/**
 * Database schema check
 * Ensures required tables and columns exist at startup.
 */
require('dotenv').config();
const db = require('./db');
const path = require('path');
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: []
  },
  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,
        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: 'is_server_source',
        sql: "ALTER TABLE prometheus_sources ADD COLUMN is_server_source TINYINT(1) DEFAULT 1 AFTER description"
      },
      {
        name: 'type',
        sql: "ALTER TABLE prometheus_sources ADD COLUMN type VARCHAR(50) DEFAULT 'prometheus' AFTER is_server_source"
      }
    ]
  },
  site_settings: {
    createSql: `
      CREATE TABLE IF NOT EXISTS site_settings (
        id INT PRIMARY KEY DEFAULT 1,
        page_name VARCHAR(255) DEFAULT 'Data Visualization Display Wall',
        show_page_name TINYINT(1) DEFAULT 1,
        title VARCHAR(255) DEFAULT 'Data Visualization Display Wall',
        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),
        network_data_sources TEXT,
        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, 'Data Visualization Display Wall', 1, 'Data Visualization Display Wall', 'dark', 0, 'tx', 1
      )
    `,
    columns: [
      {
        name: 'show_page_name',
        sql: "ALTER TABLE site_settings ADD COLUMN show_page_name TINYINT(1) DEFAULT 1 AFTER page_name"
      },
      {
        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: '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: 'network_data_sources',
        sql: "ALTER TABLE site_settings ADD COLUMN network_data_sources TEXT AFTER ps_filing"
      },
      {
        name: 'show_server_ip',
        sql: "ALTER TABLE site_settings ADD COLUMN show_server_ip TINYINT(1) DEFAULT 0 AFTER network_data_sources"
      },
      {
        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: []
  },
  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: []
  },
  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: []
  }
};

async function addColumnIfMissing(tableName, existingColumns, column) {
  if (existingColumns.has(column.name)) {
    return;
  }

  try {
    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}'.`);
  } catch (err) {
    console.error(`[Database Integrity] Failed to add '${tableName}.${column.name}':`, err.message);

    if (column.sql.includes(' AFTER ')) {
      try {
        const fallbackSql = column.sql.split(' AFTER ')[0];
        await db.query(fallbackSql);
        console.log(`[Database Integrity] Column '${column.name}' added to '${tableName}' via fallback.`);
      } catch (fallbackErr) {
        console.error(`[Database Integrity] Fallback failed for '${tableName}.${column.name}':`, fallbackErr.message);
      }
    }
  }
}

async function ensureTable(tableName, tableSchema) {
  await db.query(tableSchema.createSql);

  const [columns] = await db.query(`SHOW COLUMNS FROM \`${tableName}\``);
  const existingColumns = new Set(columns.map((column) => column.Field));

  for (const column of tableSchema.columns || []) {
    await addColumnIfMissing(tableName, existingColumns, column);
  }

  if (tableSchema.seedSql) {
    await db.query(tableSchema.seedSql);
  }
}

async function checkAndFixDatabase() {
  // Check for DB host to see if we have configuration (could be in .env or environment)
  if (!process.env.MYSQL_HOST && !fs.existsSync(path.join(__dirname, '..', '.env'))) {
    console.log('[Database Integrity] No configuration found, skipping check.');
    return false;
  }

  try {
    for (const [tableName, tableSchema] of Object.entries(SCHEMA)) {
      await ensureTable(tableName, tableSchema);
    }
    return true;
  } catch (err) {
    console.error('[Database Integrity] Startup schema check failed:', err.message);
    // Rethrow to allow caller to decide if this is fatal
    throw err;
  }
}

module.exports = checkAndFixDatabase;