path: root/mail/mail-format.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */

/*
 * Authors:
 *  Matt Loper <matt@helixcode.com>
 *  Dan Winship <danw@helixcode.com>
 *
 *  Copyright 2000, Helix Code, Inc. (http://www.helixcode.com)
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Street #330, Boston, MA 02111-1307, USA.
 *
 */

#include <config.h>
#include "mail-display.h"
#include "mail.h"
#include "e-util/e-html-utils.h"
#include "e-util/e-setup.h" /*for evolution_dir*/
#include <libgnome/libgnome.h>
#include <libgnomevfs/gnome-vfs-mime-info.h>

#include <ctype.h>    /* for isprint */
#include <string.h>   /* for strstr  */
#include <fcntl.h>

struct mail_format_data {
    CamelMimeMessage *root;
    GHashTable *urls;
    GtkHTML *html;
    GtkHTMLStream *stream;
};

static gboolean handle_text_plain            (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_text_plain_flowed     (char *text,
                          struct mail_format_data *mfd);
static gboolean handle_text_enriched         (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_text_html             (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_image                 (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_multipart_mixed       (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_multipart_related     (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_multipart_alternative (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_multipart_appledouble (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_audio                 (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_message_rfc822        (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_message_external_body (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);

static gboolean handle_unknown_type          (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);
static gboolean handle_via_bonobo            (CamelMimePart *part,
                          const char *mime_type,
                          struct mail_format_data *mfd);

/* writes the header info for a mime message into an html stream */
static void write_headers (CamelMimeMessage *message,
               struct mail_format_data *mfd);

/* dispatch html printing via mimetype */
static gboolean call_handler_function (CamelMimePart *part,
                       struct mail_format_data *mfd);

static void free_urls (gpointer data);


/**
 * mail_format_mime_message: 
 * @mime_message: the input mime message
 * @html: a GtkHTML
 * @stream: a stream on @html
 * @root: the root message being displayed (may be the same as @mime_message)
 *
 * Writes a CamelMimeMessage out into a GtkHTML
 **/
void
mail_format_mime_message (CamelMimeMessage *mime_message,
              GtkHTML *html, GtkHTMLStream *stream,
              CamelMimeMessage *root)
{
    struct mail_format_data mfd;

    g_return_if_fail (CAMEL_IS_MIME_MESSAGE (mime_message));

    mfd.html = html;
    mfd.stream = stream;
    mfd.root = root;
    mfd.urls = gtk_object_get_data (GTK_OBJECT (root), "urls");
    if (!mfd.urls) {
        mfd.urls = g_hash_table_new (g_str_hash, g_str_equal);
        gtk_object_set_data_full (GTK_OBJECT (root), "urls",
                      mfd.urls, free_urls);
    }

    write_headers (mime_message, &mfd);
    call_handler_function (CAMEL_MIME_PART (mime_message), &mfd);
}

static void
free_url (gpointer key, gpointer value, gpointer data)
{
    g_free (key);
}

static void
free_urls (gpointer data)
{
    GHashTable *urls = data;

    g_hash_table_foreach (urls, free_url, NULL);
    g_hash_table_destroy (urls);
}

static const char *
get_cid (CamelMimePart *part, struct mail_format_data *mfd)
{
    char *cid;
    gpointer orig_name, value;

    /* If we have a real Content-ID, use it. If we don't,
     * make a (syntactically invalid) fake one.
     */
    if (camel_mime_part_get_content_id (part)) {
        cid = g_strdup_printf ("cid:%s",
                       camel_mime_part_get_content_id (part));
    } else
        cid = g_strdup_printf ("cid:@@@%p", part);

    if (g_hash_table_lookup_extended (mfd->urls, cid, &orig_name, &value)) {
        g_free (cid);
        return orig_name;
    } else
        g_hash_table_insert (mfd->urls, cid, part);

    return cid;
}



/* We're maintaining a hashtable of mimetypes -> functions;
 * Those functions have the following signature...
 */
typedef gboolean (*mime_handler_fn) (CamelMimePart *part,
                     const char *mime_type,
                     struct mail_format_data *mfd);

static GHashTable *mime_function_table, *mime_fallback_table;

static void
setup_function_table (void)
{
    mime_function_table = g_hash_table_new (g_str_hash, g_str_equal);
    mime_fallback_table = g_hash_table_new (g_str_hash, g_str_equal);

    g_hash_table_insert (mime_function_table, "text/plain",
                 handle_text_plain);
    g_hash_table_insert (mime_function_table, "text/richtext",
                 handle_text_enriched);
    g_hash_table_insert (mime_function_table, "text/enriched",
                 handle_text_enriched);
    g_hash_table_insert (mime_function_table, "text/html",
                 handle_text_html);

    g_hash_table_insert (mime_function_table, "image/*",
                 handle_image);

    g_hash_table_insert (mime_function_table, "audio/*",
                 handle_audio);

    g_hash_table_insert (mime_function_table, "message/rfc822",
                 handle_message_rfc822);
    g_hash_table_insert (mime_function_table, "message/external-body",
                 handle_message_external_body);

    g_hash_table_insert (mime_function_table, "multipart/alternative",
                 handle_multipart_alternative);
    g_hash_table_insert (mime_function_table, "multipart/related",
                 handle_multipart_related);
    g_hash_table_insert (mime_function_table, "multipart/mixed",
                 handle_multipart_mixed);
    g_hash_table_insert (mime_function_table, "multipart/appledouble",
                 handle_multipart_appledouble);

    /* RFC 2046 says unrecognized text subtypes can be treated
     * as text/plain (as long as you recognize the character set),
     * and unrecognized multipart subtypes as multipart/mixed.
     */
    g_hash_table_insert (mime_fallback_table, "text/*",
                 handle_text_plain);
    g_hash_table_insert (mime_function_table, "multipart/*",
                 handle_multipart_mixed);
}

static mime_handler_fn
lookup_handler (const char *mime_type, gboolean *generic)
{
    mime_handler_fn handler_function;
    const char *whole_goad_id, *generic_goad_id;
    char *mime_type_main;

    if (mime_function_table == NULL)
        setup_function_table ();

    mime_type_main = g_strdup_printf ("%.*s/*",
                      (int)strcspn (mime_type, "/"),
                      mime_type);

    /* OK. There are 6 possibilities, which we try in this order:
     *   1) full match in the main table
     *   2) partial match in the main table
     *   3) full match in bonobo
     *   4) full match in the fallback table
     *   5) partial match in the fallback table
     *   6) partial match in bonobo
     *
     * Of these, 1-4 are considered exact matches, and 5 and 6 are
     * considered generic.
     */

    /* Check for full match in mime_function_table. */
    handler_function = g_hash_table_lookup (mime_function_table,
                        mime_type);
    if (!handler_function) {
        handler_function = g_hash_table_lookup (mime_function_table,
                            mime_type_main);
        if (handler_function) {
            /* Optimize this for the next time through. */
            g_hash_table_insert (mime_function_table,
                         g_strdup (mime_type),
                         handler_function);
        }
    }

    if (handler_function) {
        g_free (mime_type_main);
        *generic = FALSE;
        return handler_function;
    }

    whole_goad_id = gnome_vfs_mime_get_value (mime_type, "bonobo-goad-id");
    generic_goad_id = gnome_vfs_mime_get_value (mime_type_main,
                            "bonobo-goad-id");

    if (whole_goad_id && (!generic_goad_id ||
                  strcmp (whole_goad_id, generic_goad_id) != 0)) {
        /* Optimize this for the next time through. */
        g_hash_table_insert (mime_function_table,
                     g_strdup (mime_type),
                     handle_via_bonobo);
        g_free (mime_type_main);
        *generic = FALSE;
        return handle_via_bonobo;
    }

    handler_function = g_hash_table_lookup (mime_fallback_table,
                        mime_type);
    if (handler_function)
        *generic = FALSE;
    else {
        handler_function = g_hash_table_lookup (mime_fallback_table,
                            mime_type_main);
        if (!handler_function && generic_goad_id)
            handler_function = handle_via_bonobo;
        *generic = TRUE;
    }

    g_free (mime_type_main);
    return handler_function;
}

static gboolean
call_handler_function (CamelMimePart *part, struct mail_format_data *mfd)
{
    CamelDataWrapper *wrapper;
    char *mime_type;
    mime_handler_fn handler_function = NULL;
    gboolean generic, output;

    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (part));
    mime_type = camel_data_wrapper_get_mime_type (wrapper);
    g_strdown (mime_type);

    handler_function = lookup_handler (mime_type, &generic);
    if (handler_function)
        output = (*handler_function) (part, mime_type, mfd);
    else
        output = handle_unknown_type (part, mime_type, mfd);

    g_free (mime_type);
    return output;
}

static void
write_field_to_stream (const char *description, const char *value,
               gboolean bold, GtkHTML *html,
               GtkHTMLStream *stream)
{
    char *encoded_value;

    if (value) {
        unsigned char *p;

        encoded_value = e_text_to_html (value,
                        E_TEXT_TO_HTML_CONVERT_NL |
                        E_TEXT_TO_HTML_CONVERT_URLS);
        for (p = (unsigned char *)encoded_value; *p; p++) {
            if (!isprint (*p))
                *p = '?';
        }
    } else
        encoded_value = "";

    mail_html_write (html, stream,
             "<tr valign=top><%s align=right>%s</%s>"
             "<td>%s</td></tr>", bold ? "th" : "td",
             description, bold ? "th" : "td", encoded_value);
    if (value)
        g_free (encoded_value);
}

static void
write_recipients_to_stream (const gchar *recipient_type,
                const CamelInternetAddress *recipients,
                gboolean optional, gboolean bold,
                GtkHTML *html, GtkHTMLStream *stream)
{
    int i;
    char *recipients_string = NULL;
    const char *name, *addr;

    i = 0;
    while (camel_internet_address_get (recipients, i++, &name, &addr)) {
        char *old_string = recipients_string;

        if (*name) {
            recipients_string = g_strdup_printf (
                "%s%s\"%s\" <%s>",
                old_string ? old_string : "",
                old_string ? ", " : "",
                name, addr);
        } else {
            recipients_string = g_strdup_printf (
                "%s%s%s", old_string ? old_string : "",
                old_string ? ", " : "", addr);
        }
        g_free (old_string);
    }

    if (recipients_string || !optional) {
        write_field_to_stream (recipient_type, recipients_string,
                       bold, html, stream);
    }
    g_free (recipients_string);
}



static void
write_headers (CamelMimeMessage *message, struct mail_format_data *mfd)
{
    const CamelInternetAddress *recipients;

    mail_html_write (mfd->html, mfd->stream,
             "<table bgcolor=\"#EEEEEE\" width=\"100%%\" "
             "cellspacing=0 border=1>"
             "<tr><td><table>\n");

    write_field_to_stream ("From:",
                   camel_mime_message_get_from (message),
                   TRUE, mfd->html, mfd->stream);

    if (camel_mime_message_get_reply_to (message)) {
        write_field_to_stream ("Reply-To:",
                       camel_mime_message_get_reply_to (message),
                       FALSE, mfd->html, mfd->stream);
    }

    write_recipients_to_stream ("To:",
                    camel_mime_message_get_recipients (message, CAMEL_RECIPIENT_TYPE_TO),
                    FALSE, TRUE, mfd->html, mfd->stream);

    recipients = camel_mime_message_get_recipients (message, CAMEL_RECIPIENT_TYPE_CC);
    write_recipients_to_stream ("Cc:", recipients, TRUE, TRUE,
                    mfd->html, mfd->stream);
    write_field_to_stream ("Subject:",
                   camel_mime_message_get_subject (message),
                   TRUE, mfd->html, mfd->stream);

    mail_html_write (mfd->html, mfd->stream, "</table></td></tr></table></center>");
}


/* Return the contents of a text-based data wrapper, or NULL if it
 * contains only whitespace.
 */
static char *
get_data_wrapper_text (CamelDataWrapper *data)
{
    CamelStream *memstream;
    GByteArray *ba;
    char *text, *end;

    ba = g_byte_array_new ();
    memstream = camel_stream_mem_new_with_byte_array (ba);

    camel_data_wrapper_write_to_stream (data, memstream);

    for (text = ba->data, end = ba->data + ba->len; text < end; text++) {
        if (!isspace ((unsigned char)*text))
            break;
    }

    if (text < end) {
        text = g_malloc (ba->len + 1);
        memcpy (text, ba->data, ba->len);
        text[ba->len] = '\0';
    } else
        text = NULL;

    gtk_object_unref (GTK_OBJECT (memstream));
    return text;
}

/*----------------------------------------------------------------------*
 *                     Mime handling functions
 *----------------------------------------------------------------------*/

static gboolean
handle_text_plain (CamelMimePart *part, const char *mime_type,
           struct mail_format_data *mfd)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    char *text, *htmltext;
    GMimeContentField *type;
    const char *format;

    text = get_data_wrapper_text (wrapper);
    if (!text)
        return FALSE;

    /* Check for RFC 2646 flowed text. */
    type = camel_mime_part_get_content_type (part);
    format = gmime_content_field_get_parameter (type, "format");
    if (format && !g_strcasecmp (format, "flowed"))
        return handle_text_plain_flowed (text, mfd);

    mail_html_write (mfd->html, mfd->stream,
             "\n<!-- text/plain -->\n<pre>\n");

    htmltext = e_text_to_html (text, E_TEXT_TO_HTML_CONVERT_URLS);
    g_free (text);
    mail_html_write (mfd->html, mfd->stream, "%s", htmltext);
    g_free (htmltext);

    mail_html_write (mfd->html, mfd->stream, "</pre>\n");
    return TRUE;
}

static gboolean
handle_text_plain_flowed (char *buf, struct mail_format_data *mfd)
{
    char *text, *line, *eol, *p;
    int prevquoting = 0, quoting, len;
    gboolean br_pending = FALSE;

    mail_html_write (mfd->html, mfd->stream,
             "\n<!-- text/plain, flowed -->\n<tt>\n");

    for (line = buf; *line; line = eol + 1) {
        /* Process next line */
        eol = strchr (line, '\n');
        if (eol)
            *eol = '\0';

        quoting = 0;
        for (p = line; *p == '>'; p++)
            quoting++;
        if (quoting != prevquoting) {
            mail_html_write (mfd->html, mfd->stream, "%s\n",
                     prevquoting == 0 ? "<i>\n" : "");
            while (quoting > prevquoting) {
                mail_html_write (mfd->html, mfd->stream,
                         "<blockquote>");
                prevquoting++;
            }
            while (quoting < prevquoting) {
                mail_html_write (mfd->html, mfd->stream,
                         "</blockquote>");
                prevquoting--;
            }
            mail_html_write (mfd->html, mfd->stream, "%s\n",
                     prevquoting == 0 ? "</i>\n" : "");
        } else if (br_pending) {
            mail_html_write (mfd->html, mfd->stream, "<br>\n");
            br_pending = FALSE;
        }

        if (*p == ' ')
            p++;

        /* replace '<' with '&lt;', etc. */
        text = e_text_to_html (p, E_TEXT_TO_HTML_CONVERT_SPACES |
                       E_TEXT_TO_HTML_CONVERT_URLS);
        if (text && *text)
            mail_html_write (mfd->html, mfd->stream, "%s", text);
        g_free (text);

        len = strlen (p);
        if (len == 0 || p[len - 1] != ' ' || !strcmp (p, "-- "))
            br_pending = TRUE;

        if (!eol)
            break;
    }
    g_free (buf);

    mail_html_write (mfd->html, mfd->stream, "</tt>\n");
    return TRUE;
}

static void
free_byte_array (GtkWidget *widget, gpointer user_data)
{
    g_byte_array_free (user_data, TRUE);
}

/* text/enriched (RFC 1896) or text/richtext (included in RFC 1341) */
static gboolean
handle_text_enriched (CamelMimePart *part, const char *mime_type,
              struct mail_format_data *mfd)
{
    static GHashTable *translations = NULL;
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    GString *string;
    GByteArray *ba;
    char *text, *p, *xed;
    int len, nofill = 0;
    gboolean enriched;

    if (!translations) {
        translations = g_hash_table_new (g_strcase_hash,
                         g_strcase_equal);
        g_hash_table_insert (translations, "bold", "<b>");
        g_hash_table_insert (translations, "/bold", "</b>");
        g_hash_table_insert (translations, "italic", "<i>");
        g_hash_table_insert (translations, "/italic", "</i>");
        g_hash_table_insert (translations, "fixed", "<tt>");
        g_hash_table_insert (translations, "/fixed", "</tt>");
        g_hash_table_insert (translations, "smaller", "<font size=-1>");
        g_hash_table_insert (translations, "/smaller", "</font>");
        g_hash_table_insert (translations, "bigger", "<font size=+1>");
        g_hash_table_insert (translations, "/bigger", "</font>");
        g_hash_table_insert (translations, "underline", "<u>");
        g_hash_table_insert (translations, "/underline", "</u>");
        g_hash_table_insert (translations, "center", "<p align=center>");
        g_hash_table_insert (translations, "/center", "</p>");
        g_hash_table_insert (translations, "flushleft", "<p align=left>");
        g_hash_table_insert (translations, "/flushleft", "</p>");
        g_hash_table_insert (translations, "flushright", "<p align=right>");
        g_hash_table_insert (translations, "/flushright", "</p>");
        g_hash_table_insert (translations, "excerpt", "<blockquote>");
        g_hash_table_insert (translations, "/excerpt", "</blockquote>");
        g_hash_table_insert (translations, "paragraph", "<p>");
        g_hash_table_insert (translations, "signature", "<address>");
        g_hash_table_insert (translations, "/signature", "</address>");
        g_hash_table_insert (translations, "comment", "<!-- ");
        g_hash_table_insert (translations, "/comment", " -->");
        g_hash_table_insert (translations, "param", "<!-- ");
        g_hash_table_insert (translations, "/param", " -->");
        g_hash_table_insert (translations, "np", "<hr>");
    }

    text = get_data_wrapper_text (wrapper);
    if (!text)
        return FALSE;

    if (!g_strcasecmp (mime_type, "text/richtext")) {
        enriched = FALSE;
        mail_html_write (mfd->html, mfd->stream,
                 "\n<!-- text/richtext -->\n");
    } else {
        enriched = TRUE;
        mail_html_write (mfd->html, mfd->stream,
                 "\n<!-- text/enriched -->\n");
    }

    /* This is not great code, but I don't feel like fixing it right
     * now. I mean, it's just text/enriched...
     */
    p = text;
    string = g_string_sized_new (2 * strlen (p));

    while (p) {
        len = strcspn (p, " <>&\n");
        if (len)
            g_string_sprintfa (string, "%.*s", len, p);

        p += len;
        if (!*p)
            break;

        switch (*p++) {
        case ' ':
            while (*p == ' ') {
                g_string_append (string, "&nbsp;");
                p++;
            }
            g_string_append (string, " ");
            break;

        case '\n':
            g_string_append (string, " ");
            if (enriched && nofill <= 0) {
                while (*p == '\n') {
                    g_string_append (string, "<br>");
                    p++;
                }
            }
            break;

        case '>':
            g_string_append (string, "&gt;");
            break;

        case '&':
            g_string_append (string, "&amp;");
            break;

        case '<':
            if (enriched) {
                if (*p == '<') {
                    g_string_append (string, "&lt;");
                    p++;
                    break;
                }
            } else {
                if (strncmp (p, "lt>", 3) == 0) {
                    g_string_append (string, "&lt;");
                    p += 3;
                    break;
                } else if (strncmp (p, "nl>", 3) == 0) {
                    g_string_append (string, "<br>");
                    p += 3;
                    break;
                }
            }

            if (strncmp (p, "nofill>", 7) == 0) {
                nofill++;
                g_string_append (string, "<pre>");
            } else if (strncmp (p, "/nofill>", 8) == 0) {
                nofill--;
                g_string_append (string, "</pre>");
            } else {
                char *copy, *match;

                len = strcspn (p, ">");
                copy = g_strndup (p, len);
                match = g_hash_table_lookup (translations,
                                 copy);
                g_free (copy);
                if (match)
                    g_string_append (string, match);
            }

            p = strchr (p, '>');
            if (p)
                p++;
        }
    }
    g_free (text);

    ba = g_byte_array_new ();
    g_byte_array_append (ba, (const guint8 *)string->str,
                 strlen (string->str));
    g_string_free (string, TRUE);

    xed = g_strdup_printf ("x-evolution-data:%p", part);
    g_hash_table_insert (mfd->urls, xed, ba);
    gtk_signal_connect (GTK_OBJECT (mfd->root), "destroy",
                GTK_SIGNAL_FUNC (free_byte_array), ba);
    mail_html_write (mfd->html, mfd->stream,
             "<iframe src=\"%s\" frameborder=0 scrolling=no>"
             "</iframe>", xed);

    return TRUE;
}

static gboolean
handle_text_html (CamelMimePart *part, const char *mime_type,
          struct mail_format_data *mfd)
{
    mail_html_write (mfd->html, mfd->stream, "\n<!-- text/html -->\n");
    mail_html_write (mfd->html, mfd->stream,
             "<iframe src=\"%s\" frameborder=0 scrolling=no>"
             "</iframe>", get_cid (part, mfd));
    return TRUE;
}

static gboolean
handle_image (CamelMimePart *part, const char *mime_type,
          struct mail_format_data *mfd)
{
    mail_html_write (mfd->html, mfd->stream, "<img src=\"%s\">",
             get_cid (part, mfd));
    return TRUE;
}

static gboolean
handle_multipart_mixed (CamelMimePart *part, const char *mime_type,
            struct mail_format_data *mfd)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelMultipart *mp;
    int i, nparts;
    gboolean output = FALSE;

    g_return_val_if_fail (CAMEL_IS_MULTIPART (wrapper), FALSE);
    mp = CAMEL_MULTIPART (wrapper);

    nparts = camel_multipart_get_number (mp);   
    for (i = 0; i < nparts; i++) {
        if (i != 0 && output)
            mail_html_write (mfd->html, mfd->stream, "<hr>\n");

        part = camel_multipart_get_part (mp, i);

        output = call_handler_function (part, mfd);
    }

    return TRUE;
}

/* As seen in RFC 2387! */
static gboolean
handle_multipart_related (CamelMimePart *part, const char *mime_type,
              struct mail_format_data *mfd)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelMultipart *mp;
    CamelMimePart *body_part, *display_part = NULL;
    GMimeContentField *content_type;
    const char *start;
    int i, nparts;

    g_return_val_if_fail (CAMEL_IS_MULTIPART (wrapper), FALSE);
    mp = CAMEL_MULTIPART (wrapper);
    nparts = camel_multipart_get_number (mp);   

    content_type = camel_mime_part_get_content_type (part);
    start = gmime_content_field_get_parameter (content_type, "start");
    if (start) {
        int len;

        /* The "start" parameter includes <>s, which Content-Id
         * does not.
         */
        len = strlen (start) - 2;

        for (i = 0; i < nparts; i++) {
            const char *cid;

            body_part = camel_multipart_get_part (mp, i);
            cid = camel_mime_part_get_content_id (body_part);

            if (!strncmp (cid, start + 1, len) &&
                strlen (cid) == len) {
                display_part = body_part;
                break;
            }
        }

        if (!display_part) {
            /* Oops. Hrmph. */
            return handle_multipart_mixed (part, mime_type, mfd);
        }
    } else {
        /* No start parameter, so it defaults to the first part. */
        display_part = camel_multipart_get_part (mp, 0);
    }

    /* Record the Content-IDs of any non-displayed parts. */
    for (i = 0; i < nparts; i++) {
        body_part = camel_multipart_get_part (mp, i);
        if (body_part == display_part)
            continue;

        get_cid (body_part, mfd);
    }

    /* Now, display the displayed part. */
    return call_handler_function (display_part, mfd);
}

/* RFC 2046 says "display the last part that you are able to display". */
static CamelMimePart *
find_preferred_alternative (CamelMultipart *multipart, gboolean want_plain)
{
    int i, nparts;
    CamelMimePart *preferred_part = NULL;
    gboolean generic;

    nparts = camel_multipart_get_number (multipart);
    for (i = 0; i < nparts; i++) {
        CamelMimePart *part = camel_multipart_get_part (multipart, i);
        char *mime_type = gmime_content_field_get_mime_type (
            camel_mime_part_get_content_type (part));

        g_strdown (mime_type);
        if (want_plain && !strcmp (mime_type, "text/plain"))
            return part;
        if (lookup_handler (mime_type, &generic) &&
            (!preferred_part || !generic))
            preferred_part = part;
        g_free (mime_type);
    }

    return preferred_part;
}

static gboolean
handle_multipart_alternative (CamelMimePart *part, const char *mime_type,
                  struct mail_format_data *mfd)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelMultipart *multipart;
    CamelMimePart *mime_part;

    g_return_val_if_fail (CAMEL_IS_MULTIPART (wrapper), FALSE);
    multipart = CAMEL_MULTIPART (wrapper);

    mime_part = find_preferred_alternative (multipart, FALSE);
    if (mime_part)
        return call_handler_function (mime_part, mfd);
    else
        return handle_unknown_type (part, mime_type, mfd);
}

/* RFC 1740 */
static gboolean
handle_multipart_appledouble (CamelMimePart *part, const char *mime_type,
                  struct mail_format_data *mfd)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelMultipart *multipart;

    g_return_val_if_fail (CAMEL_IS_MULTIPART (wrapper), FALSE);
    multipart = CAMEL_MULTIPART (wrapper);

    /* The first part is application/applefile and is not useful
     * to us. The second part _may_ be displayable data. Most
     * likely it's application/octet-stream though.
     */
    part = camel_multipart_get_part (multipart, 1);
    return call_handler_function (part, mfd);
}

static const char *
get_url_for_icon (const char *icon_name, struct mail_format_data *mfd)
{
    static GHashTable *icons;
    char *icon_path = gnome_pixmap_file (icon_name), buf[1024], *url;
    GByteArray *ba;

    if (!icons)
        icons = g_hash_table_new (g_str_hash, g_str_equal);

    if (!icon_path)
        return "file:///dev/null";

    ba = g_hash_table_lookup (icons, icon_path);
    if (!ba) {
        int fd, nread;

        fd = open (icon_path, O_RDONLY);
        if (fd == -1) {
            g_free (icon_path);
            return "file:///dev/null";
        }

        ba = g_byte_array_new ();

        while (1) {
            nread = read (fd, buf, sizeof (buf));
            if (nread < 1)
                break;
            g_byte_array_append (ba, buf, nread);
        }
        close (fd);

        g_hash_table_insert (icons, icon_path, ba);
    }
    g_free (icon_path);

    url = g_strdup_printf ("x-evolution-data:%p", ba);
    g_hash_table_insert (mfd->urls, url, ba);

    return url;
}

static void
handle_mystery (CamelMimePart *part, struct mail_format_data *mfd,
        const char *url, const char *icon_name, const char *id,
        const char *action)
{
    const char *info;
    char *htmlinfo;
    GMimeContentField *content_type;

    mail_html_write (mfd->html, mfd->stream, "<table><tr><td>");

    /* Draw the icon, surrounded by an <a href> if we have a URL,
     * or a plain inactive border if not.
     */
    if (url) {
        mail_html_write (mfd->html, mfd->stream,
                 "<a href=\"%s\">", url);
    } else {
        mail_html_write (mfd->html, mfd->stream,
                 "<table border=2><tr><td>");
    }
    mail_html_write (mfd->html, mfd->stream, "<img src=\"%s\">",
             get_url_for_icon (icon_name, mfd));

    if (url)
        mail_html_write (mfd->html, mfd->stream, "</a>");
    else
        mail_html_write (mfd->html, mfd->stream, "</td></tr></table>");
    mail_html_write (mfd->html, mfd->stream, "</td><td>%s<br>", id);

    /* Write a description, if we have one. */
    info = camel_mime_part_get_description (part);
    if (info) {
        htmlinfo = e_text_to_html (info, E_TEXT_TO_HTML_CONVERT_URLS);
        mail_html_write (mfd->html, mfd->stream, "Description: %s<br>",
                 htmlinfo);
        g_free (htmlinfo);
    }

    /* Write the name, if we have it. */
    content_type = camel_mime_part_get_content_type (part);
    info = gmime_content_field_get_parameter (content_type, "name");
    if (!info)
        info = camel_mime_part_get_filename (part);
    if (info) {
        htmlinfo = e_text_to_html (info, 0);
        mail_html_write (mfd->html, mfd->stream, "Name: %s<br>",
                 htmlinfo);
        g_free (htmlinfo);
    }

    /* Describe the click action, if any. */
    if (action) {
        mail_html_write (mfd->html, mfd->stream,
                 "<br>Click on the icon to %s.", action);
    }

    mail_html_write (mfd->html, mfd->stream, "</td></tr></table>");
}

static gboolean
handle_audio (CamelMimePart *part, const char *mime_type,
          struct mail_format_data *mfd)
{
    char *id;
    const char *desc;

    desc = gnome_vfs_mime_get_value (mime_type, "description");
    if (desc)
        id = g_strdup_printf ("%s data", desc);
    else {
        id = g_strdup_printf ("Audio data in \"%s\" format.",
                      mime_type);
    }
    handle_mystery (part, mfd, get_cid (part, mfd), "gnome-audio2.png",
            id, "play it");
    g_free (id);

    return TRUE;
}

static gboolean
handle_message_rfc822 (CamelMimePart *part, const char *mime_type,
               struct mail_format_data *mfd)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));

    g_return_val_if_fail (CAMEL_IS_MIME_MESSAGE (wrapper), FALSE);

    mail_html_write (mfd->html, mfd->stream, "<blockquote>");
    mail_format_mime_message (CAMEL_MIME_MESSAGE (wrapper),
                  mfd->html, mfd->stream, mfd->root);
    mail_html_write (mfd->html, mfd->stream, "</blockquote>");

    return TRUE;
}

static gboolean
handle_message_external_body (CamelMimePart *part, const char *mime_type,
                  struct mail_format_data *mfd)
{
    GMimeContentField *type;
    const char *access_type;
    char *url = NULL, *desc = NULL;

    type = camel_mime_part_get_content_type (part);
    access_type = gmime_content_field_get_parameter (type, "access-type");
    if (!access_type)
        goto fallback;

    if (!g_strcasecmp (access_type, "ftp") ||
        !g_strcasecmp (access_type, "anon-ftp")) {
        const char *name, *site, *dir, *mode, *ftype;
        char *path;

        name = gmime_content_field_get_parameter (type, "name");
        site = gmime_content_field_get_parameter (type, "site");
        if (name == NULL || site == NULL)
            goto fallback;
        dir = gmime_content_field_get_parameter (type, "directory");
        mode = gmime_content_field_get_parameter (type, "mode");

        /* Generate the path. */
        if (dir) {
            const char *p = dir + strlen (dir);

            path = g_strdup_printf ("%s%s%s%s",
                        *dir == '/' ? "" : "/",
                        dir,
                        *p == '/' ? "" : "/",
                        name);
        } else {
            path = g_strdup_printf ("%s%s",
                        *name == '/' ? "" : "/",
                        name);
        }

        if (mode && *mode == 'A')
            ftype = ";type=A";
        else if (mode && *mode == 'I')
            ftype = ";type=I";
        else
            ftype = "";

        url = g_strdup_printf ("ftp://%s%s%s", site, path, ftype);
        g_free (path);
        desc = g_strdup_printf ("Pointer to FTP site (%s)", url);
    } else if (!g_strcasecmp (access_type, "local-file")) {
        const char *name, *site;

        name = gmime_content_field_get_parameter (type, "name");
        if (name == NULL)
            goto fallback;
        site = gmime_content_field_get_parameter (type, "site");

        url = g_strdup_printf ("file://%s%s", *name == '/' ? "" : "/",
                       name);
        desc = g_strdup_printf ("Pointer to local file (%s)%s%s%s",
                    name, site ? " valid at site \"" : "",
                    site ? site : "", site ? "\"" : "");
    } else if (!g_strcasecmp (access_type, "URL")) {
        const char *urlparam;
        char *s, *d;

        /* RFC 2017 */

        urlparam = gmime_content_field_get_parameter (type, "url");
        if (urlparam == NULL)
            goto fallback;

        /* For obscure MIMEy reasons, the URL may be split into
         * multiple words, and needs to be rejoined. (The URL
         * must have any real whitespace %-encoded, so we just
         * get rid of all of it.
         */
        url = g_strdup (urlparam);
        s = d = url;

        while (*s) {
            if (!isspace ((unsigned char)*s))
                *d++ = *s;
            s++;
        }
        *d = *s;

        desc = g_strdup_printf ("Pointer to remote data (%s)", url);
    }

 fallback:
    if (!desc) {
        if (access_type) {
            desc = g_strdup_printf ("Pointer to unknown external "
                        "data (\"%s\" type)",
                        access_type);
        } else
            desc = g_strdup ("Malformed external-body part.");
    }

    handle_mystery (part, mfd, url, "gnome-globe.png", desc,
            url ? "open it in a browser" : NULL);

    g_free (desc);
    g_free (url);
    return TRUE;
}

static gboolean
handle_undisplayable (CamelMimePart *part, const char *mime_type,
              struct mail_format_data *mfd)
{
    const char *desc;
    char *id;

    desc = gnome_vfs_mime_get_value (mime_type, "description");
    if (desc)
        id = g_strdup (desc);
    else
        id = g_strdup_printf ("Data of type \"%s\".", mime_type);
    handle_mystery (part, mfd, get_cid (part, mfd), "gnome-question.png",
            id, "save it to disk");
    g_free (id);

    return TRUE;
}

static gboolean
handle_unknown_type (CamelMimePart *part, const char *mime_type,
             struct mail_format_data *mfd)
{
    char *type;

    /* Don't give up quite yet. */
    type = mail_identify_mime_part (part);
    if (type) {
        mime_handler_fn handler_function;
        gboolean generic, output;

        handler_function = lookup_handler (type, &generic);
        if (handler_function &&
            handler_function != handle_unknown_type) {
            output = (*handler_function) (part, type, mfd);
            g_free (type);
            return output;
        }
    } else
        type = g_strdup (mime_type);

    /* OK. Give up. */
    handle_undisplayable (part, type, mfd);
    g_free (type);

    return TRUE;
}

static gboolean
handle_via_bonobo (CamelMimePart *part, const char *mime_type,
           struct mail_format_data *mfd)
{
    mail_html_write (mfd->html, mfd->stream,
             "<object classid=\"%s\" type=\"%s\">",
             get_cid (part, mfd), mime_type);

    /* Call handle_undisplayable to output its HTML inside the
     * <object> ... </object>. It will only be displayed if the
     * object loading fails.
     */
    handle_undisplayable (part, mime_type, mfd);

    mail_html_write (mfd->html, mfd->stream, "</object>");

    return TRUE;
}

static char *
reply_body (CamelDataWrapper *data, gboolean want_plain, gboolean *is_html)
{
    CamelMultipart *mp;
    CamelMimePart *subpart;
    int i, nparts;
    char *subtext, *old;
    const char *boundary, *disp;
    char *text = NULL;
    GMimeContentField *mime_type;

    /* We only include text, message, and multipart bodies. */
    mime_type = camel_data_wrapper_get_mime_type_field (data);

    /* FIXME: This is wrong. We don't want to include large
     * images. But if we don't do it this way, we don't get
     * the headers...
     */
    if (g_strcasecmp (mime_type->type, "message") == 0) {
        *is_html = FALSE;
        return get_data_wrapper_text (data);
    }

    if (g_strcasecmp (mime_type->type, "text") == 0) {
        *is_html = !g_strcasecmp (mime_type->subtype, "html");
        return get_data_wrapper_text (data);
    }

    /* If it's not message and it's not text, and it's not
     * multipart, we don't want to deal with it.
     */
    if (g_strcasecmp (mime_type->type, "multipart") != 0)
        return NULL;

    mp = CAMEL_MULTIPART (data);

    if (g_strcasecmp (mime_type->subtype, "alternative") == 0) {
        /* Pick our favorite alternative and reply to it. */

        subpart = find_preferred_alternative (mp, want_plain);
        if (!subpart)
            return NULL;

        data = camel_medium_get_content_object (
            CAMEL_MEDIUM (subpart));
        return reply_body (data, want_plain, is_html);
    }

    nparts = camel_multipart_get_number (mp);

    /* Otherwise, concatenate all the parts that we can. If we find
     * an HTML part in there though, return just that: We don't want
     * to deal with merging HTML and non-HTML parts.
     */
    boundary = camel_multipart_get_boundary (mp);
    for (i = 0; i < nparts; i++) {
        subpart = camel_multipart_get_part (mp, i);

        disp = camel_mime_part_get_disposition (subpart);
        if (disp && g_strcasecmp (disp, "inline") != 0)
            continue;

        data = camel_medium_get_content_object (
            CAMEL_MEDIUM (subpart));
        subtext = reply_body (data, want_plain, is_html);
        if (!subtext)
            continue;
        if (*is_html) {
            g_free (text);
            return subtext;
        }

        if (text) {
            old = text;
            text = g_strdup_printf ("%s\n--%s\n%s", text,
                        boundary, subtext);
            g_free (subtext);
            g_free (old);
        } else
            text = subtext;
    }

    if (!text)
        return NULL;

    return text;
}

EMsgComposer *
mail_generate_reply (CamelMimeMessage *message, gboolean to_all)
{
    CamelDataWrapper *contents;
    char *text, *subject, *path, *string;
    EMsgComposer *composer;
    gboolean want_plain, is_html;
    const char *repl_to, *message_id, *references;
    GList *to, *cc;

    path = g_strdup_printf ("=%s/config=/mail/msg_format", evolution_dir);
    string = gnome_config_get_string (path);
    g_free (path);
    want_plain = string && !strcasecmp (string, "plain");

    contents = camel_medium_get_content_object (CAMEL_MEDIUM (message));
    text = reply_body (contents, want_plain, &is_html);

    composer = E_MSG_COMPOSER (e_msg_composer_new ());

    /* Set the quoted reply text. */
    if (text) {
        char *repl_text;

        if (is_html) {
            repl_text = g_strdup_printf ("<blockquote><i>\n%s\n"
                             "</i></blockquote>\n",
                             text);
        } else {
            char *s, *d, *quoted_text;
            int lines, len;

            /* Count the number of lines in the body. If
             * the text ends with a \n, this will be one
             * too high, but that's ok. Allocate enough
             * space for the text and the "> "s.
             */
            for (s = text, lines = 0; s; s = strchr (s + 1, '\n'))
                lines++;
            quoted_text = g_malloc (strlen (text) + lines * 2);

            s = text;
            d = quoted_text;

            /* Copy text to quoted_text line by line,
             * prepending "> ".
             */
            while (1) {
                len = strcspn (s, "\n");
                if (len == 0 && !*s)
                    break;
                sprintf (d, "> %.*s\n", len, s);
                s += len;
                if (!*s++)
                    break;
                d += len + 3;
            }

            /* Now convert that to HTML. */
            repl_text = e_text_to_html (quoted_text,
                            E_TEXT_TO_HTML_PRE);
            g_free (quoted_text);
        }
        e_msg_composer_set_body_text (composer, repl_text);
        g_free (repl_text);
        g_free (text);
    }

    /* Set the recipients */
    repl_to = camel_mime_message_get_reply_to (message);
    if (!repl_to)
        repl_to = camel_mime_message_get_from (message);
    to = g_list_append (NULL, (gpointer)repl_to);

    if (to_all) {
        const CamelInternetAddress *recip;
        const char *name, *addr;
        char *fulladdr;
        int i;

        recip = camel_mime_message_get_recipients (message, 
            CAMEL_RECIPIENT_TYPE_TO);
        i = 0;
        cc = NULL;
        while (camel_internet_address_get (recip, i++, &name, &addr)) {
            fulladdr = g_strdup_printf ("%s <%s>", name, addr);
            cc = g_list_append (cc, fulladdr);
        }

        recip = camel_mime_message_get_recipients (message,
            CAMEL_RECIPIENT_TYPE_CC);
        i = 0;
        while (camel_internet_address_get (recip, i++, &name, &addr)) {
            fulladdr = g_strdup_printf ("%s <%s>", name, addr);
            cc = g_list_append (cc, fulladdr);
        }
    } else
        cc = NULL;

    /* Set the subject of the new message. */
    subject = (char *)camel_mime_message_get_subject (message);
    if (!subject)
        subject = g_strdup ("");
    else {
        while (*subject == ' ')
            subject++;

        if (!strncasecmp (subject, "Re: ", 4))
            subject = g_strdup (subject);
        else
            subject = g_strdup_printf ("Re: %s", subject);
    }

    e_msg_composer_set_headers (composer, to, cc, NULL, subject);
    g_list_free (to);
    g_list_free (cc);
    g_free (subject);

    /* Add In-Reply-To and References. */
    message_id = camel_medium_get_header (CAMEL_MEDIUM (message),
                          "Message-Id");
    references = camel_medium_get_header (CAMEL_MEDIUM (message),
                          "References");
    if (message_id) {
        e_msg_composer_add_header (composer, "In-Reply-To",
                       message_id);
        if (references) {
            char *reply_refs;
            reply_refs = g_strdup_printf ("%s %s", references,
                              message_id);
            e_msg_composer_add_header (composer, "References",
                           reply_refs);
            g_free (reply_refs);
        }
    } else if (references)
        e_msg_composer_add_header (composer, "References", references);

    return composer;
}

EMsgComposer *
mail_generate_forward (CamelMimeMessage *mime_message,
               gboolean forward_as_attachment,
               gboolean keep_attachments)
{
    EMsgComposer *composer;
    CamelMimePart *part;
    const char *from, *subject;
    char *fwd_subj;

    if (!forward_as_attachment)
        g_warning ("Forward as non-attachment not implemented.");
    if (!keep_attachments)
        g_warning ("Forwarding without attachments not implemented.");

    composer = E_MSG_COMPOSER (e_msg_composer_new ());

    part = camel_mime_part_new ();
    camel_mime_part_set_disposition (part, "inline");
    camel_mime_part_set_description (part, "forwarded message");
    camel_medium_set_content_object (CAMEL_MEDIUM (part),
                     CAMEL_DATA_WRAPPER (mime_message));
    camel_mime_part_set_content_type (part, "message/rfc822");

    e_msg_composer_attach (composer, part);
    gtk_object_unref (GTK_OBJECT (part));

    from = camel_mime_message_get_from (mime_message);
    subject = camel_mime_message_get_subject (mime_message);
    if (from) {
        if (subject && *subject) {
            while (*subject == ' ')
                subject++;
            fwd_subj = g_strdup_printf ("[%s] %s", from, subject);
        } else {
            fwd_subj = g_strdup_printf ("[%s] (forwarded message)",
                            from);
        }
    }
    e_msg_composer_set_headers (composer, NULL, NULL, NULL, fwd_subj);
    g_free (fwd_subj);

    return composer;
}