import pg from 'pg';
import dotenv from 'dotenv';
import { readFileSync } from 'fs';
import { fileURLToPath } from 'url';
import { dirname, join } from 'path';
import { info, error } from './logger.js';

dotenv.config();

const { Pool } = pg;

let pool = null;

/**
 * 从task-manager独立配置文件中读取数据库URI
 */
function getDatabaseUrlFromConfig() {
    try {
        // 获取当前文件的目录
        const __filename = fileURLToPath(import.meta.url);
        const __dirname = dirname(__filename);
        
        // 配置文件路径
        const configPath = join(__dirname, 'config.json');
        
        // 读取配置文件
        const configFile = readFileSync(configPath, 'utf-8');
        const config = JSON.parse(configFile);
        
        // 获取数据库URI
        const databaseUrl = config?.database?.uri;
        
        if (databaseUrl) {
            info('Database URL loaded from task-manager config.json: ' + databaseUrl.replace(/:[^:@]+@/, ':****@'));
            return databaseUrl;
        } else {
            throw new Error('database.uri not found in config.json');
        }
    } catch (err) {
        error('Error reading config.json: ' + err.message);
        // 如果读取失败，回退到环境变量
        return null;
    }
}

/**
 * 初始化数据库连接池
 */
function initPool() {
    if (pool) {
        return pool;
    }

    // 优先从task-manager独立配置文件读取
    let databaseUrl = getDatabaseUrlFromConfig();
    
    // 如果配置文件读取失败，尝试从环境变量读取
    if (!databaseUrl) {
        databaseUrl = process.env.DATABASE_URL || process.env.SQLALCHEMY_DATABASE_URI;
        if (databaseUrl) {
            info('Database URL loaded from environment variable');
        }
    }
    
    if (!databaseUrl) {
        throw new Error('Database URL not found. Please check mcp-servers/task-manager/config.json or set DATABASE_URL environment variable');
    }

    // 记录实际使用的数据库URI（隐藏密码）
    const maskedUrl = databaseUrl.replace(/:[^:@]+@/, ':****@');
    info('Initializing database pool with URI: ' + maskedUrl);

    pool = new Pool({
        connectionString: databaseUrl,
        max: 10,
        idleTimeoutMillis: 30000,
        connectionTimeoutMillis: 2000,
    });

    pool.on('error', (err) => {
        error('Unexpected error on idle client: ' + err.message);
    });

    return pool;
}

/**
 * 获取数据库连接池
 */
export function getPool() {
    if (!pool) {
        return initPool();
    }
    return pool;
}

/**
 * 获取所有待处理的任务
 */
export async function getPendingTasks() {
    info('[Task Manager] Starting to read task_list table...');
    const startTime = Date.now();
    
    const client = await getPool().connect();
    try {
        const result = await client.query(
            `SELECT task_id, task_name, task_description, status, code_name, code_path, 
                    create_time, update_time, create_by
             FROM task_list 
             WHERE status = 'pending' 
             ORDER BY create_time ASC`
        );
        
        const taskCount = result.rows.length;
        const duration = Date.now() - startTime;
        info(`[Task Manager] Finished reading task_list table. Found ${taskCount} pending task(s) in ${duration}ms`);
        
        return result.rows;
    } finally {
        client.release();
    }
}

/**
 * 根据ID获取任务
 */
export async function getTaskById(taskId) {
    const client = await getPool().connect();
    try {
        const result = await client.query(
            `SELECT task_id, task_name, task_description, status, code_name, code_path, 
                    create_time, update_time, create_by
             FROM task_list 
             WHERE task_id = $1`,
            [taskId]
        );
        return result.rows[0] || null;
    } finally {
        client.release();
    }
}

/**
 * 更新任务状态
 */
export async function updateTaskStatus(taskId, status, codeName = null, codePath = null) {
    const client = await getPool().connect();
    try {
        const updates = ['status = $1', 'update_time = CURRENT_TIMESTAMP'];
        const values = [status];
        let paramIndex = 1;

        if (codeName !== null) {
            paramIndex++;
            updates.push(`code_name = $${paramIndex}`);
            values.push(codeName);
        }

        if (codePath !== null) {
            paramIndex++;
            updates.push(`code_path = $${paramIndex}`);
            values.push(codePath);
        }

        // taskId is always the last parameter
        paramIndex++;
        values.push(taskId);

        const query = `
            UPDATE task_list 
            SET ${updates.join(', ')}
            WHERE task_id = $${paramIndex}
            RETURNING task_id, task_name, status, update_time
        `;

        const result = await client.query(query, values);
        return result.rows[0];
    } finally {
        client.release();
    }
}

/**
 * 创建新任务
 */
export async function createTask(taskName, taskDescription, createBy) {
    const client = await getPool().connect();
    try {
        const result = await client.query(
            `INSERT INTO task_list (task_name, task_description, status, create_by)
             VALUES ($1, $2, 'pending', $3)
             RETURNING task_id, task_name, task_description, status, create_time, create_by`,
            [taskName, taskDescription, createBy]
        );
        return result.rows[0];
    } finally {
        client.release();
    }
}

/**
 * 获取所有任务（用于调试）
 */
export async function getAllTasks(limit = 100) {
    const client = await getPool().connect();
    try {
        const result = await client.query(
            `SELECT task_id, task_name, task_description, status, code_name, code_path, 
                    create_time, update_time, create_by
             FROM task_list 
             ORDER BY create_time DESC
             LIMIT $1`,
            [limit]
        );
        return result.rows;
    } finally {
        client.release();
    }
}

/**
 * 关闭数据库连接池
 */
export async function closePool() {
    if (pool) {
        await pool.end();
        pool = null;
    }
}