/* OpenGL/Transitions and Effects
 * #Keywords: OpenGL, shader, effect
 *
 * Create transitions between pages using a custom fragment shader.
 *
 * The example transitions here are taken from gl-transitions.com, and you
 * can edit the shader code itself on the last page of the stack.
 *
 * The transitions work with arbitrary content. We use images, shaders
 * GL areas and plain old widgets to demonstrate this.
 *
 * The demo also shows some over-the-top effects like wobbly widgets,
 * and animated backgrounds.
 */

#include <math.h>
#include <gtk/gtk.h>
#include "gtkshaderstack.h"
#include "gtkshaderbin.h"
#include "gtkshadertoy.h"
#include "gskshaderpaintable.h"

static GtkWidget *demo_window = NULL;

static void
close_window (GtkWidget *widget)
{
  /* Reset the state */
  demo_window = NULL;
}

static void
text_changed (GtkTextBuffer *buffer,
              GtkWidget     *button)
{
  gtk_widget_set_visible (button, TRUE);
}

static void
apply_text (GtkWidget     *button,
            GtkTextBuffer *buffer)
{
  GtkWidget *stack;
  GskGLShader *shader;
  GtkTextIter start, end;
  char *text;

  stack = g_object_get_data (G_OBJECT (button), "the-stack");

  gtk_text_buffer_get_bounds (buffer, &start, &end);
  text = gtk_text_buffer_get_text (buffer, &start, &end, TRUE);

  GBytes *bytes = g_bytes_new_take (text, strlen (text));
  shader = gsk_gl_shader_new_from_bytes (bytes);

  gtk_shader_stack_set_shader (GTK_SHADER_STACK (stack), shader);

  g_object_unref (shader);
  g_bytes_unref (bytes);

  gtk_widget_set_visible (button, FALSE);
}

static void
go_back (GtkWidget     *button,
         GtkWidget     *stack)
{
  gtk_shader_stack_transition (GTK_SHADER_STACK (stack), FALSE);
}

static void
go_forward (GtkWidget     *button,
            GtkWidget     *stack)
{
  gtk_shader_stack_transition (GTK_SHADER_STACK (stack), TRUE);
}

static void
clicked_cb (GtkGestureClick *gesture,
            guint            n_pressed,
            double           x,
            double           y,
            gpointer         data)
{
  gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_CLAIMED);
}

static GtkWidget *
ripple_bin_new (void)
{
  GtkWidget *bin = gtk_shader_bin_new ();
  static GskGLShader *shader = NULL;

  if (shader == NULL)
    shader = gsk_gl_shader_new_from_resource ("/gltransition/ripple.glsl");

  gtk_shader_bin_add_shader (GTK_SHADER_BIN (bin), shader, GTK_STATE_FLAG_PRELIGHT, GTK_STATE_FLAG_PRELIGHT, 20);

  return bin;
}

static GtkWidget *
new_shadertoy (const char *path)
{
  GBytes *shader;
  GtkWidget *toy;

  toy = gtk_shadertoy_new ();
  shader = g_resources_lookup_data (path, 0, NULL);
  gtk_shadertoy_set_image_shader (GTK_SHADERTOY (toy),
                                  g_bytes_get_data (shader, NULL));
  g_bytes_unref (shader);

  return toy;
}

static gboolean
update_paintable (GtkWidget     *widget,
                  GdkFrameClock *frame_clock,
                  gpointer       user_data)
{
  GskShaderPaintable *paintable;
  gint64 frame_time;

  paintable = GSK_SHADER_PAINTABLE (gtk_picture_get_paintable (GTK_PICTURE (widget)));
  frame_time = gdk_frame_clock_get_frame_time (frame_clock);
  gsk_shader_paintable_update_time (paintable, 0, frame_time);

  return G_SOURCE_CONTINUE;
}

static GtkWidget *
make_shader_stack (const char *name,
                   const char *resource_path,
                   int active_child,
                   GtkWidget  *scale)
{
  GtkWidget *stack, *child, *widget, *vbox, *hbox, *bin;
  GtkWidget *label, *button, *tv;
  GskGLShader *shader;
  GObjectClass *class;
  GParamSpecFloat *pspec;
  GtkAdjustment *adjustment;
  GtkTextBuffer *buffer;
  GBytes *bytes;
  GtkEventController *controller;
  GdkPaintable *paintable;

  stack = gtk_shader_stack_new ();
  shader = gsk_gl_shader_new_from_resource (resource_path);
  gtk_shader_stack_set_shader (GTK_SHADER_STACK (stack), shader);
  g_object_unref (shader);

  child = gtk_picture_new_for_resource ("/css_blendmodes/ducky.png");
  gtk_picture_set_can_shrink (GTK_PICTURE (child), TRUE);
  gtk_shader_stack_add_child (GTK_SHADER_STACK (stack), child);

  shader = gsk_gl_shader_new_from_resource ("/gltransition/cogs2.glsl");
  paintable = gsk_shader_paintable_new (shader, NULL);

  child = gtk_picture_new_for_paintable (paintable);
  gtk_widget_add_tick_callback (child, update_paintable, NULL, NULL);
  gtk_picture_set_can_shrink (GTK_PICTURE (child), TRUE);
  gtk_shader_stack_add_child (GTK_SHADER_STACK (stack), child);

  child = gtk_picture_new_for_resource ("/transparent/portland-rose.jpg");
  gtk_picture_set_can_shrink (GTK_PICTURE (child), TRUE);
  gtk_shader_stack_add_child (GTK_SHADER_STACK (stack), child);

  child = new_shadertoy ("/shadertoy/neon.glsl");
  gtk_shader_stack_add_child (GTK_SHADER_STACK (stack), child);

  child = gtk_box_new (GTK_ORIENTATION_VERTICAL, 6);

  class = g_type_class_ref (GTK_TYPE_SHADER_STACK);
  pspec = G_PARAM_SPEC_FLOAT (g_object_class_find_property (class, "duration"));

  adjustment = gtk_range_get_adjustment (GTK_RANGE (scale));
  if (gtk_adjustment_get_lower (adjustment) == 0.0 &&
      gtk_adjustment_get_upper (adjustment) == 0.0)
    {
      gtk_adjustment_configure (adjustment,
                                pspec->default_value,
                                pspec->minimum,
                                pspec->maximum,
                                0.1, 0.5, 0);
    }

  g_type_class_unref (class);

  g_object_bind_property (adjustment, "value",
                          stack, "duration",
                          G_BINDING_DEFAULT);

  widget = gtk_scrolled_window_new ();
  gtk_scrolled_window_set_has_frame (GTK_SCROLLED_WINDOW (widget), TRUE);
  gtk_widget_set_hexpand (widget, TRUE);
  gtk_widget_set_vexpand (widget, TRUE);

  controller = GTK_EVENT_CONTROLLER (gtk_gesture_click_new ());
  gtk_gesture_single_set_button (GTK_GESTURE_SINGLE (controller), 0);
  g_signal_connect (controller, "released", G_CALLBACK (clicked_cb), NULL);
  gtk_event_controller_set_propagation_phase (controller, GTK_PHASE_BUBBLE);
  gtk_widget_add_controller (GTK_WIDGET (widget), controller);

  tv = gtk_text_view_new ();
  gtk_text_view_set_left_margin (GTK_TEXT_VIEW (tv), 4);
  gtk_text_view_set_right_margin (GTK_TEXT_VIEW (tv), 4);
  gtk_text_view_set_top_margin (GTK_TEXT_VIEW (tv), 4);
  gtk_text_view_set_bottom_margin (GTK_TEXT_VIEW (tv), 4);
  buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (tv));
  bytes = g_resources_lookup_data (resource_path, 0, NULL);
  gtk_text_buffer_set_text (buffer,
                            (const char *)g_bytes_get_data (bytes, NULL),
                            g_bytes_get_size (bytes));
  g_bytes_unref (bytes);
  gtk_scrolled_window_set_child (GTK_SCROLLED_WINDOW (widget), tv);

  gtk_box_append (GTK_BOX (child), widget);

  gtk_shader_stack_add_child (GTK_SHADER_STACK (stack), child);

  gtk_shader_stack_set_active (GTK_SHADER_STACK (stack), active_child);

  vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 6);

  widget = gtk_center_box_new ();
  label = gtk_label_new (name);
  gtk_widget_add_css_class (label, "title-4");
  gtk_widget_set_size_request (label, -1, 26);
  gtk_center_box_set_center_widget (GTK_CENTER_BOX (widget), label);

  button = gtk_button_new_from_icon_name ("view-refresh-symbolic");
  g_signal_connect (buffer, "changed", G_CALLBACK (text_changed), button);
  g_object_set_data (G_OBJECT (button), "the-stack", stack);
  g_signal_connect (button, "clicked", G_CALLBACK (apply_text), buffer);
  gtk_widget_set_halign (button, GTK_ALIGN_CENTER);
  gtk_widget_set_valign (button, GTK_ALIGN_CENTER);
  gtk_widget_add_css_class (button, "small");
  gtk_widget_set_visible (button, FALSE);
  gtk_center_box_set_end_widget (GTK_CENTER_BOX (widget), button);

  gtk_box_append (GTK_BOX (vbox), widget);

  GtkWidget *bin2 = ripple_bin_new ();
  gtk_shader_bin_set_child (GTK_SHADER_BIN (bin2), stack);

  gtk_box_append (GTK_BOX (vbox), bin2);

  hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 6);
  gtk_widget_set_halign (hbox, GTK_ALIGN_CENTER);

  gtk_box_append (GTK_BOX (vbox), hbox);

  button = gtk_button_new_from_icon_name ("go-previous-symbolic");
  g_signal_connect (button, "clicked", G_CALLBACK (go_back), stack);
  bin = ripple_bin_new ();
  gtk_shader_bin_set_child (GTK_SHADER_BIN (bin), button);
  gtk_box_append (GTK_BOX (hbox), bin);

  button = gtk_button_new_from_icon_name ("go-next-symbolic");
  g_signal_connect (button, "clicked", G_CALLBACK (go_forward), stack);
  bin = ripple_bin_new ();
  gtk_shader_bin_set_child (GTK_SHADER_BIN (bin), button);
  gtk_box_append (GTK_BOX (hbox), bin);

  return vbox;
}

static void
remove_provider (gpointer data)
{
  GtkStyleProvider *provider = GTK_STYLE_PROVIDER (data);

  gtk_style_context_remove_provider_for_display (gdk_display_get_default (), provider);
  g_object_unref (provider);
}

static GtkWidget *
create_gltransition_window (GtkWidget *do_widget)
{
  GtkWidget *window, *headerbar, *scale, *outer_grid, *grid, *background;
  GdkPaintable *paintable;
  GtkCssProvider *provider;

  window = gtk_window_new ();
  gtk_window_set_display (GTK_WINDOW (window),  gtk_widget_get_display (do_widget));
  gtk_window_set_title (GTK_WINDOW (window), "Transitions and Effects");
  headerbar = gtk_header_bar_new ();
  scale = gtk_scale_new (GTK_ORIENTATION_HORIZONTAL, NULL);
  gtk_scale_set_draw_value (GTK_SCALE (scale), FALSE);
  gtk_widget_set_size_request (scale, 100, -1);
  gtk_widget_set_tooltip_text (scale, "Transition duration");
  gtk_header_bar_pack_end (GTK_HEADER_BAR (headerbar), scale);
  gtk_window_set_titlebar (GTK_WINDOW (window), headerbar);
  gtk_window_set_default_size (GTK_WINDOW (window), 800, 600);
  g_signal_connect (window, "destroy", G_CALLBACK (close_window), NULL);

  outer_grid = gtk_grid_new ();
  gtk_window_set_child (GTK_WINDOW (window), outer_grid);

  paintable = gsk_shader_paintable_new (gsk_gl_shader_new_from_resource ("/gltransition/background.glsl"), NULL);
  background = gtk_picture_new_for_paintable (paintable);
  gtk_widget_add_tick_callback (background, update_paintable, NULL, NULL);

  gtk_grid_attach (GTK_GRID (outer_grid),
                   background,
                   0, 0, 1, 1);

  grid = gtk_grid_new ();
  gtk_grid_attach (GTK_GRID (outer_grid),
                   grid,
                   0, 0, 1, 1);

  gtk_widget_set_halign (grid, GTK_ALIGN_CENTER);
  gtk_widget_set_valign (grid, GTK_ALIGN_CENTER);
  gtk_widget_set_margin_start (grid, 12);
  gtk_widget_set_margin_end (grid, 12);
  gtk_widget_set_margin_top (grid, 12);
  gtk_widget_set_margin_bottom (grid, 12);
  gtk_grid_set_row_spacing (GTK_GRID (grid), 6);
  gtk_grid_set_column_spacing (GTK_GRID (grid), 6);
  gtk_grid_set_row_homogeneous (GTK_GRID (grid), TRUE);
  gtk_grid_set_column_homogeneous (GTK_GRID (grid), TRUE);

  gtk_grid_attach (GTK_GRID (grid),
                   make_shader_stack ("Wind", "/gltransition/wind.glsl", 0, scale),
                   0, 0, 1, 1);
  gtk_grid_attach (GTK_GRID (grid),
                   make_shader_stack ("Radial", "/gltransition/radial.glsl", 1, scale),
                   1, 0, 1, 1);
  gtk_grid_attach (GTK_GRID (grid),
                   make_shader_stack ("Crosswarp", "/gltransition/crosswarp.glsl", 2, scale),
                   0, 1, 1, 1);
  gtk_grid_attach (GTK_GRID (grid),
                   make_shader_stack ("Kaleidoscope", "/gltransition/kaleidoscope.glsl", 3, scale),
                   1, 1, 1, 1);

  provider = gtk_css_provider_new ();
  gtk_css_provider_load_from_string (provider, "button.small { padding: 0; }");
  gtk_style_context_add_provider_for_display (gdk_display_get_default (),
                                              GTK_STYLE_PROVIDER (provider),
                                              GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);

  g_object_set_data_full (G_OBJECT (window), "provider", provider, remove_provider);

  return window;
}

GtkWidget *
do_gltransition (GtkWidget *do_widget)
{
  if (!demo_window)
    demo_window = create_gltransition_window (do_widget);

  if (!gtk_widget_get_visible (demo_window))
    gtk_widget_set_visible (demo_window, TRUE);
  else
    gtk_window_destroy (GTK_WINDOW (demo_window));

  return demo_window;
}