/**
 * Database schema check
 * Ensures required tables and columns exist at startup.
 */
const path = require('path');
require('dotenv').config({ path: path.join(__dirname, '..', '.env') });
const db = require('./db');
const fs = require('fs');

const SCHEMA = {
  users: {
    createSql: `
      CREATE TABLE IF NOT EXISTS users (
        id INT AUTO_INCREMENT PRIMARY KEY,
        username VARCHAR(255) NOT NULL UNIQUE,
        password VARCHAR(255) NOT NULL,
        salt VARCHAR(255) NOT NULL,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
    `,
    columns: [
      { name: 'username', sql: "ALTER TABLE users ADD COLUMN username VARCHAR(255) NOT NULL UNIQUE AFTER id" },
      { name: 'password', sql: "ALTER TABLE users ADD COLUMN password VARCHAR(255) NOT NULL AFTER username" },
      { name: 'salt', sql: "ALTER TABLE users ADD COLUMN salt VARCHAR(255) NOT NULL AFTER password" }
    ]
  },
  prometheus_sources: {
    createSql: `
      CREATE TABLE IF NOT EXISTS prometheus_sources (
        id INT AUTO_INCREMENT PRIMARY KEY,
        name VARCHAR(255) NOT NULL,
        url VARCHAR(500) NOT NULL,
        description TEXT,
        is_server_source TINYINT(1) DEFAULT 1,
        is_overview_source TINYINT(1) DEFAULT 1,
        is_detail_source TINYINT(1) DEFAULT 1,
        type VARCHAR(50) DEFAULT 'prometheus',
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
    `,
    columns: [
      { name: 'name', sql: "ALTER TABLE prometheus_sources ADD COLUMN name VARCHAR(255) NOT NULL AFTER id" },
      { name: 'url', sql: "ALTER TABLE prometheus_sources ADD COLUMN url VARCHAR(500) NOT NULL AFTER name" },
      { name: 'description', sql: "ALTER TABLE prometheus_sources ADD COLUMN description TEXT AFTER url" },
      { name: 'is_server_source', sql: "ALTER TABLE prometheus_sources ADD COLUMN is_server_source TINYINT(1) DEFAULT 1 AFTER description" },
      { name: 'is_overview_source', sql: "ALTER TABLE prometheus_sources ADD COLUMN is_overview_source TINYINT(1) DEFAULT 1 AFTER is_server_source" },
      { name: 'is_detail_source', sql: "ALTER TABLE prometheus_sources ADD COLUMN is_detail_source TINYINT(1) DEFAULT 1 AFTER is_overview_source" },
      { name: 'type', sql: "ALTER TABLE prometheus_sources ADD COLUMN type VARCHAR(50) DEFAULT 'prometheus' AFTER is_detail_source" }
    ]
  },
  site_settings: {
    createSql: `
      CREATE TABLE IF NOT EXISTS site_settings (
        id INT PRIMARY KEY DEFAULT 1,
        page_name VARCHAR(255) DEFAULT '数据可视化展示大屏',
        show_page_name TINYINT(1) DEFAULT 1,
        title VARCHAR(255) DEFAULT '数据可视化展示大屏',
        logo_url TEXT,
        logo_url_dark TEXT,
        favicon_url TEXT,
        default_theme VARCHAR(20) DEFAULT 'dark',
        show_95_bandwidth TINYINT(1) DEFAULT 0,
        p95_type VARCHAR(20) DEFAULT 'tx',
        require_login_for_server_details TINYINT(1) DEFAULT 1,
        blackbox_source_id INT,
        latency_source VARCHAR(100),
        latency_dest VARCHAR(100),
        latency_target VARCHAR(255),
        icp_filing VARCHAR(255),
        ps_filing VARCHAR(255),
        show_server_ip TINYINT(1) DEFAULT 0,
        ip_metric_name VARCHAR(100) DEFAULT NULL,
        ip_label_name VARCHAR(100) DEFAULT 'address',
        custom_metrics JSON DEFAULT NULL,
        updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
    `,
    seedSql: `
      INSERT IGNORE INTO site_settings (
        id, page_name, show_page_name, title, default_theme, show_95_bandwidth, p95_type, require_login_for_server_details
      ) VALUES (
        1, '数据可视化展示大屏', 1, '数据可视化展示大屏', 'dark', 0, 'tx', 1
      )
    `,
    columns: [
      { name: 'page_name', sql: "ALTER TABLE site_settings ADD COLUMN page_name VARCHAR(255) DEFAULT '数据可视化展示大屏' AFTER id" },
      { name: 'show_page_name', sql: "ALTER TABLE site_settings ADD COLUMN show_page_name TINYINT(1) DEFAULT 1 AFTER page_name" },
      { name: 'title', sql: "ALTER TABLE site_settings ADD COLUMN title VARCHAR(255) DEFAULT '数据可视化展示大屏' AFTER show_page_name" },
      { name: 'logo_url', sql: "ALTER TABLE site_settings ADD COLUMN logo_url TEXT AFTER title" },
      { name: 'logo_url_dark', sql: "ALTER TABLE site_settings ADD COLUMN logo_url_dark TEXT AFTER logo_url" },
      { name: 'favicon_url', sql: "ALTER TABLE site_settings ADD COLUMN favicon_url TEXT AFTER logo_url_dark" },
      { name: 'default_theme', sql: "ALTER TABLE site_settings ADD COLUMN default_theme VARCHAR(20) DEFAULT 'dark' AFTER favicon_url" },
      { name: 'show_95_bandwidth', sql: "ALTER TABLE site_settings ADD COLUMN show_95_bandwidth TINYINT(1) DEFAULT 0 AFTER default_theme" },
      { name: 'p95_type', sql: "ALTER TABLE site_settings ADD COLUMN p95_type VARCHAR(20) DEFAULT 'tx' AFTER show_95_bandwidth" },
      { name: 'require_login_for_server_details', sql: "ALTER TABLE site_settings ADD COLUMN require_login_for_server_details TINYINT(1) DEFAULT 1 AFTER p95_type" },
      { name: 'blackbox_source_id', sql: "ALTER TABLE site_settings ADD COLUMN blackbox_source_id INT AFTER require_login_for_server_details" },
      { name: 'latency_source', sql: "ALTER TABLE site_settings ADD COLUMN latency_source VARCHAR(100) AFTER blackbox_source_id" },
      { name: 'latency_dest', sql: "ALTER TABLE site_settings ADD COLUMN latency_dest VARCHAR(100) AFTER latency_source" },
      { name: 'latency_target', sql: "ALTER TABLE site_settings ADD COLUMN latency_target VARCHAR(255) AFTER latency_dest" },
      { name: 'icp_filing', sql: "ALTER TABLE site_settings ADD COLUMN icp_filing VARCHAR(255) AFTER latency_target" },
      { name: 'ps_filing', sql: "ALTER TABLE site_settings ADD COLUMN ps_filing VARCHAR(255) AFTER icp_filing" },
      { name: 'show_server_ip', sql: "ALTER TABLE site_settings ADD COLUMN show_server_ip TINYINT(1) DEFAULT 0 AFTER ps_filing" },
      { name: 'ip_metric_name', sql: "ALTER TABLE site_settings ADD COLUMN ip_metric_name VARCHAR(100) DEFAULT NULL AFTER show_server_ip" },
      { name: 'ip_label_name', sql: "ALTER TABLE site_settings ADD COLUMN ip_label_name VARCHAR(100) DEFAULT 'address' AFTER ip_metric_name" },
      { name: 'custom_metrics', sql: "ALTER TABLE site_settings ADD COLUMN custom_metrics JSON DEFAULT NULL AFTER ip_label_name" }
    ]
  },
  traffic_stats: {
    createSql: `
      CREATE TABLE IF NOT EXISTS traffic_stats (
        id INT AUTO_INCREMENT PRIMARY KEY,
        rx_bytes BIGINT UNSIGNED DEFAULT 0,
        tx_bytes BIGINT UNSIGNED DEFAULT 0,
        rx_bandwidth DOUBLE DEFAULT 0,
        tx_bandwidth DOUBLE DEFAULT 0,
        timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        UNIQUE INDEX (timestamp)
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
    `,
    columns: [
      { name: 'rx_bytes', sql: "ALTER TABLE traffic_stats ADD COLUMN rx_bytes BIGINT UNSIGNED DEFAULT 0 AFTER id" },
      { name: 'tx_bytes', sql: "ALTER TABLE traffic_stats ADD COLUMN tx_bytes BIGINT UNSIGNED DEFAULT 0 AFTER rx_bytes" },
      { name: 'rx_bandwidth', sql: "ALTER TABLE traffic_stats ADD COLUMN rx_bandwidth DOUBLE DEFAULT 0 AFTER tx_bytes" },
      { name: 'tx_bandwidth', sql: "ALTER TABLE traffic_stats ADD COLUMN tx_bandwidth DOUBLE DEFAULT 0 AFTER rx_bandwidth" }
    ]
  },
  server_locations: {
    createSql: `
      CREATE TABLE IF NOT EXISTS server_locations (
        id INT AUTO_INCREMENT PRIMARY KEY,
        ip VARCHAR(255) NOT NULL UNIQUE,
        country CHAR(2),
        country_name VARCHAR(100),
        region VARCHAR(100),
        city VARCHAR(100),
        latitude DOUBLE,
        longitude DOUBLE,
        last_updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
    `,
    columns: [
      { name: 'ip', sql: "ALTER TABLE server_locations ADD COLUMN ip VARCHAR(255) NOT NULL UNIQUE AFTER id" },
      { name: 'country', sql: "ALTER TABLE server_locations ADD COLUMN country CHAR(2) AFTER ip" },
      { name: 'country_name', sql: "ALTER TABLE server_locations ADD COLUMN country_name VARCHAR(100) AFTER country" },
      { name: 'region', sql: "ALTER TABLE server_locations ADD COLUMN region VARCHAR(100) AFTER country_name" },
      { name: 'city', sql: "ALTER TABLE server_locations ADD COLUMN city VARCHAR(100) AFTER region" },
      { name: 'latitude', sql: "ALTER TABLE server_locations ADD COLUMN latitude DOUBLE AFTER city" },
      { name: 'longitude', sql: "ALTER TABLE server_locations ADD COLUMN longitude DOUBLE AFTER latitude" }
    ]
  },
  latency_routes: {
    createSql: `
      CREATE TABLE IF NOT EXISTS latency_routes (
        id INT AUTO_INCREMENT PRIMARY KEY,
        source_id INT NOT NULL,
        latency_source VARCHAR(100) NOT NULL,
        latency_dest VARCHAR(100) NOT NULL,
        latency_target VARCHAR(255) NOT NULL,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
    `,
    columns: [
      { name: 'source_id', sql: "ALTER TABLE latency_routes ADD COLUMN source_id INT NOT NULL AFTER id" },
      { name: 'latency_source', sql: "ALTER TABLE latency_routes ADD COLUMN latency_source VARCHAR(100) NOT NULL AFTER source_id" },
      { name: 'latency_dest', sql: "ALTER TABLE latency_routes ADD COLUMN latency_dest VARCHAR(100) NOT NULL AFTER latency_source" },
      { name: 'latency_target', sql: "ALTER TABLE latency_routes ADD COLUMN latency_target VARCHAR(255) NOT NULL AFTER latency_dest" }
    ]
  }
};

async function ensureTable(tableName, tableSchema) {
  try {
    // 1. Ensure table exists
    await db.query(tableSchema.createSql);
    
    // 2. Check columns
    const [columns] = await db.query(`SHOW COLUMNS FROM \`${tableName}\``);
    const existingColumns = new Set(columns.map((column) => column.Field));
    
    console.log(`[Database Integrity] Table '${tableName}' verified (${columns.length} columns)`);

    for (const column of tableSchema.columns || []) {
      if (!existingColumns.has(column.name)) {
        console.log(`[Database Integrity] Missing column '${column.name}' in '${tableName}'. Adding it...`);
        await db.query(column.sql);
        console.log(`[Database Integrity] Column '${column.name}' added to '${tableName}'.`);
      }
    }

    // 3. Seed data
    if (tableSchema.seedSql) {
      const [rows] = await db.query(`SELECT count(*) as count FROM \`${tableName}\``);
      if (rows[0].count === 0) {
        console.log(`[Database Integrity] Table '${tableName}' is empty. Seeding initial data...`);
        await db.query(tableSchema.seedSql);
      }
    }
  } catch (err) {
    console.error(`[Database Integrity] Error ensuring table '${tableName}':`, err.message);
    throw err;
  }
}

async function checkAndFixDatabase() {
  console.log('[Database Integrity] Starting comprehensive database audit...');
  
  // Try to check if we can even connect
  try {
    const health = await db.checkHealth();
    if (health.status !== 'up') {
      console.warn(`[Database Integrity] initial health check failed: ${health.error}`);
      // If we can't connect, maybe the DB itself doesn't exist?
      // For now, we rely on the pool to handle connection retries/errors.
    }
  } catch (e) {
    // Ignore health check errors, let ensureTable handle the primary queries
  }

  try {
    let tablesChecked = 0;
    for (const [tableName, tableSchema] of Object.entries(SCHEMA)) {
      await ensureTable(tableName, tableSchema);
      tablesChecked++;
    }
    console.log(`[Database Integrity] Audit complete. ${tablesChecked} tables verified and healthy.`);
    return true;
  } catch (err) {
    console.error('[Database Integrity] ❌ Audit failed:', err.message);
    throw err;
  }
}

module.exports = checkAndFixDatabase;