//////////////////////////////////////////////////////////////////////
// This file is part of Remere's Map Editor
//////////////////////////////////////////////////////////////////////
// Remere's Map Editor 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.
//
// Remere's Map Editor 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 "main.h"
#include "light_drawer.h"
#include "gl_renderer.h"

#include "gl_compat.h"

LightDrawer::LightDrawer() {
	texture = 0;
	buffer.resize(static_cast<size_t>(rme::ClientMapWidth * rme::ClientMapHeight * rme::PixelFormatRGBA));
	global_color = wxColor(50, 50, 50, 255);
}

LightDrawer::~LightDrawer() {
	unloadGLTexture();

	lights.clear();
}

void LightDrawer::draw(int map_x, int map_y, int end_x, int end_y, int scroll_x, int scroll_y, GLRenderer* renderer) {
	if (texture == 0) {
		createGLTexture();
	}

	int w = end_x - map_x;
	int h = end_y - map_y;

	buffer.resize(static_cast<size_t>(w * h * rme::PixelFormatRGBA));

	for (int x = 0; x < w; ++x) {
		for (int y = 0; y < h; ++y) {
			int mx = (map_x + x);
			int my = (map_y + y);
			int index = (y * w + x);
			int color_index = index * rme::PixelFormatRGBA;

			buffer[color_index] = global_color.Red();
			buffer[color_index + 1] = global_color.Green();
			buffer[color_index + 2] = global_color.Blue();
			buffer[color_index + 3] = global_color.Alpha();

			for (auto &light : lights) {
				float intensity = calculateIntensity(mx, my, light);
				if (intensity == 0.f) {
					continue;
				}
				wxColor light_color = colorFromEightBit(light.color);
				uint8_t red = static_cast<uint8_t>(light_color.Red() * intensity);
				uint8_t green = static_cast<uint8_t>(light_color.Green() * intensity);
				uint8_t blue = static_cast<uint8_t>(light_color.Blue() * intensity);
				buffer[color_index] = std::max(buffer[color_index], red);
				buffer[color_index + 1] = std::max(buffer[color_index + 1], green);
				buffer[color_index + 2] = std::max(buffer[color_index + 2], blue);
			}
		}
	}

	const int draw_x = map_x * rme::TileSize - scroll_x;
	const int draw_y = map_y * rme::TileSize - scroll_y;
	int draw_width = w * rme::TileSize;
	int draw_height = h * rme::TileSize;

	glBindTexture(GL_TEXTURE_2D, texture);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer.data());
	renderer->flush();
	renderer->setBlendMode(GL_DST_COLOR, GL_ONE_MINUS_SRC_ALPHA);

	renderer->drawTexturedQuad(static_cast<float>(draw_x), static_cast<float>(draw_y), static_cast<float>(draw_width), static_cast<float>(draw_height), texture, { 255, 255, 255, 255 });
	renderer->flush();

	renderer->resetBlendMode();
}

void LightDrawer::setGlobalLightColor(uint8_t color) {
	global_color = colorFromEightBit(color);
}

void LightDrawer::addLight(int map_x, int map_y, int map_z, const SpriteLight &light) {
	if (map_z <= rme::MapGroundLayer) {
		map_x -= (rme::MapGroundLayer - map_z);
		map_y -= (rme::MapGroundLayer - map_z);
	}

	if (map_x <= 0 || map_x >= rme::MapMaxWidth || map_y <= 0 || map_y >= rme::MapMaxHeight) {
		return;
	}

	uint8_t intensity = std::min(light.intensity, static_cast<uint8_t>(rme::MaxLightIntensity));

	if (!lights.empty()) {
		Light &previous = lights.back();
		if (previous.map_x == map_x && previous.map_y == map_y && previous.color == light.color) {
			previous.intensity = std::max(previous.intensity, intensity);
			return;
		}
	}

	lights.push_back(Light { static_cast<uint16_t>(map_x), static_cast<uint16_t>(map_y), light.color, intensity });
}

void LightDrawer::clear() noexcept {
	lights.clear();
}

void LightDrawer::createGLTexture() {
	glGenTextures(1, &texture);
}

void LightDrawer::unloadGLTexture() {
	if (texture != 0) {
		GLRenderer::invalidateTexture(texture);
		glDeleteTextures(1, &texture);
	}
}