/**
 * Hook for fetching and managing dashboard data
 */

import { useState, useCallback, useRef } from 'react';
import { dashboardService, type DashboardKPIs, type DateRange, type AIRemarkUtilization, type ApproverPerformance, type DepartmentStats, type PriorityDistribution, type UpcomingDeadline, type RecentActivity, type CriticalRequest } from '@/services/dashboard.service';
import { ActivityData } from '@/components/dashboard/ActivityFeedItem';
import type { CriticalAlertData } from '@/components/dashboard/CriticalAlertCard';

interface UseDashboardDataOptions {
  isAdmin: boolean;
  viewAsUser?: boolean; // For admin to view as normal user
  userId?: string; // User ID for filtering - needed to fetch user-initiated requests
  dateRange: DateRange;
  customStartDate?: Date;
  customEndDate?: Date;
  onPaginationUpdate: {
    activity: (page: number, totalPages: number, totalRecords: number) => void;
    critical: (page: number, totalPages: number, totalRecords: number) => void;
    deadlines: (page: number, totalPages: number, totalRecords: number) => void;
    approver: (page: number, totalPages: number, totalRecords: number) => void;
  };
}

export function useDashboardData({
  isAdmin,
  viewAsUser = false,
  userId, // User ID for filtering user-initiated requests
  dateRange,
  customStartDate,
  customEndDate,
  onPaginationUpdate,
}: UseDashboardDataOptions) {
  const [kpis, setKpis] = useState<DashboardKPIs | null>(null);
  const [recentActivity, setRecentActivity] = useState<ActivityData[]>([]);
  const [criticalRequests, setCriticalRequests] = useState<(CriticalRequest | CriticalAlertData)[]>([]);
  const [departmentStats, setDepartmentStats] = useState<DepartmentStats[]>([]);
  const [priorityDistribution, setPriorityDistribution] = useState<PriorityDistribution[]>([]);
  const [upcomingDeadlines, setUpcomingDeadlines] = useState<UpcomingDeadline[]>([]);
  const [aiRemarkUtilization, setAiRemarkUtilization] = useState<AIRemarkUtilization | null>(null);
  const [approverPerformance, setApproverPerformance] = useState<ApproverPerformance[]>([]);
  const [loading, setLoading] = useState(true);
  const [refreshing, setRefreshing] = useState(false);

  // Use ref to store latest pagination callbacks to avoid dependency issues
  const paginationCallbacksRef = useRef(onPaginationUpdate);
  paginationCallbacksRef.current = onPaginationUpdate;

  const fetchDashboardData = useCallback(async (showRefreshing = false) => {
    try {
      if (showRefreshing) {
        setRefreshing(true);
      } else {
        setLoading(true);
      }

      // Fetch common data for all users
      const commonPromises = [
        dashboardService.getKPIs(dateRange, customStartDate, customEndDate, viewAsUser),
        dashboardService.getRecentActivity(1, 10, viewAsUser),
        dashboardService.getCriticalRequests(1, 10, viewAsUser),
        dashboardService.getUpcomingDeadlines(1, 10, viewAsUser)
      ];

      // For normal users (or admin viewing as user): 
      // Fetch user-INITIATED requests stats separately for "My Requests" card
      // This ensures "My Requests" only shows requests they created, not all requests they're involved in
      const userInitiatedPromise = (!isAdmin && userId) 
        ? dashboardService.getRequestStats(
            dateRange,
            customStartDate?.toISOString(),
            customEndDate?.toISOString(),
            undefined, // status
            undefined, // priority
            undefined, // templateType
            undefined, // department
            userId,    // initiator - filter by user's ID to get ONLY their initiated requests
            undefined, // approver
            undefined, // approverType
            undefined, // search
            undefined, // slaCompliance
            viewAsUser // viewAsUser - treat as normal user even if admin
          )
        : null;

      // Fetch admin-only data if user is admin
      const adminPromises = isAdmin ? [
        dashboardService.getDepartmentStats(dateRange, customStartDate, customEndDate),
        dashboardService.getPriorityDistribution(dateRange, customStartDate, customEndDate),
        dashboardService.getAIRemarkUtilization(dateRange, customStartDate, customEndDate),
        dashboardService.getApproverPerformance(dateRange, 1, 10, customStartDate, customEndDate)
      ] : [];

      // Fetch all data in parallel
      const [commonResults, userInitiatedStats, adminResults] = await Promise.all([
        Promise.all(commonPromises),
        userInitiatedPromise,
        Promise.all(adminPromises)
      ]);
      
      const kpisData = commonResults[0] as DashboardKPIs;
      const activityResult = commonResults[1] as { activities: RecentActivity[]; pagination: { currentPage: number; totalPages: number; totalRecords: number; limit: number } };
      const criticalResult = commonResults[2] as { criticalRequests: CriticalRequest[]; pagination: { currentPage: number; totalPages: number; totalRecords: number; limit: number } };
      const deadlinesResult = commonResults[3] as { deadlines: UpcomingDeadline[]; pagination: { currentPage: number; totalPages: number; totalRecords: number; limit: number } };

      // For normal users: Override requestVolume with user-initiated requests only
      // This makes "My Requests" show only requests they created
      // Other KPIs (approverLoad, etc.) remain as-is since they need all involved requests
      if (!isAdmin && userInitiatedStats) {
        kpisData.requestVolume = userInitiatedStats;
      }

      setKpis(kpisData);
      setRecentActivity(activityResult.activities);
      paginationCallbacksRef.current.activity(
        activityResult.pagination.currentPage,
        activityResult.pagination.totalPages,
        activityResult.pagination.totalRecords
      );
      
      setCriticalRequests(criticalResult.criticalRequests);
      paginationCallbacksRef.current.critical(
        criticalResult.pagination.currentPage,
        criticalResult.pagination.totalPages,
        criticalResult.pagination.totalRecords
      );
      
      setUpcomingDeadlines(deadlinesResult.deadlines);
      paginationCallbacksRef.current.deadlines(
        deadlinesResult.pagination.currentPage,
        deadlinesResult.pagination.totalPages,
        deadlinesResult.pagination.totalRecords
      );
      
      // Only set admin-specific data if user is admin
      if (isAdmin && adminResults.length >= 4) {
        const deptStats = adminResults[0] as DepartmentStats[];
        const priorityDist = adminResults[1] as PriorityDistribution[];
        const aiUtilization = adminResults[2] as AIRemarkUtilization;
        const approverResult = adminResults[3] as { performance: ApproverPerformance[]; pagination: { currentPage: number; totalPages: number; totalRecords: number; limit: number } };
        setDepartmentStats(deptStats);
        setPriorityDistribution(priorityDist);
        setAiRemarkUtilization(aiUtilization);
        setApproverPerformance(approverResult.performance);
        paginationCallbacksRef.current.approver(
          approverResult.pagination.currentPage,
          approverResult.pagination.totalPages,
          approverResult.pagination.totalRecords
        );
      } else if (!isAdmin) {
        // Reset admin-specific data for normal users
        setDepartmentStats([]);
        setPriorityDistribution([]);
        setAiRemarkUtilization(null);
        setApproverPerformance([]);
      }
    } catch (error) {
      console.error('Failed to fetch dashboard data:', error);
    } finally {
      setLoading(false);
      setRefreshing(false);
    }
  }, [isAdmin, viewAsUser, userId, dateRange, customStartDate, customEndDate]);

  // Fetch individual data with pagination
  const fetchRecentActivities = useCallback(async (page: number = 1) => {
    try {
      const result = await dashboardService.getRecentActivity(page, 10, viewAsUser);
      setRecentActivity(result.activities);
      paginationCallbacksRef.current.activity(
        result.pagination.currentPage,
        result.pagination.totalPages,
        result.pagination.totalRecords
      );
    } catch (error) {
      console.error('Failed to fetch recent activities:', error);
    }
  }, [viewAsUser]);

  const fetchCriticalRequests = useCallback(async (page: number = 1) => {
    try {
      const result = await dashboardService.getCriticalRequests(page, 10, viewAsUser);
      setCriticalRequests(result.criticalRequests);
      paginationCallbacksRef.current.critical(
        result.pagination.currentPage,
        result.pagination.totalPages,
        result.pagination.totalRecords
      );
    } catch (error) {
      console.error('Failed to fetch critical requests:', error);
    }
  }, [viewAsUser]);

  const fetchUpcomingDeadlines = useCallback(async (page: number = 1) => {
    try {
      const result = await dashboardService.getUpcomingDeadlines(page, 10, viewAsUser);
      setUpcomingDeadlines(result.deadlines);
      paginationCallbacksRef.current.deadlines(
        result.pagination.currentPage,
        result.pagination.totalPages,
        result.pagination.totalRecords
      );
    } catch (error) {
      console.error('Failed to fetch upcoming deadlines:', error);
    }
  }, [viewAsUser]);

  const fetchApproverPerformance = useCallback(async (page: number = 1) => {
    try {
      const result = await dashboardService.getApproverPerformance(dateRange, page, 10, customStartDate, customEndDate);
      setApproverPerformance(result.performance);
      paginationCallbacksRef.current.approver(
        result.pagination.currentPage,
        result.pagination.totalPages,
        result.pagination.totalRecords
      );
    } catch (error) {
      console.error('Failed to fetch approver performance:', error);
    }
  }, [dateRange, customStartDate, customEndDate]);

  return {
    kpis,
    recentActivity,
    criticalRequests,
    departmentStats,
    priorityDistribution,
    upcomingDeadlines,
    aiRemarkUtilization,
    approverPerformance,
    loading,
    refreshing,
    fetchDashboardData,
    fetchRecentActivities,
    fetchCriticalRequests,
    fetchUpcomingDeadlines,
    fetchApproverPerformance,
  };
}