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

/*

 * Copyright (C) 2018 Sébastien Wilmet <swilmet@gnome.org>

 *

 * 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, see <http://www.gnu.org/licenses/>.

 */

#include "dh-web-view.h"

#include <math.h>

#include <glib/gi18n.h>

struct _DhWebViewPrivate {

        gchar *search_text;

        gdouble total_scroll_delta_y;

};

static const gdouble zoom_levels[] = {

        0.5,            /* 50% */

        0.8408964152,   /* 75% */

        1.0,            /* 100% */

        1.1892071149,   /* 125% */

        1.4142135623,   /* 150% */

        1.6817928304,   /* 175% */

        2.0,            /* 200% */

        2.8284271247,   /* 300% */

        4.0             /* 400% */

};

static const guint n_zoom_levels = G_N_ELEMENTS (zoom_levels);

#define ZOOM_DEFAULT (zoom_levels[2])

G_DEFINE_TYPE_WITH_PRIVATE (DhWebView, dh_web_view, WEBKIT_TYPE_WEB_VIEW)

static gint

get_current_zoom_level_index (DhWebView *view)

{

        gdouble zoom_level;

        gdouble previous;

        guint i;

        zoom_level = webkit_web_view_get_zoom_level (WEBKIT_WEB_VIEW (view));

        previous = zoom_levels[0];

        for (i = 1; i < n_zoom_levels; i++) {

                gdouble current = zoom_levels[i];

                gdouble mean = sqrt (previous * current);

                if (zoom_level <= mean)

                        return i - 1;

                previous = current;

        }

        return n_zoom_levels - 1;

}

static void

bump_zoom_level (DhWebView *view,

                 gint       bump_amount)

{

        gint zoom_level_index;

        gdouble new_zoom_level;

        if (bump_amount == 0)

                return;

        zoom_level_index = get_current_zoom_level_index (view) + bump_amount;

        zoom_level_index = CLAMP (zoom_level_index, 0, (gint)n_zoom_levels - 1);

        new_zoom_level = zoom_levels[zoom_level_index];

        webkit_web_view_set_zoom_level (WEBKIT_WEB_VIEW (view), new_zoom_level);

}

static gboolean

dh_web_view_scroll_event (GtkWidget      *widget,

                          GdkEventScroll *scroll_event)

{

        DhWebView *view = DH_WEB_VIEW (widget);

        gdouble delta_y;

        if ((scroll_event->state & GDK_CONTROL_MASK) == 0)

                goto chain_up;

        switch (scroll_event->direction) {

                case GDK_SCROLL_UP:

                        bump_zoom_level (view, 1);

                        return GDK_EVENT_STOP;

                case GDK_SCROLL_DOWN:

                        bump_zoom_level (view, -1);

                        return GDK_EVENT_STOP;

                case GDK_SCROLL_LEFT:

                case GDK_SCROLL_RIGHT:

                        break;

                case GDK_SCROLL_SMOOTH:

                        gdk_event_get_scroll_deltas ((GdkEvent *)scroll_event, NULL, &delta_y);

                        view->priv->total_scroll_delta_y += delta_y;

                        /* Avoiding direct float comparison.

                         * -1 and 1 are the thresholds for bumping the zoom level,

                         * which can be adjusted for taste.

                         */

                        if ((gint)view->priv->total_scroll_delta_y <= -1) {

                                view->priv->total_scroll_delta_y = 0.f;

                                bump_zoom_level (view, 1);

                        } else if ((gint)view->priv->total_scroll_delta_y >= 1) {

                                view->priv->total_scroll_delta_y = 0.f;

                                bump_zoom_level (view, -1);

                        }

                        return GDK_EVENT_STOP;

                default:

                        g_warn_if_reached ();

        }

chain_up:

        if (GTK_WIDGET_CLASS (dh_web_view_parent_class)->scroll_event == NULL)

                return GDK_EVENT_PROPAGATE;

        return GTK_WIDGET_CLASS (dh_web_view_parent_class)->scroll_event (widget, scroll_event);

}

static void

dh_web_view_constructed (GObject *object)

{

        WebKitWebView *view = WEBKIT_WEB_VIEW (object);

        WebKitSettings *settings;

        if (G_OBJECT_CLASS (dh_web_view_parent_class)->constructed != NULL)

                G_OBJECT_CLASS (dh_web_view_parent_class)->constructed (object);

        /* Disable some things we have no need for. */

        settings = webkit_web_view_get_settings (view);

        webkit_settings_set_enable_html5_database (settings, FALSE);

        webkit_settings_set_enable_html5_local_storage (settings, FALSE);

        webkit_settings_set_enable_plugins (settings, FALSE);

}

static void

dh_web_view_finalize (GObject *object)

{

        DhWebView *view = DH_WEB_VIEW (object);

        g_free (view->priv->search_text);

        G_OBJECT_CLASS (dh_web_view_parent_class)->finalize (object);

}

static void

dh_web_view_class_init (DhWebViewClass *klass)

{

        GObjectClass *object_class = G_OBJECT_CLASS (klass);

        GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

        object_class->constructed = dh_web_view_constructed;

        object_class->finalize = dh_web_view_finalize;

        widget_class->scroll_event = dh_web_view_scroll_event;

}

static void

dh_web_view_init (DhWebView *view)

{

        view->priv = dh_web_view_get_instance_private (view);

        view->priv->total_scroll_delta_y = 0.f;

        gtk_widget_set_hexpand (GTK_WIDGET (view), TRUE);

        gtk_widget_set_vexpand (GTK_WIDGET (view), TRUE);

}

DhWebView *

dh_web_view_new (void)

{

        return g_object_new (DH_TYPE_WEB_VIEW, NULL);

}

const gchar *

dh_web_view_get_devhelp_title (DhWebView *view)

{

        const gchar *title;

        g_return_val_if_fail (DH_IS_WEB_VIEW (view), NULL);

        title = webkit_web_view_get_title (WEBKIT_WEB_VIEW (view));

        if (title == NULL || title[0] == '\0')

                title = _("Empty Page");

        return title;

}

/*

 * dh_web_view_set_search_text:

 * @view: a #DhWebView.

 * @search_text: (nullable): the search string, or %NULL.

 *

 * A more convenient API (for Devhelp needs) than #WebKitFindController. If

 * @search_text is not empty, it calls webkit_find_controller_search() if not

 * already done. If @search_text is empty or %NULL, it calls

 * webkit_find_controller_search_finish().

 */

void

dh_web_view_set_search_text (DhWebView   *view,

                             const gchar *search_text)

{

        WebKitFindController *find_controller;

        g_return_if_fail (DH_IS_WEB_VIEW (view));

        if (g_strcmp0 (view->priv->search_text, search_text) == 0)

                return;

        g_free (view->priv->search_text);

        view->priv->search_text = g_strdup (search_text);

        find_controller = webkit_web_view_get_find_controller (WEBKIT_WEB_VIEW (view));

        if (search_text != NULL && search_text[0] != '\0') {

                /* If webkit_find_controller_search() is called a second time

                 * with the same parameters it's not a NOP, it launches a new

                 * search, apparently, which screws up search_next() and

                 * search_previous(). So we must call it only once for the same

                 * search string.

                 */

                webkit_find_controller_search (find_controller,

                                               search_text,

                                               WEBKIT_FIND_OPTIONS_WRAP_AROUND |

                                               WEBKIT_FIND_OPTIONS_CASE_INSENSITIVE,

                                               G_MAXUINT);

        } else {

                /* It's fine to call it several times. But unfortunately it

                 * doesn't change the WebKitFindController:text property. So we

                 * must store our own search_text.

                 */

                webkit_find_controller_search_finish (find_controller);

        }

}

void

dh_web_view_search_next (DhWebView *view)

{

        WebKitFindController *find_controller;

        g_return_if_fail (DH_IS_WEB_VIEW (view));

        if (view->priv->search_text == NULL || view->priv->search_text[0] == '\0')

                return;

        find_controller = webkit_web_view_get_find_controller (WEBKIT_WEB_VIEW (view));

        webkit_find_controller_search_next (find_controller);

}

void

dh_web_view_search_previous (DhWebView *view)

{

        WebKitFindController *find_controller;

        g_return_if_fail (DH_IS_WEB_VIEW (view));

        if (view->priv->search_text == NULL || view->priv->search_text[0] == '\0')

                return;

        find_controller = webkit_web_view_get_find_controller (WEBKIT_WEB_VIEW (view));

        webkit_find_controller_search_previous (find_controller);

}

gboolean

dh_web_view_can_zoom_in (DhWebView *view)

{

        gint zoom_level_index;

        g_return_val_if_fail (DH_IS_WEB_VIEW (view), FALSE);

        zoom_level_index = get_current_zoom_level_index (view);

        return zoom_level_index < ((gint)n_zoom_levels - 1);

}

gboolean

dh_web_view_can_zoom_out (DhWebView *view)

{

        gint zoom_level_index;

        g_return_val_if_fail (DH_IS_WEB_VIEW (view), FALSE);

        zoom_level_index = get_current_zoom_level_index (view);

        return zoom_level_index > 0;

}

gboolean

dh_web_view_can_reset_zoom (DhWebView *view)

{

        gint zoom_level_index;

        g_return_val_if_fail (DH_IS_WEB_VIEW (view), FALSE);

        zoom_level_index = get_current_zoom_level_index (view);

        return zoom_levels[zoom_level_index] != ZOOM_DEFAULT;

}

void

dh_web_view_zoom_in (DhWebView *view)

{

        g_return_if_fail (DH_IS_WEB_VIEW (view));

        bump_zoom_level (view, 1);

}

void

dh_web_view_zoom_out (DhWebView *view)

{

        g_return_if_fail (DH_IS_WEB_VIEW (view));

        bump_zoom_level (view, -1);

}

void

dh_web_view_reset_zoom (DhWebView *view)

{

        g_return_if_fail (DH_IS_WEB_VIEW (view));

        webkit_web_view_set_zoom_level (WEBKIT_WEB_VIEW (view), ZOOM_DEFAULT);

}