#include "SparkEmitter.h"
#include <random>
#include <cmath>
#include "OpenGlExtensions.h"

namespace ZL {

	SparkEmitter::SparkEmitter()
		: emissionRate(100.0f), isActive(true), drawDataDirty(true), maxParticles(200) {
		particles.resize(maxParticles);
		drawPositions.reserve(maxParticles * 6);
		drawTexCoords.reserve(maxParticles * 6);
		lastEmissionTime = std::chrono::steady_clock::now();

		sparkQuad.data = VertexDataStruct();
	}

	SparkEmitter::SparkEmitter(const std::vector<Vector3f>& positions, float rate)
		: emissionPoints(positions), emissionRate(rate), isActive(true),
		drawDataDirty(true), maxParticles(positions.size() * 100) {
		particles.resize(maxParticles);
		drawPositions.reserve(maxParticles * 6);
		drawTexCoords.reserve(maxParticles * 6);
		lastEmissionTime = std::chrono::steady_clock::now();

		sparkQuad.data = VertexDataStruct();
	}

	SparkEmitter::SparkEmitter(const std::vector<Vector3f>& positions,
		std::shared_ptr<Texture> tex,
		float rate)
		: emissionPoints(positions), texture(tex), emissionRate(rate),
		isActive(true), drawDataDirty(true), maxParticles(positions.size() * 100) {
		particles.resize(maxParticles);
		drawPositions.reserve(maxParticles * 6);
		drawTexCoords.reserve(maxParticles * 6);
		lastEmissionTime = std::chrono::steady_clock::now();

		sparkQuad.data = VertexDataStruct();
	}

	void SparkEmitter::setTexture(std::shared_ptr<Texture> tex) {
		texture = tex;
	}

	void SparkEmitter::prepareDrawData() {
		if (!drawDataDirty) return;

		drawPositions.clear();
		drawTexCoords.clear();

		if (getActiveParticleCount() == 0) {
			drawDataDirty = false;
			return;
		}

		std::vector<std::pair<const SparkParticle*, float>> sortedParticles;
		sortedParticles.reserve(getActiveParticleCount());

		for (const auto& particle : particles) {
			if (particle.active) {
				sortedParticles.push_back({ &particle, particle.position.v[2] });
			}
		}

		std::sort(sortedParticles.begin(), sortedParticles.end(),
			[](const auto& a, const auto& b) {
				return a.second > b.second;
			});

		for (const auto& [particlePtr, depth] : sortedParticles) {
			const auto& particle = *particlePtr;
			Vector3f pos = particle.position;
			float size = 0.04f * particle.scale;

			drawPositions.push_back({ pos.v[0] - size, pos.v[1] - size, pos.v[2] });
			drawTexCoords.push_back({ 0.0f, 0.0f });

			drawPositions.push_back({ pos.v[0] - size, pos.v[1] + size, pos.v[2] });
			drawTexCoords.push_back({ 0.0f, 1.0f });

			drawPositions.push_back({ pos.v[0] + size, pos.v[1] + size, pos.v[2] });
			drawTexCoords.push_back({ 1.0f, 1.0f });

			drawPositions.push_back({ pos.v[0] - size, pos.v[1] - size, pos.v[2] });
			drawTexCoords.push_back({ 0.0f, 0.0f });

			drawPositions.push_back({ pos.v[0] + size, pos.v[1] + size, pos.v[2] });
			drawTexCoords.push_back({ 1.0f, 1.0f });

			drawPositions.push_back({ pos.v[0] + size, pos.v[1] - size, pos.v[2] });
			drawTexCoords.push_back({ 1.0f, 0.0f });
		}

		drawDataDirty = false;
	}

	void SparkEmitter::draw(Renderer& renderer, float zoom, int screenWidth, int screenHeight) {
		if (getActiveParticleCount() == 0) {
			return;
		}

		if (!texture) {
			return;
		}

		prepareDrawData();

		if (drawPositions.empty()) {
			return;
		}

		sparkQuad.data.PositionData = drawPositions;
		sparkQuad.data.TexCoordData = drawTexCoords;
		sparkQuad.RefreshVBO();

		static const std::string defaultShaderName = "default";
		static const std::string vPositionName = "vPosition";
		static const std::string vTexCoordName = "vTexCoord";
		static const std::string textureUniformName = "Texture";

		renderer.shaderManager.PushShader(defaultShaderName);
		renderer.RenderUniform1i(textureUniformName, 0);
		renderer.EnableVertexAttribArray(vPositionName);
		renderer.EnableVertexAttribArray(vTexCoordName);

		float aspectRatio = static_cast<float>(screenWidth) / static_cast<float>(screenHeight);
		renderer.PushPerspectiveProjectionMatrix(1.0 / 1.5, aspectRatio, 1, 1000);

		glBindTexture(GL_TEXTURE_2D, texture->getTexID());

		glEnable(GL_BLEND);
		glBlendFunc(GL_SRC_ALPHA, GL_ONE);// Аддитивное смешивание для эффекта свечения

		renderer.PushMatrix();
		renderer.LoadIdentity();
		renderer.TranslateMatrix({ 0, 0, -1.0f * zoom });

		renderer.DrawVertexRenderStruct(sparkQuad);

		renderer.PopMatrix();
		renderer.PopProjectionMatrix();

		glDisable(GL_BLEND);

		renderer.DisableVertexAttribArray(vPositionName);
		renderer.DisableVertexAttribArray(vTexCoordName);
		renderer.shaderManager.PopShader();
	}

	void SparkEmitter::update(float deltaTimeMs) {
		auto currentTime = std::chrono::steady_clock::now();
		auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(
			currentTime - lastEmissionTime).count();

		if (isActive && elapsed >= emissionRate) {
			emit();
			lastEmissionTime = currentTime;
			drawDataDirty = true;
		}

		bool anyChanged = false;
		for (auto& particle : particles) {
			if (particle.active) {
				Vector3f oldPosition = particle.position;
				float oldScale = particle.scale;

				particle.position.v[0] += particle.velocity.v[0] * deltaTimeMs / 1000.0f;
				particle.position.v[1] += particle.velocity.v[1] * deltaTimeMs / 1000.0f;
				particle.position.v[2] += particle.velocity.v[2] * deltaTimeMs / 1000.0f;

				particle.lifeTime += deltaTimeMs;

				if (particle.lifeTime >= particle.maxLifeTime) {
					particle.active = false;
					anyChanged = true;
				}
				else {
					float lifeRatio = particle.lifeTime / particle.maxLifeTime;
					particle.scale = 1.0f - lifeRatio * 0.8f;

					if (oldPosition.v[0] != particle.position.v[0] ||
						oldPosition.v[1] != particle.position.v[1] ||
						oldPosition.v[2] != particle.position.v[2] ||
						oldScale != particle.scale) {
						anyChanged = true;
					}
				}
			}
		}

		if (anyChanged) {
			drawDataDirty = true;
		}
	}

	void SparkEmitter::emit() {
		if (emissionPoints.empty()) return;
		bool emitted = false;

		for (int i = 0; i < emissionPoints.size(); ++i) {
			bool particleFound = false;

			for (auto& particle : particles) {
				if (!particle.active) {
					initParticle(particle, i);
					particle.active = true;
					particle.lifeTime = 0;
					particle.position = emissionPoints[i];
					particle.emitterIndex = i;
					particleFound = true;
					emitted = true;
					break;
				}
			}

			if (!particleFound && !particles.empty()) {
				size_t oldestIndex = 0;
				float maxLifeTime = 0;

				for (size_t j = 0; j < particles.size(); ++j) {
					if (particles[j].lifeTime > maxLifeTime) {
						maxLifeTime = particles[j].lifeTime;
						oldestIndex = j;
					}
				}

				initParticle(particles[oldestIndex], i);
				particles[oldestIndex].active = true;
				particles[oldestIndex].lifeTime = 0;
				particles[oldestIndex].position = emissionPoints[i];
				particles[oldestIndex].emitterIndex = i;
				emitted = true;
			}
		}

		if (emitted) {
			drawDataDirty = true;
		}
	}

	void SparkEmitter::setEmissionPoints(const std::vector<Vector3f>& positions) {
		emissionPoints = positions;
		maxParticles = positions.size() * 100;
		particles.resize(maxParticles);
		drawDataDirty = true;
	}

	void SparkEmitter::initParticle(SparkParticle& particle, int emitterIndex) {
		particle.velocity = getRandomVelocity(emitterIndex);
		particle.scale = 1.0f;
		particle.maxLifeTime = 800.0f + (rand() % 400);
		particle.emitterIndex = emitterIndex;
	}

	Vector3f SparkEmitter::getRandomVelocity(int emitterIndex) {
		static std::random_device rd;
		static std::mt19937 gen(rd());
		static std::uniform_real_distribution<> angleDist(0, 2 * M_PI);
		static std::uniform_real_distribution<> speedDist(0.5f, 2.0f);
		static std::uniform_real_distribution<> zSpeedDist(1.0f, 3.0f);

		float angle = angleDist(gen);
		float speed = speedDist(gen);
		float zSpeed = zSpeedDist(gen);

		if (emitterIndex == 0) {
			return Vector3f{
				cosf(angle) * speed - 0.3f,
				sinf(angle) * speed,
				zSpeed
			};
		}
		else {
			return Vector3f{
				cosf(angle) * speed + 0.3f,
				sinf(angle) * speed,
				zSpeed
			};
		}
	}

	const std::vector<SparkParticle>& SparkEmitter::getParticles() const {
		return particles;
	}

	size_t SparkEmitter::getActiveParticleCount() const {
		size_t count = 0;
		for (const auto& particle : particles) {
			if (particle.active) {
				count++;
			}
		}
		return count;
	}

} // namespace ZL