package com.imyeyu.inject;

import com.imyeyu.inject.annotation.Import;
import com.imyeyu.inject.annotation.TimiInjectApplication;
import com.imyeyu.java.bean.CallbackArg;
import com.imyeyu.utils.Text;
import com.imyeyu.utils.Time;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Method;
import java.nio.charset.StandardCharsets;
import java.util.List;
import java.util.stream.Collectors;

/**
 * Timi 控制反转框架
 *
 * @author 夜雨
 */
public class TimiInject {

	private static final Logger log = LoggerFactory.getLogger(TimiInject.class);

	private final BeanContext context;
	private final BeanFactory factory;

	private TimiInject(BeanContext context, BeanFactory factory) {
		this.context = context;
		this.factory = factory;
	}

	/**
	 * 启动应用并初始化容器
	 */
	public static TimiInject run(Class<?> applicationClass) {
		return run(applicationClass, null);
	}

	/**
	 * 启动应用并初始化容器（支持初始化前注册外部 Bean）
	 *
	 * @param initializer 初始化前回调
	 */
	public static TimiInject run(Class<?> applicationClass, CallbackArg<TimiInject> initializer) {
		printBanner();

		long startTime = Time.now();
		StartupStatistics statistics = new StartupStatistics();

		log.info("Initializing TimiInject for {} ...", applicationClass.getSimpleName());

		TimiInjectApplication annotation = applicationClass.getAnnotation(TimiInjectApplication.class);
		if (annotation == null) {
			throw new InjectException("Application class must be annotated with @TimiInjectApplication");
		}

		BeanContext context = new BeanContext();
		BeanFactory factory = new BeanFactory(context, statistics);
		BeanScanner scanner = new BeanScanner(context, statistics);

		String[] basePackages = annotation.value();
		if (basePackages.length == 0) {
			basePackages = new String[] {applicationClass.getPackage().getName()};
		}

		log.info("Scanning packages: {}", String.join(", ", basePackages));
		scanner.scan(basePackages);
		processImports(applicationClass, scanner, context);
		log.info("Scanned {} classes, registered {} beans", statistics.scannedClasses, statistics.registeredBeans);

		TimiInject inject = new TimiInject(context, factory);
		if (initializer != null) {
			initializer.handler(inject);
		}

		log.info("Performing inversion of control...");
		factory.initializeSingletons();
		log.info("initialization completed!");
		log.info("\tTotal beans: {}", statistics.registeredBeans);
		log.info("\tInjected fields: {}", statistics.injectedFields);
		log.info("\tPostConstruct invocations: {}", statistics.postConstructInvocations);
		log.info("\tScan time: {} ms", statistics.scanEndTime - statistics.scanStartTime);
		log.info("\tIOC time: {} ms", statistics.iocEndTime - statistics.iocStartTime);
		log.info("\tInjection time: {} ms", statistics.injectionTotalTime);
		log.info("\tPostConstruct time: {} ms", statistics.postConstructTotalTime);
		log.info("\tTotal startup time: {} ms", Time.now() - startTime);
		return inject;
	}

	/**
	 * 获取 Bean 实例（按类型）
	 */
	public <T> T getBean(Class<T> type) {
		return factory.getBean(type);
	}

	/**
	 * 获取 Bean 实例（按名称和类型）
	 */
	public <T> T getBean(String name, Class<T> type) {
		return factory.getBean(name, type);
	}

	/**
	 * 注册 Bean 实例
	 */
	public void registerBean(String name, Object bean) {
		context.registerSingleton(name, bean);
		log.debug("Registered singleton bean: {} ({})", name, bean.getClass().getName());
	}

	/**
	 * 对已存在的对象执行字段注入，适用于无法通过构造器创建的对象
	 *
	 * @param target 需要注入依赖的目标对象
	 */
	public void inject(Object target) {
		factory.injectFields(target);
	}

	/**
	 * 导出依赖图
	 */
	public String exportDependencyGraph() {
		StringBuilder graph = new StringBuilder();
		graph.append("=== Dependency Graph ===\n\n");

		for (BeanDefinition definition : context.getAllDefinitions()) {
			graph.append(formatBeanInfo(definition));
			graph.append("\n");
		}

		return graph.toString();
	}

	private String formatBeanInfo(BeanDefinition definition) {
		StringBuilder info = new StringBuilder();
		info.append("Bean: ").append(definition.getName()).append("\n");
		info.append("  Type: ").append(definition.getType().getName()).append("\n");
		info.append("  Scope: ").append(definition.getScope()).append("\n");
		info.append("  Primary: ").append(definition.isPrimary()).append("\n");

		if (definition.isFactoryBean()) {
			info.append("  Factory: @Bean ").append(definition.getFactoryMethod().getName()).append("()\n");
		} else if (definition.getConstructor() != null) {
			info.append("  Constructor: ").append(definition.getConstructor().getParameterCount()).append(" parameters\n");
		}

		List<Method> postConstructs = definition.getPostConstructs();
		if (!postConstructs.isEmpty()) {
			info.append("  PostConstruct: ");
			for (int i = 0; i < postConstructs.size(); i++) {
				if (i > 0) {
					info.append(", ");
				}
				info.append(postConstructs.get(i).getName()).append("()");
			}
			info.append("\n");
		}

		return info.toString();
	}

	private static void processImports(Class<?> applicationClass, BeanScanner scanner, BeanContext context) {
		if (!applicationClass.isAnnotationPresent(Import.class)) {
			return;
		}
		Import importAnnotation = applicationClass.getAnnotation(Import.class);
		Class<?>[] importClasses = importAnnotation.value();
		for (Class<?> importClass : importClasses) {
			if (Module.class.isAssignableFrom(importClass)) {
				try {
					Module module = (Module) importClass.getDeclaredConstructor().newInstance();
					module.configure(context);
					log.debug("Loaded module: {}", importClass.getName());
				} catch (Exception e) {
					throw new InjectException("Failed to instantiate module: %s".formatted(importClass.getName()), e);
				}
			} else {
				// 检查是否已经通过包扫描注册
				String beanName = Text.camelCaseClassName(importClass);
				if (!context.containsBean(beanName)) {
					scanner.processClass(importClass);
					log.debug("Imported configuration: {}", importClass.getName());
				} else {
					log.debug("Skip importing already registered class: {}", importClass.getName());
				}
			}
		}
	}

	/**
	 * 输出启动 Banner
	 */
	private static void printBanner() {
		String bannerContent = loadBanner();
		if (!bannerContent.isEmpty()) {
			System.out.println(bannerContent);
		}
	}

	/**
	 * 加载 Banner 内容
	 * 优先加载 banner.txt，如果不存在则加载 defBanner.txt
	 *
	 * @return Banner 内容
	 */
	private static String loadBanner() {
		// 优先尝试加载自定义 banner.txt
		String banner = loadBannerFromResource("banner.txt");
		if (banner != null) {
			return banner;
		}
		// 加载默认 banner
		banner = loadBannerFromResource("defBanner.txt");
		if (banner != null) {
			return banner;
		}
		// 如果都加载失败，返回空字符串
		return "";
	}

	/**
	 * 从资源文件加载 Banner
	 *
	 * @param resourceName 资源文件名
	 * @return Banner 内容，如果加载失败返回 null
	 */
	private static String loadBannerFromResource(String resourceName) {
		try {
			InputStream inputStream = TimiInject.class.getClassLoader().getResourceAsStream(resourceName);
			if (inputStream == null) {
				return null;
			}

			try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8))) {
				return reader.lines().collect(Collectors.joining("\n"));
			}
		} catch (Exception e) {
			log.debug("Failed to load banner from {}: {}", resourceName, e.getMessage());
			return null;
		}
	}
}