#include "UiManager.h"
#include "Utils.h"
#include <fstream>
#include <iostream>
#include <algorithm>

namespace ZL {

	using json = nlohmann::json;

	void UiButton::buildMesh() {
		mesh.data.PositionData.clear();
		mesh.data.TexCoordData.clear();

		float x0 = rect.x;
		float y0 = rect.y;
		float x1 = rect.x + rect.w;
		float y1 = rect.y + rect.h;

		mesh.data.PositionData.push_back({ x0, y0, 0 });
		mesh.data.TexCoordData.push_back({ 0, 0 });

		mesh.data.PositionData.push_back({ x0, y1, 0 });
		mesh.data.TexCoordData.push_back({ 0, 1 });

		mesh.data.PositionData.push_back({ x1, y1, 0 });
		mesh.data.TexCoordData.push_back({ 1, 1 });

		mesh.data.PositionData.push_back({ x0, y0, 0 });
		mesh.data.TexCoordData.push_back({ 0, 0 });

		mesh.data.PositionData.push_back({ x1, y1, 0 });
		mesh.data.TexCoordData.push_back({ 1, 1 });

		mesh.data.PositionData.push_back({ x1, y0, 0 });
		mesh.data.TexCoordData.push_back({ 1, 0 });

		mesh.RefreshVBO();
	}

	void UiButton::draw(Renderer& renderer) const {
		if (!texNormal) return;
		const std::shared_ptr<Texture>* tex = &texNormal;
		switch (state) {
		case ButtonState::Normal: tex = &texNormal; break;
		case ButtonState::Hover: tex = &texHover; break;
		case ButtonState::Pressed: tex = &texPressed; break;
		}
		if (!(*tex)) return;

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

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

		glBindTexture(GL_TEXTURE_2D, (*tex)->getTexID());
		renderer.DrawVertexRenderStruct(mesh);

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

	// UiManager implementation
	void UiManager::loadFromFile(const std::string& path, Renderer& renderer, const std::string& zipFile) {
		std::ifstream in(path);
		if (!in.is_open()) {
			std::cerr << "UiManager: failed to open " << path << std::endl;
			throw std::runtime_error("Failed to load UI file: " + path);
		}

		json j;
		try {
			in >> j;
		}
		catch (const std::exception& e) {
			std::cerr << "UiManager: json parse error: " << e.what() << std::endl;
			throw std::runtime_error("Failed to load UI file: " + path);
		}

		if (!j.contains("root") || !j["root"].is_object()) {
			std::cerr << "UiManager: root node missing or invalid" << std::endl;
			throw std::runtime_error("Failed to load UI file: " + path);
		}

		root = parseNode(j["root"], renderer, zipFile);
		layoutNode(root);
		buttons.clear();
		collectButtons(root);

		for (auto& b : buttons) {
			b->buildMesh();
		}
	}

	std::shared_ptr<UiNode> UiManager::parseNode(const json& j, Renderer& renderer, const std::string& zipFile) {
		auto node = std::make_shared<UiNode>();
		if (j.contains("type") && j["type"].is_string()) node->type = j["type"].get<std::string>();
		if (j.contains("name") && j["name"].is_string()) node->name = j["name"].get<std::string>();

		if (j.contains("x")) node->rect.x = j["x"].get<float>();
		if (j.contains("y")) node->rect.y = j["y"].get<float>();
		if (j.contains("width")) node->rect.w = j["width"].get<float>();
		if (j.contains("height")) node->rect.h = j["height"].get<float>();

		if (j.contains("orientation") && j["orientation"].is_string()) node->orientation = j["orientation"].get<std::string>();
		if (j.contains("spacing")) node->spacing = j["spacing"].get<float>();

		if (node->type == "Button") {
			auto btn = std::make_shared<UiButton>();
			btn->name = node->name;
			btn->rect = node->rect;

			if (!j.contains("textures") || !j["textures"].is_object()) {
				std::cerr << "UiManager: Button '" << btn->name << "' missing textures" << std::endl;
				throw std::runtime_error("UI button textures missing");
			}
			auto t = j["textures"];
			auto loadTex = [&](const std::string& key)->std::shared_ptr<Texture> {
				if (!t.contains(key) || !t[key].is_string()) return nullptr;
				std::string path = t[key].get<std::string>();
				try {
					auto data = CreateTextureDataFromPng(path.c_str(), zipFile.c_str());
					return std::make_shared<Texture>(data);
				}
				catch (const std::exception& e) {
					std::cerr << "UiManager: failed load texture " << path << " : " << e.what() << std::endl;
					throw std::runtime_error("UI texture load failed: " + path);
				}
				};

			btn->texNormal = loadTex("normal");
			btn->texHover = loadTex("hover");
			btn->texPressed = loadTex("pressed");

			node->button = btn;
		}

		// parse children
		if (j.contains("children") && j["children"].is_array()) {
			for (const auto& ch : j["children"]) {
				node->children.push_back(parseNode(ch, renderer, zipFile));
			}
		}

		return node;
	}

	void UiManager::layoutNode(const std::shared_ptr<UiNode>& node) {
		for (auto& child : node->children) {
			child->rect.x += node->rect.x;
			child->rect.y += node->rect.y;
		}

		if (node->type == "LinearLayout") {
			std::string orient = node->orientation;
			std::transform(orient.begin(), orient.end(), orient.begin(), ::tolower);

			float cursorX = node->rect.x;
			float cursorY = node->rect.y;
			for (auto& child : node->children) {
				if (orient == "horizontal") {
					child->rect.x = cursorX;
					child->rect.y = node->rect.y;
					cursorX += child->rect.w + node->spacing;
				}
				else {
					child->rect.x = node->rect.x;
					child->rect.y = cursorY;
					cursorY += child->rect.h + node->spacing;
				}
				layoutNode(child);
			}
		}
		else {
			for (auto& child : node->children) {
				layoutNode(child);
			}
		}
	}

	void UiManager::collectButtons(const std::shared_ptr<UiNode>& node) {
		if (node->button) {
			buttons.push_back(node->button);
		}
		for (auto& c : node->children) collectButtons(c);
	}

	bool UiManager::setButtonCallback(const std::string& name, std::function<void(const std::string&)> cb) {
		auto b = findButton(name);
		if (!b) {
			std::cerr << "UiManager: setButtonCallback failed, button not found: " << name << std::endl;
			return false;
		}
		b->onClick = std::move(cb);
		return true;
	}

	bool UiManager::pushMenuFromFile(const std::string& path, Renderer& renderer, const std::string& zipFile) {
		MenuState prev;
		prev.root = root;
		prev.buttons = buttons;
		prev.pressedButton = pressedButton;
		prev.path = "";

		try {
			loadFromFile(path, renderer, zipFile);
			menuStack.push_back(std::move(prev));
			return true;
		}
		catch (const std::exception& e) {
			std::cerr << "UiManager: pushMenuFromFile failed to load " << path << " : " << e.what() << std::endl;
			return false;
		}
	}

	bool UiManager::popMenu() {
		if (menuStack.empty()) {
			std::cerr << "UiManager: popMenu called but menu stack is empty" << std::endl;
			return false;
		}
		auto s = menuStack.back();
		menuStack.pop_back();

		root = s.root;
		buttons = s.buttons;
		pressedButton = s.pressedButton;

		for (auto& b : buttons) {
			if (b) b->buildMesh();
		}

		return true;
	}

	void UiManager::clearMenuStack() {
		menuStack.clear();
	}

	void UiManager::draw(Renderer& renderer) {
		if (!root) return;

		renderer.PushProjectionMatrix(Environment::width, Environment::height, -1, 1);
		renderer.PushMatrix();
		renderer.LoadIdentity();

		for (const auto& b : buttons) {
			b->draw(renderer);
		}

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

	void UiManager::onMouseMove(int x, int y) {
		for (auto& b : buttons) {
			if (b->rect.contains((float)x, (float)y)) {
				if (b->state != ButtonState::Pressed) b->state = ButtonState::Hover;
			}
			else {
				if (b->state != ButtonState::Pressed) b->state = ButtonState::Normal;
			}
		}
	}

	void UiManager::onMouseDown(int x, int y) {
		for (auto& b : buttons) {
			if (b->rect.contains((float)x, (float)y)) {
				b->state = ButtonState::Pressed;
				pressedButton = b;
			}
			else {
				// leave others 
			}
		}
	}

	void UiManager::onMouseUp(int x, int y) {
		for (auto& b : buttons) {
			bool contains = b->rect.contains((float)x, (float)y);
			if (b->state == ButtonState::Pressed) {
				if (contains && pressedButton == b) {
					if (b->onClick) {
						b->onClick(b->name);
					}
				}
				b->state = contains ? ButtonState::Hover : ButtonState::Normal;
			}
		}
		pressedButton.reset();
	}

	std::shared_ptr<UiButton> UiManager::findButton(const std::string& name) {
		for (auto& b : buttons) if (b->name == name) return b;
		return nullptr;
	}

} // namespace ZL