/*
 * This file is part of wl-overlay: show overlays with images and text in Wayland
 * Copyright © 2022 Midgard
 * 
 * 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 3 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 <stdbool.h>
#include <math.h>
#include <cairo/cairo.h>
#include <pango/pangocairo.h>
#include "common.h"
#include "state.h"


#define float_is_zero(number) (number < 1e-8)


static void
set_source_argb_cairo(cairo_t *cairo, struct color_argb *color) {
	cairo_set_source_rgba(cairo, color->r, color->g, color->b, color->a);
}

static void
draw_rounded_rectangle(cairo_t *cr, int x, int y, int width, int height, int radius)
{
	cairo_new_sub_path(cr);
	cairo_arc(cr, x + radius,         y + radius,          radius, M_PI,     3*M_PI/2);
	cairo_arc(cr, x + width - radius, y + radius,          radius, 3*M_PI/2, 0);
	cairo_arc(cr, x + width - radius, y + height - radius, radius, 0,        M_PI/2);
	cairo_arc(cr, x + radius,         y + height - radius, radius, M_PI/2,   M_PI);
	cairo_close_path(cr);
}

void
draw_frame_into(uint32_t *data, struct user_request *user_request, const int width, const int height)
{
	cairo_surface_t *cairo_target_surface = cairo_image_surface_create_for_data(
			(unsigned char *)data, CAIRO_FORMAT_ARGB32, width, height, width * 4);
	cairo_t *cairo = cairo_create(cairo_target_surface);

	/* Draw background */
	if (!float_is_zero(user_request->backdrop.a)) {
		set_source_argb_cairo(cairo, &user_request->backdrop);
		draw_rounded_rectangle(cairo, 0, 0, width, height, user_request->border_radius);
		cairo_fill(cairo);
	}

	/* Load and draw PNG */
	if (strcmp("", user_request->graphics_filename) != STR_EQUAL) {
		cairo_save(cairo);
		cairo_surface_t *cairo_png_surface = cairo_image_surface_create_from_png(user_request->graphics_filename);
		if (cairo_surface_status(cairo_png_surface) != CAIRO_STATUS_SUCCESS) {
			fprintf(stderr, "Failed to open PNG image.\n");
			exit(1);
		}

		/* Set transformations to fit image in box */
		int img_width  = cairo_image_surface_get_width(cairo_png_surface);
		int img_height = cairo_image_surface_get_height(cairo_png_surface);
		double width_scale  =  ((double)width  - 2*user_request->padding)            / img_width;
		double height_scale = (((double)height - 2*user_request->padding) * 3 / 4.0) / img_height;
		double scale = MIN(width_scale, height_scale);
		if (scale > 1.0) scale = 1.0;
		cairo_translate(cairo,
				(width        - img_width *scale)/2.0,
				(3*height/4.0 - img_height*scale)/2.0);
		cairo_scale(cairo, scale, scale);

		cairo_set_source_surface(cairo, cairo_png_surface, 0.0, 0.0);
		cairo_paint(cairo);
		cairo_surface_destroy(cairo_png_surface);
		cairo_restore(cairo);
	}

	/* Draw text */
	if (user_request->text) {
		PangoLayout *layout = pango_cairo_create_layout(cairo);
		pango_layout_set_text(layout, user_request->text, -1);
		pango_layout_set_alignment(layout, PANGO_ALIGN_CENTER);
		pango_layout_set_width(layout, (width - 2*user_request->padding) * PANGO_SCALE);
		PangoFontDescription *desc = pango_font_description_from_string(user_request->font);
		pango_layout_set_font_description(layout, desc);
		pango_font_description_free(desc);
		set_source_argb_cairo(cairo, &user_request->text_color);
		int text_width = 0, text_height = 0;
		pango_layout_get_size(layout, &text_width, &text_height);
		cairo_move_to(cairo, user_request->padding, 3*height/4.0);
		pango_cairo_show_layout(cairo, layout);
		g_object_unref(layout);
	}

	cairo_surface_destroy(cairo_target_surface);
	cairo_destroy(cairo);
}