/*
 * Cagebreak: A Wayland tiling compositor.
 *
 * Copyright (C) 2020 The Cagebreak Authors
 * Copyright (C) 2018-2020 Jente Hidskes
 * Copyright (C) 2019 The Sway authors
 *
 * See the LICENSE file accompanying this file.
 */

#include <stdlib.h>
#include <wayland-server-core.h>
#include <wlr/backend.h>
#include <wlr/render/wlr_renderer.h>
#include <wlr/types/wlr_box.h>
#include <wlr/types/wlr_matrix.h>
#include <wlr/types/wlr_output.h>
#include <wlr/types/wlr_output_damage.h>
#include <wlr/types/wlr_output_layout.h>
#include <wlr/types/wlr_surface.h>
#include <wlr/util/log.h>
#include <wlr/util/region.h>

#include "message.h"
#include "output.h"
#include "seat.h"
#include "server.h"
#include "util.h"
#include "view.h"
#include "workspace.h"

static void
scissor_output(struct wlr_output *output, pixman_box32_t *rect) {
	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);

	struct wlr_box box = {
	    .x = rect->x1,
	    .y = rect->y1,
	    .width = rect->x2 - rect->x1,
	    .height = rect->y2 - rect->y1,
	};

	int output_width, output_height;
	wlr_output_transformed_resolution(output, &output_width, &output_height);
	enum wl_output_transform transform =
	    wlr_output_transform_invert(output->transform);
	wlr_box_transform(&box, &box, transform, output_width, output_height);

	wlr_renderer_scissor(renderer, &box);
}

struct render_data {
	pixman_region32_t *damage;
	int tile_width, tile_height;
};

static void
render_texture(struct wlr_output *wlr_output, pixman_region32_t *output_damage,
               struct wlr_texture *texture, const struct wlr_box *box,
               const float matrix[static 9]) {
	struct wlr_renderer *renderer =
	    wlr_backend_get_renderer(wlr_output->backend);

	pixman_region32_t damage;
	pixman_region32_init(&damage);
	pixman_region32_union_rect(&damage, &damage, box->x, box->y, box->width,
	                           box->height);
	pixman_region32_intersect(&damage, &damage, output_damage);
	if(!pixman_region32_not_empty(&damage)) {
		goto damage_finish;
	}

	int nrects;
	pixman_box32_t *rects = pixman_region32_rectangles(&damage, &nrects);
	for(int i = 0; i < nrects; i++) {
		scissor_output(wlr_output, &rects[i]);
		wlr_render_texture_with_matrix(renderer, texture, matrix, 1.0F);
	}

damage_finish:
	pixman_region32_fini(&damage);
}

static void
render_surface_iterator(struct cg_output *output, struct wlr_surface *surface,
                        struct wlr_box *box, void *user_data) {
	struct render_data *data = user_data;
	struct wlr_output *wlr_output = output->wlr_output;
	pixman_region32_t *output_damage = data->damage;

	struct wlr_texture *texture = wlr_surface_get_texture(surface);
	if(!texture) {
		wlr_log(WLR_DEBUG, "Cannot obtain surface texture");
		return;
	}

	scale_box(box, wlr_output->scale);

	float matrix[9];
	enum wl_output_transform transform =
	    wlr_output_transform_invert(surface->current.transform);
	wlr_matrix_project_box(matrix, box, transform, 0.0F,
	                       wlr_output->transform_matrix);

	if(data->tile_width != 0) {
		box->width =
		    box->width > data->tile_width ? data->tile_width : box->width;
	}
	if(data->tile_height != 0) {
		box->height =
		    box->height > data->tile_height ? data->tile_height : box->height;
	}
	render_texture(wlr_output, output_damage, texture, box, matrix);
}

static void
render_drag_icons(struct cg_output *output, pixman_region32_t *damage,
                  struct wl_list *drag_icons) {
	struct render_data data = {
	    .damage = damage,
	    .tile_width = 0,
	    .tile_height = 0,
	};
	output_drag_icons_for_each_surface(output, drag_icons,
	                                   render_surface_iterator, &data);
}

/**
 * Render all toplevels without descending into popups.
 */
static void
render_view_toplevels(struct cg_view *view, struct cg_output *output,
                      pixman_region32_t *damage) {
	struct render_data data = {
	    .damage = damage,
	    .tile_width = 0,
	    .tile_height = 0,
	};
	// TODO: improve run time behaviour of view_get_tile
	struct cg_tile *view_tile = view_get_tile(view);
	if(view_tile != NULL) {
		if(view_tile->tile.width != view->wlr_surface->current.width ||
		   view_tile->tile.height != view->wlr_surface->current.height) {
			view_damage_whole(view);
		}
		data.tile_width = view_tile->tile.width;
		data.tile_height = view_tile->tile.height;
	}

	double ox, oy;
	ox = view->ox;
	oy = view->oy;
	output_surface_for_each_surface(output, view->wlr_surface, ox, oy,
	                                render_surface_iterator, &data);
}

static void
render_popup_iterator(struct cg_output *output, struct wlr_surface *surface,
                      struct wlr_box *box, void *data) {
	/* Render this popup's surface. */
	render_surface_iterator(output, surface, box, data);

	/* Render this popup's child toplevels. */
	output_surface_for_each_surface(output, surface, box->x, box->y,
	                                render_surface_iterator, data);
}

static void
render_view_popups(struct cg_view *view, struct cg_output *output,
                   pixman_region32_t *damage) {
	struct render_data data = {
	    .damage = damage,
	    .tile_width = 0,
	    .tile_height = 0,
	};
	output_view_for_each_popup(output, view, render_popup_iterator, &data);
}

void
output_render(struct cg_output *output, pixman_region32_t *damage) {
	struct cg_server *server = output->server;
	struct wlr_output *wlr_output = output->wlr_output;

	struct wlr_renderer *renderer =
	    wlr_backend_get_renderer(wlr_output->backend);
	if(!renderer) {
		wlr_log(WLR_DEBUG, "Expected the output backend to have a renderer");
		return;
	}

	wlr_renderer_begin(renderer, wlr_output->width, wlr_output->height);

	if(!pixman_region32_not_empty(damage)) {
		wlr_log(WLR_DEBUG, "Output isn't damaged but needs a buffer swap");
		goto renderer_end;
	}

#ifdef DEBUG
	if(server->debug_damage_tracking) {
		wlr_renderer_clear(renderer, (float[]){1.0F, 0.0F, 0.0F, 1.0F});
	}
#endif

	int nrects;
	pixman_box32_t *rects = pixman_region32_rectangles(damage, &nrects);
	for(int i = 0; i < nrects; i++) {
		scissor_output(wlr_output, &rects[i]);
		wlr_renderer_clear(renderer, server->bg_color);
	}

	bool first = true;
	for(struct cg_tile *tile =
	        output->workspaces[output->curr_workspace]->focused_tile;
	    first ||
	    tile != output->workspaces[output->curr_workspace]->focused_tile;
	    tile = tile->next) {
		first = false;
		/* Only render visible views */
		if(tile->view != NULL) {
			render_view_toplevels(tile->view, output, damage);
		}
	}

	struct cg_view *view;
	wl_list_for_each_reverse(
	    view, &output->workspaces[output->curr_workspace]->unmanaged_views,
	    link) {
		render_view_toplevels(view, output, damage);
	}

	struct cg_view *focused_view = seat_get_focus(server->seat);
	if(focused_view != NULL) {
		render_view_popups(focused_view, output, damage);
	}

	struct cg_message *message;
	wl_list_for_each_reverse(message, &output->messages, link) {
		float matrix[9];
		wlr_matrix_project_box(matrix, message->position,
		                       WL_OUTPUT_TRANSFORM_NORMAL, 0.0F,
		                       wlr_output->transform_matrix);
		render_texture(output->wlr_output, damage, message->message,
		               message->position, matrix);
	}
	render_drag_icons(output, damage, &server->seat->drag_icons);

renderer_end:
	/* Draw software cursor in case hardware cursors aren't
	   available. This is a no-op when they are. */
	wlr_output_render_software_cursors(wlr_output, damage);
	wlr_renderer_scissor(renderer, NULL);
	wlr_renderer_end(renderer);

	int output_width, output_height;
	wlr_output_transformed_resolution(wlr_output, &output_width,
	                                  &output_height);

	pixman_region32_t frame_damage;
	pixman_region32_init(&frame_damage);

	enum wl_output_transform transform =
	    wlr_output_transform_invert(wlr_output->transform);
	wlr_region_transform(&frame_damage, &output->damage->current, transform,
	                     output_width, output_height);

#ifdef DEBUG
	if(server->debug_damage_tracking) {
		pixman_region32_union_rect(&frame_damage, &frame_damage, 0, 0,
		                           output_width, output_height);
	}
#endif

	wlr_output_set_damage(wlr_output, &frame_damage);
	pixman_region32_fini(&frame_damage);

	if(!wlr_output_commit(wlr_output)) {
		wlr_log(WLR_ERROR, "Could not commit output");
	}
}