path: root/modules/prefer-plain/e-mail-parser-prefer-plain.c

/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

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

#include <string.h>
#include <gtk/gtk.h>
#include <glib/gi18n.h>

#include "e-mail-parser-prefer-plain.h"

#include <em-format/e-mail-extension-registry.h>
#include <em-format/e-mail-parser-extension.h>
#include <em-format/e-mail-part.h>
#include <em-format/e-mail-part-utils.h>

#include <libebackend/libebackend.h>

#define d(x)

typedef struct _EMailParserPreferPlain EMailParserPreferPlain;
typedef struct _EMailParserPreferPlainClass EMailParserPreferPlainClass;

typedef EExtension EMailParserPreferPlainLoader;
typedef EExtensionClass EMailParserPreferPlainLoaderClass;

struct _EMailParserPreferPlain {
    EMailParserExtension parent;

    GSettings *settings;
    gint mode;
    gboolean show_suppressed;
};

struct _EMailParserPreferPlainClass {
    EMailParserExtensionClass parent_class;
};

GType e_mail_parser_prefer_plain_get_type (void);

enum {
    PREFER_HTML,
    PREFER_PLAIN,
    ONLY_PLAIN
};

G_DEFINE_DYNAMIC_TYPE (
    EMailParserPreferPlain,
    e_mail_parser_prefer_plain,
    E_TYPE_MAIL_PARSER_EXTENSION)

static const gchar *parser_mime_types[] = {
    "multipart/alternative",
    "text/html",
    NULL
};

static struct {
    const gchar *key;
    const gchar *label;
    const gchar *description;
} epp_options[] = {
    { "normal",
      N_("Show HTML if present"),
      N_("Let Evolution choose the best part to show.") },

    { "prefer_plain",
      N_("Show plain text if present"),
      N_("Show plain text part, if present, otherwise "
         "let Evolution choose the best part to show.") },

    { "only_plain",
      N_("Only ever show plain text"),
      N_("Always show plain text part and make attachments "
         "from other parts, if requested.") },
};

enum {
    PROP_0,
    PROP_MODE,
    PROP_SHOW_SUPPRESSED
};

static void
make_part_attachment (EMailParser *parser,
                      CamelMimePart *part,
                      GString *part_id,
                      gboolean force_html,
                      GCancellable *cancellable,
                      GQueue *out_mail_parts)
{
    CamelContentType *ct;

    ct = camel_mime_part_get_content_type (part);

    if (camel_content_type_is (ct, "text", "html")) {
        GQueue work_queue = G_QUEUE_INIT;
        EMailPart *mail_part;
        gint len;

        /* always show HTML as attachments and not inline */
        camel_mime_part_set_disposition (part, "attachment");

        if (camel_mime_part_get_filename (part) == NULL) {
            gchar *filename;

            filename = g_strdup_printf ("%s.html", _("attachment"));
            camel_mime_part_set_filename (part, filename);
            g_free (filename);
        }

        len = part_id->len;
        g_string_append (part_id, ".text_html");
        mail_part = e_mail_part_new (part, part_id->str);
        e_mail_part_set_mime_type (mail_part, "text/html");
        g_string_truncate (part_id, len);

        g_queue_push_tail (&work_queue, mail_part);

        e_mail_parser_wrap_as_attachment (
            parser, part, part_id, &work_queue);

        e_queue_transfer (&work_queue, out_mail_parts);

    } else if (force_html && CAMEL_IS_MIME_MESSAGE (part)) {
        /* Note, the message was asked to be formatted as
         * text/html; but the message may already be text/html. */
        CamelMimePart *new_part;
        CamelDataWrapper *content;

        content = camel_medium_get_content (CAMEL_MEDIUM (part));
        g_return_if_fail (content != NULL);

        new_part = camel_mime_part_new ();
        camel_medium_set_content (CAMEL_MEDIUM (new_part), content);

        e_mail_parser_parse_part (
            parser, new_part, part_id,
            cancellable, out_mail_parts);

        g_object_unref (new_part);
    } else {
        e_mail_parser_parse_part (
            parser, part, part_id, cancellable, out_mail_parts);
    }
}

static void
hide_parts (GQueue *work_queue)
{
    GList *head, *link;

    head = g_queue_peek_head_link (work_queue);

    for (link = head; link != NULL; link = g_list_next (link)) {
        EMailPart *mail_part = link->data;

        mail_part->is_hidden = TRUE;
    }
}

static gboolean
empe_prefer_plain_parse (EMailParserExtension *extension,
                         EMailParser *parser,
                         CamelMimePart *part,
                         GString *part_id,
                         GCancellable *cancellable,
                         GQueue *out_mail_parts)
{
    EMailParserPreferPlain *emp_pp;
    CamelMultipart *mp;
    gint i, nparts, partidlen;
    CamelContentType *ct;
    gboolean has_calendar = FALSE;
    gboolean has_html = FALSE;
    gboolean prefer_html;
    GQueue plain_text_parts = G_QUEUE_INIT;
    GQueue work_queue = G_QUEUE_INIT;

    emp_pp = (EMailParserPreferPlain *) extension;
    prefer_html = (emp_pp->mode == PREFER_HTML);

    ct = camel_mime_part_get_content_type (part);

    /* We can actually parse HTML, but just discard it
     * when "Only ever show plain text" mode is set. */
    if (camel_content_type_is (ct, "text", "html")) {

        /* Prevent recursion, fall back to next (real text/html) parser */
        if (strstr (part_id->str, ".alternative-prefer-plain.") != NULL)
            return FALSE;

        /* Not enforcing text/plain, so use real parser. */
        if (emp_pp->mode != ONLY_PLAIN)
            return FALSE;

        /* Enforcing text/plain but got only HTML part, so add it
         * as attachment to not show empty message preview, which
         * is confusing. */
        make_part_attachment (
            parser, part, part_id, FALSE,
            cancellable, out_mail_parts);

        return TRUE;
    }

    partidlen = part_id->len;

    mp = (CamelMultipart *) camel_medium_get_content (CAMEL_MEDIUM (part));

    if (!CAMEL_IS_MULTIPART (mp))
        return e_mail_parser_parse_part_as (
            parser, part, part_id,
            "application/vnd.evolution.source",
            cancellable, out_mail_parts);

    nparts = camel_multipart_get_number (mp);
    for (i = 0; i < nparts; i++) {
        CamelMimePart *sp;

        sp = camel_multipart_get_part (mp, i);
        ct = camel_mime_part_get_content_type (sp);

        g_string_truncate (part_id, partidlen);
        g_string_append_printf (part_id, ".alternative-prefer-plain.%d", i);

        if (camel_content_type_is (ct, "text", "html")) {
            if (prefer_html) {
                e_mail_parser_parse_part (
                    parser, sp, part_id,
                    cancellable, &work_queue);
            } else if (emp_pp->show_suppressed) {
                make_part_attachment (
                    parser, sp, part_id, FALSE,
                    cancellable, &work_queue);
            }

            has_html = TRUE;

        } else if (camel_content_type_is (ct, "text", "plain")) {
            e_mail_parser_parse_part (
                parser, sp, part_id,
                cancellable, &plain_text_parts);

        /* Always show calendar part! */
        } else if (camel_content_type_is (ct, "text", "calendar") ||
               camel_content_type_is (ct, "text", "x-calendar")) {

            /* Hide everything else, displaying
             * native calendar part only. */
            hide_parts (&work_queue);

            e_mail_parser_parse_part (
                parser, sp, part_id, cancellable, &work_queue);

            has_calendar = TRUE;

        /* Multiparts can represent a text/html message
         * with other things like embedded images, etc. */
        } else if (camel_content_type_is (ct, "multipart", "*")) {
            GQueue inner_queue = G_QUEUE_INIT;
            GList *head, *link;
            gboolean multipart_has_html = FALSE;

            e_mail_parser_parse_part (
                parser, sp, part_id, cancellable, &inner_queue);

            head = g_queue_peek_head_link (&inner_queue);

            /* Check whether the multipart contains a text/html part */
            for (link = head; link != NULL; link = g_list_next (link)) {
                EMailPart *mail_part = link->data;

                if (e_mail_part_id_has_substr (mail_part, ".text_html")) {
                    multipart_has_html = TRUE;
                    break;
                }
            }

            if (multipart_has_html && !prefer_html) {
                if (emp_pp->show_suppressed) {
                    e_mail_parser_wrap_as_attachment (
                        parser, sp, part_id,
                        &inner_queue);
                } else {
                    hide_parts (&inner_queue);
                }
            }

            e_queue_transfer (&inner_queue, &work_queue);

            has_html |= multipart_has_html;

        /* Parse everything else as an attachment */
        } else {
            GQueue inner_queue = G_QUEUE_INIT;

            e_mail_parser_parse_part (
                parser, sp, part_id,
                cancellable, &inner_queue);
            e_mail_parser_wrap_as_attachment (
                parser, sp, part_id, &inner_queue);

            e_queue_transfer (&inner_queue, &work_queue);
        }
    }

    /* Don't hide the plain text if there's nothing else to display */
    if (has_calendar || (has_html && prefer_html))
        hide_parts (&plain_text_parts);

    if (!g_queue_is_empty (&plain_text_parts) && !g_queue_is_empty (&work_queue) && has_html) {
        /* a text/html part is hidden, but not marked as attachment,
         * thus do that now, when there exists a text/plain part */
        GList *qiter;

        for (qiter = g_queue_peek_head_link (&work_queue); qiter; qiter = g_list_next (qiter)) {
            EMailPart *mpart = qiter->data;
            const gchar *mime_type;

            mime_type = e_mail_part_get_mime_type (mpart);

            if (mpart && mpart->is_hidden && g_strcmp0 (mime_type, "text/html") == 0) {
                e_mail_part_set_is_attachment (mpart, TRUE);
            }
        }
    }

    /* plain_text parts should be always first */
    e_queue_transfer (&plain_text_parts, out_mail_parts);
    e_queue_transfer (&work_queue, out_mail_parts);

    g_string_truncate (part_id, partidlen);

    return TRUE;
}

static void
e_mail_parser_prefer_plain_get_property (GObject *object,
                                         guint property_id,
                                         GValue *value,
                                         GParamSpec *pspec)
{
    EMailParserPreferPlain *parser;

    parser = (EMailParserPreferPlain *) object;

    switch (property_id) {
        case PROP_MODE:
            g_value_set_int (value, parser->mode);
            return;
        case PROP_SHOW_SUPPRESSED:
            g_value_set_boolean (value, parser->show_suppressed);
            return;
    }

    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}

static void
e_mail_parser_prefer_plain_set_property (GObject *object,
                                         guint property_id,
                                         const GValue *value,
                                         GParamSpec *pspec)
{
    EMailParserPreferPlain *parser;

    parser = (EMailParserPreferPlain *) object;

    switch (property_id) {
        case PROP_MODE:
            parser->mode = g_value_get_int (value);
            return;
        case PROP_SHOW_SUPPRESSED:
            parser->show_suppressed = g_value_get_boolean (value);
            return;
    }

    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}

static void
e_mail_parser_prefer_plain_dispose (GObject *object)
{
    EMailParserPreferPlain *parser;

    parser = (EMailParserPreferPlain *) object;

    g_clear_object (&parser->settings);

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

static void
e_mail_parser_prefer_plain_class_init (EMailParserPreferPlainClass *class)
{
    GObjectClass *object_class;
    EMailParserExtensionClass *extension_class;

    object_class = G_OBJECT_CLASS (class);
    object_class->get_property = e_mail_parser_prefer_plain_get_property;
    object_class->set_property = e_mail_parser_prefer_plain_set_property;
    object_class->dispose = e_mail_parser_prefer_plain_dispose;

    extension_class = E_MAIL_PARSER_EXTENSION_CLASS (class);
    extension_class->mime_types = parser_mime_types;
    extension_class->parse = empe_prefer_plain_parse;

    g_object_class_install_property (
        object_class,
        PROP_MODE,
        g_param_spec_int (
            "mode",
            "Mode",
            NULL,
            PREFER_HTML,
            ONLY_PLAIN,
            PREFER_HTML,
            G_PARAM_READABLE | G_PARAM_WRITABLE));

    g_object_class_install_property (
        object_class,
        PROP_SHOW_SUPPRESSED,
        g_param_spec_boolean (
            "show-suppressed",
            "Show Suppressed",
            NULL,
            FALSE,
            G_PARAM_READABLE | G_PARAM_WRITABLE));
}

void
e_mail_parser_prefer_plain_class_finalize (EMailParserPreferPlainClass *class)
{
}

static gboolean
parser_mode_get_mapping (GValue *value,
                         GVariant *variant,
                         gpointer user_data)
{
    gint i;

    const gchar *key = g_variant_get_string (variant, NULL);
    if (key) {
        for (i = 0; i < G_N_ELEMENTS (epp_options); i++) {
            if (!strcmp (epp_options[i].key, key)) {
                g_value_set_int (value, i);
                return TRUE;
            }
        }
    } else {
        g_value_set_int (value, 0);
    }

    return TRUE;
}

static GVariant *
parser_mode_set_mapping (const GValue *value,
                         const GVariantType *expected_type,
                         gpointer user_data)
{
    return g_variant_new_string (epp_options[g_value_get_int (value)].key);
}

static void
e_mail_parser_prefer_plain_init (EMailParserPreferPlain *parser)
{
    gchar *key;
    gint i;

    parser->settings = g_settings_new ("org.gnome.evolution.plugin.prefer-plain");
    g_settings_bind_with_mapping (
        parser->settings, "mode",
        parser, "mode", G_SETTINGS_BIND_DEFAULT,
        parser_mode_get_mapping,
        parser_mode_set_mapping,
        NULL, NULL);
    g_settings_bind (
        parser->settings, "show-suppressed",
        parser, "show-suppressed", G_SETTINGS_BIND_DEFAULT);

    /* Initialize the settings */
    key = g_settings_get_string (parser->settings, "mode");
    if (key) {
        for (i = 0; i < G_N_ELEMENTS (epp_options); i++) {
            if (!strcmp (epp_options[i].key, key)) {
                parser->mode = i;
                break;
            }
        }
        g_free (key);
    } else {
        parser->mode = 0;
    }

    parser->show_suppressed = g_settings_get_boolean (parser->settings, "show-suppressed");
}

void
e_mail_parser_prefer_plain_type_register (GTypeModule *type_module)
{
    e_mail_parser_prefer_plain_register_type (type_module);
}