/**
 * Data Integrity Service
 * 
 * Handles validation and repair of broken references and other data integrity issues.
 */

import { logger } from './logger.js';
import { normalizedCacheStore as cacheStore } from './normalizedCacheStore.js';
import { jiraAssetsClient, JiraObjectNotFoundError } from './jiraAssetsClient.js';
import type { CMDBObject } from '../generated/jira-types.js';
import type { DatabaseAdapter } from './database/interface.js';

export interface BrokenReference {
  object_id: string;
  attribute_id: number;
  reference_object_id: string;
  field_name: string;
  object_type_name: string;
  object_key: string;
  label: string;
}

export interface RepairResult {
  total: number;
  repaired: number;
  deleted: number;
  failed: number;
  errors: Array<{ reference: BrokenReference; error: string }>;
}

export interface ValidationResult {
  brokenReferences: number;
  objectsWithBrokenRefs: number;
  lastValidated: string;
}

class DataIntegrityService {
  /**
   * Validate all references in the cache
   */
  async validateReferences(): Promise<ValidationResult> {
    const brokenCount = await cacheStore.getBrokenReferencesCount();
    
    // Count unique objects with broken references
    const brokenRefs = await cacheStore.getBrokenReferences(10000, 0);
    const uniqueObjectIds = new Set(brokenRefs.map(ref => ref.object_id));
    
    return {
      brokenReferences: brokenCount,
      objectsWithBrokenRefs: uniqueObjectIds.size,
      lastValidated: new Date().toISOString(),
    };
  }

  /**
   * Repair broken references
   * 
   * @param mode - 'delete': Remove broken references, 'fetch': Try to fetch missing objects from Jira, 'dry-run': Just report
   * @param batchSize - Number of references to process at a time
   * @param maxRepairs - Maximum number of repairs to attempt (0 = unlimited)
   */
  async repairBrokenReferences(
    mode: 'delete' | 'fetch' | 'dry-run' = 'fetch',
    batchSize: number = 100,
    maxRepairs: number = 0
  ): Promise<RepairResult> {
    const result: RepairResult = {
      total: 0,
      repaired: 0,
      deleted: 0,
      failed: 0,
      errors: [],
    };

    let offset = 0;
    let processed = 0;

    while (true) {
      // Fetch batch of broken references
      const brokenRefs = await cacheStore.getBrokenReferences(batchSize, offset);
      
      if (brokenRefs.length === 0) break;
      
      result.total += brokenRefs.length;

      for (const ref of brokenRefs) {
        // Check max repairs limit
        if (maxRepairs > 0 && processed >= maxRepairs) {
          logger.info(`DataIntegrityService: Reached max repairs limit (${maxRepairs})`);
          break;
        }

        try {
          if (mode === 'dry-run') {
            // Just count, don't repair
            processed++;
            continue;
          }

          if (mode === 'fetch') {
            // Try to fetch the referenced object from Jira
            const fetchResult = await this.validateAndFetchReference(ref.reference_object_id);
            
            if (fetchResult.exists && fetchResult.object) {
              // Object was successfully fetched and cached
              logger.debug(`DataIntegrityService: Repaired reference from ${ref.object_key}.${ref.field_name} to ${ref.reference_object_id}`);
              result.repaired++;
            } else {
              // Object doesn't exist in Jira, delete the reference
              await this.deleteBrokenReference(ref);
              logger.debug(`DataIntegrityService: Deleted broken reference from ${ref.object_key}.${ref.field_name} to ${ref.reference_object_id} (object not found in Jira)`);
              result.deleted++;
            }
          } else if (mode === 'delete') {
            // Directly delete the broken reference
            await this.deleteBrokenReference(ref);
            result.deleted++;
          }

          processed++;
        } catch (error) {
          const errorMessage = error instanceof Error ? error.message : String(error);
          logger.error(`DataIntegrityService: Failed to repair reference from ${ref.object_key}.${ref.field_name} to ${ref.reference_object_id}`, error);
          result.failed++;
          result.errors.push({
            reference: ref,
            error: errorMessage,
          });
        }
      }

      // Check if we should continue
      if (brokenRefs.length < batchSize || (maxRepairs > 0 && processed >= maxRepairs)) {
        break;
      }

      offset += batchSize;
    }

    logger.info(`DataIntegrityService: Repair completed - Total: ${result.total}, Repaired: ${result.repaired}, Deleted: ${result.deleted}, Failed: ${result.failed}`);
    
    return result;
  }

  /**
   * Validate and fetch a referenced object
   */
  private async validateAndFetchReference(
    referenceObjectId: string
  ): Promise<{ exists: boolean; object?: CMDBObject }> {
    // 1. Check cache first
    const db = (cacheStore as any).db;
    if (db) {
      const typedDb = db as DatabaseAdapter;
      const objRow = await typedDb.queryOne<{
        id: string;
        object_type_name: string;
      }>(`
        SELECT id, object_type_name
        FROM objects
        WHERE id = ?
      `, [referenceObjectId]);

      if (objRow) {
        const cached = await cacheStore.getObject(objRow.object_type_name as any, referenceObjectId);
        if (cached) {
          return { exists: true, object: cached };
        }
      }
    }

    // 2. Try to fetch from Jira
    try {
      const jiraObj = await jiraAssetsClient.getObject(referenceObjectId);
      if (jiraObj) {
        // Parse and cache
        const parsed = await jiraAssetsClient.parseObject(jiraObj);
        if (parsed) {
          await cacheStore.upsertObject(parsed._objectType, parsed);
          await cacheStore.extractAndStoreRelations(parsed._objectType, parsed);
          return { exists: true, object: parsed };
        }
      }
    } catch (error) {
      if (error instanceof JiraObjectNotFoundError) {
        return { exists: false };
      }
      // Re-throw other errors
      throw error;
    }

    return { exists: false };
  }

  /**
   * Delete a broken reference
   */
  private async deleteBrokenReference(ref: BrokenReference): Promise<void> {
    const db = (cacheStore as any).db;
    if (!db) {
      throw new Error('Database not available');
    }

    await db.execute(`
      DELETE FROM attribute_values
      WHERE object_id = ? 
        AND attribute_id = ?
        AND reference_object_id = ?
    `, [ref.object_id, ref.attribute_id, ref.reference_object_id]);
  }

  /**
   * Cleanup orphaned attribute values (values without parent object)
   */
  async cleanupOrphanedAttributeValues(): Promise<number> {
    const db = (cacheStore as any).db;
    if (!db) {
      throw new Error('Database not available');
    }

    const result = await db.execute(`
      DELETE FROM attribute_values
      WHERE object_id NOT IN (SELECT id FROM objects)
    `);

    logger.info(`DataIntegrityService: Cleaned up ${result} orphaned attribute values`);
    return result;
  }

  /**
   * Cleanup orphaned relations (relations where source or target doesn't exist)
   */
  async cleanupOrphanedRelations(): Promise<number> {
    const db = (cacheStore as any).db;
    if (!db) {
      throw new Error('Database not available');
    }

    const result = await db.execute(`
      DELETE FROM object_relations
      WHERE source_id NOT IN (SELECT id FROM objects)
         OR target_id NOT IN (SELECT id FROM objects)
    `);

    logger.info(`DataIntegrityService: Cleaned up ${result} orphaned relations`);
    return result;
  }

  /**
   * Full integrity check and repair
   */
  async fullIntegrityCheck(repair: boolean = false): Promise<{
    validation: ValidationResult;
    repair?: RepairResult;
    orphanedValues: number;
    orphanedRelations: number;
  }> {
    logger.info('DataIntegrityService: Starting full integrity check...');

    const validation = await this.validateReferences();
    const orphanedValues = await this.cleanupOrphanedAttributeValues();
    const orphanedRelations = await this.cleanupOrphanedRelations();

    let repairResult: RepairResult | undefined;
    if (repair) {
      repairResult = await this.repairBrokenReferences('fetch', 100, 0);
    }

    logger.info('DataIntegrityService: Integrity check completed', {
      brokenReferences: validation.brokenReferences,
      orphanedValues,
      orphanedRelations,
      repaired: repairResult?.repaired || 0,
      deleted: repairResult?.deleted || 0,
    });

    return {
      validation,
      repair: repairResult,
      orphanedValues,
      orphanedRelations,
    };
  }
}

export const dataIntegrityService = new DataIntegrityService();