/*
 * cog-webkit-utils.c
 * Copyright (C) 2018 Adrian Perez <aperez@igalia.com>
 *
 * Distributed under terms of the MIT license.
 */

#include "cog-webkit-utils.h"
#include <stdlib.h>
#include <string.h>

static const char error_message_template[] =
    "<!DOCTYPE html><html><head><title>%s</title><style type='text/css'>\n"
    "html { background: #fffafa; color: #0f0f0f; }\n"
    "h3 { font-weight: 600; color: #fffafa; background: #555;\n"
    "     border-radius: 3px; padding: 0.15em 0.5em; margin-bottom: 0.25em }\n"
    "p { margin-left: 0.5em; margin-right: 0.5em }\n"
    "p.uri { size: 70%%; font-family: monospace; color: #888;\n"
    "        margin-left: 0.75em; margin-top: 0 }\n"
    ".try-again { text-align: center; font-size: 1em; \n"
    "             height: 100%%; margin: 1em; }\n"
    "</style></head><body>\n"
    "  <h3>%s</h3>\n"
    "  <p class='uri'>%s</p>\n"
    "  <p>%s</p>\n"
    "<button onclick=\"window.location.href = '%s'\" class=\"try-again\">Try again</button>"
    "</body></html>";

gboolean
load_error_page (WebKitWebView *web_view,
                 const char    *failing_uri,
                 const char    *title,
                 const char    *message)
{
    g_warning ("<%s> %s: %s", failing_uri, title, message);

    g_autofree char *html = g_strdup_printf(error_message_template, title, title, failing_uri, message, failing_uri);
    webkit_web_view_load_alternate_html (web_view,
                                         html,
                                         failing_uri,
                                         NULL);
    return TRUE;
}

/**
 * cog_handle_web_view_load_failed:
 * @web_view: A [class@WebKit.WebView].
 * @load_event: Load event.
 * @failing_uri: URI that failed to load.
 * @error: Load error.
 * @userdata: User data.
 *
 * Handles page load errors, showing a simple error page if needed and
 * logging a message to the standard error output.
 *
 * This function is typically used in a callback that handles the
 * [signal@WebKit.WebView::load-failed] signal, and can be used directly
 * as a callback for it:
 *
 * ```c
 * WebKitWebView* web_view = webkit_web_view_new(...);
 * g_signal_connect(web_view, "load-failed",
 *                  G_CALLBACK(cog_handle_web_view_load_failed), NULL);
 * ```
 *
 * Returns: Whether other signal handlers should be skipped.
 */
gboolean
cog_handle_web_view_load_failed (WebKitWebView  *web_view,
                                 WebKitLoadEvent load_event,
                                 char           *failing_uri,
                                 GError         *error,
                                 void           *userdata)
{
    // If the resource is going to be shown by a plug-in or a
    // media engine (for the case of API WPE2) just return FALSE and
    // let WebKit handle it.
#if COG_USE_WPE2
    if (g_error_matches(error, WEBKIT_MEDIA_ERROR, WEBKIT_MEDIA_ERROR_WILL_HANDLE_LOAD))
#else
    if (g_error_matches(error, WEBKIT_PLUGIN_ERROR, WEBKIT_PLUGIN_ERROR_WILL_HANDLE_LOAD))
#endif
        return FALSE;

    // Ignore cancellation errors as the active URI may be changing
    if (g_error_matches (error,
                         WEBKIT_NETWORK_ERROR,
                         WEBKIT_NETWORK_ERROR_CANCELLED))
        return FALSE;

    return load_error_page (web_view,
                            failing_uri,
                            "Page load error",
                            error ? error->message : "No error message");
}


static char*
format_tls_error (GTlsCertificateFlags errors)
{
    static const char prefix[] = "TLS certificate ";
    GString *str = g_string_new (prefix);

    if (errors & G_TLS_CERTIFICATE_UNKNOWN_CA)
        g_string_append (str, " has unknown CA,");
    if (errors & G_TLS_CERTIFICATE_BAD_IDENTITY)
        g_string_append (str, " identity mismatch,");
    if (errors & G_TLS_CERTIFICATE_NOT_ACTIVATED)
        g_string_append (str, " has activation time in the future,");
    if (errors & G_TLS_CERTIFICATE_EXPIRED)
        g_string_append (str, " is expired,");
    if (errors & G_TLS_CERTIFICATE_REVOKED)
        g_string_append (str, " is revoked,");
    if (errors & G_TLS_CERTIFICATE_INSECURE)
        g_string_append (str, " uses insecure algorithm,");
    if (errors & G_TLS_CERTIFICATE_GENERIC_ERROR)
        g_string_append (str, " cannot be validated,");

    if (strcmp (str->str, prefix)) {
        g_string_truncate (str, str->len - 1);
        g_string_append_c (str, '.');
    } else {
        g_string_append (str, " unknown error.");
    }

    return g_string_free (str, FALSE);
}

/**
 * cog_handle_web_view_load_failed_with_tls_errors:
 * @web_view: A [class@WebKit.WebView].
 * @load_event: Load event.
 * @failing_uri: URI that failed to load.
 * @error: Load error.
 * @userdata: User data.
 *
 * Handles TLS page load errors, showing a simple error page if needed and
 * logging a message to the standard error output.
 *
 * This function is typically used in a callback that handles the
 * [signal@WebKit.WebView::load-failed-with-tls-errors] signal, and can
 * be used directly as a callback for it:
 *
 * ```c
 * WebKitWebView* web_view = webkit_web_view_new(...);
 * g_signal_connect(web_view, "load-failed-with-tls-errors",
 *                  G_CALLBACK(cog_handle_web_view_load_failed_with_tls_errors),
 *                  NULL);
 * ```
 *
 * Returns: Whether other signal handler should be skipped.
 */
gboolean
cog_handle_web_view_load_failed_with_tls_errors (WebKitWebView       *web_view,
                                                 char                *failing_uri,
                                                 GTlsCertificate     *certificate,
                                                 GTlsCertificateFlags errors,
                                                 void                *user_data)
{
    g_autofree char *error_string = format_tls_error (errors);
    return load_error_page (web_view,
                            failing_uri,
                            "TLS Error",
                            error_string);
}

/**
 * cog_handle_web_view_web_process_terminated:
 * @web_view: A [class@WebKit.WebView].
 * @reason: Cause for process termination.
 * @userdata: User data.
 *
 * Handles unexpected web process termination, showing a simple error page
 * and logging a message to the standard error output.
 *
 * This function is typically used in a callback that handles the
 * [signal@WebKit.WebView::web-process-terminated] signal, and can be
 * used directly as a callback for it:
 *
 * ```c
 * WebKitWebView* web_view = webkit_web_view_new(...);
 * g_signal_connect(web_view, "web-process-terminated",
 *                  G_CALLBACK(cog_handle_web_view_web_process_terminated),
 *                  NULL);
 * ```
 */
gboolean
cog_handle_web_view_web_process_terminated (WebKitWebView                     *web_view,
                                            WebKitWebProcessTerminationReason  reason,
                                            void                              *userdata)
{
    const char *message = NULL;
    const char *title = NULL;

    switch (reason) {
        case WEBKIT_WEB_PROCESS_CRASHED:
            message = "The renderer process crashed. Reloading the page may"
                " fix intermittent failures.";
            title = "Crash!";
            break;

        case WEBKIT_WEB_PROCESS_EXCEEDED_MEMORY_LIMIT:
            message = "The renderer process ran out of memory. You may try"
                " reloading the page to restart it.";
            title = "Out of memory!";
            break;

        default:
            g_assert_not_reached ();
    }
    return load_error_page (web_view,
                            webkit_web_view_get_uri (web_view),
                            title,
                            message);
}

/**
 * cog_handle_web_view_web_process_terminated_exit:
 * @web_view: A [class@WebKit.WebView].
 * @reason: Cause for process termination.
 * @userdata: Integer to use as exit status packed as a pointer.
 *
 * Handles unexpected web process termination, exiting the program with the
 * value passed as `userdata` as status.
 *
 * This function is typically used as a callback for the
 * [signal@WebKit.WebView::web-process-terminated-signal]:
 *
 * ```c
 * WebKitWebView* web_view = webkit_web_view_new(...);
 * g_signal_connect(web_view, "web-process-terminated",
 *                  G_CALLBACK(cog_handle_web_view_web_process_terminated_exit),
 *                  GINT_TO_POINTER(EXIT_FAILURE));
 * ```
 */
gboolean
cog_handle_web_view_web_process_terminated_exit (WebKitWebView                     *web_view,
                                                 WebKitWebProcessTerminationReason  reason,
                                                 void                              *userdata)
{
    const char *reason_string = NULL;

    switch (reason) {
        case WEBKIT_WEB_PROCESS_CRASHED:
            reason_string = "crashed";
            break;
        case WEBKIT_WEB_PROCESS_EXCEEDED_MEMORY_LIMIT:
            reason_string = "ran out of memory";
            break;
        default:
            g_assert_not_reached ();
    }

    g_critical ("The renderer process %s, exiting...", reason_string);
    exit (GPOINTER_TO_INT (userdata));
}


struct RestartData {
    unsigned tries;
    unsigned max_tries;
    unsigned try_window_ms;
    unsigned tries_timeout_id;
};


static gboolean
reset_recovery_tries (struct RestartData *restart)
{
    restart->tries = 0;
    restart->tries_timeout_id = 0;
    return G_SOURCE_REMOVE;
}


static gboolean
on_web_process_terminated_restart (WebKitWebView                     *web_view,
                                   WebKitWebProcessTerminationReason  reason,
                                   struct RestartData                *restart)
{
#if GLIB_CHECK_VERSION(2, 56, 0)
    g_clear_handle_id (&restart->tries_timeout_id, g_source_remove);
#else
    if (restart->tries_timeout_id) {
        g_source_remove (restart->tries_timeout_id);
        restart->tries_timeout_id = 0;
    }
#endif // GLIB_CHECK_VERSION

    if (++restart->tries >= restart->max_tries) {
        g_critical ("Renderer process terminated and failed to recover within %ums",
                    restart->try_window_ms);
        // Chain up to the handler that renders an error page.
        return cog_handle_web_view_web_process_terminated (web_view, reason, NULL);
    }

    g_warning ("Renderer process terminated, restarting (attempt %u/%u).",
               restart->tries, restart->max_tries);
    webkit_web_view_reload (web_view);

    // Reset the count of attempts if the Web process does not crash again
    // during the configure time window.
    restart->tries_timeout_id = g_timeout_add (restart->try_window_ms,
                                               (GSourceFunc) reset_recovery_tries,
                                               restart);
    return TRUE;
}


static void
free_restart_data (void *restart, G_GNUC_UNUSED GClosure *closure)
{
    g_slice_free (struct RestartData, restart);
}

/**
 * cog_web_view_connect_web_process_terminated_restart_handler:
 * @web_view: A [class@WebKit.WebView].
 * @max_tries: Maximum number of attempts in the retry window.
 * @try_window_ms: Length of the retry window in milliseconds.
 *
 * Handles unexpected web process termination, trying to restart the web
 * process up to a maximum number of attempts during a retry window.
 *
 * Once the web process has been terminated, a retry window timer will
 * be started with a duration of `try_window_ms` milliseconds. During
 * this time, restarting the web process will be attempted up to a
 * maximum amount of attempts (`max_tries`):
 *
 * - If the maximum number of attempts is reached within the retry window
 *   time, an error page will be displayed.
 * - If the retry window timer expires without the web process being
 *   terminated again, the count of attempts done is reset to zero.
 *
 * This function will connect its own callback to the
 * [signal@WebKit.WebView::web-process-terminated] signal. The identifier
 * of the installed signal handler is returned, which allows to disconnect
 * it if needed.
 *
 * Returns: Identifier of the installed signal handler.
 */
gulong
cog_web_view_connect_web_process_terminated_restart_handler (WebKitWebView *web_view,
                                                             unsigned       max_tries,
                                                             unsigned       try_window_ms)
{
    g_return_val_if_fail (WEBKIT_IS_WEB_VIEW (web_view), 0);
    g_return_val_if_fail (max_tries > 0, 0);

    struct RestartData *restart = g_slice_new0 (struct RestartData);
    restart->max_tries = max_tries;
    restart->try_window_ms = try_window_ms;

    return g_signal_connect_data (web_view,
                                  "web-process-terminated",
                                  G_CALLBACK (on_web_process_terminated_restart),
                                  restart,
                                  free_restart_data,
                                  0);
}

/**
 * cog_web_view_connect_default_error_handlers:
 * @web_view: A [class@WebKit.WebView].
 *
 * Install the default error signal handlers.
 *
 * Connects [id@cog_handle_web_view_load_failed],
 * [id@cog_handle_web_view_load_failed_with_tls_errors], and
 * [id@cog_handle_web_view_web_process_terminated] as callbacks for
 * their respective signals.
 *
 * If there was any handler already connected for any of the signals,
 * the default handler for it will not be used.
 */
void
cog_web_view_connect_default_error_handlers (WebKitWebView *web_view)
{
    static const struct {
        const char *sig;
        const void *hnd;
    } handlers[] = {
        { "load-failed",
            cog_handle_web_view_load_failed },
        { "load-failed-with-tls-errors",
            cog_handle_web_view_load_failed_with_tls_errors },
        { "web-process-terminated",
            cog_handle_web_view_web_process_terminated },
    };
    
    for (unsigned i = 0; i < G_N_ELEMENTS (handlers); i++) {
        /*
         * Check whether a handler has already been connected for the
         * signal, and skip adding the default one here if found.
         */
        unsigned signal_id = g_signal_lookup (handlers[i].sig,
                                              WEBKIT_TYPE_WEB_VIEW);
        g_assert (signal_id != 0);

        unsigned long handler_id =
            g_signal_handler_find (web_view,
                                   G_SIGNAL_MATCH_ID,
                                   signal_id,
                                   0,     /* detail */
                                   NULL,  /* closure */
                                   NULL,  /* func */
                                   NULL   /* data */);

        if (handler_id == 0)
            g_signal_connect (web_view, handlers[i].sig, handlers[i].hnd, NULL);
    }
}

/**
 * cog_handle_web_view_load_changed:
 * @web_view: A [class@WebKit.WebView].
 * @load_event: Load event.
 * @userdata: User data.
 *
 * Handles page load status changes, writing status reports to the
 * standard error output.
 *
 * This function is typically used as a callback for the
 * [signal@WebKit.WebView::load-changed] signal:
 *
 * ```c
 * WebKitWebView* web_view = webkit_web_view_new(...);
 * g_signal_connect(web_view, "load-changed",
 *                  G_CALLBACK(cog_handle_web_view_load_changed), NULL);
 * ```
 */
void
cog_handle_web_view_load_changed (WebKitWebView  *web_view,
                                  WebKitLoadEvent load_event,
                                  void           *userdata)
{
    const char *info = NULL;
    switch (load_event) {
        case WEBKIT_LOAD_STARTED:
            info = "Load started.";
            break;
        case WEBKIT_LOAD_REDIRECTED:
            info = "Redirected.";
            break;
        case WEBKIT_LOAD_COMMITTED:
            info = "Loading...";
            break;
        case WEBKIT_LOAD_FINISHED:
            info = "Loaded successfully.";
            break;
    }

    g_message ("<%s> %s", webkit_web_view_get_uri (web_view), info);
}

/**
 * cog_web_view_connect_default_progress_handlers:
 * @web_view: A [class@WebKit.WebView].
 *
 * Install the default page load progress signal handlers.
 *
 * Connects [id@cog_handle_web_view_load_changed] as a callback to its
 * respective signal.
 */
void
cog_web_view_connect_default_progress_handlers (WebKitWebView *web_view)
{
    static const struct {
        const char *sig;
        const void *hnd;
    } handlers[] = {
        { "load-changed", cog_handle_web_view_load_changed },
    };

    for (unsigned i = 0; i < G_N_ELEMENTS (handlers); i++)
        g_signal_connect (web_view, handlers[i].sig, handlers[i].hnd, NULL);
}

/**
 * cog_webkit_settings_apply_from_key_file:
 * @settings: A [class@WebKit.Settings] object.
 * @key_file: A loaded key file.
 * @group: Name of a group from the key file.
 * @error: (out) (nullable): Location where to store an error, if any.
 *
 * Reads values from a given `group` of a [struct@GLib.KeyFile] object,
 * and uses them to set the writable properties of a [class@WebKit.Settings]
 * object.
 *
 * Returns: Whether the settings were successfully applied.
 */
gboolean
cog_webkit_settings_apply_from_key_file (WebKitSettings *settings,
                                         GKeyFile       *key_file,
                                         const char     *group,
                                         GError        **error)
{
    g_return_val_if_fail (WEBKIT_IS_SETTINGS (settings), FALSE);
    g_return_val_if_fail (key_file != NULL, FALSE);

    GObjectClass* object_class = G_OBJECT_GET_CLASS (settings);

    unsigned n_properties = 0;
    g_autofree GParamSpec* const* properties =
        g_object_class_list_properties (object_class, &n_properties);

    for (unsigned i = 0; i < n_properties; i++) {
        g_autoptr(GError) lookup_error = NULL;
        if (!g_key_file_has_key (key_file,
                                 group,
                                 properties[i]->name,
                                 &lookup_error)) {
            if (lookup_error) {
                g_propagate_error (error, g_steal_pointer (&lookup_error));
                return FALSE;
            }
            continue;  // Setting missing in GKeyFile, skip it.
        }

        const GType prop_type = G_PARAM_SPEC_VALUE_TYPE (properties[i]);
        switch (prop_type) {
            case G_TYPE_BOOLEAN: {
                gboolean value = g_key_file_get_boolean (key_file,
                                                         group,
                                                         properties[i]->name,
                                                         &lookup_error);
                if (!value && lookup_error) {
                    g_propagate_error (error, g_steal_pointer (&lookup_error));
                    return FALSE;
                }
                g_object_set (settings, properties[i]->name, value, NULL);
                break;
            }

            case G_TYPE_UINT: {
                guint64 value = g_key_file_get_uint64 (key_file,
                                                       group,
                                                       properties[i]->name,
                                                       &lookup_error);
                if (value == 0 && lookup_error) {
                    g_propagate_error (error, g_steal_pointer (&lookup_error));
                    return FALSE;
                } else if (value > G_MAXUINT) {
                    g_set_error (error,
                                 G_KEY_FILE_ERROR,
                                 G_KEY_FILE_ERROR_INVALID_VALUE,
                                 "Value for '%s' exceeds maximum integer size",
                                 properties[i]->name);
                    return FALSE;
                }
                g_object_set (settings, properties[i]->name, (guint) value, NULL);
                break;
            }

            case G_TYPE_STRING: {
                g_autofree char* value =
                    g_key_file_get_string (key_file,
                                           group,
                                           properties[i]->name,
                                           &lookup_error);
                if (!value) {
                    g_assert (lookup_error);
                    g_propagate_error (error, g_steal_pointer (&lookup_error));
                    return FALSE;
                }
                g_object_set (settings, properties[i]->name, value, NULL);
                break;
            }
        }
    }

    return TRUE;
}
