import {
  Injectable,
  NotFoundException,
  ConflictException,
  BadRequestException,
  Inject,
} from "@nestjs/common";
import { Logger } from "nestjs-pino";
import { PrismaService } from "../common/prisma/prisma.service";
import { getErrorMessage } from "../common/utils/error.util";
import { MappingCacheService } from "./cache/mapping-cache.service";
import { MappingValidatorService } from "./validation/mapping-validator.service";
import {
  UserIdMapping,
  CreateMappingRequest,
  UpdateMappingRequest,
  MappingSearchFilters,
  MappingStats,
  BulkMappingResult,
} from "./types/mapping.types";

@Injectable()
export class MappingsService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly cacheService: MappingCacheService,
    private readonly validator: MappingValidatorService,
    @Inject(Logger) private readonly logger: Logger
  ) {}

  /**
   * Create a new user mapping
   */
  async createMapping(request: CreateMappingRequest): Promise<UserIdMapping> {
    try {
      // Validate request
      const validation = this.validator.validateCreateRequest(request);
      this.validator.logValidationResult("Create mapping", validation, {
        userId: request.userId,
      });

      if (!validation.isValid) {
        throw new BadRequestException(`Invalid mapping data: ${validation.errors.join(", ")}`);
      }

      // Sanitize input
      const sanitizedRequest = this.validator.sanitizeCreateRequest(request);

      // Check for conflicts
      const existingMappings = await this.getAllMappingsFromDb();
      const conflictValidation = await this.validator.validateNoConflicts(
        sanitizedRequest,
        existingMappings
      );

      if (!conflictValidation.isValid) {
        throw new ConflictException(`Mapping conflict: ${conflictValidation.errors.join(", ")}`);
      }

      // Create in database
      const created = await this.prisma.idMapping.create({
        data: sanitizedRequest,
      });

      const mapping: UserIdMapping = {
        userId: created.userId,
        whmcsClientId: created.whmcsClientId,
        sfAccountId: created.sfAccountId || undefined,
        createdAt: created.createdAt,
        updatedAt: created.updatedAt,
      };

      // Cache the new mapping
      await this.cacheService.setMapping(mapping);

      this.logger.log(`Created mapping for user ${mapping.userId}`, {
        whmcsClientId: mapping.whmcsClientId,
        sfAccountId: mapping.sfAccountId,
        warnings: validation.warnings,
      });

      return mapping;
    } catch (error) {
      this.logger.error(`Failed to create mapping for user ${request.userId}`, {
        error: getErrorMessage(error),
        request: this.sanitizeForLog(request),
      });
      throw error;
    }
  }

  /**
   * Find mapping by user ID
   */
  async findByUserId(userId: string): Promise<UserIdMapping | null> {
    try {
      // Validate user ID
      if (!userId) {
        throw new BadRequestException("User ID is required");
      }

      // Try cache first
      const cached = await this.cacheService.getByUserId(userId);
      if (cached) {
        this.logger.debug(`Cache hit for user mapping: ${userId}`);
        return cached;
      }

      // Fetch from database
      const dbMapping = await this.prisma.idMapping.findUnique({
        where: { userId },
      });

      if (!dbMapping) {
        this.logger.debug(`No mapping found for user ${userId}`);
        return null;
      }

      const mapping: UserIdMapping = {
        userId: dbMapping.userId,
        whmcsClientId: dbMapping.whmcsClientId,
        sfAccountId: dbMapping.sfAccountId || undefined,
        createdAt: dbMapping.createdAt,
        updatedAt: dbMapping.updatedAt,
      };

      // Cache the result
      await this.cacheService.setMapping(mapping);

      this.logger.debug(`Found mapping for user ${userId}`, {
        whmcsClientId: mapping.whmcsClientId,
        sfAccountId: mapping.sfAccountId,
      });

      return mapping;
    } catch (error) {
      this.logger.error(`Failed to find mapping for user ${userId}`, {
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Find mapping by WHMCS client ID
   */
  async findByWhmcsClientId(whmcsClientId: number): Promise<UserIdMapping | null> {
    try {
      // Validate WHMCS client ID
      if (!whmcsClientId || whmcsClientId < 1) {
        throw new BadRequestException("Valid WHMCS client ID is required");
      }

      // Try cache first
      const cached = await this.cacheService.getByWhmcsClientId(whmcsClientId);
      if (cached) {
        this.logger.debug(`Cache hit for WHMCS client mapping: ${whmcsClientId}`);
        return cached;
      }

      // Fetch from database
      const dbMapping = await this.prisma.idMapping.findUnique({
        where: { whmcsClientId },
      });

      if (!dbMapping) {
        this.logger.debug(`No mapping found for WHMCS client ${whmcsClientId}`);
        return null;
      }

      const mapping: UserIdMapping = {
        userId: dbMapping.userId,
        whmcsClientId: dbMapping.whmcsClientId,
        sfAccountId: dbMapping.sfAccountId || undefined,
        createdAt: dbMapping.createdAt,
        updatedAt: dbMapping.updatedAt,
      };

      // Cache the result
      await this.cacheService.setMapping(mapping);

      this.logger.debug(`Found mapping for WHMCS client ${whmcsClientId}`, {
        userId: mapping.userId,
        sfAccountId: mapping.sfAccountId,
      });

      return mapping;
    } catch (error) {
      this.logger.error(`Failed to find mapping for WHMCS client ${whmcsClientId}`, {
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Find mapping by Salesforce account ID
   */
  async findBySfAccountId(sfAccountId: string): Promise<UserIdMapping | null> {
    try {
      // Validate Salesforce account ID
      if (!sfAccountId) {
        throw new BadRequestException("Salesforce account ID is required");
      }

      // Try cache first
      const cached = await this.cacheService.getBySfAccountId(sfAccountId);
      if (cached) {
        this.logger.debug(`Cache hit for SF account mapping: ${sfAccountId}`);
        return cached;
      }

      // Fetch from database
      const dbMapping = await this.prisma.idMapping.findFirst({
        where: { sfAccountId },
      });

      if (!dbMapping) {
        this.logger.debug(`No mapping found for SF account ${sfAccountId}`);
        return null;
      }

      const mapping: UserIdMapping = {
        userId: dbMapping.userId,
        whmcsClientId: dbMapping.whmcsClientId,
        sfAccountId: dbMapping.sfAccountId || undefined,
        createdAt: dbMapping.createdAt,
        updatedAt: dbMapping.updatedAt,
      };

      // Cache the result
      await this.cacheService.setMapping(mapping);

      this.logger.debug(`Found mapping for SF account ${sfAccountId}`, {
        userId: mapping.userId,
        whmcsClientId: mapping.whmcsClientId,
      });

      return mapping;
    } catch (error) {
      this.logger.error(`Failed to find mapping for SF account ${sfAccountId}`, {
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Update an existing mapping
   */
  async updateMapping(userId: string, updates: UpdateMappingRequest): Promise<UserIdMapping> {
    try {
      // Validate request
      const validation = this.validator.validateUpdateRequest(userId, updates);
      this.validator.logValidationResult("Update mapping", validation, {
        userId,
      });

      if (!validation.isValid) {
        throw new BadRequestException(`Invalid update data: ${validation.errors.join(", ")}`);
      }

      // Get existing mapping
      const existing = await this.findByUserId(userId);
      if (!existing) {
        throw new NotFoundException(`Mapping not found for user ${userId}`);
      }

      // Sanitize input
      const sanitizedUpdates = this.validator.sanitizeUpdateRequest(updates);

      // Check for conflicts if WHMCS client ID is being changed
      if (
        sanitizedUpdates.whmcsClientId &&
        sanitizedUpdates.whmcsClientId !== existing.whmcsClientId
      ) {
        const conflictingMapping = await this.findByWhmcsClientId(sanitizedUpdates.whmcsClientId);
        if (conflictingMapping && conflictingMapping.userId !== userId) {
          throw new ConflictException(
            `WHMCS client ${sanitizedUpdates.whmcsClientId} is already mapped to user ${conflictingMapping.userId}`
          );
        }
      }

      // Update in database
      const updated = await this.prisma.idMapping.update({
        where: { userId },
        data: sanitizedUpdates,
      });

      const newMapping: UserIdMapping = {
        userId: updated.userId,
        whmcsClientId: updated.whmcsClientId,
        sfAccountId: updated.sfAccountId || undefined,
        createdAt: updated.createdAt,
        updatedAt: updated.updatedAt,
      };

      // Update cache
      await this.cacheService.updateMapping(existing, newMapping);

      this.logger.log(`Updated mapping for user ${userId}`, {
        changes: sanitizedUpdates,
        warnings: validation.warnings,
      });

      return newMapping;
    } catch (error) {
      this.logger.error(`Failed to update mapping for user ${userId}`, {
        error: getErrorMessage(error),
        updates: this.sanitizeForLog(updates),
      });
      throw error;
    }
  }

  /**
   * Delete a mapping
   */
  async deleteMapping(userId: string): Promise<void> {
    try {
      // Get existing mapping
      const existing = await this.findByUserId(userId);
      if (!existing) {
        throw new NotFoundException(`Mapping not found for user ${userId}`);
      }

      // Validate deletion
      const validation = this.validator.validateDeletion(existing);
      this.validator.logValidationResult("Delete mapping", validation, {
        userId,
      });

      // Delete from database
      await this.prisma.idMapping.delete({
        where: { userId },
      });

      // Remove from cache
      await this.cacheService.deleteMapping(existing);

      this.logger.log(`Deleted mapping for user ${userId}`, {
        whmcsClientId: existing.whmcsClientId,
        sfAccountId: existing.sfAccountId,
        warnings: validation.warnings,
      });
    } catch (error) {
      this.logger.error(`Failed to delete mapping for user ${userId}`, {
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Search mappings with filters
   */
  async searchMappings(filters: MappingSearchFilters): Promise<UserIdMapping[]> {
    try {
      const whereClause: any = {};

      if (filters.userId) {
        whereClause.userId = filters.userId;
      }

      if (filters.whmcsClientId) {
        whereClause.whmcsClientId = filters.whmcsClientId;
      }

      if (filters.sfAccountId) {
        whereClause.sfAccountId = filters.sfAccountId;
      }

      if (filters.hasWhmcsMapping !== undefined) {
        if (filters.hasWhmcsMapping) {
          whereClause.whmcsClientId = { not: null };
        } else {
          whereClause.whmcsClientId = null;
        }
      }

      if (filters.hasSfMapping !== undefined) {
        if (filters.hasSfMapping) {
          whereClause.sfAccountId = { not: null };
        } else {
          whereClause.sfAccountId = null;
        }
      }

      const dbMappings = await this.prisma.idMapping.findMany({
        where: whereClause,
        orderBy: { createdAt: "desc" },
      });

      const mappings: UserIdMapping[] = dbMappings.map(mapping => ({
        userId: mapping.userId,
        whmcsClientId: mapping.whmcsClientId,
        sfAccountId: mapping.sfAccountId || undefined,
        createdAt: mapping.createdAt,
        updatedAt: mapping.updatedAt,
      }));

      this.logger.debug(`Found ${mappings.length} mappings matching filters`, filters);
      return mappings;
    } catch (error) {
      this.logger.error("Failed to search mappings", {
        error: getErrorMessage(error),
        filters,
      });
      throw error;
    }
  }

  /**
   * Get mapping statistics
   */
  async getMappingStats(): Promise<MappingStats> {
    try {
      const [totalCount, whmcsCount, sfCount, completeCount] = await Promise.all([
        this.prisma.idMapping.count(),
        this.prisma.idMapping.count({
          where: { whmcsClientId: { not: null as any } },
        }),
        this.prisma.idMapping.count({
          where: { sfAccountId: { not: null } },
        }),
        this.prisma.idMapping.count({
          where: {
            AND: [{ whmcsClientId: { not: null as any } }, { sfAccountId: { not: null } }],
          },
        }),
      ]);

      const stats: MappingStats = {
        totalMappings: totalCount,
        whmcsMappings: whmcsCount,
        salesforceMappings: sfCount,
        completeMappings: completeCount,
        orphanedMappings: 0, // Would need to check against actual user records
      };

      this.logger.debug("Generated mapping statistics", stats);
      return stats;
    } catch (error) {
      this.logger.error("Failed to get mapping statistics", {
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Bulk create mappings
   */
  async bulkCreateMappings(mappings: CreateMappingRequest[]): Promise<BulkMappingResult> {
    const result: BulkMappingResult = {
      successful: 0,
      failed: 0,
      errors: [],
    };

    try {
      // Validate all mappings first
      const validations = this.validator.validateBulkMappings(mappings);

      for (let i = 0; i < mappings.length; i++) {
        const mapping = mappings[i];
        const validation = validations[i].validation;

        try {
          if (!validation.isValid) {
            throw new Error(validation.errors.join(", "));
          }

          await this.createMapping(mapping);
          result.successful++;
        } catch (error) {
          result.failed++;
          result.errors.push({
            index: i,
            error: getErrorMessage(error),
            data: mapping,
          });
        }
      }

      this.logger.log(
        `Bulk create completed: ${result.successful} successful, ${result.failed} failed`
      );
      return result;
    } catch (error) {
      this.logger.error("Bulk create mappings failed", {
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Check if user has mapping
   */
  async hasMapping(userId: string): Promise<boolean> {
    try {
      // Try cache first
      const cached = await this.cacheService.getByUserId(userId);
      if (cached) {
        return true;
      }

      // Check database
      const mapping = await this.prisma.idMapping.findUnique({
        where: { userId },
        select: { userId: true },
      });

      return mapping !== null;
    } catch (error) {
      this.logger.error(`Failed to check mapping for user ${userId}`, {
        error: getErrorMessage(error),
      });
      return false;
    }
  }

  /**
   * Invalidate cache for a user
   */
  async invalidateCache(userId: string): Promise<void> {
    // Get the current mapping to invalidate all related cache keys
    const mapping = await this.cacheService.getByUserId(userId);
    if (mapping) {
      await this.cacheService.deleteMapping(mapping);
    }
    this.logger.log(`Invalidated mapping cache for user ${userId}`);
  }

  /**
   * Health check
   */
  async healthCheck(): Promise<{ status: string; details: any }> {
    try {
      // Test database connectivity
      await this.prisma.idMapping.count();

      return {
        status: "healthy",
        details: {
          database: "connected",
          cache: "available",
          timestamp: new Date().toISOString(),
        },
      };
    } catch (error) {
      this.logger.error("Mapping service health check failed", {
        error: getErrorMessage(error),
      });
      return {
        status: "unhealthy",
        details: {
          error: getErrorMessage(error),
          timestamp: new Date().toISOString(),
        },
      };
    }
  }

  // Private helper methods

  private async getAllMappingsFromDb(): Promise<UserIdMapping[]> {
    const dbMappings = await this.prisma.idMapping.findMany();
    return dbMappings.map(mapping => ({
      userId: mapping.userId,
      whmcsClientId: mapping.whmcsClientId,
      sfAccountId: mapping.sfAccountId || undefined,
      createdAt: mapping.createdAt,
      updatedAt: mapping.updatedAt,
    }));
  }

  private sanitizeForLog(data: any): any {
    // Remove sensitive data from logs if needed
    const sanitized = { ...data };
    // Add any sanitization logic here
    return sanitized;
  }

  /**
   * Legacy method support (for backward compatibility)
   */
  async create(data: CreateMappingRequest): Promise<UserIdMapping> {
    this.logger.warn("Using legacy create method - please update to createMapping");
    return this.createMapping(data);
  }

  /**
   * Legacy method support (for backward compatibility)
   */
  async createMappingLegacy(data: CreateMappingRequest): Promise<UserIdMapping> {
    this.logger.warn("Using legacy createMapping method - please update to createMapping");
    return this.createMapping(data);
  }

  /**
   * Legacy method support (for backward compatibility)
   */
  async updateMappingLegacy(userId: string, updates: any): Promise<UserIdMapping> {
    this.logger.warn("Using legacy updateMapping method - please update to updateMapping");
    return this.updateMapping(userId, updates);
  }
}