/**
 * @file        健康检查服务
 * @author      hotok
 * @date        2025-06-28
 * @lastEditor  hotok
 * @lastEditTime 2025-06-28
 * @description 系统健康状态检查业务逻辑，包括数据库、Redis等依赖检查
 */

import type { Context } from 'elysia';
import { Redis } from '@/utils/redis';
import { pool } from '@/utils/mysql';
import { Logger } from '@/plugins/logger/logger.service';

// 临时内联类型定义
interface ComponentStatus {
    status: 'healthy' | 'unhealthy' | 'degraded';
    responseTime?: number;
    error?: string;
    details?: Record<string, any>;
}

interface HealthStatus {
    code: number;
    message: string;
    data: {
        status: 'healthy' | 'unhealthy' | 'degraded';
        timestamp: string;
        uptime: number;
        responseTime: number;
        version: string;
        environment: string;
        error?: string;
        components: {
            mysql?: ComponentStatus;
            redis?: ComponentStatus;
            [key: string]: ComponentStatus | undefined;
        };
    };
}

interface DetailedHealthStatus extends HealthStatus {
    data: HealthStatus['data'] & {
        system?: {
            platform: string;
            arch: string;
            nodeVersion: string;
            runtime: string;
            pid: number;
            cwd: string;
        };
        performance?: {
            cpuUsage: {
                user: number;
                system: number;
            };
            memoryUsage: {
                rss: number;
                heapTotal: number;
                heapUsed: number;
                external: number;
                arrayBuffers: number;
            };
            uptime: number;
        };
    };
}

/**
 * 健康检查服务类
 * 提供系统及依赖服务的健康状态检查
 */
class HealthService {
    /**
     * Redis实例
     */
    private redis: Redis;

    constructor() {
        this.redis = new Redis();
    }

    /**
     * 获取基本健康状态
     * @param ctx Elysia上下文
     * @returns 健康状态信息
     */
    async getHealthStatus(ctx: Context): Promise<HealthStatus> {
        const startTime = Date.now();
        const timestamp = new Date().toISOString();
        
        try {
            // 并行检查所有依赖
            const [mysqlStatus, redisStatus] = await Promise.allSettled([
                this.checkMysqlHealth(),
                this.checkRedisHealth(),
            ]);

            /** 系统整体状态 */
            const overallStatus = this.determineOverallStatus([
                mysqlStatus.status === 'fulfilled' ? mysqlStatus.value : { status: 'unhealthy', error: 'Connection failed' },
                redisStatus.status === 'fulfilled' ? redisStatus.value : { status: 'unhealthy', error: 'Connection failed' },
            ]);

            const responseTime = Date.now() - startTime;

            return {
                code: overallStatus === 'healthy' ? 0 : 1,
                message: overallStatus === 'healthy' ? '所有服务运行正常' : '部分服务异常',
                data: {
                    status: overallStatus,
                    timestamp,
                    uptime: process.uptime(),
                    responseTime,
                    version: process.env.npm_package_version || '1.0.0',
                    environment: process.env.NODE_ENV || 'development',
                    components: {
                        mysql: mysqlStatus.status === 'fulfilled' ? mysqlStatus.value : { status: 'unhealthy', error: 'Connection failed' },
                        redis: redisStatus.status === 'fulfilled' ? redisStatus.value : { status: 'unhealthy', error: 'Connection failed' },
                    },
                },
            };
        } catch (error) {
            Logger.error(error as Error);
            return {
                code: 1,
                message: '健康检查异常',
                data: {
                    status: 'unhealthy',
                    timestamp,
                    uptime: process.uptime(),
                    responseTime: Date.now() - startTime,
                    version: process.env.npm_package_version || '1.0.0',
                    environment: process.env.NODE_ENV || 'development',
                    error: 'Health check failed',
                    components: {},
                },
            };
        }
    }

    /**
     * 获取详细健康状态
     * @param ctx Elysia上下文
     * @returns 详细健康状态信息
     */
    async getDetailedHealthStatus(ctx: Context): Promise<DetailedHealthStatus> {
        const startTime = Date.now();
        const timestamp = new Date().toISOString();
        
        try {
            // 获取基本健康状态
            const basicHealth = await this.getHealthStatus(ctx);
            
            // 获取系统资源信息
            const systemInfo = this.getSystemInfo();
            
            return {
                ...basicHealth,
                data: {
                    ...basicHealth.data,
                    system: systemInfo,
                    performance: {
                        cpuUsage: process.cpuUsage(),
                        memoryUsage: process.memoryUsage(),
                        uptime: process.uptime(),
                    },
                },
            };
        } catch (error) {
            Logger.error(error as Error);
            return {
                code: 1,
                message: '详细健康检查异常',
                data: {
                    status: 'unhealthy',
                    timestamp,
                    uptime: process.uptime(),
                    responseTime: Date.now() - startTime,
                    version: process.env.npm_package_version || '1.0.0',
                    environment: process.env.NODE_ENV || 'development',
                    error: 'Detailed health check failed',
                    components: {},
                },
            };
        }
    }

    /**
     * 检查MySQL健康状态
     * @returns MySQL组件状态
     */
    private async checkMysqlHealth(): Promise<ComponentStatus> {
        try {
            const startTime = Date.now();
            await pool.execute('SELECT 1');
            const responseTime = Date.now() - startTime;
            
            return {
                status: 'healthy',
                responseTime,
                details: {
                    connection: 'active',
                    host: process.env.DB_HOST || 'localhost',
                    port: process.env.DB_PORT || '3306',
                },
            };
        } catch (error) {
            Logger.error(error as Error);
            return {
                status: 'unhealthy',
                error: (error as Error).message,
                details: {
                    connection: 'failed',
                    host: process.env.DB_HOST || 'localhost',
                    port: process.env.DB_PORT || '3306',
                },
            };
        }
    }

    /**
     * 检查Redis健康状态
     * @returns Redis组件状态
     */
    private async checkRedisHealth(): Promise<ComponentStatus> {
        try {
            const startTime = Date.now();
            const isHealthy = await this.redis.checkRedisHealth();
            const responseTime = Date.now() - startTime;
            
            if (isHealthy) {
                const redisStatus = this.redis.getRedisStatus();
                return {
                    status: 'healthy',
                    responseTime,
                    details: {
                        connection: 'active',
                        ...redisStatus.config,
                    },
                };
            } else {
                return {
                    status: 'unhealthy',
                    error: 'Redis ping failed',
                    details: {
                        connection: 'failed',
                    },
                };
            }
        } catch (error) {
            Logger.error(error as Error);
            return {
                status: 'unhealthy',
                error: (error as Error).message,
                details: {
                    connection: 'failed',
                },
            };
        }
    }

    /**
     * 确定整体状态
     * @param components 各组件状态
     * @returns 整体状态
     */
    private determineOverallStatus(components: ComponentStatus[]): 'healthy' | 'unhealthy' | 'degraded' {
        const healthyCount = components.filter(c => c.status === 'healthy').length;
        const totalCount = components.length;
        
        if (healthyCount === totalCount) {
            return 'healthy';
        } else if (healthyCount === 0) {
            return 'unhealthy';
        } else {
            return 'degraded';
        }
    }

    /**
     * 获取系统信息
     * @returns 系统信息
     */
    private getSystemInfo() {
        return {
            platform: process.platform,
            arch: process.arch,
            nodeVersion: process.version,
            runtime: 'Bun',
            pid: process.pid,
            cwd: process.cwd(),
        };
    }
}

/**
 * 导出健康检查服务实例
 */
export const healthService = new HealthService();