path: root/mail/mail-format.c

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

/*
 * Author :
 *  Matt Loper <matt@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-format.h"
#include "mail-display.h"
#include "camel/hash-table-utils.h"

#include <libgnome/libgnome.h>

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

static void handle_text_plain            (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_text_enriched         (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_text_html             (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_image                 (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_multipart_mixed       (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_multipart_related     (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_multipart_alternative (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_audio                 (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_message_rfc822        (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);

static void handle_unknown_type          (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);
static void handle_via_bonobo            (CamelMimePart *part,
                      CamelMimeMessage *root,
                      GtkBox *box);

/* encodes some characters into their 'escaped' version;
 * so '<' turns into '&lt;', and '"' turns into '&quot;' */
static gchar *text_to_html (const guchar *input, guint len,
                guint *encoded_len_return, gboolean add_pre,
                gboolean convert_newlines_to_br);

/* writes the header info for a mime message into an html stream */
static void write_headers (CamelMimeMessage *mime_message, GtkBox *box);

/* dispatch html printing via mimetype */
static void call_handler_function (CamelMimePart *part,
                   CamelMimeMessage *root,
                   GtkBox *box);



/**
 * mail_format_mime_message: 
 * @mime_message: the input mime message
 * @box: GtkBox to stack elements into.
 *
 * Writes a CamelMimeMessage out, as a series of GtkHTML objects,
 * into the provided box.
 **/
void
mail_format_mime_message (CamelMimeMessage *mime_message, GtkBox *box)
{
    g_return_if_fail (CAMEL_IS_MIME_MESSAGE (mime_message));
    g_return_if_fail (GTK_IS_BOX (box));

    write_headers (mime_message, box);
    call_handler_function (CAMEL_MIME_PART (mime_message),
                   mime_message, box);
}

static char *
get_cid (CamelMimePart *part, CamelMimeMessage *root)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    char *cid;

    /* 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 (camel_mime_part_get_content_id (part));
    else
        cid = g_strdup_printf ("@@@%p", wrapper);

    gtk_object_set_data (GTK_OBJECT (root), cid, wrapper);
    return cid;
}

/* This tries to create a tag, given a mimetype and the child of a
 * mime message. It can return NULL if it can't match the mimetype to
 * a bonobo object.
 */
static char *
get_bonobo_tag_for_object (CamelMimePart *part, CamelMimeMessage *root)
{
    GMimeContentField *type;
    char *cid = get_cid (part, root), *mimetype;
    const char *goad_id;

    type = camel_data_wrapper_get_mime_type_field (
        camel_medium_get_content_object (CAMEL_MEDIUM (part)));
    mimetype = g_strdup_printf ("%s/%s", type->type, type->subtype);
    goad_id = gnome_mime_get_value (mimetype, "bonobo-goad-id");
    g_free (mimetype);

    if (!goad_id)
        goad_id = gnome_mime_get_value (type->type, "bonobo-goad-id");

    if (goad_id) {
        return g_strdup_printf ("<object classid=\"%s\"> "
                    "<param name=\"uid\" "
                    "value=\"cid:%s\"></object>",
                    goad_id, cid);
    } else
        return NULL;
}


/* We're maintaining a hashtable of mimetypes -> functions;
 * Those functions have the following signature...
 */
typedef void (*mime_handler_fn) (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box);

static GHashTable *mime_function_table;
static GHashTable *mime_icon_table;

static void
setup_function_table (void)
{
    mime_function_table = g_hash_table_new (g_strcase_hash,
                        g_strcase_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, "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);
    /* RFC 2046 says unrecognized multipart subtypes should be
     * treated like multipart/mixed.
     */
    g_hash_table_insert (mime_function_table, "multipart",
                 handle_multipart_mixed);
}

static CamelStream *
icon_stream (char *path)
{
    GByteArray *ba;
    char buf[8192];
    int fd, nread;

    fd = open (path, O_RDONLY);
    if (fd == -1)
        return 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);
    return camel_stream_mem_new_with_byte_array (ba, CAMEL_STREAM_MEM_READ);
}

static void
setup_icon_table (void)
{
    char *path;

    mime_icon_table = g_hash_table_new (g_strcase_hash,
                        g_strcase_equal);

    path = gnome_pixmap_file ("gnome-audio2.png");
    if (path) {
        g_hash_table_insert (mime_icon_table, "audio",
                     icon_stream (path));
        g_free (path);
    }
    path = gnome_pixmap_file ("gnome-graphics.png");
    if (path) {
        g_hash_table_insert (mime_icon_table, "image",
                     icon_stream (path));
        g_free (path);
    }
    path = gnome_pixmap_file ("gnome-qeye.png");
    if (path) {
        g_hash_table_insert (mime_icon_table, "video",
                     icon_stream (path));
        g_free (path);
    }
    path = gnome_pixmap_file ("gnome-question.png");
    if (path) {
        g_hash_table_insert (mime_icon_table, "unknown",
                     icon_stream (path));
        g_free (path);
    }
}

static mime_handler_fn
lookup_handler (CamelMimePart *part)
{
    CamelDataWrapper *wrapper;
    mime_handler_fn handler_function;
    const char *goad_id;
    char *mimetype_whole = NULL;
    char *mimetype_main = NULL;

    g_return_val_if_fail (CAMEL_IS_MIME_PART (part), NULL);

    if (mime_function_table == NULL) {
        setup_function_table ();
        setup_icon_table ();
    }

    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (part));

    /* Try to find a handler function in our own lookup table. */
    mimetype_whole = camel_data_wrapper_get_mime_type (wrapper);
    g_strdown (mimetype_whole);

    handler_function = g_hash_table_lookup (mime_function_table,
                        mimetype_whole);
    if (handler_function)
        goto out;

    mimetype_main = g_strdup (wrapper->mime_type->type);
    g_strdown (mimetype_main);

    handler_function = g_hash_table_lookup (mime_function_table,
                        mimetype_main);
    if (handler_function)
        goto out;

    /* See if there's a bonobo control that can show the object. */
    goad_id = gnome_mime_get_value (mimetype_whole, "bonobo-goad-id");
    if (goad_id) {
        handler_function = handle_via_bonobo;
        goto out;
    }

    goad_id = gnome_mime_get_value (mimetype_main, "bonobo-goad-id");
    if (goad_id)
        handler_function = handle_via_bonobo;

 out:
    if (mimetype_whole)
        g_free (mimetype_whole);
    if (mimetype_main)
        g_free (mimetype_main);

    return handler_function;
}

static void
call_handler_function (CamelMimePart *part, CamelMimeMessage *root,
               GtkBox *box)
{
    CamelDataWrapper *wrapper;
    mime_handler_fn handler_function = NULL;

    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (part));

    handler_function = lookup_handler (part);

    if (handler_function)
        (*handler_function) (part, root, box);
    else
        handle_unknown_type (part, root, box);
}


/* Convert plain text into equivalent-looking valid HTML. */
static gchar *
text_to_html (const guchar *input, guint len,
          guint *encoded_len_return, gboolean add_pre,
          gboolean convert_newlines_to_br)
{
    const guchar *cur = input;
    guchar *buffer = NULL;
    guchar *out = NULL;
    gint buffer_size = 0;

    /* Allocate a translation buffer.  */
    buffer_size = len * 2 + 5;
    buffer = g_malloc (buffer_size);

    out = buffer;
    if (add_pre)
        out += sprintf (out, "<PRE>\n");

    while (len--) {
        if (out - buffer > buffer_size - 100) {
            gint index = out - buffer;

            buffer_size *= 2;
            buffer = g_realloc (buffer, buffer_size);
            out = buffer + index;
        }

        switch (*cur) {
        case '<':
            strcpy (out, "&lt;");
            out += 4;
            break;

        case '>':
            strcpy (out, "&gt;");
            out += 4;
            break;

        case '&':
            strcpy (out, "&amp;");
            out += 5;
            break;

        case '"':
            strcpy (out, "&quot;");
            out += 6;
            break;

        case '\n':
            *out++ = *cur;
            if (convert_newlines_to_br) {
                strcpy (out, "<br>");
                out += 4;
            }
            break;

        default:
            if ((*cur >= 0x20 && *cur < 0x80) ||
                (*cur == '\r' || *cur == '\t')) {
                /* Default case, just copy. */
                *out++ = *cur;
            } else
                out += g_snprintf(out, 9, "&#%d;", *cur);
            break;
        }

        cur++;
    }

    if (add_pre)
        strcpy (out, "</PRE>");
    else
        *out = '\0';
    if (encoded_len_return)
        *encoded_len_return = out - buffer;

    return buffer;
}

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

    if (value) {
        unsigned char *p;

        encoded_value = text_to_html (value, strlen(value),
                          NULL, FALSE, TRUE);
        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 GList *recipients, gboolean bold,
                GtkHTML *html,
                GtkHTMLStreamHandle *stream)
{
    gchar *recipients_string = NULL;

    while (recipients) {
        gchar *old_string = recipients_string;
        recipients_string =
            g_strdup_printf ("%s%s%s",
                     old_string ? old_string : "",
                     old_string ? "; " : "",
                     (gchar *)recipients->data);
        g_free (old_string);

        recipients = recipients->next;
    }

    write_field_to_stream (recipient_type, recipients_string,
                   bold, html, stream);
    g_free (recipients_string);
}



static void
write_headers (CamelMimeMessage *mime_message, GtkBox *box)
{
    const GList *recipients;
    GtkHTML *html;
    GtkHTMLStreamHandle *stream;

    mail_html_new (&html, &stream, mime_message, FALSE);
    mail_html_write (html, stream, "%s%s", HTML_HEADER,
             "<BODY TEXT=\"#000000\" BGCOLOR=\"#EEEEEE\">\n");

    mail_html_write (html, stream, "<table>");

    /* A few fields will probably be available from the mime_message;
     * for each one that's available, write it to the output stream
     * with a helper function, 'write_field_to_stream'.
     */

    write_field_to_stream ("From:",
                   camel_mime_message_get_from (mime_message),
                   TRUE, html, stream);

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

    write_recipients_to_stream ("To:",
                    camel_mime_message_get_recipients (mime_message, CAMEL_RECIPIENT_TYPE_TO),
                    TRUE, html, stream);

    recipients = camel_mime_message_get_recipients (mime_message, CAMEL_RECIPIENT_TYPE_CC);
    if (recipients)
        write_recipients_to_stream ("Cc:", recipients, TRUE, html, stream);
    write_field_to_stream ("Subject:",
                   camel_mime_message_get_subject (mime_message),
                   TRUE, html, stream);

    mail_html_write (html, stream, "</table>");

    mail_html_end (html, stream, TRUE, box);
}

#define MIME_TYPE_WHOLE(a)  (gmime_content_field_get_mime_type ( \
                                      camel_mime_part_get_content_type (CAMEL_MIME_PART (a))))
#define MIME_TYPE_MAIN(a)  ((camel_mime_part_get_content_type (CAMEL_MIME_PART (a)))->type)
#define MIME_TYPE_SUB(a)   ((camel_mime_part_get_content_type (CAMEL_MIME_PART (a)))->subtype)


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

static void
handle_text_plain (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    GtkHTML *html;
    GtkHTMLStreamHandle *stream;
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    char *text;
    CamelStream *wrapper_output_stream;
    gchar tmp_buffer[4096];
    gint nb_bytes_read;
    gboolean empty_text = TRUE;

    mail_html_new (&html, &stream, root, TRUE);
    mail_html_write (html, stream, "\n<!-- text/plain -->\n<pre>\n");

    /* Get the output stream of the data wrapper. */
    wrapper_output_stream = camel_data_wrapper_get_output_stream (wrapper);
    camel_stream_reset (wrapper_output_stream);

    do {
        /* Read next chunk of text. */
        nb_bytes_read = camel_stream_read (wrapper_output_stream,
                           tmp_buffer,
                           sizeof (tmp_buffer));

        /* If there's any text, write it to the stream. */
        if (nb_bytes_read > 0) {
            int returned_strlen;

            empty_text = FALSE;

            /* replace '<' with '&lt;', etc. */
            text = text_to_html (tmp_buffer,
                         nb_bytes_read,
                         &returned_strlen,
                         FALSE, FALSE);
            gtk_html_write (html, stream, text,
                    returned_strlen);
            g_free (text);
        }
    } while (!camel_stream_eos (wrapper_output_stream));

    if (empty_text)
        mail_html_write (html, stream, "<b>(empty)</b>");

    mail_html_write (html, stream, "</pre>\n");
    mail_html_end (html, stream, TRUE, box);
}

/* text/enriched (RFC 1896) or text/richtext (included in RFC 1341) */
static void
handle_text_enriched (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    static GHashTable *translations = NULL;
    GtkHTML *html;
    GtkHTMLStreamHandle *stream;
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelStream *memstream;
    GByteArray *ba;
    char *p;
    int len, nofill = 0;

    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, "nl", "<br>");
        g_hash_table_insert (translations, "np", "<hr>");
    }

    mail_html_new (&html, &stream, root, TRUE);
    mail_html_write (html, stream, "\n<!-- text/enriched -->\n");

    ba = g_byte_array_new ();
    memstream = camel_stream_mem_new_with_byte_array (ba, CAMEL_STREAM_MEM_WRITE);
    camel_data_wrapper_write_to_stream (wrapper, memstream);
    g_byte_array_append (ba, "", 1);

    p = ba->data;

    while (p) {
        len = strcspn (p, " <>&\n");
        if (len)
            gtk_html_write (html, stream, p, len);

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

        switch (*p++) {
        case ' ':
            while (*p == ' ') {
                mail_html_write (html, stream, "&nbsp;");
                p++;
            }
            mail_html_write (html, stream, " ");
            break;

        case '\n':
            mail_html_write (html, stream, " ");
            if (nofill <= 0) {
                while (*p == '\n') {
                    mail_html_write (html, stream, "<br>");
                    p++;
                }
            }
            break;

        case '>':
            mail_html_write (html, stream, "&gt;");
            break;

        case '&':
            mail_html_write (html, stream, "&amp;");
            break;

        case '<':
            if (*p == '<') {
                mail_html_write (html, stream, "&lt;");
                break;
            }

            if (strncmp (p, "lt>", 3) == 0)
                mail_html_write (html, stream, "&lt;");
            else if (strncmp (p, "nofill>", 7) == 0) {
                nofill++;
                mail_html_write (html, stream, "<pre>");
            } else if (strncmp (p, "/nofill>", 8) == 0) {
                nofill--;
                mail_html_write (html, stream, "</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)
                    mail_html_write (html, stream, match);
            }

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

    mail_html_end (html, stream, TRUE, box);
}

static void
handle_text_html (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    GtkHTML *html;
    GtkHTMLStreamHandle *stream;
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelStream *wrapper_output_stream;
    gchar tmp_buffer[4096];
    gint nb_bytes_read;
    gboolean empty_text = TRUE;

    mail_html_new (&html, &stream, root, FALSE);
    mail_html_write (html, stream, "\n<!-- text/html -->\n");

    /* Get the output stream of the data wrapper. */
    wrapper_output_stream = camel_data_wrapper_get_output_stream (wrapper);
    camel_stream_reset (wrapper_output_stream);

    do {
        /* Read next chunk of text. */
        nb_bytes_read = camel_stream_read (wrapper_output_stream,
                           tmp_buffer, 4096);

        /* If there's any text, write it to the stream */
        if (nb_bytes_read > 0) {
            empty_text = FALSE;
            
            /* Write the buffer to the html stream */
            gtk_html_write (html, stream, tmp_buffer,
                    nb_bytes_read);
        }
    } while (!camel_stream_eos (wrapper_output_stream));

    if (empty_text)
        mail_html_write (html, stream, "<b>(empty)</b>");

    mail_html_end (html, stream, FALSE, box);
}

static void
handle_image (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    GtkHTML *html;
    GtkHTMLStreamHandle *stream;
    char *cid;

    cid = get_cid (part, root);
    mail_html_new (&html, &stream, root, TRUE);
    mail_html_write (html, stream, "<img src=\"cid:%s\">", cid);
    mail_html_end (html, stream, TRUE, box);
    g_free (cid);
}

static void
handle_multipart_mixed (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelMultipart *mp;
    int i, nparts;

    g_return_if_fail (CAMEL_IS_MULTIPART (wrapper));
    mp = CAMEL_MULTIPART (wrapper);

    nparts = camel_multipart_get_number (mp);   
    for (i = 0; i < nparts; i++) {
        CamelMimeBodyPart *body_part =
            camel_multipart_get_part (mp, i);

        call_handler_function (CAMEL_MIME_PART (body_part), root, box);
    }
}

/* As seen in RFC 2387! */
static void
handle_multipart_related (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelMultipart *mp;
    CamelMimeBodyPart *body_part, *display_part = NULL;
    GMimeContentField *content_type;
    const char *start;
    int i, nparts;

    g_return_if_fail (CAMEL_IS_MULTIPART (wrapper));
    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 (
                CAMEL_MIME_PART (body_part));

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

        if (!display_part) {
            /* Oops. Hrmph. */
            handle_multipart_mixed (part, root, box);
        }
    } 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++) {
        char *cid;

        body_part = camel_multipart_get_part (mp, i);
        if (body_part == display_part)
            continue;

        part = CAMEL_MIME_PART (body_part);
        cid = get_cid (part, root);
        g_free (cid);
    }           

    /* Now, display the displayed part. */
    call_handler_function (CAMEL_MIME_PART (display_part), root, box);
}

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

    nparts = camel_multipart_get_number (multipart);
    for (i = 0; i < nparts; i++) {
        CamelMimePart *part = CAMEL_MIME_PART (
            camel_multipart_get_part (multipart, i));

        if (lookup_handler (part))
            preferred_part = part;
    }

    return preferred_part;
}

static void
handle_multipart_alternative (CamelMimePart *part, CamelMimeMessage *root,
                  GtkBox *box)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    CamelMultipart *multipart;
    CamelMimePart *mime_part;

    g_return_if_fail (CAMEL_IS_MULTIPART (wrapper));
    multipart = CAMEL_MULTIPART (wrapper);

    mime_part = find_preferred_alternative (multipart); 
    if (mime_part)
        call_handler_function (mime_part, root, box);
    else
        handle_unknown_type (part, root, box);
}

void
stream_destroy_notify (gpointer data)
{
    camel_stream_close (data);
}

static void
handle_mystery (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box,
        char *icon_cid, char *id, char *action)
{
    GtkHTML *html;
    GtkHTMLStreamHandle *stream;
    char *cid;

    cid = get_cid (part, root);
    mail_html_new (&html, &stream, root, TRUE);
    mail_html_write (html, stream, "<table><tr><td><a href=\"camel:%p\">"
             "<img src=\"camel:%p\"></a></td>"
             "<td>%s<br><br>Click on the icon to %s."
             "</td></tr></table>", get_cid (part, root),
             icon_cid, id, action);
    mail_html_end (html, stream, TRUE, box);
}

static void
handle_audio (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    char *cid, *id;

    cid = g_hash_table_lookup (mime_icon_table, "audio");
    id = g_strdup_printf ("Audio data in \"%s\" format.",
                  camel_mime_part_get_content_type (part)->subtype);
    handle_mystery (part, root, box, cid, id, "play it");
    g_free (id);
}

static void
handle_message_rfc822 (CamelMimePart *part, CamelMimeMessage *root,
               GtkBox *box)
{
    CamelDataWrapper *wrapper =
        camel_medium_get_content_object (CAMEL_MEDIUM (part));
    GtkWidget *subbox, *frame;

    g_return_if_fail (CAMEL_IS_MIME_MESSAGE (wrapper));

    subbox = gtk_vbox_new (FALSE, 2);
    mail_format_mime_message (CAMEL_MIME_MESSAGE (wrapper),
                  GTK_BOX (subbox));

    frame = gtk_frame_new (NULL);
    gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
    gtk_container_set_border_width (GTK_CONTAINER (frame), 8);
    gtk_box_pack_start (box, frame, FALSE, FALSE, 0);
    gtk_container_add (GTK_CONTAINER (frame), subbox);
    gtk_widget_show_all (frame);
}

static void
handle_unknown_type (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    char *cid, *id;

    cid = g_hash_table_lookup (mime_icon_table, "unknown");
    id = g_strdup_printf ("Unknown data of type \"%s/%s\".",
                  camel_mime_part_get_content_type (part)->type,
                  camel_mime_part_get_content_type (part)->subtype);
    handle_mystery (part, root, box, cid, id, "save it to disk");
    g_free (id);
}

static void
handle_via_bonobo (CamelMimePart *part, CamelMimeMessage *root, GtkBox *box)
{
    GtkHTML *html;
    GtkHTMLStreamHandle *stream;
    char *bonobo_tag = get_bonobo_tag_for_object (part, root);

    g_return_if_fail (bonobo_tag);

    mail_html_new (&html, &stream, root, TRUE);
    mail_html_write (html, stream, bonobo_tag);
    mail_html_end (html, stream, TRUE, box);

    g_free (bonobo_tag);
}


static char *
get_data_wrapper_text (CamelDataWrapper *data)
{
    CamelStream *memstream;
    GByteArray *ba;
    char *text;

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

    camel_data_wrapper_write_to_stream (data, memstream);
    text = g_malloc (ba->len + 1);
    memcpy (text, ba->data, ba->len);
    text[ba->len] = '\0';

    camel_stream_close (memstream);
    return text;
}

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

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

    if (strcasecmp (mime_type->type, "message") == 0)
        return get_data_wrapper_text (data);

    if (strcasecmp (mime_type->type, "text") == 0) {
        *html = !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 (strcasecmp (mime_type->type, "multipart") != 0)
        return NULL;

    mp = CAMEL_MULTIPART (data);

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

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

        return reply_body (camel_medium_get_content_object (CAMEL_MEDIUM (subpart)), html);
    }

    nparts = camel_multipart_get_number (mp);

    /* If any subpart is HTML, pull it out and reply to it by itself.
     * (If we supported any other non-plain text types, we'd do the
     * same for them here.)
     */
    for (i = 0; i < nparts; i++) {
        subpart = CAMEL_MIME_PART (camel_multipart_get_part (mp, i));
        subtype = camel_mime_part_get_content_type (subpart)->subtype;

        if (strcasecmp (subtype, "html") == 0)
            return reply_body (camel_medium_get_content_object (CAMEL_MEDIUM (subpart)), html);
    }

    /* Otherwise, concatenate all the parts that:
     *   - are text/plain or message
     *   - are not explicitly tagged with non-inline disposition
     */
    *html = FALSE;
    boundary = camel_multipart_get_boundary (mp);
    for (i = disparts = 0; i < nparts; i++) {
        subpart = CAMEL_MIME_PART (camel_multipart_get_part (mp, i));

        mime_type = camel_mime_part_get_content_type (subpart);
        if (strcasecmp (mime_type->type, "text") == 0) {
            if (strcasecmp (mime_type->subtype, "plain") != 0)
                continue;
        } else if (strcasecmp (mime_type->type, "message") != 0)
            continue;

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

        data = camel_medium_get_content_object (CAMEL_MEDIUM (subpart));
        subtext = get_data_wrapper_text (data);
        if (text) {
            old = text;
            text = g_strdup_printf ("%s\n--%s\n%s", text,
                        boundary, subtext);
            g_free (subtext);
            g_free (old);
            disparts++;
        } else
            text = subtext;
    }

    if (!text)
        return NULL;

    if (disparts > 1) {
        old = text;
        text = g_strdup_printf ("%s\n--%s--\n", text, boundary);
        g_free (old);
    }

    return text;
}

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

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

    composer = E_MSG_COMPOSER (e_msg_composer_new ());

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

        if (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 = text_to_html (quoted_text,
                          strlen (quoted_text),
                          &len, TRUE, FALSE);
            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, repl_to);

    if (to_all) {
        const GList *recip;

        recip = camel_mime_message_get_recipients (message, 
            CAMEL_RECIPIENT_TYPE_TO);
        cc = g_list_copy (recip);

        recip = camel_mime_message_get_recipients (message,
            CAMEL_RECIPIENT_TYPE_CC);
        while (recip) {
            cc = g_list_append (cc, recip->data);
            recip = recip->next;
        }
    } else
        cc = NULL;

    /* Set the subject of the new message. */
    subject = camel_mime_message_get_subject (message);
    if (!subject)
        subject = g_strdup ("");
    else 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;
}

/* This is part of the temporary kludge below. */
#ifndef HAVE_MKSTEMP
#include <fcntl.h>
#include <sys/stat.h>
#endif

EMsgComposer *
mail_generate_forward (CamelMimeMessage *mime_message,
               gboolean forward_as_attachment,
               gboolean keep_attachments)
{
    EMsgComposer *composer;
    char *tmpfile;
    int fd;
    CamelStream *stream;

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

    /* For now, we kludge by writing out a temp file. Later,
     * EMsgComposer will support attaching CamelMimeParts directly,
     * or something. FIXME.
     */
    tmpfile = g_strdup ("/tmp/evolution-kludge-XXXX");
#ifdef HAVE_MKSTEMP
    fd = mkstemp (tmpfile);
#else
    if (mktemp (tmpfile)) {
        fd = open (tmpfile, O_RDWR | O_CREAT | O_EXCL,
               S_IRUSR | S_IWUSR);
    } else
        fd = -1;
#endif
    if (fd == -1) {
        g_warning ("Couldn't create temp file for forwarding");
        g_free (tmpfile);
        return NULL;
    }

    stream = camel_stream_fs_new_with_fd (fd);
    camel_data_wrapper_write_to_stream (CAMEL_DATA_WRAPPER (mime_message),
                        stream);
    camel_stream_close (stream);

    composer = E_MSG_COMPOSER (e_msg_composer_new ());
    e_msg_composer_attachment_bar_attach (E_MSG_COMPOSER_ATTACHMENT_BAR (composer->attachment_bar), tmpfile);
    g_free (tmpfile);

    /* FIXME: should we default a subject? */

    return composer;
}