/**
 * Audit Service
 * Based on: docs/foundation/Agent_Governance_Protocol_v1.md
 * 
 * Provides access to governance events for audit and analysis
 */

import { db } from '../../infra/db/client';
import { logger } from '../../infra/logger/logger';
import {
  GovernanceEvent,
  GovernanceEventType,
  AuditEventFilter,
  GovernanceScope,
} from '../../domain/governance/types';

export interface AuditEventRow {
  id: string;
  event_type: GovernanceEventType;
  subject: string;
  actor_id: string;
  target_id: string;
  scope: GovernanceScope;
  payload: Record<string, unknown>;
  version: string;
  status: 'pending' | 'published' | 'failed';
  created_at: Date;
  published_at?: Date;
}

export class AuditService {
  /**
   * Get audit events with filters
   */
  async getEvents(filter: AuditEventFilter): Promise<{
    events: GovernanceEvent[];
    total: number;
  }> {
    const conditions: string[] = [];
    const params: (string | Date | number)[] = [];
    let paramIndex = 1;
    
    if (filter.eventType) {
      conditions.push(`event_type = $${paramIndex++}`);
      params.push(filter.eventType);
    }
    
    if (filter.actorId) {
      conditions.push(`actor_id = $${paramIndex++}`);
      params.push(filter.actorId);
    }
    
    if (filter.targetId) {
      conditions.push(`target_id = $${paramIndex++}`);
      params.push(filter.targetId);
    }
    
    if (filter.scope) {
      conditions.push(`scope = $${paramIndex++}`);
      params.push(filter.scope);
    }
    
    if (filter.createdAtFrom) {
      conditions.push(`created_at >= $${paramIndex++}`);
      params.push(filter.createdAtFrom);
    }
    
    if (filter.createdAtTo) {
      conditions.push(`created_at <= $${paramIndex++}`);
      params.push(filter.createdAtTo);
    }
    
    const whereClause = conditions.length > 0 ? `WHERE ${conditions.join(' AND ')}` : '';
    
    // Get total count
    const countResult = await db.query<{ count: string }>(
      `SELECT COUNT(*) as count FROM event_outbox ${whereClause}`,
      params
    );
    
    const total = parseInt(countResult.rows[0].count, 10);
    
    // Get events
    const limit = filter.limit || 50;
    const offset = filter.offset || 0;
    
    params.push(limit, offset);
    
    const result = await db.query<AuditEventRow>(
      `SELECT id, event_type, subject, actor_id, target_id, scope, payload, version, status, created_at, published_at
       FROM event_outbox
       ${whereClause}
       ORDER BY created_at DESC
       LIMIT $${paramIndex++} OFFSET $${paramIndex++}`,
      params
    );
    
    const events: GovernanceEvent[] = result.rows.map(row => ({
      id: row.id,
      eventType: row.event_type,
      subject: row.subject,
      actorId: row.actor_id,
      targetId: row.target_id,
      scope: row.scope,
      payload: row.payload,
      version: row.version,
      status: row.status,
      createdAt: row.created_at,
      publishedAt: row.published_at,
    }));
    
    return { events, total };
  }

  /**
   * Get single event by ID
   */
  async getEvent(eventId: string): Promise<GovernanceEvent | null> {
    const result = await db.query<AuditEventRow>(
      `SELECT id, event_type, subject, actor_id, target_id, scope, payload, version, status, created_at, published_at
       FROM event_outbox
       WHERE id = $1`,
      [eventId]
    );
    
    if (result.rows.length === 0) {
      return null;
    }
    
    const row = result.rows[0];
    return {
      id: row.id,
      eventType: row.event_type,
      subject: row.subject,
      actorId: row.actor_id,
      targetId: row.target_id,
      scope: row.scope,
      payload: row.payload,
      version: row.version,
      status: row.status,
      createdAt: row.created_at,
      publishedAt: row.published_at,
    };
  }

  /**
   * Get events by actor
   */
  async getEventsByActor(actorId: string, limit = 50): Promise<GovernanceEvent[]> {
    const result = await this.getEvents({ actorId, limit });
    return result.events;
  }

  /**
   * Get events by target
   */
  async getEventsByTarget(targetId: string, limit = 50): Promise<GovernanceEvent[]> {
    const result = await this.getEvents({ targetId, limit });
    return result.events;
  }

  /**
   * Get events by scope
   */
  async getEventsByScope(scope: GovernanceScope, limit = 50): Promise<GovernanceEvent[]> {
    const result = await this.getEvents({ scope, limit });
    return result.events;
  }

  /**
   * Get event statistics
   */
  async getEventStats(
    fromDate?: Date,
    toDate?: Date
  ): Promise<{
    totalEvents: number;
    eventsByType: Record<string, number>;
    eventsByDay: Array<{ date: string; count: number }>;
    topActors: Array<{ actorId: string; count: number }>;
  }> {
    const conditions: string[] = [];
    const params: (string | Date)[] = [];
    let paramIndex = 1;
    
    if (fromDate) {
      conditions.push(`created_at >= $${paramIndex++}`);
      params.push(fromDate);
    }
    
    if (toDate) {
      conditions.push(`created_at <= $${paramIndex++}`);
      params.push(toDate);
    }
    
    const whereClause = conditions.length > 0 ? `WHERE ${conditions.join(' AND ')}` : '';
    
    // Total events
    const totalResult = await db.query<{ count: string }>(
      `SELECT COUNT(*) as count FROM event_outbox ${whereClause}`,
      params
    );
    
    const totalEvents = parseInt(totalResult.rows[0].count, 10);
    
    // Events by type
    const byTypeResult = await db.query<{ event_type: string; count: string }>(
      `SELECT event_type, COUNT(*) as count 
       FROM event_outbox ${whereClause}
       GROUP BY event_type`,
      params
    );
    
    const eventsByType: Record<string, number> = {};
    byTypeResult.rows.forEach(row => {
      eventsByType[row.event_type] = parseInt(row.count, 10);
    });
    
    // Events by day
    const byDayResult = await db.query<{ date: string; count: string }>(
      `SELECT DATE(created_at) as date, COUNT(*) as count 
       FROM event_outbox ${whereClause}
       GROUP BY DATE(created_at)
       ORDER BY date DESC
       LIMIT 30`,
      params
    );
    
    const eventsByDay = byDayResult.rows.map(row => ({
      date: row.date,
      count: parseInt(row.count, 10),
    }));
    
    // Top actors
    const topActorsResult = await db.query<{ actor_id: string; count: string }>(
      `SELECT actor_id, COUNT(*) as count 
       FROM event_outbox ${whereClause} AND actor_id IS NOT NULL
       GROUP BY actor_id
       ORDER BY count DESC
       LIMIT 10`,
      params
    );
    
    const topActors = topActorsResult.rows.map(row => ({
      actorId: row.actor_id,
      count: parseInt(row.count, 10),
    }));
    
    return {
      totalEvents,
      eventsByType,
      eventsByDay,
      topActors,
    };
  }

  /**
   * Get governance events for specific entity
   */
  async getEntityHistory(
    entityType: 'agent' | 'microdao' | 'district' | 'node' | 'room',
    entityId: string,
    limit = 50
  ): Promise<GovernanceEvent[]> {
    const result = await db.query<AuditEventRow>(
      `SELECT id, event_type, subject, actor_id, target_id, scope, payload, version, status, created_at, published_at
       FROM event_outbox
       WHERE target_id = $1 OR actor_id = $1 OR scope LIKE $2
       ORDER BY created_at DESC
       LIMIT $3`,
      [entityId, `%${entityId}%`, limit]
    );
    
    return result.rows.map(row => ({
      id: row.id,
      eventType: row.event_type,
      subject: row.subject,
      actorId: row.actor_id,
      targetId: row.target_id,
      scope: row.scope,
      payload: row.payload,
      version: row.version,
      status: row.status,
      createdAt: row.created_at,
      publishedAt: row.published_at,
    }));
  }
}

export const auditService = new AuditService();