }

        link = g_list_next (link);
    }

    g_string_printf(emf->part_id, "%s", oldpartid);
    g_free (oldpartid);

    em_format_pull_level (emf);
}

static void
emf_multipart_signed (EMFormat *emf,
                      CamelStream *stream,
                      CamelMimePart *part,
                      const EMFormatHandler *info,
                      GCancellable *cancellable,
                      gboolean is_fallback)
{
    CamelMimePart *cpart;
    CamelMultipartSigned *mps;
    CamelCipherContext *cipher = NULL;
    EMFormatCache *emfc;

    /* should this perhaps run off a key of ".secured" ? */
    emfc = g_hash_table_lookup (emf->inline_table, emf->part_id->str);
    if (emfc && emfc->valid) {
        em_format_format_secure (
            emf, stream, emfc->secured,
            camel_cipher_validity_clone (emfc->valid),
            cancellable);
        return;
    }

    mps = (CamelMultipartSigned *)camel_medium_get_content ((CamelMedium *)part);
    if (!CAMEL_IS_MULTIPART_SIGNED (mps)
        || (cpart = camel_multipart_get_part ((CamelMultipart *)mps,
        CAMEL_MULTIPART_SIGNED_CONTENT)) == NULL) {
        em_format_format_error (
            emf, stream, _("Could not parse MIME message. "
            "Displaying as source."));
        em_format_format_source (emf, stream, part, cancellable);
        return;
    }

    /* FIXME: Should be done via a plugin interface */
    /* FIXME: duplicated in em-format-html-display.c */
    if (mps->protocol) {
#ifdef ENABLE_SMIME
        if (g_ascii_strcasecmp("application/x-pkcs7-signature", mps->protocol) == 0
            || g_ascii_strcasecmp("application/pkcs7-signature", mps->protocol) == 0) {
            cipher = camel_smime_context_new (emf->session);
            emf->validity_found |= EM_FORMAT_VALIDITY_FOUND_SMIME;
        } else
#endif
            if (g_ascii_strcasecmp("application/pgp-signature", mps->protocol) == 0) {
                cipher = camel_gpg_context_new (emf->session);
                emf->validity_found |= EM_FORMAT_VALIDITY_FOUND_PGP;
            }
    }

    emf->validity_found |= EM_FORMAT_VALIDITY_FOUND_SIGNED;

    if (cipher == NULL) {
        em_format_format_error(emf, stream, _("Unsupported signature format"));
        em_format_part_as (
            emf, stream, part,
            "multipart/mixed", cancellable);
    } else {
        CamelCipherValidity *valid;
        GError *local_error = NULL;

        valid = camel_cipher_context_verify_sync (
            cipher, part, cancellable, &local_error);
        if (valid == NULL) {
            em_format_format_error (
                emf, stream, local_error->message ?
                _("Error verifying signature") :
                _("Unknown error verifying signature"));
            if (local_error->message != NULL)
                em_format_format_error (
                    emf, stream, "%s",
                    local_error->message);
            g_clear_error (&local_error);

            em_format_part_as (
                emf, stream, part,
                "multipart/mixed", cancellable);
        } else {
            if (emfc == NULL)
                emfc = emf_insert_cache (emf, emf->part_id->str);

            emfc->valid = camel_cipher_validity_clone (valid);
            g_object_ref ((emfc->secured = cpart));

            add_validity_found (emf, valid);
            em_format_format_secure (
                emf, stream, cpart, valid, cancellable);
        }

        g_object_unref (cipher);
    }
}

/* RFC 4155 */
static void
emf_application_mbox (EMFormat *emf,
                      CamelStream *stream,
                      CamelMimePart *mime_part,
                      const EMFormatHandler *info,
                      GCancellable *cancellable,
                      gboolean is_fallback)
{
    const EMFormatHandler *handle;
    CamelMimeParser *parser;
    CamelStream *mem_stream;
    camel_mime_parser_state_t state;

    /* Extract messages from the application/mbox part and
     * render them as a flat list of messages. */

    /* XXX If the mbox has multiple messages, maybe render them
     *     as a multipart/digest so each message can be expanded
     *     or collapsed individually.
     *
     *     See attachment_handler_mail_x_uid_list() for example. */

    /* XXX This is based on em_utils_read_messages_from_stream().
     *     Perhaps refactor that function to return an array of
     *     messages instead of assuming we want to append them
     *     to a folder? */

    handle = em_format_find_handler (emf, "x-evolution/message/rfc822");
    g_return_if_fail (handle != NULL);

    parser = camel_mime_parser_new ();
    camel_mime_parser_scan_from (parser, TRUE);

    mem_stream = camel_stream_mem_new ();
    camel_data_wrapper_decode_to_stream_sync (
        camel_medium_get_content (CAMEL_MEDIUM (mime_part)),
        mem_stream, NULL, NULL);
    camel_seekable_stream_seek (
        CAMEL_SEEKABLE_STREAM (mem_stream), 0, CAMEL_STREAM_SET, NULL);
    camel_mime_parser_init_with_stream (parser, mem_stream, NULL);
    g_object_unref (mem_stream);

    /* Extract messages from the mbox. */
    state = camel_mime_parser_step (parser, NULL, NULL);
    while (state == CAMEL_MIME_PARSER_STATE_FROM) {
        CamelMimeMessage *message;

        message = camel_mime_message_new ();
        mime_part = CAMEL_MIME_PART (message);

        if (!camel_mime_part_construct_from_parser_sync (mime_part, parser, NULL, NULL)) {
            g_object_unref (message);
            break;
        }

        /* Render the message. */
        handle->handler (
            emf, stream, mime_part,
            handle, cancellable, FALSE);

        g_object_unref (message);

        /* Skip past CAMEL_MIME_PARSER_STATE_FROM_END. */
        camel_mime_parser_step (parser, NULL, NULL);

        state = camel_mime_parser_step (parser, NULL, NULL);
    }

    g_object_unref (parser);
}

static void
emf_message_rfc822 (EMFormat *emf,
                    CamelStream *stream,
                    CamelMimePart *part,
                    const EMFormatHandler *info,
                    GCancellable *cancellable,
                    gboolean is_fallback)
{
    CamelDataWrapper *dw = camel_medium_get_content ((CamelMedium *)part);
    const EMFormatHandler *handle;
    gint len;

    if (!CAMEL_IS_MIME_MESSAGE (dw)) {
        em_format_format_source (emf, stream, part, cancellable);
        return;
    }

    len = emf->part_id->len;
    g_string_append_printf(emf->part_id, ".rfc822");

    handle = em_format_find_handler(emf, "x-evolution/message/rfc822");
    if (handle)
        handle->handler (
            emf, stream, CAMEL_MIME_PART (dw),
            handle, cancellable, FALSE);

    g_string_truncate (emf->part_id, len);
}

static void
emf_message_deliverystatus (EMFormat *emf,
                            CamelStream *stream,
                            CamelMimePart *part,
                            const EMFormatHandler *info,
                            GCancellable *cancellable,
                            gboolean is_fallback)
{
    em_format_format_text (
        emf, stream, (CamelDataWrapper *)part, cancellable);
}

static void
emf_inlinepgp_signed (EMFormat *emf,
                      CamelStream *stream,
                      CamelMimePart *ipart,
                      const EMFormatHandler *info,
                      GCancellable *cancellable,
                      gboolean is_fallback)
{
    CamelStream *filtered_stream;
    CamelMimeFilterPgp *pgp_filter;
    CamelContentType *content_type;
    CamelCipherContext *cipher;
    CamelCipherValidity *valid;
    CamelDataWrapper *dw;
    CamelMimePart *opart;
    CamelStream *ostream;
    gchar *type;
    GError *local_error = NULL;

    if (!ipart) {
        em_format_format_error(emf, stream, _("Unknown error verifying signature"));
        return;
    }

    emf->validity_found |= EM_FORMAT_VALIDITY_FOUND_SIGNED | EM_FORMAT_VALIDITY_FOUND_PGP;

    cipher = camel_gpg_context_new (emf->session);
    /* Verify the signature of the message */
    valid = camel_cipher_context_verify_sync (
        cipher, ipart, cancellable, &local_error);
    if (!valid) {
        em_format_format_error (
            emf, stream, local_error->message ?
            _("Error verifying signature") :
            _("Unknown error verifying signature"));
        if (local_error->message)
            em_format_format_error (
                emf, stream, "%s", local_error->message);
        em_format_format_source (emf, stream, ipart, cancellable);
        /* I think this will loop: em_format_part_as(emf, stream, part, "text/plain"); */
        g_clear_error (&local_error);
        g_object_unref (cipher);
        return;
    }

    /* Setup output stream */
    ostream = camel_stream_mem_new ();
    filtered_stream = camel_stream_filter_new (ostream);

    /* Add PGP header / footer filter */
    pgp_filter = (CamelMimeFilterPgp *)camel_mime_filter_pgp_new ();
    camel_stream_filter_add (
        CAMEL_STREAM_FILTER (filtered_stream),
        CAMEL_MIME_FILTER (pgp_filter));
    g_object_unref (pgp_filter);

    /* Pass through the filters that have been setup */
    dw = camel_medium_get_content ((CamelMedium *)ipart);
    camel_data_wrapper_decode_to_stream_sync (
        dw, (CamelStream *)filtered_stream, NULL, NULL);
    camel_stream_flush ((CamelStream *)filtered_stream, NULL, NULL);
    g_object_unref (filtered_stream);

    /* Create a new text/plain MIME part containing the signed
     * content preserving the original part's Content-Type params. */
    content_type = camel_mime_part_get_content_type (ipart);
    type = camel_content_type_format (content_type);
    content_type = camel_content_type_decode (type);
    g_free (type);

    g_free (content_type->type);
    content_type->type = g_strdup ("text");
    g_free (content_type->subtype);
    content_type->subtype = g_strdup ("plain");
    type = camel_content_type_format (content_type);
    camel_content_type_unref (content_type);

    dw = camel_data_wrapper_new ();
    camel_data_wrapper_construct_from_stream_sync (dw, ostream, NULL, NULL);
    camel_data_wrapper_set_mime_type (dw, type);
    g_free (type);

    opart = camel_mime_part_new ();
    camel_medium_set_content ((CamelMedium *) opart, dw);
    camel_data_wrapper_set_mime_type_field ((CamelDataWrapper *) opart, dw->mime_type);

    add_validity_found (emf, valid);
    /* Pass it off to the real formatter */
    em_format_format_secure (emf, stream, opart, valid, cancellable);

    /* Clean Up */
    g_object_unref (dw);
    g_object_unref (opart);
    g_object_unref (ostream);
    g_object_unref (cipher);
}

static void
emf_inlinepgp_encrypted (EMFormat *emf,
                         CamelStream *stream,
                         CamelMimePart *ipart,
                         const EMFormatHandler *info,
                         GCancellable *cancellable,
                         gboolean is_fallback)
{
    CamelCipherContext *cipher;
    CamelCipherValidity *valid;
    CamelMimePart *opart;
    CamelDataWrapper *dw;
    gchar *mime_type;
    GError *local_error = NULL;

    emf->validity_found |=
        EM_FORMAT_VALIDITY_FOUND_ENCRYPTED |
        EM_FORMAT_VALIDITY_FOUND_PGP;

    cipher = camel_gpg_context_new (emf->session);
    opart = camel_mime_part_new ();

    /* Decrypt the message */
    valid = camel_cipher_context_decrypt_sync (
        cipher, ipart, opart, cancellable, &local_error);

    if (!valid) {
        em_format_format_error (
            emf, stream, _("Could not parse PGP message: "));
        if (local_error->message != NULL)
            em_format_format_error (
                emf, stream, "%s", local_error->message);
        else
            em_format_format_error (
                emf, stream, _("Unknown error"));
        em_format_format_source (emf, stream, ipart, cancellable);
        /* I think this will loop: em_format_part_as(emf, stream, part, "text/plain"); */

        g_clear_error (&local_error);
        g_object_unref (cipher);
        g_object_unref (opart);
        return;
    }

    dw = camel_medium_get_content ((CamelMedium *)opart);
    mime_type = camel_data_wrapper_get_mime_type (dw);

    /* this ensures to show the 'opart' as inlined, if possible */
    if (mime_type && g_ascii_strcasecmp (mime_type, "application/octet-stream") == 0) {
        const gchar *snoop = em_format_snoop_type (opart);

        if (snoop)
            camel_data_wrapper_set_mime_type (dw, snoop);
    }

    preserve_charset_in_content_type (ipart, opart);
    g_free (mime_type);

    add_validity_found (emf, valid);
    /* Pass it off to the real formatter */
    em_format_format_secure (emf, stream, opart, valid, cancellable);

    /* Clean Up */
    g_object_unref (opart);
    g_object_unref (cipher);
}

static EMFormatHandler type_builtin_table[] = {
#ifdef ENABLE_SMIME
    { (gchar *) "application/x-pkcs7-mime",
      emf_application_xpkcs7mime,
      EM_FORMAT_HANDLER_INLINE_DISPOSITION },
#endif
    { (gchar *) "application/mbox", emf_application_mbox, EM_FORMAT_HANDLER_INLINE },
    { (gchar *) "multipart/alternative", emf_multipart_alternative },
    { (gchar *) "multipart/appledouble", emf_multipart_appledouble },
    { (gchar *) "multipart/encrypted", emf_multipart_encrypted },
    { (gchar *) "multipart/mixed", emf_multipart_mixed },
    { (gchar *) "multipart/signed", emf_multipart_signed },
    { (gchar *) "multipart/related", emf_multipart_related },
    { (gchar *) "multipart/*", emf_multipart_mixed },
    { (gchar *) "message/rfc822", emf_message_rfc822, EM_FORMAT_HANDLER_INLINE },
    { (gchar *) "message/news", emf_message_rfc822, EM_FORMAT_HANDLER_INLINE },
    { (gchar *) "message/delivery-status", emf_message_deliverystatus },
    { (gchar *) "message/*", emf_message_rfc822, EM_FORMAT_HANDLER_INLINE },

    /* Insert brokenly-named parts here */
#ifdef ENABLE_SMIME
    { (gchar *) "application/pkcs7-mime",
      emf_application_xpkcs7mime,
      EM_FORMAT_HANDLER_INLINE_DISPOSITION },
#endif

    /* internal types */
    { (gchar *) "application/x-inlinepgp-signed", emf_inlinepgp_signed },
    { (gchar *) "application/x-inlinepgp-encrypted", emf_inlinepgp_encrypted },
};

static void
emf_builtin_init (EMFormatClass *class)
{
    gint ii;

    for (ii = 0; ii < G_N_ELEMENTS (type_builtin_table); ii++)
        g_hash_table_insert (
            class->type_handlers,
            type_builtin_table[ii].mime_type,
            &type_builtin_table[ii]);
}

/**
 * em_format_snoop_type:
 * @part:
 *
 * Tries to snoop the mime type of a part.
 *
 * Return value: NULL if unknown (more likely application/octet-stream).
 **/
const gchar *
em_format_snoop_type (CamelMimePart *part)
{
    /* cache is here only to be able still return const gchar * */
    static GHashTable *types_cache = NULL;

    const gchar *filename;
    gchar *name_type = NULL, *magic_type = NULL, *res, *tmp;
    CamelDataWrapper *dw;

    filename = camel_mime_part_get_filename (part);
    if (filename != NULL)
        name_type = e_util_guess_mime_type (filename, FALSE);

    dw = camel_medium_get_content ((CamelMedium *)part);
    if (!camel_data_wrapper_is_offline (dw)) {
        GByteArray *byte_array;
        CamelStream *stream;

        byte_array = g_byte_array_new ();
        stream = camel_stream_mem_new_with_byte_array (byte_array);

        if (camel_data_wrapper_decode_to_stream_sync (dw, stream, NULL, NULL) > 0) {
            gchar *content_type;

            content_type = g_content_type_guess (
                filename, byte_array->data,
                byte_array->len, NULL);

            if (content_type != NULL)
                magic_type = g_content_type_get_mime_type (content_type);

            g_free (content_type);
        }

        g_object_unref (stream);
    }

    d(printf("snooped part, magic_type '%s' name_type '%s'\n", magic_type, name_type));

    /* If gvfs doesn't recognize the data by magic, but it
     * contains English words, it will call it text/plain. If the
     * filename-based check came up with something different, use
     * that instead and if it returns "application/octet-stream"
     * try to do better with the filename check.
     */

    if (magic_type) {
        if (name_type
            && (!strcmp(magic_type, "text/plain")
            || !strcmp(magic_type, "application/octet-stream")))
            res = name_type;
        else
            res = magic_type;
    } else
        res = name_type;

    if (res != name_type)
        g_free (name_type);

    if (res != magic_type)
        g_free (magic_type);

    if (!types_cache)
        types_cache = g_hash_table_new_full (
            g_str_hash, g_str_equal,
            (GDestroyNotify) g_free,
            (GDestroyNotify) NULL);

    if (res) {
        tmp = g_hash_table_lookup (types_cache, res);
        if (tmp) {
            g_free (res);
            res = tmp;
        } else {
            g_hash_table_insert (types_cache, res, res);
        }
    }

    return res;

    /* We used to load parts to check their type, we dont anymore,
       see bug #11778 for some discussion */
}