path: root/camel/camel-formatter.c

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

/*--------------------------------*-C-*---------------------------------*
 *
 * 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 "camel-formatter.h"
#include "camel-data-wrapper.h"
#include "camel-mime-message.h"
#include "camel-multipart.h"
#include "camel-recipient.h"

#include "camel-log.h"
#include <libgnome/libgnome.h>
#include <ctype.h>    /* for isprint */
#include <string.h>   /* for strstr  */

/*
 * The CamelFormatter takes a mime message, and produces html from it,
 * through the single function camel_formatter_mime_message_to_html().
 * The flow of execution goes something like this:
 *
 *     camel_formatter_mime_message_to_html()
 *                 |
 *                 V
 *        call_handler_function()
 *
 * Then, 'call_handler_function' acts as a dispatcher, using a
 * hashtable to match a mime type to one of the following functions;
 * note that the below functions sometimes then use
 * 'call_handler_function()' to continue the process recursively.
 */

static void handle_text_plain           (CamelFormatter *formatter,
                             CamelDataWrapper *wrapper);
static void handle_text_html            (CamelFormatter *formatter,
                             CamelDataWrapper *wrapper);
static void handle_image                (CamelFormatter *formatter,
                         CamelDataWrapper *wrapper);
static void handle_vcard                (CamelFormatter *formatter,
                         CamelDataWrapper *wrapper);
static void handle_mime_part            (CamelFormatter *formatter,
                             CamelDataWrapper *wrapper);
static void handle_multipart_mixed      (CamelFormatter *formatter,
                         CamelDataWrapper *wrapper);
static void handle_multipart_related    (CamelFormatter *formatter,
                         CamelDataWrapper *wrapper);
static void handle_multipart_alternative(CamelFormatter *formatter,
                         CamelDataWrapper *wrapper);
static void handle_unknown_type         (CamelFormatter *formatter,
                         CamelDataWrapper *wrapper);

/* 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);

/* compares strings case-insensitively */
static gint strcase_equal (gconstpointer v, gconstpointer v2);
static gchar* str_tolower (gchar* str);

/* writes the header info for a mime message into a stream */
static void write_header_info_to_stream (CamelMimeMessage* mime_message,
                     CamelStream* stream);

/* dispatch html printing via mimetype */
static void call_handler_function (CamelFormatter* formatter,
                   CamelDataWrapper* wrapper,
                   gchar* mimetype_whole, 
                   gchar* mimetype_main);

static GtkObjectClass *parent_class = NULL;

struct _CamelFormatterPrivate {
    CamelDataWrapper *current_root;
    CamelStream *stream;
    GHashTable *attachments;
};


static void
debug (const gchar *format, ...)
{
    va_list args;
    gchar *string;
    
    g_return_if_fail (format != NULL);
    
    va_start (args, format);
    string = g_strdup_vprintf (format, args);
    va_end (args);
    
    fputs (string, stdout);
    fflush (stdout);
    
    g_free (string);
}

static void
initialize_camel_formatter (CamelFormatter* formatter,
                CamelDataWrapper* data_wrapper,
                CamelStream* stream)
{
    CamelFormatterPrivate* fmt = formatter->priv;

    /* initialize members of our formatter */
    fmt->current_root = data_wrapper;
    fmt->stream = stream;
    if (fmt->attachments)
        g_hash_table_destroy (fmt->attachments);
    fmt->attachments = g_hash_table_new (g_str_hash, strcase_equal);
}


/**
 * camel_formatter_wrapper_to_html: 
 * @formatter: the camel formatter object
 * @data_wrapper: the data wrapper
 * @stream: byte stream where data will be written 
 *
 * Writes a CamelDataWrapper out, as html, into a stream passed in as
 * a parameter.
 **/
void camel_formatter_wrapper_to_html (CamelFormatter* formatter,
                      CamelDataWrapper* data_wrapper,
                      CamelStream* stream_out)
{
    CamelFormatterPrivate* fmt = formatter->priv;
    gchar *mimetype_whole =
        g_strdup_printf ("%s/%s",
                 data_wrapper->mime_type->type,
                 data_wrapper->mime_type->subtype);

    g_print ("camel_formatter_wrapper_to_html: entered\n");
    g_assert (formatter && data_wrapper && stream_out);

    /* give the root CamelDataWrapper and the stream to the formatter */
    initialize_camel_formatter (formatter, data_wrapper, stream_out);
    
    if (stream_out) {
        
        /* write everything to the stream */
        camel_stream_write_string (
            fmt->stream, "<html><body bgcolor=\"white\">\n");
        call_handler_function (
            formatter,
            data_wrapper,
            mimetype_whole,
            data_wrapper->mime_type->type);
        
        camel_stream_write_string (fmt->stream, "\n</body></html>\n");
    }
    

    g_free (mimetype_whole);
}


/**
 * camel_formatter_mime_message_to_html: 
 * @formatter: the camel formatter object
 * @mime_message: the input mime message
 * @header_stream: byte stream where data will be written (can be
 * NULL)
 * @body_stream: byte stream where data will be written (required)
 *
 * Writes a CamelMimeMessage out, as html, into a stream passed in as
 * a parameter.
 **/
void
camel_formatter_mime_message_to_html (CamelFormatter* formatter,
                      CamelMimeMessage* mime_message,
                      CamelStream* header_stream,
                      CamelStream* body_stream)
{
    g_print ("camel_formatter_mime_message_to_html: entered\n");

    g_assert (formatter != NULL);
    g_assert (CAMEL_IS_FORMATTER (formatter));
    g_assert (mime_message != NULL);
    g_assert (CAMEL_IS_MIME_MESSAGE (mime_message));
    
    g_assert (header_stream || body_stream);

    /* give the root CamelDataWrapper and the stream to the
           formatter */
    initialize_camel_formatter (formatter,
                    CAMEL_DATA_WRAPPER (mime_message),
                    body_stream);
    
    if (body_stream) {
        /* Write the contents of the mime message to the stream */
        camel_stream_write_string (body_stream, "<html><body>\n");
        call_handler_function (
            formatter,
            CAMEL_DATA_WRAPPER (mime_message),
            "message/rfc822",
            "message");
        camel_stream_write_string (body_stream, "\n</body></html>\n");
    }
    
    /* write the subj:, to:, from: etc. fields out as html to the
           header stream */
    if (header_stream)
        write_header_info_to_stream (mime_message,
                         header_stream);
}

/* we're maintaining a hashtable of mimetypes -> functions;
 * those functions have the following signature...*/
typedef void (*mime_handler_fn) (CamelFormatter *formatter,
                 CamelDataWrapper *data_wrapper);

static gchar*
lookup_unique_id (CamelDataWrapper* root, CamelDataWrapper* child)
{
    /* ** FIXME : replace this with a string representing
       the location of the objetc in the tree */
    /* TODO: assert our return value != NULL */

    gchar *temp_hack_uid;

    temp_hack_uid = g_strdup_printf ("%p", camel_data_wrapper_get_output_stream (child));

    return temp_hack_uid;
}

static GHashTable* mime_function_table;

/* 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 gchar*
get_bonobo_tag_for_object (CamelFormatter* formatter,
               CamelDataWrapper* wrapper,
               gchar* mimetype)
{
    
    CamelDataWrapper* root = formatter->priv->current_root;
    char* uid = lookup_unique_id (root, wrapper);
    const char* goad_id = gnome_mime_get_value (
        mimetype, "bonobo-goad-id");
    
    g_assert (root);
    
    if (goad_id) {
        
        char* tag = g_strdup_printf (
            "<object classid=\"%s\"> <param name=\"uid\" value=\"camel://%s\"> </object>",
            goad_id, uid);
        
        debug ("get_bonobo_tag_for_object: goad id %s found for mime type %s\n", goad_id, mimetype);
        return tag;
    }
    else
        return NULL;
}


/*
 * This takes a mimetype, and tries to map that mimetype to a function
 * or a bonobo object.
 *
 * - If it's mapped to a bonobo object, this function prints a tag
 *   into the stream, designating the bonobo object and a place that
 *   the bonobo object can find data to hydrate from
 *
 * - otherwise, the mimetype is mapped to another function, which can
 *   print into the stream
 */
static void
call_handler_function (CamelFormatter* formatter,
               CamelDataWrapper* wrapper,
               gchar* mimetype_whole_in, /* ex. "image/jpeg" */
               gchar* mimetype_main_in)  /* ex. "image" */
{
    mime_handler_fn handler_function = NULL;
    gchar* mimetype_whole = NULL;
    gchar* mimetype_main = NULL;

    g_assert (formatter);
    g_assert (mimetype_whole_in || mimetype_main_in);
    g_assert (wrapper);
    
/*
 * Try to find a handler function in our own lookup table
 */
    if (mimetype_whole_in) {
        mimetype_whole = str_tolower (mimetype_whole_in);
        
        handler_function = g_hash_table_lookup (
            mime_function_table, mimetype_whole);
    }

    if (mimetype_main_in)
        mimetype_main = str_tolower (mimetype_main_in); 

    if (mimetype_main && !handler_function)
        handler_function = g_hash_table_lookup (
            mime_function_table, mimetype_main);
/*
 * Upon failure, try to find a bonobo object to show the object
 */
    if (!handler_function) {

        gchar* bonobo_tag = NULL;

        if (mimetype_whole)
            bonobo_tag = get_bonobo_tag_for_object (
                formatter, wrapper, mimetype_whole);

        if (mimetype_main && !bonobo_tag)
            bonobo_tag = get_bonobo_tag_for_object (
                formatter, wrapper, mimetype_main);         

        if (bonobo_tag) {

            /* we can print a tag, and return! */
            camel_stream_write_string (
                formatter->priv->stream, bonobo_tag);
            g_free (bonobo_tag);
            if (mimetype_whole) g_free (mimetype_whole);
            if (mimetype_main) g_free (mimetype_main);          
            
            return; 
        }
    }
/*
 * Use either a handler function we've found, or a default handler
 */
    if (handler_function)
        (*handler_function)(formatter, wrapper);
    else {
        handle_unknown_type (formatter, wrapper);
        debug ("no function or bonobo object found for mimetype \"%s\"\n",
               mimetype_whole?mimetype_whole:mimetype_main);
    }
    if (mimetype_whole) g_free (mimetype_whole);
    if (mimetype_main) g_free (mimetype_main);              
}


/*----------------------------------------------------------------------*
 *     Header (ex. "subj:", "from:") helper functions for mime msgs
 *----------------------------------------------------------------------*/

/* This routine was originally written by Daniel Velliard, (C) 1998
 * World Wide Web Consortium.
 * - It will (for example) turn the input 'ab <c>' into 'ab &lt;c&gt;'
 * - It has also been altered to turn '\n' into <br>. */
static gchar *
text_to_html (const guchar *input,
         guint len,
         guint *encoded_len_return)
{
    const guchar *cur = input;
    guchar *buffer = NULL;
    guchar *out = NULL;
    gint buffer_size = 0;
    guint count;

    /* Allocate a translation buffer.  */
    buffer_size = 1000;
    buffer = g_malloc (buffer_size);

    out = buffer;
    count = 0;

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

            buffer_size *= 2;
            buffer = g_realloc (buffer, buffer_size);
            out = &buffer[index];
        }

        /* By default one has to encode at least '<', '>', '"'
                   and '&'.  */
        if (*cur == '<') {
            *out++ = '&';
            *out++ = 'l';
            *out++ = 't';
            *out++ = ';';
        } else if (*cur == '>') {
            *out++ = '&';
            *out++ = 'g';
            *out++ = 't';
            *out++ = ';';
        } else if (*cur == '&') {
            *out++ = '&';
            *out++ = 'a';
            *out++ = 'm';
            *out++ = 'p';
            *out++ = ';';
        } else if (*cur == '"') {
            *out++ = '&';
            *out++ = 'q';
            *out++ = 'u';
            *out++ = 'o';
            *out++ = 't';
            *out++ = ';';
        } else if (((*cur >= 0x20) && (*cur < 0x80))
               || (*cur == '\n') || (*cur == '\r') || (*cur == '\t')) {
            /* Default case, just copy. */
            *out++ = *cur;
        } else {
            char buf[10], *ptr;

            g_snprintf(buf, 9, "&#%d;", *cur);

            ptr = buf;
            while (*ptr != 0)
                *out++ = *ptr++;
        }

        /* turn newlines into <br> */
        if (*cur == '\n') {
            *out++ = '<';
            *out++ = 'b';
            *out++ = 'r';
            *out++ = '>';               
        }
    

        cur++;
        count++;
    }

    *out = 0;
    *encoded_len_return = out - buffer;

    return buffer;
}


static void
write_field_to_stream (const gchar* description, const gchar* value,
               CamelStream *stream, gboolean as_table_row)
{
    gchar *s;
    guint ev_length;
    gchar* encoded_value = value?text_to_html (
        value, strlen(value), &ev_length):"";
    int i;
    for (i = 0; i < strlen (value); i++)
        if (!isprint(encoded_value[i]))
            encoded_value[i] = 'Z';
    
    g_assert (description && value);
    
    s = g_strdup_printf ("%s<b>%s</b>%s%s%s\n",
                 as_table_row?"<tr><td>":"",
                 description,
                 as_table_row?"</td><td>":" ",
                 encoded_value,
                 as_table_row?"</td></tr>":"<br>");

    camel_stream_write_string (stream, s);
    g_free (encoded_value);
    g_free (s);
}


static void
write_recipients_to_stream (const gchar* recipient_type,
                const GList* recipients,
                CamelStream* stream,
                gboolean as_table_row)
{
    /* list of recipients, like "elvis@graceland; bart@springfield" */
    gchar *recipients_string = NULL;
    g_assert (recipient_type && stream);
    
    /* Write out each recipient of 'recipient_type' to the stream */
    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, stream,
                   as_table_row);

    g_free (recipients_string);
}



static void
write_header_info_to_stream (CamelMimeMessage* mime_message,
                 CamelStream* stream)
{
    gchar *s = NULL;
    const GList *recipients = NULL;

    g_assert (mime_message && stream);

    camel_stream_write_string (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'. */
    if ((s = (gchar*)camel_mime_message_get_subject (mime_message))) {
        write_field_to_stream ("Subject: ", s, stream, TRUE);
    }

    if ((s = (gchar*)camel_mime_message_get_from (mime_message))) {
        write_field_to_stream ("From: ", s, stream, TRUE);
    }

    if ((s = (gchar*)camel_mime_message_get_received_date (mime_message))) {
        write_field_to_stream ("Received Date: ", s, stream, TRUE);
    }

    if ((s = (gchar*)camel_mime_message_get_sent_date (mime_message))) {
        write_field_to_stream ("Sent Date: ", s, stream, TRUE);
    }       
 
    /* Fill out the "To:" recipients line */
    recipients = camel_mime_message_get_recipients (
        mime_message, CAMEL_RECIPIENT_TYPE_TO);
    
    if (recipients)
        write_recipients_to_stream ("To:", recipients, stream, TRUE);

    /* Fill out the "CC:" recipients line */
    recipients = camel_mime_message_get_recipients (
        mime_message, CAMEL_RECIPIENT_TYPE_CC);
    if (recipients)
        write_recipients_to_stream ("CC:", recipients, stream, TRUE);   

    /* Fill out the "BCC:" recipients line */
    recipients = camel_mime_message_get_recipients (
        mime_message, CAMEL_RECIPIENT_TYPE_BCC);    
    if (recipients)
        write_recipients_to_stream ("BCC:", recipients, stream, TRUE);

    camel_stream_write_string (stream, "</table>"); 
}

/* case-insensitive string comparison */
static gint
strcase_equal (gconstpointer v, gconstpointer v2)
{
    return g_strcasecmp ((const gchar*) v, (const gchar*)v2) == 0;
}

static gchar*
str_tolower (gchar* str)
{
    int i;
    int len = strlen (str);
    gchar* new_str = g_strdup (str);
    
    for (i = 0; i < len; i++) {
        new_str[i] = tolower (str[i]);
    }
    return new_str;
}

 
#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 (CamelFormatter *formatter, CamelDataWrapper *wrapper)
{
    gchar* text;
    CamelStream *wrapper_output_stream;
    gchar tmp_buffer[4096];
    gint nb_bytes_read;
    gboolean empty_text = TRUE;

    debug ("handle_text_plain: entered\n");
    
    camel_stream_write_string (formatter->priv->stream,
                   "\n<!-- text/plain below -->\n");

    if (strcmp (wrapper->mime_type->subtype, "richtext") == 0) {

        camel_stream_write_string (
            formatter->priv->stream,
            "<center><b><table bgcolor=\"b0b0ff\" cellpadding=3><tr><td>Warning: the following richtext may not");
        camel_stream_write_string (
            formatter->priv->stream,
            " be formatted correctly. </b></td></tr></table></center><br>");
    }

    /* 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) {
            
            int returned_strlen;
            
            empty_text = FALSE;

            /* replace '<' with '&lt;', etc. */
            text = text_to_html (tmp_buffer,
                         nb_bytes_read,
                         &returned_strlen);
            
            camel_stream_write_string (formatter->priv->stream, text);
            g_free (text);
        }
        
        
    } while (!camel_stream_eos (wrapper_output_stream));


    if (empty_text) {
        debug ("Warning: handle_text_plain: text part is empty!\n");
        camel_stream_write_string (formatter->priv->stream,
                       "<b>(empty)</b>");
    }
    
    debug ("handle_text_plain: exiting\n");
}

static void
handle_text_html (CamelFormatter *formatter, CamelDataWrapper *wrapper)
{
    CamelStream *wrapper_output_stream;
    gchar tmp_buffer[4096];
    gint nb_bytes_read;
    gboolean empty_text = TRUE;
    

    debug ("handle_text_html: entered\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);

    /* write the header */
    camel_stream_write_string (formatter->priv->stream,
                       "\n<!-- text/html below -->\n");

    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 formater output  stream */
            camel_stream_write (formatter->priv->stream, tmp_buffer, nb_bytes_read);
        }
        
        
    } while (!camel_stream_eos (wrapper_output_stream));


    if (empty_text) {
        debug ("Warning: handle_text_html: html part is empty!\n");
        camel_stream_write_string (formatter->priv->stream,
                       "<b>(empty)</b>");
    }

    debug ("handle_text_html: exiting\n");      
}

static void
handle_image (CamelFormatter *formatter, CamelDataWrapper *wrapper)
{
    gchar* uuid;
    gchar* tag;
    
    debug ("handle_image: entered\n");

    uuid = lookup_unique_id (formatter->priv->current_root, wrapper);
    
    tag = g_strdup_printf ("<img src=\"camel://%s\">\n", uuid);
    camel_stream_write_string (formatter->priv->stream, tag);
    debug ("handle_image: tag=%s\n", tag);
    g_free (uuid);
    g_free (tag);       
    
    debug ("handle_image: exiting\n");  
}

static void
handle_vcard (CamelFormatter *formatter, CamelDataWrapper *wrapper)
{
    gchar* vcard = NULL;
    debug ("handle_vcard: entered\n");

    camel_stream_write_string (formatter->priv->stream,
                   "\n<!-- image below -->\n"); 
//  camel_stream_write_string (formatter->priv->stream, vcard);
//  g_free (vcard);
        
    debug ("handle_vcard: exiting\n");  
}

static void
handle_mime_part (CamelFormatter *formatter,
          CamelDataWrapper *wrapper)
{
    CamelMimePart* mime_part; 
    CamelDataWrapper* message_contents; 

    g_assert (formatter);
    g_assert (wrapper);
    g_assert (CAMEL_IS_MIME_PART (wrapper));
    
    mime_part = CAMEL_MIME_PART (wrapper);
    message_contents =
        camel_medium_get_content_object (CAMEL_MEDIUM (mime_part));
    
    g_assert (message_contents);
    
    debug ("handle_mime_part: entered\n");
    camel_stream_write_string (formatter->priv->stream,
                   "\n<!-- mime message below -->\n");
    
//  camel_stream_write_string (formatter->priv->stream,
//                 "<table width=95% border=1><tr><td>\n\n");       

    /* dispatch the correct handler function for the mime type */
    call_handler_function (formatter, message_contents,
                   MIME_TYPE_WHOLE (mime_part),
                   MIME_TYPE_MAIN (mime_part));
    
    /* close up the table we opened */
//  camel_stream_write_string (formatter->priv->stream,
//                 "\n\n</td></tr></table>\n\n");
    
    debug ("handle_mime_part: exiting\n");
}


/*
 * multipart-alternative helper function --
 * returns NULL if no text/html or text/plan msg is found
 */
static CamelMimePart*
find_preferred_displayable_body_part_in_multipart_alternative (
    CamelMultipart* multipart)
{
    int i, max_multiparts;
    CamelMimePart* html_part = NULL;
    CamelMimePart* plain_part = NULL;   

    /* find out out many parts are in it...*/
    max_multiparts = camel_multipart_get_number (multipart);

        /* TODO: DO LEAF-LOOKUP HERE FOR OTHER MIME-TYPES!!! */

    for (i = 0; i < max_multiparts; i++) {
        CamelMimeBodyPart* body_part =
            camel_multipart_get_part (multipart, i);

        if (!strcase_equal (MIME_TYPE_MAIN (body_part), "text"))
            continue;
        
        if (strcase_equal (MIME_TYPE_SUB (body_part), "plain")) {
            plain_part = CAMEL_MIME_PART (body_part);
        }
        else if (strcase_equal (MIME_TYPE_SUB (body_part), "html")) {
            html_part = CAMEL_MIME_PART (body_part);
        }
    }

    if (html_part)
        return html_part;
    if (plain_part)
        return plain_part;
    return NULL;
}


/* called for each body part in a multipart/mixed */
static void
print_camel_body_part (CamelMimeBodyPart* body_part,
               CamelFormatter* formatter,
               gboolean* text_printed_yet)
{
    CamelDataWrapper* contents =
        camel_medium_get_content_object (CAMEL_MEDIUM (body_part));
    gboolean is_text =
        strcase_equal (MIME_TYPE_MAIN (body_part), "text");

    if (is_text && *text_printed_yet)
        return;

    call_handler_function (formatter, contents, MIME_TYPE_WHOLE (body_part),
                   MIME_TYPE_MAIN (body_part));
    camel_stream_write_string (formatter->priv->stream, "\n<hr>\n");
}



/* Our policy here is this:
   (1) print text/(plain|html) parts found
   (2) print vcards and images inline
   (3) treat all other parts as attachments */
static void
handle_multipart_mixed (CamelFormatter *formatter,
            CamelDataWrapper *wrapper)
{
    CamelMultipart* mp;
    gboolean text_printed_yet = FALSE;

    g_assert (formatter);
    g_assert (wrapper);
    g_assert (CAMEL_IS_MULTIPART (wrapper));
    
    mp = CAMEL_MULTIPART (wrapper);
    g_assert (mp);
    
//  debug ("handle_multipart_mixed: entered\n");


    {
        int i, max_multiparts;

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

            print_camel_body_part (body_part, formatter, &text_printed_yet);
        }
    }


//  debug ("handle_multipart_mixed: exiting\n");    
}

static void
handle_multipart_related (CamelFormatter *formatter,
              CamelDataWrapper *wrapper)
{
    CamelMultipart* mp = CAMEL_MULTIPART (wrapper);
    debug ("handle_multipart_related: entered\n");

    debug ("handle_multipart_related: NYI!!\n");
    
    /* TODO: read RFC, in terms of how a one message
             may refer to another object */ 

    debug ("handle_multipart_related: exiting\n");  
}

/*
   The current policy for multipart/alternative is this: 

   if (we find a text/html body part)
       we print it
   else if (we find a text/plain body part)
       we print it
   else
       we print nothing
*/
static void
handle_multipart_alternative (CamelFormatter *formatter,
                CamelDataWrapper *wrapper)
{
    CamelMultipart* multipart = CAMEL_MULTIPART (wrapper);
    CamelMimePart* mime_part;
    
    debug ("handle_multipart_alternative: entered\n");

    mime_part =
        find_preferred_displayable_body_part_in_multipart_alternative(
        multipart); 
    if (mime_part) {

        CamelDataWrapper* contents =
            camel_medium_get_content_object (
                CAMEL_MEDIUM (mime_part));

        call_handler_function (formatter, contents,
                       MIME_TYPE_WHOLE (mime_part),
                       MIME_TYPE_MAIN (mime_part));
    }
    
    debug ("handle_multipart_alternative: exiting\n");      
}

static void
handle_unknown_type (CamelFormatter *formatter,
             CamelDataWrapper *wrapper)
{
    gchar* tag;
    CamelDataWrapper* root = formatter->priv->current_root;
    char* uid = lookup_unique_id (root, wrapper);   

    debug ("handle_unknown_type: entered\n");
    
    tag = g_strdup_printf ("<a href=\"camel://%s\">click-me-to-save</a>\n",
                   uid);

    camel_stream_write_string (formatter->priv->stream, tag);

    debug ("handle_unknown_type: exiting\n");
}

/*----------------------------------------------------------------------*
 *                   Standard Gtk+ class functions
 *----------------------------------------------------------------------*/

CamelFormatter*
camel_formatter_new ()
{
    return (gtk_type_new (CAMEL_FORMATTER_TYPE));
}


static void           
_finalize (GtkObject* object)
{
    CamelFormatter *formatter = CAMEL_FORMATTER (object);

    if (formatter->priv->attachments)
        g_hash_table_destroy (formatter->priv->attachments);
    
    g_free (formatter->priv);
    
    GTK_OBJECT_CLASS (parent_class)->finalize (object);
}

static void
camel_formatter_class_init (CamelFormatterClass *camel_formatter_class)
{
    GtkObjectClass *gtk_object_class =
        GTK_OBJECT_CLASS (camel_formatter_class);

    parent_class = gtk_type_class (gtk_object_get_type ());

    mime_function_table =
        g_hash_table_new (g_str_hash, strcase_equal);

#define ADD_HANDLER(a,b) g_hash_table_insert (mime_function_table, a, b)

    /* hook up mime types to functions that handle them */
    ADD_HANDLER ("text/plain", handle_text_plain);
    ADD_HANDLER ("text/richtext", handle_text_plain);   
    ADD_HANDLER ("text/html", handle_text_html);
    ADD_HANDLER ("multipart/alternative", handle_multipart_alternative);
    ADD_HANDLER ("multipart/related", handle_multipart_related);
    ADD_HANDLER ("multipart/mixed", handle_multipart_mixed);    
    ADD_HANDLER ("message/rfc822", handle_mime_part);
    ADD_HANDLER ("image", handle_image);
    ADD_HANDLER ("vcard", handle_vcard);            

    /* body parts don't have mime parts per se, so camel
       sticks on the following one */
    ADD_HANDLER ("mime/body-part", handle_mime_part);
    
        /* virtual method overload */
    gtk_object_class->finalize = _finalize;
}
 

static void
camel_formatter_init (gpointer object, gpointer klass) 
{
    CamelFormatter* cmf = CAMEL_FORMATTER (object);
    cmf->priv = g_new (CamelFormatterPrivate, 1);
    cmf->priv->attachments = NULL;
}

 
GtkType
camel_formatter_get_type (void)
{
    static GtkType camel_formatter_type = 0;
    
    if (!camel_formatter_type)  {
        GtkTypeInfo camel_formatter_info =  
        {
            "CamelFormatter",
            sizeof (CamelFormatter),
            sizeof (CamelFormatterClass),
            (GtkClassInitFunc) camel_formatter_class_init,
            (GtkObjectInitFunc) camel_formatter_init,
                /* reserved_1 */ NULL,
                /* reserved_2 */ NULL,
            (GtkClassInitFunc) NULL,
        };
        
        camel_formatter_type = gtk_type_unique (
            gtk_object_get_type (),
            &camel_formatter_info);
    }
    
    return camel_formatter_type;
}