import {
  Injectable,
  NotFoundException,
  ConflictException,
  BadRequestException,
  Inject,
} from "@nestjs/common";
import { Logger } from "nestjs-pino";
import { PrismaService } from "@bff/infra/database/prisma.service";
import { getErrorMessage } from "@bff/core/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
  ) {}

  async createMapping(request: CreateMappingRequest): Promise<UserIdMapping> {
    try {
      const validation = this.validator.validateCreateRequest(request);
      this.logger.debug("Validation result: Create mapping", validation);
      if (!validation.isValid) {
        throw new BadRequestException(`Invalid mapping data: ${validation.errors.join(", ")}`);
      }

      const sanitizedRequest = this.validator.sanitizeCreateRequest(request);

      const [byUser, byWhmcs, bySf] = await Promise.all([
        this.prisma.idMapping.findUnique({ where: { userId: sanitizedRequest.userId } }),
        this.prisma.idMapping.findUnique({ where: { whmcsClientId: sanitizedRequest.whmcsClientId } }),
        sanitizedRequest.sfAccountId
          ? this.prisma.idMapping.findFirst({ where: { sfAccountId: sanitizedRequest.sfAccountId } })
          : Promise.resolve(null),
      ]);

      if (byUser) {
        throw new ConflictException(`User ${sanitizedRequest.userId} already has a mapping`);
      }
      if (byWhmcs) {
        throw new ConflictException(
          `WHMCS client ${sanitizedRequest.whmcsClientId} is already mapped to user ${byWhmcs.userId}`
        );
      }
      if (bySf) {
        this.logger.warn(
          `Salesforce account ${sanitizedRequest.sfAccountId} is already mapped to user ${bySf.userId}`
        );
      }

      let created;
      try {
        created = await this.prisma.idMapping.create({ data: sanitizedRequest });
      } catch (e) {
        const msg = getErrorMessage(e);
        if (msg.includes("P2002") || /unique/i.test(msg)) {
          throw new ConflictException("Mapping violates uniqueness constraints");
        }
        throw e;
      }

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

      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;
    }
  }

  async findBySfAccountId(sfAccountId: string): Promise<UserIdMapping | null> {
    try {
      if (!sfAccountId) {
        throw new BadRequestException("Salesforce Account ID is required");
      }

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

      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,
      };

      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;
    }
  }

  async findByUserId(userId: string): Promise<UserIdMapping | null> {
    try {
      if (!userId) {
        throw new BadRequestException("User ID is required");
      }

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

      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,
      };

      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;
    }
  }

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

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

      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,
      };

      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;
    }
  }

  async updateMapping(userId: string, updates: UpdateMappingRequest): Promise<UserIdMapping> {
    try {
      const validation = this.validator.validateUpdateRequest(userId, updates);
      this.logger.debug("Validation result: Update mapping", validation);
      if (!validation.isValid) {
        throw new BadRequestException(`Invalid update data: ${validation.errors.join(", ")}`);
      }

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

      const sanitizedUpdates = this.validator.sanitizeUpdateRequest(updates);
      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}`
          );
        }
      }

      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,
      };

      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;
    }
  }

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

      const validation = this.validator.validateDeletion(existing);
      this.logger.debug("Validation result: Delete mapping", validation);

      await this.prisma.idMapping.delete({ where: { userId } });
      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;
    }
  }

  async searchMappings(filters: MappingSearchFilters): Promise<UserIdMapping[]> {
    try {
      const whereClause: Record<string, unknown> = {};
      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) {
        whereClause.whmcsClientId = filters.hasWhmcsMapping ? { not: null } : null;
      }
      if (filters.hasSfMapping !== undefined) {
        whereClause.sfAccountId = filters.hasSfMapping ? { not: null } : 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;
    }
  }

  async getMappingStats(): Promise<MappingStats> {
    try {
      const [totalCount, whmcsCount, sfCount, completeCount] = await Promise.all([
        this.prisma.idMapping.count(),
        this.prisma.idMapping.count(),
        this.prisma.idMapping.count({ where: { sfAccountId: { not: null } } }),
        this.prisma.idMapping.count({ where: { sfAccountId: { not: null } } }),
      ]);

      const stats: MappingStats = {
        totalMappings: totalCount,
        whmcsMappings: whmcsCount,
        salesforceMappings: sfCount,
        completeMappings: completeCount,
        orphanedMappings: 0,
      };
      this.logger.debug("Generated mapping statistics", stats);
      return stats;
    } catch (error) {
      this.logger.error("Failed to get mapping statistics", { error: getErrorMessage(error) });
      throw error;
    }
  }

  async hasMapping(userId: string): Promise<boolean> {
    try {
      const cached = await this.cacheService.getByUserId(userId);
      if (cached) return true;
      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;
    }
  }

  async invalidateCache(userId: string): Promise<void> {
    const mapping = await this.cacheService.getByUserId(userId);
    if (mapping) {
      await this.cacheService.deleteMapping(mapping);
    }
    this.logger.log(`Invalidated mapping cache for user ${userId}`);
  }

  private sanitizeForLog(data: unknown): Record<string, unknown> {
    try {
      const plain: unknown = JSON.parse(JSON.stringify(data ?? {}));
      if (plain && typeof plain === "object" && !Array.isArray(plain)) {
        return plain as Record<string, unknown>;
      }
      return { value: plain } as Record<string, unknown>;
    } catch {
      return { value: String(data) } as Record<string, unknown>;
    }
  }
}