import { Injectable } from "@nestjs/common";
import {
  SUPPORT_CASE_CATEGORY,
  SUPPORT_CASE_PRIORITY,
  SUPPORT_CASE_STATUS,
  supportCaseFilterSchema,
  supportCaseListSchema,
  type SupportCase,
  type SupportCaseFilter,
  type SupportCaseList,
  type SupportCasePriority,
  type SupportCaseStatus,
} from "@customer-portal/domain/support";

const OPEN_STATUSES: SupportCaseStatus[] = [
  SUPPORT_CASE_STATUS.OPEN,
  SUPPORT_CASE_STATUS.IN_PROGRESS,
  SUPPORT_CASE_STATUS.WAITING_ON_CUSTOMER,
];

const RESOLVED_STATUSES: SupportCaseStatus[] = [
  SUPPORT_CASE_STATUS.RESOLVED,
  SUPPORT_CASE_STATUS.CLOSED,
];

const HIGH_PRIORITIES: SupportCasePriority[] = [
  SUPPORT_CASE_PRIORITY.HIGH,
  SUPPORT_CASE_PRIORITY.CRITICAL,
];

@Injectable()
export class SupportService {
  // Placeholder dataset until Salesforce integration is ready
  private readonly cases: SupportCase[] = [
    {
      id: 12001,
      subject: "VPS Performance Issues",
      status: SUPPORT_CASE_STATUS.IN_PROGRESS,
      priority: SUPPORT_CASE_PRIORITY.HIGH,
      category: SUPPORT_CASE_CATEGORY.TECHNICAL,
      createdAt: "2025-08-14T10:30:00Z",
      updatedAt: "2025-08-15T14:20:00Z",
      lastReply: "2025-08-15T14:20:00Z",
      description: "Experiencing slow response times on VPS server, CPU usage appears high.",
      assignedTo: "Technical Support Team",
    },
    {
      id: 12002,
      subject: "Billing Question - Invoice #12345",
      status: SUPPORT_CASE_STATUS.WAITING_ON_CUSTOMER,
      priority: SUPPORT_CASE_PRIORITY.MEDIUM,
      category: SUPPORT_CASE_CATEGORY.BILLING,
      createdAt: "2025-08-13T16:45:00Z",
      updatedAt: "2025-08-14T09:30:00Z",
      lastReply: "2025-08-14T09:30:00Z",
      description: "Need clarification on charges in recent invoice.",
      assignedTo: "Billing Department",
    },
    {
      id: 12003,
      subject: "SSL Certificate Installation",
      status: SUPPORT_CASE_STATUS.RESOLVED,
      priority: SUPPORT_CASE_PRIORITY.LOW,
      category: SUPPORT_CASE_CATEGORY.TECHNICAL,
      createdAt: "2025-08-12T08:15:00Z",
      updatedAt: "2025-08-12T15:45:00Z",
      lastReply: "2025-08-12T15:45:00Z",
      description: "Request assistance with SSL certificate installation on shared hosting.",
      assignedTo: "Technical Support Team",
    },
    {
      id: 12004,
      subject: "Feature Request: Control Panel Enhancement",
      status: SUPPORT_CASE_STATUS.OPEN,
      priority: SUPPORT_CASE_PRIORITY.LOW,
      category: SUPPORT_CASE_CATEGORY.FEATURE_REQUEST,
      createdAt: "2025-08-11T13:20:00Z",
      updatedAt: "2025-08-11T13:20:00Z",
      description: "Would like to see improved backup management in the control panel.",
      assignedTo: "Development Team",
    },
    {
      id: 12005,
      subject: "Server Migration Assistance",
      status: SUPPORT_CASE_STATUS.CLOSED,
      priority: SUPPORT_CASE_PRIORITY.MEDIUM,
      category: SUPPORT_CASE_CATEGORY.TECHNICAL,
      createdAt: "2025-08-10T11:00:00Z",
      updatedAt: "2025-08-11T17:30:00Z",
      lastReply: "2025-08-11T17:30:00Z",
      description: "Need help migrating website from old server to new VPS.",
      assignedTo: "Migration Team",
    },
  ];

  async listCases(rawFilters?: SupportCaseFilter): Promise<SupportCaseList> {
    const filters = supportCaseFilterSchema.parse(rawFilters ?? {});
    const filteredCases = this.applyFilters(this.cases, filters);
    const result = {
      cases: filteredCases,
      summary: this.buildSummary(filteredCases),
    };
    return supportCaseListSchema.parse(result);
  }

  private applyFilters(cases: SupportCase[], filters: SupportCaseFilter): SupportCase[] {
    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.id}`.toLowerCase();
        if (!haystack.includes(search)) {
          return false;
        }
      }
      return true;
    });
  }

  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,
    };
  }
}