import { Injectable, Inject, NotFoundException, ForbiddenException } from "@nestjs/common";
import { Logger } from "nestjs-pino";
import {
  SUPPORT_CASE_PRIORITY,
  SUPPORT_CASE_STATUS,
  type SupportCase,
  type SupportCaseFilter,
  type SupportCaseList,
  type CreateCaseRequest,
  type CreateCaseResponse,
} from "@customer-portal/domain/support";
import { SalesforceCaseService } from "@bff/integrations/salesforce/services/salesforce-case.service";
import { MappingsService } from "@bff/modules/id-mappings/mappings.service";
import { getErrorMessage } from "@bff/core/utils/error.util";

/**
 * Status values that indicate an open/active case
 * (Display values after mapping from Salesforce Japanese API names)
 */
const OPEN_STATUSES: string[] = [
  SUPPORT_CASE_STATUS.NEW,
  SUPPORT_CASE_STATUS.IN_PROGRESS,
  SUPPORT_CASE_STATUS.AWAITING_APPROVAL,
];

/**
 * Status values that indicate a resolved/closed case
 * (Display values after mapping from Salesforce Japanese API names)
 */
const RESOLVED_STATUSES: string[] = [
  SUPPORT_CASE_STATUS.VPN_PENDING,
  SUPPORT_CASE_STATUS.PENDING,
  SUPPORT_CASE_STATUS.RESOLVED,
  SUPPORT_CASE_STATUS.CLOSED,
];

/**
 * Priority values that indicate high priority
 */
const HIGH_PRIORITIES: string[] = [SUPPORT_CASE_PRIORITY.HIGH];

@Injectable()
export class SupportService {
  constructor(
    private readonly caseService: SalesforceCaseService,
    private readonly mappingsService: MappingsService,
    @Inject(Logger) private readonly logger: Logger
  ) {}

  /**
   * List cases for a user with optional filters
   */
  async listCases(userId: string, filters?: SupportCaseFilter): Promise<SupportCaseList> {
    const accountId = await this.getAccountIdForUser(userId);

    try {
      // SalesforceCaseService now returns SupportCase[] directly using domain mappers
      const cases = await this.caseService.getCasesForAccount(accountId);

      const filteredCases = this.applyFilters(cases, filters);
      const summary = this.buildSummary(filteredCases);

      return { cases: filteredCases, summary };
    } catch (error) {
      this.logger.error("Failed to list support cases", {
        userId,
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Get a single case by ID
   */
  async getCase(userId: string, caseId: string): Promise<SupportCase> {
    const accountId = await this.getAccountIdForUser(userId);

    try {
      // SalesforceCaseService now returns SupportCase directly using domain mappers
      const supportCase = await this.caseService.getCaseById(caseId, accountId);

      if (!supportCase) {
        throw new NotFoundException("Support case not found");
      }

      return supportCase;
    } catch (error) {
      if (error instanceof NotFoundException) {
        throw error;
      }
      this.logger.error("Failed to get support case", {
        userId,
        caseId,
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Create a new support case
   */
  async createCase(userId: string, request: CreateCaseRequest): Promise<CreateCaseResponse> {
    const accountId = await this.getAccountIdForUser(userId);

    try {
      const result = await this.caseService.createCase({
        subject: request.subject,
        description: request.description,
        category: request.category,
        priority: request.priority,
        accountId,
      });

      this.logger.log("Support case created", {
        userId,
        caseId: result.id,
        caseNumber: result.caseNumber,
      });

      return result;
    } catch (error) {
      this.logger.error("Failed to create support case", {
        userId,
        error: getErrorMessage(error),
      });
      throw error;
    }
  }

  /**
   * Get Salesforce account ID for a user
   */
  private async getAccountIdForUser(userId: string): Promise<string> {
    const mapping = await this.mappingsService.findByUserId(userId);

    if (!mapping?.sfAccountId) {
      this.logger.warn("No Salesforce account mapping found for user", { userId });
      throw new ForbiddenException("Account not linked to Salesforce");
    }

    return mapping.sfAccountId;
  }

  /**
   * Apply filters to cases
   */
  private applyFilters(cases: SupportCase[], filters?: SupportCaseFilter): SupportCase[] {
    if (!filters) {
      return cases;
    }

    const search = filters.search?.toLowerCase().trim();

    return cases.filter(supportCase => {
      if (filters.status && supportCase.status !== filters.status) {
        return false;
      }
      if (filters.priority && supportCase.priority !== filters.priority) {
        return false;
      }
      if (filters.category && supportCase.category !== filters.category) {
        return false;
      }
      if (search) {
        const haystack =
          `${supportCase.subject} ${supportCase.description} ${supportCase.caseNumber}`.toLowerCase();
        if (!haystack.includes(search)) {
          return false;
        }
      }
      return true;
    });
  }

  /**
   * Build summary statistics for cases
   */
  private buildSummary(cases: SupportCase[]): SupportCaseList["summary"] {
    const open = cases.filter(c => OPEN_STATUSES.includes(c.status)).length;
    const highPriority = cases.filter(c => HIGH_PRIORITIES.includes(c.priority)).length;
    const resolved = cases.filter(c => RESOLVED_STATUSES.includes(c.status)).length;

    return {
      total: cases.length,
      open,
      highPriority,
      resolved,
    };
  }
}