/* gcc `pkg-config --cflags --libs gdk-x11-2.0 xscrnsaver` ${CFLAGS} $< -o $@
 *
 * Copyright (C) 2007 Ray Strode <rstrode@redhat.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 Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * Authors: Ray Strode <rstrode@redhat.com>
 */
#include <stdlib.h>

#include <glib.h>

#include <X11/Xlib.h>
#include <X11/extensions/scrnsaver.h>

#include <gdk/gdkx.h>
#include <gdk/gdk.h>

#include <cairo.h>

typedef struct _TestScreensaverEngine
{
    GdkWindow *window;

    void (* draw) (struct _TestScreensaverEngine *, cairo_t *cairo_context);
} TestScreensaverEngine;

typedef struct _TestScreensaverHead
{
    int number;
    GdkRectangle area;
    TestScreensaverEngine *engine;
} TestScreensaverHead;

typedef enum _TestScreensaverState
{
    TEST_SCREENSAVER_STATE_UNKNOWN = 0,
    TEST_SCREENSAVER_STATE_ACTIVE,
    TEST_SCREENSAVER_STATE_INACTIVE,
    TEST_SCREENSAVER_STATE_DISABLED
} TestScreensaverState;

typedef struct _TestScreensaver
{
    GMainContext *context;
    GdkScreen *screen;
    GdkDrawable *drawable;
    GdkWindow *toplevel_window;
    gint notify_event_number;

    TestScreensaverState state;
    GList *heads;
    GdkRegion *head_layout;

    guint timeout_id;
} TestScreensaver;

static GdkWindow *
create_engine_window (GdkWindow    *toplevel_window,
                      GdkRectangle *area)
{
    GdkWindow *window;
    GdkWindowAttr attributes;
    static gint attributes_mask = GDK_WA_COLORMAP
                                  | GDK_WA_VISUAL
                                  | GDK_WA_X
                                  | GDK_WA_Y;
    static GdkEventMask event_mask = GDK_EXPOSURE_MASK
                                     | GDK_KEY_PRESS_MASK
                                     | GDK_ENTER_NOTIFY_MASK
                                     | GDK_LEAVE_NOTIFY_MASK
                                     | GDK_FOCUS_CHANGE_MASK
                                     | GDK_STRUCTURE_MASK
                                     | GDK_BUTTON_MOTION_MASK
                                     | GDK_POINTER_MOTION_HINT_MASK
                                     | GDK_BUTTON_PRESS_MASK
                                     | GDK_BUTTON_RELEASE_MASK;

    attributes.window_type = GDK_WINDOW_TOPLEVEL;
    attributes.wclass = GDK_INPUT_OUTPUT;
    attributes.colormap = 
        gdk_drawable_get_colormap (GDK_DRAWABLE (toplevel_window));
    attributes.visual = 
        gdk_drawable_get_visual (GDK_DRAWABLE (toplevel_window));
    attributes.x = area->x;
    attributes.y = area->y;
    attributes.width = area->width;
    attributes.height = area->height;
    attributes.event_mask = event_mask;

    window = gdk_window_new (toplevel_window, &attributes, attributes_mask);

    return window;
}

static void
test_screensaver_engine_do_draw (TestScreensaverEngine *engine,
                                 cairo_t               *cairo_context)
{

    cairo_set_source_rgba (cairo_context, g_random_double (), 
                           g_random_double (), g_random_double (),
                           g_random_double () * .5);
    cairo_paint (cairo_context);
}

TestScreensaverEngine *
test_screensaver_engine_new (GdkWindow    *toplevel_window,
                             GdkRectangle *area)
{
    TestScreensaverEngine *engine;

    engine = g_slice_new0 (TestScreensaverEngine);

    engine->window = create_engine_window (toplevel_window, area);
    engine->draw = test_screensaver_engine_do_draw;

    return engine;
}

void
test_screensaver_engine_free (TestScreensaverEngine *engine)
{
    gdk_window_destroy (engine->window);
    g_slice_free (TestScreensaverEngine, engine);
}

TestScreensaverHead *
test_screensaver_head_new (int           monitor_number,
                           GdkRectangle *area)
{
    TestScreensaverHead *head;

    head = g_slice_new0 (TestScreensaverHead);
    head->number = monitor_number;
    head->area = *area;
    head->engine = NULL;

    return head;
}

void
test_screensaver_head_free (TestScreensaverHead *head)
{
    test_screensaver_engine_free (head->engine);
    g_slice_free (TestScreensaverHead, head);
}

TestScreensaver *
test_screensaver_new (GMainContext *context,
                      GdkScreen    *screen)
{
    TestScreensaver *screensaver;
    GdkWindow *root_window;

    if (context == NULL)
        context = g_main_context_default ();

    root_window = gdk_screen_get_root_window (screen);

    screensaver = g_slice_new0 (TestScreensaver);
    screensaver->context = g_main_context_ref (context);
    screensaver->screen = screen;
    screensaver->drawable = GDK_DRAWABLE (root_window);
    screensaver->state = TEST_SCREENSAVER_STATE_UNKNOWN;
    screensaver->heads = NULL;
    screensaver->head_layout = gdk_region_new ();

    return screensaver;
}

void
test_screensaver_free (TestScreensaver *screensaver)
{
    g_main_context_unref (screensaver->context);
    gdk_region_destroy (screensaver->head_layout);
    g_slice_free (TestScreensaver, screensaver);
}

static gboolean
test_screensaver_query_for_notify_event_number (TestScreensaver *screensaver)
{
    int event_base, error_base;

    event_base = 0;
    if (!XScreenSaverQueryExtension (GDK_SCREEN_XDISPLAY (screensaver->screen),
                                     &event_base, &error_base))
      return FALSE;

    screensaver->notify_event_number = event_base + ScreenSaverNotify;
    g_debug ("notify event number is %d", screensaver->notify_event_number);

    return TRUE;
}

gboolean
test_screensaver_unset_window_background (TestScreensaver *screensaver)
{
    XSetWindowAttributes attributes = { 0 };
    GdkVisual *visual;
    int x, y, width, height, border_width, depth;
    guint class;
    gulong mask;

    x = 0;
    y = 0;
    border_width = 0;
    width = gdk_screen_get_width (screensaver->screen);
    height = gdk_screen_get_height (screensaver->screen);

    depth = gdk_drawable_get_depth (screensaver->drawable);
    visual = gdk_drawable_get_visual (screensaver->drawable);
    class = InputOutput;

    mask = CWBackPixmap;
    attributes.background_pixmap = None;

    gdk_error_trap_push ();
    XScreenSaverSetAttributes (GDK_SCREEN_XDISPLAY (screensaver->screen),
                               GDK_DRAWABLE_XID (screensaver->drawable),
                               x, y, width, height, border_width,
                               depth, class, GDK_VISUAL_XVISUAL (visual),
                               mask, &attributes);
    gdk_flush ();
    if (gdk_error_trap_pop () != Success)
        return FALSE;

    return TRUE;
}

static void
update_screensaver_state_from_info (TestScreensaver  *screensaver,
                                    XScreenSaverInfo *info)
{
    switch (info->state)
    {
        case ScreenSaverOn:
            g_debug ("server says screensaver is active");
            screensaver->state = TEST_SCREENSAVER_STATE_ACTIVE;
            break;

        case ScreenSaverOff:
            g_debug ("server says screensaver is inactive");
            screensaver->state = TEST_SCREENSAVER_STATE_INACTIVE;
            break;

        case ScreenSaverDisabled:
            g_debug ("server says screensaver is disabled");
            screensaver->state = TEST_SCREENSAVER_STATE_DISABLED;
            break;

        default:
            g_assert_not_reached ();
            break;
    }
}

static void
update_screensaver_toplevel_window_from_info (TestScreensaver  *screensaver,
                                              XScreenSaverInfo *info)
{
    if ((screensaver->toplevel_window == NULL) ||
        (info->window != GDK_WINDOW_XWINDOW (screensaver->toplevel_window)))
    {
        GdkDisplay *display;
        GdkWindow *toplevel_window;

        display = gdk_screen_get_display (screensaver->screen);
        toplevel_window = gdk_window_foreign_new_for_display (display, info->window);

        if (toplevel_window != NULL)
        {
            g_debug ("updating screensaver window to %lx",
                     (gulong) GDK_WINDOW_XWINDOW (toplevel_window));
            screensaver->toplevel_window = toplevel_window;
        }
        else
          g_error ("could not set up screensaver toplevel for 0x%x", info->window);
    }
    else
        g_debug ("screensaver toplevel is already set up");
}

static void
clip_area_against_head_layout (TestScreensaver *screensaver,
                               GdkRectangle    *area)
{
    GdkRegion *new_region;

    new_region = gdk_region_rectangle (area);

    gdk_region_subtract (new_region, screensaver->head_layout);
    gdk_region_get_clipbox (new_region, area);
}

static void
add_area_to_head_layout (TestScreensaver *screensaver,
                         GdkRectangle    *area)
{
    gdk_region_union_with_rect (screensaver->head_layout, area);
}

static void
add_monitor_to_layout (TestScreensaver *screensaver,
                       gint             monitor_number)
{
	TestScreensaverHead *head;
	GdkRectangle area;
    GdkOverlapType overlap_type;

	gdk_screen_get_monitor_geometry (screensaver->screen,
                                     monitor_number, &area);
    g_debug ("monitor %d has geometry %dx%d+%d+%d",
             monitor_number, area.x, area.y,
             area.width, area.height);

    overlap_type = gdk_region_rect_in (screensaver->head_layout, &area);

    switch (overlap_type)
    {
        case GDK_OVERLAP_RECTANGLE_IN:
            break;

        case GDK_OVERLAP_RECTANGLE_PART:
            g_debug ("monitor %d overlaps existing layout, clipping...",
                     monitor_number);
            clip_area_against_head_layout (screensaver, &area);

            /* fall through */

        case GDK_OVERLAP_RECTANGLE_OUT:
            head = test_screensaver_head_new (monitor_number, &area);
            g_debug ("head %d has geometry %dx%d+%d+%d",
                    head->number, head->area.x, head->area.y,
                    head->area.width, head->area.height);
            screensaver->heads = g_list_prepend (screensaver->heads,
                                                 head);

            add_area_to_head_layout (screensaver, &head->area);
            break;
    }
}

static void
setup_head_geometry (TestScreensaver *screensaver)
{
    int number_of_monitors, i;

    g_assert (screensaver->heads == NULL);

    number_of_monitors = gdk_screen_get_n_monitors (screensaver->screen);

    /* FIXME: need to add these in order of largest monitor to smallest
     * monitor
     */
    for (i = 0; i < number_of_monitors; i++)
        add_monitor_to_layout (screensaver, i);
}

#ifdef SUPPORT_DYNAMIC_HEAD_SETUPS
static void
clear_head_geometry (TestScreensaver *screensaver)
{
    g_list_foreach (screensaver->heads, (GFunc) test_screensaver_head_free,
                    NULL);
    g_list_free (screensaver->heads);
    screensaver->heads = NULL;
}

static void
update_head_geometry (TestScreensaver *screensaver)
{
    clear_head_geometry (screensaver);
    setup_head_geometry (screensaver);
}
#endif

static void
free_engine_from_head (TestScreensaverHead *head,
                       GdkWindow           *toplevel_window)
{
    g_assert (head->engine->window != toplevel_window);

    test_screensaver_engine_free (head->engine);
    head->engine = NULL;
}

static void
create_engine_for_head (TestScreensaverHead *head,
                        GdkWindow           *toplevel_window)
{
    g_assert (head->engine == NULL);

    head->engine = test_screensaver_engine_new (toplevel_window,
                                                &head->area);
}

static void
show_engine_for_head (TestScreensaverHead *head)
{
    TestScreensaverEngine *engine;

    engine = head->engine;
    gdk_window_show (engine->window);
}

static void
test_screensaver_fade_to_black (TestScreensaver *screensaver)
{
    cairo_t *cairo_context;
    int i;

    gdk_error_trap_push ();
    cairo_context = gdk_cairo_create (screensaver->toplevel_window);
    cairo_set_source_rgba (cairo_context, 0.0, 0.0, 0.0, 0.5);
    for (i = 0; i < 10; i++)
    {
        cairo_paint (cairo_context);
        gdk_flush ();
    }
    cairo_destroy (cairo_context);

    gdk_flush ();
    gdk_error_trap_push ();
}

static void
draw_engine_for_head (TestScreensaverHead *head)
{
    cairo_t *cairo_context;
    TestScreensaverEngine *engine;

    engine = head->engine;

    g_debug ("drawing engine for head %d", head->number);
    cairo_context = gdk_cairo_create (engine->window);
    engine->draw (engine, cairo_context);
    cairo_destroy (cairo_context);
    gdk_flush ();
}

static gboolean
draw_heads (TestScreensaver *screensaver)
{
    g_debug ("drawing heads");
    g_list_foreach (screensaver->heads, (GFunc) draw_engine_for_head, NULL);
    return TRUE;
}

static void
test_screensaver_activate (TestScreensaver *screensaver)
{
    test_screensaver_fade_to_black (screensaver);

    g_list_foreach (screensaver->heads, (GFunc) create_engine_for_head,
                    screensaver->toplevel_window);
    g_list_foreach (screensaver->heads, (GFunc) show_engine_for_head,
                    screensaver->toplevel_window);

    screensaver->timeout_id = g_timeout_add (1000, (GSourceFunc) draw_heads,
                                             screensaver);
}

static void
test_screensaver_deactivate (TestScreensaver *screensaver)
{
    g_source_remove (screensaver->timeout_id);
    screensaver->timeout_id = 0;

    g_list_foreach (screensaver->heads, (GFunc) free_engine_from_head,
                    screensaver->toplevel_window);
}

static void
test_screensaver_toggle (TestScreensaver *screensaver)
{
    switch (screensaver->state)
    {
        case TEST_SCREENSAVER_STATE_ACTIVE:
            test_screensaver_activate (screensaver);
            break;

        case TEST_SCREENSAVER_STATE_INACTIVE:
        case TEST_SCREENSAVER_STATE_DISABLED:
            test_screensaver_deactivate (screensaver);
            break;

        default:
            break;
    }
}

static gboolean
handle_screensaver_event (TestScreensaver *screensaver)
{
    XScreenSaverInfo *info;
    GdkWindow *old_toplevel_window;

    info = XScreenSaverAllocInfo ();

    g_debug ("querying for updated server screensaver state information");
    if (!XScreenSaverQueryInfo (GDK_SCREEN_XDISPLAY (screensaver->screen),
                                GDK_DRAWABLE_XID (screensaver->drawable),
                                info))
    {
        g_debug ("could not query for updated server screensaver "
                 "state information");
        XFree (info);
        return FALSE;
    }

    old_toplevel_window = screensaver->toplevel_window;

    g_debug ("updating internal state from server screensaver state "
             "information");
    update_screensaver_state_from_info (screensaver, info); 

    g_debug ("updating toplevel window from server screensaver state "
             "information");
    update_screensaver_toplevel_window_from_info (screensaver, info); 

    test_screensaver_toggle (screensaver);

    XFree (info);
    return TRUE;
}

static GdkFilterReturn
on_event (XEvent          *xevent,
          GdkEvent        *event,
          TestScreensaver *screensaver)
{
    if (xevent->type != screensaver->notify_event_number)
        return GDK_FILTER_CONTINUE;

    g_debug ("received screensaver event");
    handle_screensaver_event (screensaver);

    return GDK_FILTER_CONTINUE;
}

void
test_screensaver_listen_for_events (TestScreensaver *screensaver)
{
    gulong mask;
                             
    mask = ScreenSaverCycleMask | ScreenSaverNotifyMask;
    XScreenSaverSelectInput (GDK_SCREEN_XDISPLAY (screensaver->screen),
                             GDK_DRAWABLE_XID (screensaver->drawable),
                             mask);

    gdk_window_add_filter (NULL, (GdkFilterFunc) on_event, screensaver);
}

gboolean
test_screensaver_register (TestScreensaver *screensaver)
{
    g_debug ("checking for screensaver extension");
    if (!test_screensaver_query_for_notify_event_number (screensaver))
    {
        g_debug ("could not find screensaver extension on display");
        return FALSE;
    }

    g_debug ("setting screensaver background to be clear");
    if (!test_screensaver_unset_window_background (screensaver))
    {
        g_debug ("could not set screensaver background");
        return FALSE;
    }

    g_debug ("listening for screensaver events");
    test_screensaver_listen_for_events (screensaver);

    g_debug ("setting up head geometry");
    setup_head_geometry (screensaver);

    return TRUE;
}

int
main (int    argc,
      char **argv)
{
    GMainLoop *loop;
    GMainContext *context;
    GdkScreen *screen;
    TestScreensaver *screensaver;

    g_debug ("opening display '%s'", g_getenv ("DISPLAY"));
    gdk_init (&argc, &argv);

    context = NULL;
    loop = g_main_loop_new (context, FALSE);

    screen = gdk_screen_get_default ();

    g_debug ("creating test screensaver on screen %d",
             gdk_screen_get_number (screen));
    screensaver = test_screensaver_new (context, screen);

    g_debug ("registering test screensaver on screen %d",
             gdk_screen_get_number (screen));

    if (!test_screensaver_register (screensaver))
    {
        g_printerr ("could not register screensaver on screen %d",
                    gdk_screen_get_number (screen));
        return 1;
    }

    g_debug ("simulating idle");
    g_spawn_command_line_async ("xset s activate", NULL);

    g_debug ("running event loop");
    g_main_loop_run (loop);

    test_screensaver_free (screensaver);
    g_main_loop_unref (loop);

    return 0;
}

/* vim: set sw=4 ts=4 expandtab */