#define _POSIX_C_SOURCE 200809L
#include <assert.h>
#include <stdlib.h>
#include <time.h>
#include <wayland-server.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_layout.h>
#include <wlr/types/wlr_surface.h>
#include <wlr/types/wlr_wl_shell.h>
#include "log.h"
#include "sway/container.h"
#include "sway/input/input-manager.h"
#include "sway/input/seat.h"
#include "sway/layers.h"
#include "sway/layout.h"
#include "sway/output.h"
#include "sway/server.h"
#include "sway/view.h"

/**
 * Rotate a child's position relative to a parent. The parent size is (pw, ph),
 * the child position is (*sx, *sy) and its size is (sw, sh).
 */
static void rotate_child_position(double *sx, double *sy, double sw, double sh,
		double pw, double ph, float rotation) {
	if (rotation != 0.0) {
		// Coordinates relative to the center of the subsurface
		double ox = *sx - pw/2 + sw/2,
			oy = *sy - ph/2 + sh/2;
		// Rotated coordinates
		double rx = cos(-rotation)*ox - sin(-rotation)*oy,
			ry = cos(-rotation)*oy + sin(-rotation)*ox;
		*sx = rx + pw/2 - sw/2;
		*sy = ry + ph/2 - sh/2;
	}
}

static void render_surface(struct wlr_surface *surface,
		struct wlr_output *wlr_output, struct timespec *when,
		double lx, double ly, float rotation) {
	if (!wlr_surface_has_buffer(surface)) {
		return;
	}
	struct wlr_output_layout *layout = root_container.sway_root->output_layout;
	int width = surface->current->width;
	int height = surface->current->height;
	int render_width = width * wlr_output->scale;
	int render_height = height * wlr_output->scale;
	int owidth, oheight;
	wlr_output_effective_resolution(wlr_output, &owidth, &oheight);

	// FIXME: view coords are inconsistently assumed to be in output or layout coords
	struct wlr_box layout_box = {
		.x = lx + wlr_output->lx, .y = ly + wlr_output->ly,
		.width = render_width, .height = render_height,
	};
	if (wlr_output_layout_intersects(layout, wlr_output, &layout_box)) {
		struct wlr_box render_box = {
			.x = lx, .y = ly,
			.width = render_width, .height = render_height
		};
		float matrix[9];
		wlr_matrix_project_box(matrix, &render_box, surface->current->transform,
			0, wlr_output->transform_matrix);
		wlr_render_texture_with_matrix(server.renderer, surface->texture,
			matrix, 1.0f); // TODO: configurable alpha

		wlr_surface_send_frame_done(surface, when);
	}

	struct wlr_subsurface *subsurface;
	wl_list_for_each(subsurface, &surface->subsurface_list, parent_link) {
		struct wlr_surface_state *state = subsurface->surface->current;
		double sx = state->subsurface_position.x;
		double sy = state->subsurface_position.y;
		double sw = state->buffer_width / state->scale;
		double sh = state->buffer_height / state->scale;
		rotate_child_position(&sx, &sy, sw, sh, width, height, rotation);

		render_surface(subsurface->surface, wlr_output, when,
			lx + sx, ly + sy, rotation);
	}
}

static void render_xdg_v6_popups(struct wlr_xdg_surface_v6 *surface,
		struct wlr_output *wlr_output, struct timespec *when, double base_x,
		double base_y, float rotation) {
	double width = surface->surface->current->width;
	double height = surface->surface->current->height;

	struct wlr_xdg_popup_v6 *popup_state;
	wl_list_for_each(popup_state, &surface->popups, link) {
		struct wlr_xdg_surface_v6 *popup = popup_state->base;
		if (!popup->configured) {
			continue;
		}

		double popup_width = popup->surface->current->width;
		double popup_height = popup->surface->current->height;

		double popup_sx, popup_sy;
		wlr_xdg_surface_v6_popup_get_position(popup, &popup_sx, &popup_sy);
		rotate_child_position(&popup_sx, &popup_sy, popup_width, popup_height,
			width, height, rotation);

		render_surface(popup->surface, wlr_output, when,
			base_x + popup_sx, base_y + popup_sy, rotation);
		render_xdg_v6_popups(popup, wlr_output, when,
			base_x + popup_sx, base_y + popup_sy, rotation);
	}
}

static void render_wl_shell_surface(struct wlr_wl_shell_surface *surface,
		struct wlr_output *wlr_output, struct timespec *when,
		double lx, double ly, float rotation,
		bool is_child) {
	if (is_child || surface->state != WLR_WL_SHELL_SURFACE_STATE_POPUP) {
		render_surface(surface->surface, wlr_output, when,
			lx, ly, rotation);

		double width = surface->surface->current->width;
		double height = surface->surface->current->height;

		struct wlr_wl_shell_surface *popup;
		wl_list_for_each(popup, &surface->popups, popup_link) {
			double popup_width = popup->surface->current->width;
			double popup_height = popup->surface->current->height;

			double popup_x = popup->transient_state->x;
			double popup_y = popup->transient_state->y;
			rotate_child_position(&popup_x, &popup_y, popup_width, popup_height,
				width, height, rotation);

			render_wl_shell_surface(popup, wlr_output, when,
				lx + popup_x, ly + popup_y, rotation, true);
		}
	}
}

struct render_data {
	struct sway_output *output;
	struct timespec *now;
};

static void output_frame_view(swayc_t *view, void *data) {
	struct render_data *rdata = data;
	struct sway_output *output = rdata->output;
	struct timespec *now = rdata->now;
	struct wlr_output *wlr_output = output->wlr_output;
	struct sway_view *sway_view = view->sway_view;
	struct wlr_surface *surface = sway_view->surface;

	if (!surface) {
		return;
	}

	switch (sway_view->type) {
	case SWAY_XDG_SHELL_V6_VIEW: {
		int window_offset_x = view->sway_view->wlr_xdg_surface_v6->geometry.x;
		int window_offset_y = view->sway_view->wlr_xdg_surface_v6->geometry.y;
		render_surface(surface, wlr_output, now,
			view->x - window_offset_x, view->y - window_offset_y, 0);
		render_xdg_v6_popups(sway_view->wlr_xdg_surface_v6, wlr_output,
			now, view->x - window_offset_x, view->y - window_offset_y, 0);
		break;
	}
	case SWAY_WL_SHELL_VIEW:
		render_wl_shell_surface(sway_view->wlr_wl_shell_surface, wlr_output,
			now, view->x, view->y, 0, false);
		break;
	case SWAY_XWAYLAND_VIEW:
		render_surface(surface, wlr_output, now, view->x, view->y, 0);
		break;
	default:
		break;
	}
}

static void render_layer(struct sway_output *output,
		const struct wlr_box *output_layout_box,
		struct timespec *when,
		struct wl_list *layer) {
	struct sway_layer_surface *sway_layer;
	wl_list_for_each(sway_layer, layer, link) {
		struct wlr_layer_surface *layer = sway_layer->layer_surface;
		render_surface(layer->surface, output->wlr_output, when,
				sway_layer->geo.x + output_layout_box->x,
				sway_layer->geo.y + output_layout_box->y, 0);
		wlr_surface_send_frame_done(layer->surface, when);
	}
}

static void output_frame_notify(struct wl_listener *listener, void *data) {
	struct sway_output *soutput = wl_container_of(listener, soutput, frame);
	struct wlr_output *wlr_output = data;
	struct sway_server *server = soutput->server;
	float clear_color[] = {0.25f, 0.25f, 0.25f, 1.0f};
	struct wlr_renderer *renderer = wlr_backend_get_renderer(wlr_output->backend);
	wlr_renderer_clear(renderer, clear_color);

	int buffer_age = -1;
	wlr_output_make_current(wlr_output, &buffer_age);
	wlr_renderer_begin(server->renderer, wlr_output->width, wlr_output->height);

	struct timespec now;
	clock_gettime(CLOCK_MONOTONIC, &now);

	struct wlr_output_layout *layout = root_container.sway_root->output_layout;
	const struct wlr_box *output_box = wlr_output_layout_get_box(
			layout, wlr_output);

	render_layer(soutput, output_box, &now,
			&soutput->layers[ZWLR_LAYER_SHELL_V1_LAYER_BACKGROUND]);
	render_layer(soutput, output_box, &now,
			&soutput->layers[ZWLR_LAYER_SHELL_V1_LAYER_BOTTOM]);

	struct sway_seat *seat = input_manager_current_seat(input_manager);
	swayc_t *focus = sway_seat_get_focus_inactive(seat, soutput->swayc);
	swayc_t *workspace = (focus->type == C_WORKSPACE ?
			focus :
			swayc_parent_by_type(focus, C_WORKSPACE));

	struct render_data rdata = {
		.output = soutput,
		.now = &now,
	};
	swayc_descendants_of_type(workspace, C_VIEW, output_frame_view, &rdata);

	// render unmanaged views on top
	struct sway_view *view;
	wl_list_for_each(view, &root_container.sway_root->unmanaged_views,
			unmanaged_view_link) {
		if (view->type == SWAY_XWAYLAND_VIEW) {
			// the only kind of unamanged view right now is xwayland override redirect
			int view_x = view->wlr_xwayland_surface->x;
			int view_y = view->wlr_xwayland_surface->y;
			render_surface(view->surface, wlr_output, &soutput->last_frame,
					view_x, view_y, 0);
		}
	}

	// TODO: Consider revising this when fullscreen windows are supported
	render_layer(soutput, output_box, &now,
			&soutput->layers[ZWLR_LAYER_SHELL_V1_LAYER_TOP]);
	render_layer(soutput, output_box, &now,
			&soutput->layers[ZWLR_LAYER_SHELL_V1_LAYER_OVERLAY]);

	wlr_renderer_end(server->renderer);
	wlr_output_swap_buffers(wlr_output, &now, NULL);
	soutput->last_frame = now;
}

static void handle_output_destroy(struct wl_listener *listener, void *data) {
	struct sway_output *output = wl_container_of(listener, output, destroy);
	struct wlr_output *wlr_output = data;
	wlr_log(L_DEBUG, "Output %p %s removed", wlr_output, wlr_output->name);

	destroy_output(output->swayc);
}

static void handle_output_mode(struct wl_listener *listener, void *data) {
	struct sway_output *output = wl_container_of(listener, output, mode);
	arrange_layers(output);
	arrange_windows(output->swayc, -1, -1);
}

void handle_new_output(struct wl_listener *listener, void *data) {
	struct sway_server *server = wl_container_of(listener, server, new_output);
	struct wlr_output *wlr_output = data;
	wlr_log(L_DEBUG, "New output %p: %s", wlr_output, wlr_output->name);

	struct sway_output *output = calloc(1, sizeof(struct sway_output));
	if (!output) {
		return;
	}
	output->wlr_output = wlr_output;
	wlr_output->data = output;
	output->server = server;

	if (!wl_list_empty(&wlr_output->modes)) {
		struct wlr_output_mode *mode =
			wl_container_of(wlr_output->modes.prev, mode, link);
		wlr_output_set_mode(wlr_output, mode);
	}

	output->swayc = new_output(output);
	if (!output->swayc) {
		free(output);
		return;
	}

	size_t len = sizeof(output->layers) / sizeof(output->layers[0]);
	for (size_t i = 0; i < len; ++i) {
		wl_list_init(&output->layers[i]);
	}

	sway_input_manager_configure_xcursor(input_manager);

	wl_signal_add(&wlr_output->events.frame, &output->frame);
	output->frame.notify = output_frame_notify;
	wl_signal_add(&wlr_output->events.destroy, &output->destroy);
	output->destroy.notify = handle_output_destroy;
	wl_signal_add(&wlr_output->events.mode, &output->mode);
	output->mode.notify = handle_output_mode;

	arrange_layers(output);
	arrange_windows(&root_container, -1, -1);
}