const { query } = require('../database/db');

class AiInsight {
  /**
   * Get AI insight by cycle and kandang
   * @param {string} cycleId - Cycle ID
   * @param {string|null} kandangId - Kandang ID (null for all kandangs)
   * @returns {Promise<Object|null>} Insight object or null if not found or expired
   */
  static async getByCycleAndKandang(cycleId, kandangId = null) {
    try {
      const result = await query(
        `SELECT * FROM ai_insights
         WHERE cycle_id = $1
         AND ($2::text IS NULL AND kandang_id IS NULL OR kandang_id = $2)
         AND expires_at > NOW()
         ORDER BY generated_at DESC
         LIMIT 1`,
        [cycleId, kandangId]
      );

      if (result.rows.length === 0) return null;

      return this.formatInsight(result.rows[0]);
    } catch (error) {
      console.error('Error getting AI insight:', error);
      throw error;
    }
  }

  /**
   * Create or update AI insight
   * @param {Object} insightData - Insight data
   * @returns {Promise<Object>} Created/updated insight
   */
  static async upsert(insightData) {
    try {
      const { cycleId, kandangId, insightText, version = 'v1' } = insightData;

      // Calculate expiry date (6 hours from now)
      const expiresAt = new Date();
      expiresAt.setHours(expiresAt.getHours() + 6);

      // Check if insight already exists
      const existing = await this.getByCycleAndKandang(cycleId, kandangId);

      if (existing) {
        // Update existing
        const result = await query(
          `UPDATE ai_insights
           SET insight_text = $1, version = $2, generated_at = NOW(), expires_at = $3, updated_at = NOW()
           WHERE id = $4
           RETURNING *`,
          [insightText, version, expiresAt, existing.id]
        );

        return this.formatInsight(result.rows[0]);
      } else {
        // Create new
        const result = await query(
          `INSERT INTO ai_insights (cycle_id, kandang_id, insight_text, version, generated_at, expires_at)
           VALUES ($1, $2, $3, $4, NOW(), $5)
           RETURNING *`,
          [cycleId, kandangId, insightText, version, expiresAt]
        );

        return this.formatInsight(result.rows[0]);
      }
    } catch (error) {
      console.error('Error upserting AI insight:', error);
      throw error;
    }
  }

  /**
   * Delete expired insights
   * @returns {Promise<number>} Number of deleted rows
   */
  static async cleanupExpired() {
    try {
      const result = await query(
        'DELETE FROM ai_insights WHERE expires_at < NOW()',
        []
      );

      return result.rowCount;
    } catch (error) {
      console.error('Error cleaning up expired insights:', error);
      throw error;
    }
  }

  /**
   * Format database row to API response format
   * @param {Object} row - Database row
   * @returns {Object} Formatted insight
   */
  static formatInsight(row) {
    return {
      id: row.id,
      cycleId: row.cycle_id,
      kandangId: row.kandang_id,
      insightText: row.insight_text,
      version: row.version,
      generatedAt: row.generated_at,
      expiresAt: row.expires_at,
      createdAt: row.created_at,
      updatedAt: row.updated_at,
    };
  }
}

module.exports = AiInsight;