/*
 * e-mail-backend.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) version 3.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the program; if not, see <http://www.gnu.org/licenses/>
 *
 * Authors:
 *   Jonathon Jongsma <jonathon.jongsma@collabora.co.uk>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 * Copyright (C) 2009 Intel Corporation
 *
 */

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

#include "e-mail-backend.h"

#include <string.h>
#include <glib/gstdio.h>
#include <glib/gi18n-lib.h>
#include <libedataserver/e-data-server-util.h>

#include <shell/e-shell.h>

#include <libevolution-utils/e-alert-dialog.h>
#include <libevolution-utils/e-alert-sink.h>

#include <misc/e-account-combo-box.h>

#include <libemail-utils/e-account-utils.h>
#include <libemail-engine/e-mail-folder-utils.h>
#include <libemail-engine/e-mail-session.h>
#include <libemail-engine/e-mail-store-utils.h>
#include <libemail-engine/mail-config.h>
#include <libemail-engine/mail-folder-cache.h>
#include <libemail-engine/mail-ops.h>

#include <mail/e-mail-migrate.h>
#include <mail/e-mail-ui-session.h>
#include <mail/em-event.h>
#include <mail/em-folder-tree-model.h>
#include <mail/em-utils.h>
#include <mail/mail-autofilter.h>
#include <mail/mail-send-recv.h>
#include <mail/mail-vfolder-ui.h>

#define E_MAIL_BACKEND_GET_PRIVATE(obj) \
	(G_TYPE_INSTANCE_GET_PRIVATE \
	((obj), E_TYPE_MAIL_BACKEND, EMailBackendPrivate))

#define E_MAIL_BACKEND_GET_PRIVATE(obj) \
	(G_TYPE_INSTANCE_GET_PRIVATE \
	((obj), E_TYPE_MAIL_BACKEND, EMailBackendPrivate))

#define QUIT_POLL_INTERVAL 1  /* seconds */

struct _EMailBackendPrivate {
	EMailSession *session;
	GHashTable *jobs;
};

enum {
	PROP_0,
	PROP_SESSION
};

/* FIXME Kill this thing.  It's a horrible hack. */
extern gint camel_application_is_exiting;

G_DEFINE_ABSTRACT_TYPE (
	EMailBackend,
	e_mail_backend,
	E_TYPE_SHELL_BACKEND)

static const gchar *
mail_shell_backend_get_data_dir (EShellBackend *backend)
{
	return mail_session_get_data_dir ();
}

static const gchar *
mail_shell_backend_get_config_dir (EShellBackend *backend)
{
	return mail_session_get_config_dir ();
}

static gchar *
mail_backend_uri_to_evname (const gchar *uri,
                            const gchar *prefix)
{
	const gchar *data_dir;
	gchar *basename;
	gchar *filename;
	gchar *safe;

	/* Converts a folder URI to a GalView filename. */

	data_dir = mail_session_get_data_dir ();

	safe = g_strdup (uri);
	e_filename_make_safe (safe);
	basename = g_strdup_printf ("%s%s.xml", prefix, safe);
	filename = g_build_filename (data_dir, basename, NULL);
	g_free (basename);
	g_free (safe);

	return filename;
}

/* Callback for various asynchronous CamelStore operations where
 * the EActivity's reference count is used as a counting semaphore. */
static void
mail_backend_store_operation_done_cb (CamelStore *store,
                                      GAsyncResult *result,
                                      EActivity *activity)
{
	/* FIXME Not checking result for error.  To fix this, we need
	 *       separate callbacks to call different finish functions
	 *       and then submit an EAlert on error. */

	g_object_unref (activity);
}

static void
mail_backend_prepare_for_offline_cb (EShell *shell,
                                     EActivity *activity,
                                     EMailBackend *backend)
{
	GtkWindow *window;
	EMailSession *session;
	GList *list, *link;
	gboolean synchronize = FALSE;

	window = e_shell_get_active_window (shell);
	session = e_mail_backend_get_session (backend);

	if (e_shell_get_network_available (shell) &&
		e_shell_backend_is_started (E_SHELL_BACKEND (backend)))
		synchronize = em_utils_prompt_user (
			window, NULL, "mail:ask-quick-offline", NULL);

	if (!synchronize) {
		mail_cancel_all ();
		camel_session_set_network_available (
			CAMEL_SESSION (session), FALSE);
	}

	list = camel_session_list_services (CAMEL_SESSION (session));

	for (link = list; link != NULL; link = g_list_next (link)) {
		CamelService *service;

		service = CAMEL_SERVICE (link->data);

		if (!CAMEL_IS_STORE (service))
			continue;

		/* FIXME Not passing a GCancellable. */
		e_mail_store_go_offline (
			CAMEL_STORE (service), G_PRIORITY_DEFAULT,
			NULL, (GAsyncReadyCallback)
			mail_backend_store_operation_done_cb,
			g_object_ref (activity));
	}

	g_list_free (list);
}

static void
mail_backend_prepare_for_online_cb (EShell *shell,
                                    EActivity *activity,
                                    EMailBackend *backend)
{
	EMailSession *session;
	GList *list, *link;

	session = e_mail_backend_get_session (backend);
	camel_session_set_online (CAMEL_SESSION (session), TRUE);

	list = camel_session_list_services (CAMEL_SESSION (session));

	for (link = list; link != NULL; link = g_list_next (link)) {
		CamelService *service;
		EAccount *account;
		const gchar *uid;

		service = CAMEL_SERVICE (link->data);

		if (!CAMEL_IS_STORE (service))
			continue;

		uid = camel_service_get_uid (service);
		account = e_get_account_by_uid (uid);

		if (account != NULL && !account->enabled)
			continue;

		/* FIXME Not passing a GCancellable. */
		e_mail_store_go_online (
			CAMEL_STORE (service), G_PRIORITY_DEFAULT,
			NULL, (GAsyncReadyCallback)
			mail_backend_store_operation_done_cb,
			g_object_ref (activity));
	}

	g_list_free (link);
}

/* Helper for mail_backend_prepare_for_quit_cb() */
static void
mail_backend_delete_junk (CamelService *service,
                          EMailBackend *backend)
{
	CamelFolder *folder;
	GPtrArray *uids;
	guint32 flags;
	guint32 mask;
	guint ii;

	/* FIXME camel_store_get_junk_folder_sync() may block. */
	folder = camel_store_get_junk_folder_sync (
		CAMEL_STORE (service), NULL, NULL);
	if (folder == NULL)
		return;

	uids = camel_folder_get_uids (folder);
	flags = mask = CAMEL_MESSAGE_DELETED | CAMEL_MESSAGE_SEEN;

	camel_folder_freeze (folder);

	for (ii = 0; ii < uids->len; ii++) {
		const gchar *uid = uids->pdata[ii];
		camel_folder_set_message_flags (folder, uid, flags, mask);
	}

	camel_folder_thaw (folder);

	camel_folder_free_uids (folder, uids);
}

/* Helper for mail_backend_prepare_for_quit_cb() */
static gboolean
mail_backend_poll_to_quit (EActivity *activity)
{
	return mail_msg_active ();
}

/* Helper for mail_backend_prepare_for_quit_cb() */
static void
mail_backend_ready_to_quit (EActivity *activity)
{
	emu_free_mail_cache ();

	/* Do this last.  It may terminate the process. */
	g_object_unref (activity);
}

static void
mail_backend_prepare_for_quit_cb (EShell *shell,
                                  EActivity *activity,
                                  EMailBackend *backend)
{
	EAccountList *account_list;
	EMailSession *session;
	GList *list, *link;
	gboolean delete_junk;
	gboolean empty_trash;

	session = e_mail_backend_get_session (backend);

	delete_junk = e_mail_backend_delete_junk_policy_decision (backend);
	empty_trash = e_mail_backend_empty_trash_policy_decision (backend);

	camel_application_is_exiting = TRUE;

	account_list = e_get_account_list ();
	e_account_list_prune_proxies (account_list);

	mail_vfolder_shutdown ();

	/* Cancel all pending activities. */
	mail_cancel_all ();

	list = camel_session_list_services (CAMEL_SESSION (session));

	if (delete_junk) {
		for (link = list; link != NULL; link = g_list_next (link)) {
			CamelService *service;

			service = CAMEL_SERVICE (link->data);

			if (!CAMEL_IS_STORE (service))
				continue;

			mail_backend_delete_junk (service, backend);
		}
	}

	for (link = list; link != NULL; link = g_list_next (link)) {
		CamelService *service;

		service = CAMEL_SERVICE (link->data);

		if (!CAMEL_IS_STORE (service))
			continue;

		/* FIXME Not passing a GCancellable. */
		/* FIXME This operation should be queued. */
		camel_store_synchronize (
			CAMEL_STORE (service),
			empty_trash, G_PRIORITY_DEFAULT,
			NULL, (GAsyncReadyCallback)
			mail_backend_store_operation_done_cb,
			g_object_ref (activity));
	}

	g_list_free (list);

	/* Now we poll until all activities are actually cancelled or finished.
	 * Reffing the activity delays quitting; the reference count
	 * acts like a counting semaphore. */
	if (mail_msg_active ())
		g_timeout_add_seconds_full (
			G_PRIORITY_DEFAULT, QUIT_POLL_INTERVAL,
			(GSourceFunc) mail_backend_poll_to_quit,
			g_object_ref (activity),
			(GDestroyNotify) mail_backend_ready_to_quit);
	else
		mail_backend_ready_to_quit (g_object_ref (activity));
}

static void
mail_backend_quit_requested_cb (EShell *shell,
                                EShellQuitReason reason,
                                EShellBackend *mail_shell_backend)
{
	EMailBackend *backend;
	EMailSession *session;
	CamelFolder *folder;
	GtkWindow *window;
	gint response;

	window = e_shell_get_active_window (shell);

	/* We can quit immediately if offline. */
	if (!e_shell_get_online (shell))
		return;

	/* Or if another Evolution process asked us to. */
	if (reason == E_SHELL_QUIT_REMOTE_REQUEST)
		return;

	/* In express mode, don't raise mail request in non mail window. */
	if (e_shell_get_express_mode (shell) &&
		strcmp(e_shell_window_get_active_view((EShellWindow *)window), "mail") != 0)
		return;

	if (!e_shell_backend_is_started (mail_shell_backend))
		return;

	/* Check Outbox for any unsent messages. */

	backend = E_MAIL_BACKEND (mail_shell_backend);
	session = e_mail_backend_get_session (backend);

	folder = e_mail_session_get_local_folder (
		session, E_MAIL_LOCAL_FOLDER_OUTBOX);
	if (folder == NULL)
		return;

	if (camel_folder_summary_get_visible_count (folder->summary) == 0)
		return;

	response = e_alert_run_dialog_for_args (
		window, "mail:exit-unsaved", NULL);

	if (response == GTK_RESPONSE_YES)
		return;

	e_shell_cancel_quit (shell);
}

static void
mail_backend_folder_deleted_cb (MailFolderCache *folder_cache,
                                CamelStore *store,
                                const gchar *folder_name,
                                EMailBackend *backend)
{
	CamelStoreClass *class;
	EAccountList *account_list;
	EIterator *iterator;
	EMailSession *session;
	EAlertSink *alert_sink;
	const gchar *local_drafts_folder_uri;
	const gchar *local_sent_folder_uri;
	gboolean write_config = FALSE;
	gchar *uri;

	/* Check whether the deleted folder was a designated Drafts or
	 * Sent folder for any mail account, and if so revert the setting
	 * to the equivalent local folder, which is always present. */

	class = CAMEL_STORE_GET_CLASS (store);
	g_return_if_fail (class->compare_folder_name != NULL);

	session = e_mail_backend_get_session (backend);
	alert_sink = e_mail_backend_get_alert_sink (backend);

	local_drafts_folder_uri =
		e_mail_session_get_local_folder_uri (
		session, E_MAIL_LOCAL_FOLDER_DRAFTS);

	local_sent_folder_uri =
		e_mail_session_get_local_folder_uri (
		session, E_MAIL_LOCAL_FOLDER_SENT);

	uri = e_mail_folder_uri_build (store, folder_name);

	account_list = e_get_account_list ();
	iterator = e_list_get_iterator (E_LIST (account_list));

	while (e_iterator_is_valid (iterator)) {
		EAccount *account;

		/* XXX EIterator misuses const. */
		account = (EAccount *) e_iterator_get (iterator);

		if (account->sent_folder_uri != NULL) {
			gboolean match;

			match = class->compare_folder_name (
				account->sent_folder_uri, uri);

			if (match) {
				g_free (account->sent_folder_uri);
				account->sent_folder_uri =
					g_strdup (local_sent_folder_uri);
				write_config = TRUE;
			}
		}

		if (account->drafts_folder_uri != NULL) {
			gboolean match;

			match = class->compare_folder_name (
				account->drafts_folder_uri, uri);

			if (match) {
				g_free (account->drafts_folder_uri);
				account->drafts_folder_uri =
					g_strdup (local_drafts_folder_uri);
				write_config = TRUE;
			}
		}

		e_iterator_next (iterator);
	}

	g_object_unref (iterator);
	g_free (uri);

	if (write_config)
		mail_config_write ();

	/* This does something completely different.
	 * XXX Make it a separate signal handler? */
	mail_filter_delete_folder (store, folder_name, alert_sink);
}

static void
mail_backend_folder_renamed_cb (MailFolderCache *folder_cache,
                                CamelStore *store,
                                const gchar *old_folder_name,
                                const gchar *new_folder_name,
                                EMailBackend *backend)
{
	CamelStoreClass *class;
	EAccountList *account_list;
	EIterator *iterator;
	gboolean write_config = FALSE;
	gchar *old_uri;
	gchar *new_uri;
	gint ii;

	const gchar *cachenames[] = {
		"views/current_view-",
		"views/custom_view-"
	};

	class = CAMEL_STORE_GET_CLASS (store);
	g_return_if_fail (class->compare_folder_name != NULL);

	old_uri = e_mail_folder_uri_build (store, old_folder_name);
	new_uri = e_mail_folder_uri_build (store, new_folder_name);

	account_list = e_get_account_list ();
	iterator = e_list_get_iterator (E_LIST (account_list));

	while (e_iterator_is_valid (iterator)) {
		EAccount *account;

		/* XXX EIterator misuses const. */
		account = (EAccount *) e_iterator_get (iterator);

		if (account->sent_folder_uri != NULL) {
			gboolean match;

			match = class->compare_folder_name (
				account->sent_folder_uri, old_uri);

			if (match) {
				g_free (account->sent_folder_uri);
				account->sent_folder_uri = g_strdup (new_uri);
				write_config = TRUE;
			}
		}

		if (account->drafts_folder_uri != NULL) {
			gboolean match;

			match = class->compare_folder_name (
				account->drafts_folder_uri, old_uri);

			if (match) {
				g_free (account->drafts_folder_uri);
				account->drafts_folder_uri = g_strdup (new_uri);
				write_config = TRUE;
			}
		}

		e_iterator_next (iterator);
	}

	g_object_unref (iterator);

	if (write_config)
		mail_config_write ();

	/* Rename GalView files. */

	for (ii = 0; ii < G_N_ELEMENTS (cachenames); ii++) {
		gchar *oldname;
		gchar *newname;

		oldname = mail_backend_uri_to_evname (old_uri, cachenames[ii]);
		newname = mail_backend_uri_to_evname (new_uri, cachenames[ii]);

		/* Ignore errors; doesn't matter. */
		g_rename (oldname, newname);

		g_free (oldname);
		g_free (newname);
	}

	g_free (old_uri);
	g_free (new_uri);

	/* This does something completely different.
	 * XXX Make it a separate signal handler? */
	mail_filter_rename_folder (
		store, old_folder_name, new_folder_name);
}

static void
mail_backend_folder_changed_cb (MailFolderCache *folder_cache,
                                CamelStore *store,
                                const gchar *folder_name,
                                gint new_messages,
                                const gchar *msg_uid,
                                const gchar *msg_sender,
                                const gchar *msg_subject,
                                EMailBackend *mail_backend)
{
	EMEvent *event = em_event_peek ();
	EMEventTargetFolder *target;
	EMFolderTreeModel *model;
	gchar *folder_uri;
	gint folder_type;
	CamelFolderInfoFlags flags = 0;

	folder_uri = e_mail_folder_uri_build (store, folder_name);

	if (folder_uri != NULL) {
		CamelFolder *folder = NULL;

		if (mail_folder_cache_get_folder_from_uri (
				folder_cache, folder_uri, &folder))
			if (folder != NULL &&
				!mail_folder_cache_get_folder_info_flags (
				folder_cache, folder, &flags))
				g_return_if_reached ();
		if (folder != NULL)
			g_object_unref (folder);
	}

	g_free (folder_uri);

	target = em_event_target_new_folder (
		event, store, folder_name, new_messages,
		msg_uid, msg_sender, msg_subject);

	folder_type = (flags & CAMEL_FOLDER_TYPE_MASK);
	target->is_inbox = (folder_type == CAMEL_FOLDER_TYPE_INBOX);

	model = em_folder_tree_model_get_default ();
	target->display_name = em_folder_tree_model_get_folder_name (
		model, store, folder_name);

	if (target->new > 0) {
		EShell *shell;
		EShellBackend *shell_backend;

		shell_backend = E_SHELL_BACKEND (mail_backend);
		shell = e_shell_backend_get_shell (shell_backend);
		e_shell_event (shell, "mail-icon", (gpointer) "mail-unread");
	}

	/**
	 * @Event: folder.changed
	 * @Title: Folder changed
	 * @Target: EMEventTargetFolder
	 *
	 * folder.changed is emitted whenever a folder changes.  There is no
	 * detail on how the folder has changed.
	 *
	 * UPDATE: We tell the number of new UIDs added rather than the new
	 * mails received.
	 */
	e_event_emit (
		(EEvent *) event, "folder.changed",
		(EEventTarget *) target);
}

static void
mail_backend_job_started_cb (CamelSession *session,
                             GCancellable *cancellable,
                             EShellBackend *shell_backend)
{
	EMailBackendPrivate *priv;
	EActivity *activity;

	priv = E_MAIL_BACKEND_GET_PRIVATE (shell_backend);

	/* Make sure this operation shows up in the user interface.
	 * This message should get overridden, if not it's a bug in
	 * whatever CamelService submitted this. */
	camel_operation_push_message (
		cancellable, _("Unknown background operation"));

	activity = e_activity_new ();
	e_activity_set_cancellable (activity, cancellable);
	e_shell_backend_add_activity (shell_backend, activity);

	/* The hash table takes ownership of the activity. */
	g_hash_table_insert (priv->jobs, cancellable, activity);
}

static void
mail_backend_job_finished_cb (CamelSession *session,
                              GCancellable *cancellable,
                              const GError *error,
                              EShellBackend *shell_backend)
{
	EMailBackendPrivate *priv;
	EShellBackendClass *class;
	EActivity *activity;
	const gchar *description;

	priv = E_MAIL_BACKEND_GET_PRIVATE (shell_backend);
	class = E_SHELL_BACKEND_GET_CLASS (shell_backend);

	/* Pop the generic "background operation" message. */
	camel_operation_pop_message (cancellable);

	activity = g_hash_table_lookup (priv->jobs, cancellable);
	description = e_activity_get_text (activity);

	if (e_activity_handle_cancellation (activity, error)) {
		/* nothing to do */

	} else if (error != NULL) {
		EShell *shell;
		GtkApplication *application;
		GList *list, *iter;

		shell = e_shell_backend_get_shell (shell_backend);

		application = GTK_APPLICATION (shell);
		list = gtk_application_get_windows (application);

		/* Submit the error to an appropriate EAlertSink. */
		for (iter = list; iter != NULL; iter = g_list_next (iter)) {
			EShellView *shell_view;
			EShellContent *shell_content;

			if (!E_IS_SHELL_WINDOW (iter->data))
				continue;

			shell_view = e_shell_window_peek_shell_view (
				E_SHELL_WINDOW (iter->data), class->name);

			if (!E_IS_SHELL_VIEW (shell_view))
				continue;

			shell_content =
				e_shell_view_get_shell_content (shell_view);

			if (description != NULL && *description != '\0')
				e_alert_submit (
					E_ALERT_SINK (shell_content),
					"mail:async-error", description,
					error->message, NULL);
			else
				e_alert_submit (
					E_ALERT_SINK (shell_content),
					"mail:async-error-nodescribe",
					error->message, NULL);

			break;
		}
	}

	g_hash_table_remove (priv->jobs, cancellable);
}

static void
mail_backend_get_property (GObject *object,
                           guint property_id,
                           GValue *value,
                           GParamSpec *pspec)
{
	switch (property_id) {
		case PROP_SESSION:
			g_value_set_object (
				value,
				e_mail_backend_get_session (
				E_MAIL_BACKEND (object)));
			return;
	}

	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}

static void
mail_backend_dispose (GObject *object)
{
	EMailBackendPrivate *priv;

	priv = E_MAIL_BACKEND_GET_PRIVATE (object);

	if (priv->session != NULL) {
		g_signal_handlers_disconnect_matched (
			priv->session, G_SIGNAL_MATCH_DATA,
			0, 0, NULL, NULL, object);
		camel_session_remove_services (
			CAMEL_SESSION (priv->session));
		g_object_unref (priv->session);
		priv->session = NULL;
	}

	/* There should be no unfinished jobs left. */
	g_warn_if_fail (g_hash_table_size (priv->jobs) == 0);

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

static void
mail_backend_finalize (GObject *object)
{
	EMailBackendPrivate *priv;

	priv = E_MAIL_BACKEND_GET_PRIVATE (object);

	g_hash_table_destroy (priv->jobs);

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

	camel_shutdown ();
}

static void
mail_backend_add_store (EMailSession *session,
                        CamelStore *store,
                        EMailBackend *backend)
{
	EMFolderTreeModel *model;

	model = em_folder_tree_model_get_default ();
	em_folder_tree_model_add_store (model, store);
}

static void
mail_backend_remove_store (EMailSession *session,
                           CamelStore *store,
                           EMailBackend *backend)
{
	EMFolderTreeModel *model;

	model = em_folder_tree_model_get_default ();
	em_folder_tree_model_remove_store (model, store);
}

#define SET_ACITIVITY(cancellable, activity) \
	g_object_set_data (G_OBJECT (cancellable), "e-activity", activity)
#define GET_ACITIVITY(cancellable) \
        g_object_get_data (G_OBJECT (cancellable), "e-activity")

static void
mail_mt_create_activity (GCancellable *cancellable)
{
	EActivity *activity;

	activity = e_activity_new ();
	e_activity_set_percent (activity, 0.0);
	e_activity_set_cancellable (activity, cancellable);
	SET_ACITIVITY (cancellable, activity);
}

static void
mail_mt_submit_activity (GCancellable *cancellable)
{
	EShell *shell;
	EShellBackend *shell_backend;
	EActivity *activity;

	shell = e_shell_get_default ();
	shell_backend = e_shell_get_backend_by_name (
		shell, "mail");

	activity = GET_ACITIVITY (cancellable);
	if (activity)
		e_shell_backend_add_activity (shell_backend, activity);

}

static void
mail_mt_free_activity (GCancellable *cancellable)
{
	EActivity *activity = GET_ACITIVITY (cancellable);

	if (activity)
		g_object_unref (activity);
}

static void
mail_mt_complete_acitivity (GCancellable *cancellable)
{
	EActivity *activity = GET_ACITIVITY (cancellable);

	if (activity)
		e_activity_set_state (activity, E_ACTIVITY_COMPLETED);
}

static void
mail_mt_cancel_activity (GCancellable *cancellable)
{
	EActivity *activity = GET_ACITIVITY (cancellable);

	if (activity)
		e_activity_set_state (activity, E_ACTIVITY_CANCELLED);
}

static void
mail_mt_alert_error (GCancellable *cancellable,
                     const gchar *what,
                     const gchar *message)
{
	EShell *shell;
	EShellView *shell_view;
	EShellWindow *shell_window = NULL;
	EShellContent *shell_content;
	GList *list, *iter;
	GtkApplication *application;

	shell = e_shell_get_default ();
	application = GTK_APPLICATION (shell);
	list = gtk_application_get_windows (application);

	/* Find the most recently used EShellWindow. */
	for (iter = list; iter != NULL; iter = g_list_next (iter)) {
		if (E_IS_SHELL_WINDOW (iter->data)) {
			shell_window = E_SHELL_WINDOW (iter->data);
			break;
		}
	}

	/* If we can't find an EShellWindow then... well, screw it. */
	if (shell_window == NULL)
		return;

	shell_view = e_shell_window_get_shell_view (
		shell_window, "mail");
	shell_content = e_shell_view_get_shell_content (shell_view);

	if (what) {
		e_alert_submit (
			E_ALERT_SINK (shell_content),
			"mail:async-error", what,
			message, NULL);
	} else
		e_alert_submit (
			E_ALERT_SINK (shell_content),
			"mail:async-error-nodescribe",
			message, NULL);
}

static EAlertSink *
mail_mt_get_alert_sink ()
{
	EShell *shell;
	EShellBackend *shell_backend;

	shell = e_shell_get_default ();
	shell_backend = e_shell_get_backend_by_name (
		shell, "mail");

	return e_mail_backend_get_alert_sink (E_MAIL_BACKEND (shell_backend));
}

static void
mail_backend_constructed (GObject *object)
{
	EMailBackendPrivate *priv;
	EShell *shell;
	EShellBackend *shell_backend;
	MailFolderCache *folder_cache;

	priv = E_MAIL_BACKEND_GET_PRIVATE (object);

	shell_backend = E_SHELL_BACKEND (object);
	shell = e_shell_backend_get_shell (shell_backend);

	if (camel_init (e_get_user_data_dir (), TRUE) != 0)
		exit (0);

	camel_provider_init ();

	priv->session = e_mail_ui_session_new ();

	g_signal_connect (
		priv->session, "flush-outbox",
		G_CALLBACK (mail_send), priv->session);

	g_object_bind_property (
		shell, "online",
		priv->session, "online",
		G_BINDING_SYNC_CREATE);

	/* Propagate "activity-added" signals from
	 * the mail session to the shell backend. */
	g_signal_connect_swapped (
		priv->session, "activity-added",
		G_CALLBACK (e_shell_backend_add_activity),
		shell_backend);

	g_signal_connect (
		priv->session, "job-started",
		G_CALLBACK (mail_backend_job_started_cb),
		shell_backend);

	g_signal_connect (
		priv->session, "job-finished",
		G_CALLBACK (mail_backend_job_finished_cb),
		shell_backend);

	/* FIXME This is an evil hack that needs to die.
	 *       Give EAccountComboBox a CamelSession property. */
	e_account_combo_box_set_session (CAMEL_SESSION (priv->session));

	g_signal_connect (
		priv->session, "store-added",
		G_CALLBACK (mail_backend_add_store),
		shell_backend);

	g_signal_connect (
		priv->session, "store-removed",
		G_CALLBACK (mail_backend_remove_store),
		shell_backend);

	g_signal_connect (
		shell, "prepare-for-offline",
		G_CALLBACK (mail_backend_prepare_for_offline_cb),
		shell_backend);

	g_signal_connect (
		shell, "prepare-for-online",
		G_CALLBACK (mail_backend_prepare_for_online_cb),
		shell_backend);

	g_signal_connect (
		shell, "prepare-for-quit",
		G_CALLBACK (mail_backend_prepare_for_quit_cb),
		shell_backend);

	g_signal_connect (
		shell, "quit-requested",
		G_CALLBACK (mail_backend_quit_requested_cb),
		shell_backend);

	folder_cache = e_mail_session_get_folder_cache (priv->session);

	g_signal_connect (
		folder_cache, "folder-deleted",
		G_CALLBACK (mail_backend_folder_deleted_cb),
		shell_backend);

	g_signal_connect (
		folder_cache, "folder-renamed",
		G_CALLBACK (mail_backend_folder_renamed_cb),
		shell_backend);

	g_signal_connect (
		folder_cache, "folder-changed",
		G_CALLBACK (mail_backend_folder_changed_cb), shell_backend);

	mail_config_init (priv->session);
	mail_msg_init ();

	mail_msg_register_activities (
		mail_mt_create_activity,
		mail_mt_submit_activity,
		mail_mt_free_activity,
		mail_mt_complete_acitivity,
		mail_mt_cancel_activity,
		mail_mt_alert_error,
		mail_mt_get_alert_sink);

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

static void
e_mail_backend_class_init (EMailBackendClass *class)
{
	GObjectClass *object_class;
	EShellBackendClass *shell_backend_class;

	g_type_class_add_private (class, sizeof (EMailBackendPrivate));

	object_class = G_OBJECT_CLASS (class);
	object_class->get_property = mail_backend_get_property;
	object_class->dispose = mail_backend_dispose;
	object_class->finalize = mail_backend_finalize;
	object_class->constructed = mail_backend_constructed;

	shell_backend_class = E_SHELL_BACKEND_CLASS (class);
	shell_backend_class->migrate = e_mail_migrate;
	shell_backend_class->get_data_dir = mail_shell_backend_get_data_dir;
	shell_backend_class->get_config_dir = mail_shell_backend_get_config_dir;

	g_object_class_install_property (
		object_class,
		PROP_SESSION,
		g_param_spec_object (
			"session",
			NULL,
			NULL,
			E_TYPE_MAIL_SESSION,
			G_PARAM_READABLE));
}

static void
e_mail_backend_init (EMailBackend *backend)
{
	backend->priv = E_MAIL_BACKEND_GET_PRIVATE (backend);

	backend->priv->jobs = g_hash_table_new_full (
		(GHashFunc) g_direct_hash,
		(GEqualFunc) g_direct_equal,
		(GDestroyNotify) NULL,
		(GDestroyNotify) g_object_unref);
}

EMailSession *
e_mail_backend_get_session (EMailBackend *backend)
{
	g_return_val_if_fail (E_IS_MAIL_BACKEND (backend), NULL);

	return backend->priv->session;
}

EAlertSink *
e_mail_backend_get_alert_sink (EMailBackend *backend)
{
	EShell *shell;
	EShellView *shell_view;
	EShellBackend *shell_backend;
	EShellContent *shell_content;
	EShellWindow *shell_window = NULL;
	EShellBackendClass *class;
	GtkApplication *application;
	GList *list, *link;

	/* XXX This is meant to be a convenient but temporary hack.
	 *     It digs through the list of available EShellWindows
	 *     to find a suitable EAlertSink. */

	g_return_val_if_fail (E_IS_MAIL_BACKEND (backend), NULL);

	shell_backend = E_SHELL_BACKEND (backend);
	shell = e_shell_backend_get_shell (shell_backend);

	application = GTK_APPLICATION (shell);
	list = gtk_application_get_windows (application);

	/* Find the most recently used EShellWindow. */
	for (link = list; link != NULL; link = g_list_next (link)) {
		if (E_IS_SHELL_WINDOW (link->data)) {
			shell_window = E_SHELL_WINDOW (link->data);
			break;
		}
	}

	g_return_val_if_fail (shell_window != NULL, NULL);

	class = E_SHELL_BACKEND_GET_CLASS (shell_backend);
	shell_view = e_shell_window_get_shell_view (shell_window, class->name);
	shell_content = e_shell_view_get_shell_content (shell_view);

	return E_ALERT_SINK (shell_content);
}

gboolean
e_mail_backend_delete_junk_policy_decision (EMailBackend *backend)
{
	EMailBackendClass *class;

	g_return_val_if_fail (E_IS_MAIL_BACKEND (backend), FALSE);

	class = E_MAIL_BACKEND_GET_CLASS (backend);
	if (class->delete_junk_policy_decision == NULL)
		return FALSE;

	return class->delete_junk_policy_decision (backend);
}

gboolean
e_mail_backend_empty_trash_policy_decision (EMailBackend *backend)
{
	EMailBackendClass *class;

	g_return_val_if_fail (E_IS_MAIL_BACKEND (backend), FALSE);

	class = E_MAIL_BACKEND_GET_CLASS (backend);
	if (class->empty_trash_policy_decision == NULL)
		return FALSE;

	return class->empty_trash_policy_decision (backend);
}