const sqlite3 = require("sqlite3").verbose();
const { open } = require("sqlite");
const path = require("path");
const logger = require("./logger");

class Database {
  constructor() {
    this.db = null;
    this.dbPath = path.join(__dirname, "..", "data", "outreach.db");
  }

  async init() {
    try {
      // Create data directory if it doesn't exist
      const fs = require("fs");
      const dataDir = path.dirname(this.dbPath);
      if (!fs.existsSync(dataDir)) {
        fs.mkdirSync(dataDir, { recursive: true });
      }

      // Open database connection
      this.db = await open({
        filename: this.dbPath,
        driver: sqlite3.Database,
      });

      logger.info("Database connected", { dbPath: this.dbPath });

      // Create tables
      await this.createTables();

      return this.db;
    } catch (error) {
      logger.error("Database initialization failed", { error: error.message });
      throw error;
    }
  }

  async createTables() {
    const tables = [
      // Firms table
      `CREATE TABLE IF NOT EXISTS firms (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        firm_name TEXT NOT NULL,
        location TEXT,
        website TEXT,
        contact_email TEXT NOT NULL,
        state TEXT,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        UNIQUE(contact_email)
      )`,

      // Email campaigns table
      `CREATE TABLE IF NOT EXISTS campaigns (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name TEXT NOT NULL,
        subject TEXT NOT NULL,
        template_name TEXT NOT NULL,
        test_mode BOOLEAN DEFAULT 0,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        started_at DATETIME,
        completed_at DATETIME,
        total_emails INTEGER DEFAULT 0,
        sent_emails INTEGER DEFAULT 0,
        failed_emails INTEGER DEFAULT 0
      )`,

      // Email sends table
      `CREATE TABLE IF NOT EXISTS email_sends (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        campaign_id INTEGER,
        firm_id INTEGER,
        recipient_email TEXT NOT NULL,
        subject TEXT NOT NULL,
        status TEXT NOT NULL, -- 'sent', 'failed', 'retry', 'permanent_failure'
        error_type TEXT,
        error_message TEXT,
        retry_count INTEGER DEFAULT 0,
        tracking_id TEXT UNIQUE, -- Add tracking ID for email tracking
        sent_at DATETIME,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        FOREIGN KEY (campaign_id) REFERENCES campaigns (id),
        FOREIGN KEY (firm_id) REFERENCES firms (id)
      )`,

      // Tracking events table for email opens and clicks
      `CREATE TABLE IF NOT EXISTS tracking_events (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        tracking_id TEXT NOT NULL,
        event_type TEXT NOT NULL, -- 'open', 'click'
        event_data TEXT, -- JSON data (link_id, target_url, etc.)
        ip_address TEXT,
        user_agent TEXT,
        referer TEXT,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        FOREIGN KEY (tracking_id) REFERENCES email_sends (tracking_id)
      )`,

      // Create indexes for better performance
      `CREATE INDEX IF NOT EXISTS idx_firms_email ON firms(contact_email)`,
      `CREATE INDEX IF NOT EXISTS idx_firms_state ON firms(state)`,
      `CREATE INDEX IF NOT EXISTS idx_email_sends_campaign ON email_sends(campaign_id)`,
      `CREATE INDEX IF NOT EXISTS idx_email_sends_status ON email_sends(status)`,
      `CREATE INDEX IF NOT EXISTS idx_email_sends_tracking ON email_sends(tracking_id)`,
      `CREATE INDEX IF NOT EXISTS idx_tracking_events_tracking_id ON tracking_events(tracking_id)`,
      `CREATE INDEX IF NOT EXISTS idx_tracking_events_type ON tracking_events(event_type)`,
    ];

    for (const table of tables) {
      await this.db.exec(table);
    }

    logger.info("Database tables created/verified");
  }

  // Firm operations
  async insertFirm(firmData) {
    const { firmName, location, website, contactEmail, state } = firmData;

    try {
      const result = await this.db.run(
        `INSERT OR IGNORE INTO firms (firm_name, location, website, contact_email, state) 
         VALUES (?, ?, ?, ?, ?)`,
        [firmName, location, website, contactEmail, state]
      );

      return result.lastID;
    } catch (error) {
      logger.error("Failed to insert firm", { firmData, error: error.message });
      throw error;
    }
  }

  async insertFirmsBatch(firms) {
    const stmt = await this.db.prepare(
      `INSERT OR IGNORE INTO firms (firm_name, location, website, contact_email, state) 
       VALUES (?, ?, ?, ?, ?)`
    );

    let inserted = 0;
    for (const firm of firms) {
      try {
        const result = await stmt.run([
          firm.firmName,
          firm.location,
          firm.website,
          firm.contactEmail || firm.email,
          firm.state,
        ]);
        if (result.changes > 0) inserted++;
      } catch (error) {
        logger.warn("Failed to insert firm", {
          firm: firm.firmName,
          error: error.message,
        });
      }
    }

    await stmt.finalize();
    logger.info(`Inserted ${inserted} firms into database`);
    return inserted;
  }

  async getFirms(limit = null, offset = 0) {
    const sql = limit
      ? `SELECT * FROM firms ORDER BY id LIMIT ? OFFSET ?`
      : `SELECT * FROM firms ORDER BY id`;

    const params = limit ? [limit, offset] : [];
    return await this.db.all(sql, params);
  }

  async getFirmByEmail(email) {
    return await this.db.get("SELECT * FROM firms WHERE contact_email = ?", [
      email,
    ]);
  }

  async getFirmById(id) {
    return await this.db.get("SELECT * FROM firms WHERE id = ?", [id]);
  }

  async removeDuplicateFirms() {
    // Remove duplicates keeping the first occurrence
    const result = await this.db.run(`
      DELETE FROM firms 
      WHERE id NOT IN (
        SELECT MIN(id) 
        FROM firms 
        GROUP BY contact_email
      )
    `);

    logger.info(`Removed ${result.changes} duplicate firms`);
    return result.changes;
  }

  // Campaign operations
  async createCampaign(campaignData) {
    const { name, subject, templateName, testMode } = campaignData;

    const result = await this.db.run(
      `INSERT INTO campaigns (name, subject, template_name, test_mode) 
       VALUES (?, ?, ?, ?)`,
      [name, subject, templateName, testMode ? 1 : 0]
    );

    logger.info("Campaign created", { campaignId: result.lastID, name });
    return result.lastID;
  }

  async startCampaign(campaignId, totalEmails) {
    await this.db.run(
      `UPDATE campaigns 
       SET started_at = CURRENT_TIMESTAMP, total_emails = ? 
       WHERE id = ?`,
      [totalEmails, campaignId]
    );
  }

  async completeCampaign(campaignId, stats) {
    await this.db.run(
      `UPDATE campaigns 
       SET completed_at = CURRENT_TIMESTAMP, 
           sent_emails = ?, 
           failed_emails = ? 
       WHERE id = ?`,
      [stats.sent, stats.failed, campaignId]
    );
  }

  // Email send tracking
  async logEmailSend(emailData) {
    const {
      campaignId,
      firmId,
      recipientEmail,
      subject,
      status,
      errorType,
      errorMessage,
      retryCount,
      trackingId,
    } = emailData;

    const result = await this.db.run(
      `INSERT INTO email_sends 
       (campaign_id, firm_id, recipient_email, subject, status, error_type, error_message, retry_count, tracking_id, sent_at) 
       VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
      [
        campaignId,
        firmId,
        recipientEmail,
        subject,
        status,
        errorType,
        errorMessage,
        retryCount,
        trackingId,
        status === "sent" ? new Date().toISOString() : null,
      ]
    );

    return result.lastID;
  }

  async updateEmailSendStatus(
    emailSendId,
    status,
    errorType = null,
    errorMessage = null
  ) {
    await this.db.run(
      `UPDATE email_sends 
       SET status = ?, error_type = ?, error_message = ?, 
           sent_at = CASE WHEN ? = 'sent' THEN CURRENT_TIMESTAMP ELSE sent_at END
       WHERE id = ?`,
      [status, errorType, errorMessage, status, emailSendId]
    );
  }

  // Statistics and reporting
  async getCampaignStats(campaignId) {
    const stats = await this.db.all(
      `
      SELECT 
        status,
        COUNT(*) as count
      FROM email_sends 
      WHERE campaign_id = ? 
      GROUP BY status
    `,
      [campaignId]
    );

    const result = {
      sent: 0,
      failed: 0,
      retry: 0,
      permanent_failure: 0,
    };

    stats.forEach((stat) => {
      result[stat.status] = stat.count;
    });

    return result;
  }

  async getFailedEmails(campaignId) {
    return await this.db.all(
      `
      SELECT es.*, f.firm_name, f.contact_email
      FROM email_sends es
      JOIN firms f ON es.firm_id = f.id
      WHERE es.campaign_id = ? AND es.status IN ('failed', 'permanent_failure')
      ORDER BY es.created_at DESC
    `,
      [campaignId]
    );
  }

  async close() {
    if (this.db) {
      await this.db.close();
      this.db = null;
      logger.info("Database connection closed");
    }
  }

  // Utility methods
  async getTableCounts() {
    const counts = {};
    const tables = ["firms", "campaigns", "email_sends", "tracking_events"];

    for (const table of tables) {
      const result = await this.db.get(
        `SELECT COUNT(*) as count FROM ${table}`
      );
      counts[table] = result.count;
    }

    return counts;
  }

  // Tracking events methods
  async storeTrackingEvent(trackingId, eventType, eventData = {}) {
    const query = `
      INSERT INTO tracking_events (tracking_id, event_type, event_data, ip_address, user_agent, referer)
      VALUES (?, ?, ?, ?, ?, ?)
    `;

    await this.db.run(query, [
      trackingId,
      eventType,
      JSON.stringify(eventData),
      eventData.ip || null,
      eventData.userAgent || null,
      eventData.referer || null,
    ]);
  }

  async getTrackingEvents(trackingId) {
    const query = `
      SELECT * FROM tracking_events 
      WHERE tracking_id = ?
      ORDER BY created_at ASC
    `;

    const events = await this.db.all(query, [trackingId]);
    return events.map((event) => ({
      ...event,
      event_data: JSON.parse(event.event_data || "{}"),
    }));
  }

  async getTrackingStats(campaignId) {
    const query = `
      SELECT 
        es.tracking_id,
        es.recipient_email,
        COUNT(CASE WHEN te.event_type = 'open' THEN 1 END) as opens,
        COUNT(CASE WHEN te.event_type = 'click' THEN 1 END) as clicks,
        MIN(CASE WHEN te.event_type = 'open' THEN te.created_at END) as first_open,
        MIN(CASE WHEN te.event_type = 'click' THEN te.created_at END) as first_click
      FROM email_sends es
      LEFT JOIN tracking_events te ON es.tracking_id = te.tracking_id
      WHERE es.campaign_id = ? AND es.status = 'sent'
      GROUP BY es.tracking_id, es.recipient_email
      ORDER BY es.sent_at ASC
    `;

    return await this.db.all(query, [campaignId]);
  }
}

module.exports = new Database();