<?php

namespace App\Http\Controllers;

use App\Models\Shift;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;
use Inertia\Inertia;

class ShiftController extends Controller
{
    public function index(Request $request)
    {
        if (Auth::user()->can('manage-shifts')) {
            $query = Shift::with(['creator'])->where(function ($q) {
                if (Auth::user()->can('manage-any-shifts')) {
                    $q->whereIn('created_by',  getCompanyAndUsersId());
                } elseif (Auth::user()->can('manage-own-shifts')) {
                    $q->where('created_by', Auth::id());
                } else {
                    $q->whereRaw('1 = 0');
                }
            });

            // Handle search
            if ($request->has('search') && !empty($request->search)) {
                $query->where(function ($q) use ($request) {
                    $q->where('name', 'like', '%' . $request->search . '%')
                        ->orWhere('description', 'like', '%' . $request->search . '%');
                });
            }

            // Handle status filter
            if ($request->has('status') && !empty($request->status) && $request->status !== 'all') {
                $query->where('status', $request->status);
            }

            // Handle shift type filter
            if ($request->has('shift_type') && !empty($request->shift_type) && $request->shift_type !== 'all') {
                if ($request->shift_type === 'night') {
                    $query->where('is_night_shift', true);
                } else {
                    $query->where('is_night_shift', false);
                }
            }

            // Handle sorting
            if ($request->has('sort_field') && !empty($request->sort_field)) {
                $sortField = $request->sort_field;
                $sortDirection = $request->sort_direction ?? 'asc';
                
                if ($sortField === 'name') {
                    $query->orderBy('name', $sortDirection);
                } else {
                    $query->orderBy('created_at', 'desc');
                }
            } else {
                $query->orderBy('created_at', 'desc');
            }

            $shifts = $query->paginate($request->per_page ?? 9);

            // Stats always calculated from ALL records — never affected by filters or pagination
            $allShifts = Shift::where(function ($q) {
                if (Auth::user()->can('manage-any-shifts')) {
                    $q->whereIn('created_by', getCompanyAndUsersId());
                } elseif (Auth::user()->can('manage-own-shifts')) {
                    $q->where('created_by', Auth::id());
                } else {
                    $q->whereRaw('1 = 0');
                }
            });

            $stats = [
                'total'  => (clone $allShifts)->count(),
                'active' => (clone $allShifts)->where('status', 'active')->count(),
                'night'  => (clone $allShifts)->where('is_night_shift', true)->count(),
                'day'    => (clone $allShifts)->where('is_night_shift', false)->count(),
            ];

            return Inertia::render('hr/shifts/index', [
                'shifts'  => $shifts,
                'stats'   => $stats,
                'filters' => $request->all(['search', 'status', 'shift_type', 'sort_field', 'sort_direction', 'per_page']),
            ]);
        } else {
            return redirect()->back()->with('error', __('Permission Denied.'));
        }
    }

    public function store(Request $request)
    {
        $validated = $request->validate([
            'name' => 'required|string|max:255',
            'description' => 'nullable|string',
            'start_time' => 'required|date_format:H:i',
            'end_time' => 'required|date_format:H:i',
            'break_duration' => 'required|integer|min:0',
            'break_start_time' => 'nullable|date_format:H:i',
            'break_end_time' => 'nullable|date_format:H:i',
            'grace_period' => 'required|integer|min:0',
            'is_night_shift' => 'boolean',
            'status' => 'nullable|in:active,inactive',
        ]);

        $validated['created_by'] = creatorId();
        $validated['status'] = $validated['status'] ?? 'active';
        $validated['is_night_shift'] = $validated['is_night_shift'] ?? false;

        // Check if shift with same name already exists
        $exists = Shift::where('name', $validated['name'])
            ->whereIn('created_by', getCompanyAndUsersId())
            ->exists();

        if ($exists) {
            return redirect()->back()->with('error', __('Shift with this name already exists.'));
        }

        Shift::create($validated);

        return redirect()->back()->with('success', __('Shift created successfully.'));
    }

    public function update(Request $request, $shiftId)
    {
        $shift = Shift::where('id', $shiftId)
            ->whereIn('created_by', getCompanyAndUsersId())
            ->first();

        if ($shift) {
            try {
                $validated = $request->validate([
                    'name' => 'required|string|max:255',
                    'description' => 'nullable|string',
                    'start_time' => 'required|date_format:H:i',
                    'end_time' => 'required|date_format:H:i',
                    'break_duration' => 'required|integer|min:0',
                    'break_start_time' => 'nullable|date_format:H:i',
                    'break_end_time' => 'nullable|date_format:H:i',
                    'grace_period' => 'required|integer|min:0',
                    'is_night_shift' => 'boolean',
                    'status' => 'nullable|in:active,inactive',
                ]);

                // Check if shift with same name already exists (excluding current)
                $exists = Shift::where('name', $validated['name'])
                    ->whereIn('created_by', getCompanyAndUsersId())
                    ->where('id', '!=', $shiftId)
                    ->exists();

                if ($exists) {
                    return redirect()->back()->with('error', __('Shift with this name already exists.'));
                }

                $shift->update($validated);

                return redirect()->back()->with('success', __('Shift updated successfully'));
            } catch (\Exception $e) {
                return redirect()->back()->with('error', $e->getMessage() ?: __('Failed to update shift'));
            }
        } else {
            return redirect()->back()->with('error', __('Shift Not Found.'));
        }
    }

    public function destroy($shiftId)
    {
        $shift = Shift::where('id', $shiftId)
            ->whereIn('created_by', getCompanyAndUsersId())
            ->first();

        if ($shift) {
            try {
                $shift->delete();
                return redirect()->back()->with('success', __('Shift deleted successfully'));
            } catch (\Exception $e) {
                return redirect()->back()->with('error', $e->getMessage() ?: __('Failed to delete shift'));
            }
        } else {
            return redirect()->back()->with('error', __('Shift Not Found.'));
        }
    }

    public function toggleStatus($shiftId)
    {
        $shift = Shift::where('id', $shiftId)
            ->whereIn('created_by', getCompanyAndUsersId())
            ->first();

        if ($shift) {
            try {
                $shift->status = $shift->status === 'active' ? 'inactive' : 'active';
                $shift->save();

                return redirect()->back()->with('success', __('Shift status updated successfully'));
            } catch (\Exception $e) {
                return redirect()->back()->with('error', $e->getMessage() ?: __('Failed to update shift status'));
            }
        } else {
            return redirect()->back()->with('error', __('Shift Not Found.'));
        }
    }

    public function calendar(Request $request)
    {
        if (Auth::user()->can('manage-shifts')) {
            $month = $request->input('month', date('n'));
            $year = $request->input('year', date('Y'));
            $department_id = $request->input('department_id');
            $search = $request->input('search');

            $startDate = \Carbon\Carbon::createFromDate($year, $month, 1)->startOfMonth();
            $endDate = \Carbon\Carbon::createFromDate($year, $month, 1)->endOfMonth();

            // Setup dates header correctly (1 -> 31)
            $dates = [];
            for ($date = $startDate->copy(); $date->lte($endDate); $date->addDay()) {
                $dates[] = [
                    'date' => $date->format('Y-m-d'),
                    'day' => $date->format('d'),
                    'day_name' => $date->format('D'),
                ];
            }

            $query = \App\Models\User::with(['employee.department', 'employee.shift'])
            ->whereHas('employee', function($q) {
                $q->where('employee_status', 'active');
            });

            if ($department_id) {
                $query->whereHas('employee', function($q) use ($department_id) {
                    $q->where('department_id', $department_id);
                });
            }

            if ($search) {
                $query->where('name', 'like', "%{$search}%");
            }

            $usersRaw = $query->get();

            // Fetch daily shifts and REST DAY overrides dynamically directly from the Attendance engine records!
            $dailyShifts = \Illuminate\Support\Facades\DB::table('attendance_records')
                ->leftJoin('shifts', 'attendance_records.shift_id', '=', 'shifts.id')
                ->whereBetween('attendance_records.date', [$startDate->format('Y-m-d'), $endDate->format('Y-m-d')])
                ->select(
                    'attendance_records.employee_id as user_id', 
                    'attendance_records.date', 
                    'attendance_records.is_rest_day',
                    'attendance_records.shift_id',
                    'shifts.name as shift_name'
                )
                ->get()
                ->groupBy('user_id');

            $users = $usersRaw->map(function($user) use ($dates, $dailyShifts) {
                $grid = [];
                $userShifts = $dailyShifts->has($user->id) ? $dailyShifts[$user->id]->keyBy('date') : collect();

                foreach ($dates as $d) {
                    $dateKey = $d['date'];
                    // Default to Rest Day as per user's Socratic resolution
                    $status = 'RD';
                    $shiftName = 'Rest Day';
                    
                    if ($userShifts->has($dateKey)) {
                        $record = $userShifts[$dateKey];
                        
                        // If attendance record specifically marks it as a globally tracked Rest Day
                        if ($record->is_rest_day) {
                            $status = 'RD';
                            $shiftName = 'Rest Day';
                            $shiftId = null;
                        } else if ($record->shift_name) {
                            // Extract shift safely
                            $status = strtoupper(substr($record->shift_name, 0, 1));
                            $shiftName = $record->shift_name;
                            $shiftId = $record->shift_id;
                        } else if ($user->employee && $user->employee->shift) {
                            // Record exists, but shift mapping is blank. Fallback to employee profile shift.
                            $status = strtoupper(substr($user->employee->shift->name, 0, 1));
                            $shiftName = $user->employee->shift->name;
                            $shiftId = $user->employee->shift->id;
                        }
                    } else if ($user->employee && $user->employee->shift) {
                        // Completely blank record; safely map to their default assigned Employee Shift!
                        // Removed hardcoded Sat/Sun filters because `attendance_records` strictly dictates actual weekend behavior now!
                        $status = strtoupper(substr($user->employee->shift->name, 0, 1));
                        $shiftName = $user->employee->shift->name;
                        $shiftId = $user->employee->shift->id;
                    }

                    $grid[$dateKey] = [
                        'status' => $status,
                        'shift_name' => $shiftName,
                        'shift_id' => $shiftId ?? ''
                    ];
                }

                return [
                    'id' => $user->id,
                    'name' => $user->name,
                    'employee_code' => $user->employee ? $user->employee->employee_id : '',
                    'designation' => ($user->employee && $user->employee->designation) ? $user->employee->designation->name : '',
                    'department' => ($user->employee && $user->employee->department) ? $user->employee->department->name : '',
                    'shifts' => $grid
                ];
            });

            $departments = \App\Models\Department::select('id', 'name')->get();
            $allShifts = \App\Models\Shift::whereIn('created_by', getCompanyAndUsersId())->where('status', 'active')->get();

            return Inertia::render('hr/shifts/calendar', [
                'users' => $users,
                'dates' => $dates,
                'departments' => $departments,
                'shifts' => $allShifts,
                'filters' => [
                    'month' => $month,
                    'year' => $year,
                    'department_id' => $department_id,
                    'search' => $search
                ]
            ]);
        }
        return redirect()->back()->with('error', __('Permission Denied.'));
    }

    public function assignShift(Request $request)
    {
        if (Auth::user()->can('manage-shifts')) {
            $validated = $request->validate([
                'employee_id' => 'required|exists:users,id',
                'start_date' => 'required|date',
                'end_date' => 'required|date|after_or_equal:start_date',
                'shift_id' => 'required_without:is_rest_day|nullable|exists:shifts,id',
                'is_rest_day' => 'boolean',
            ]);

            $startDate = \Carbon\Carbon::parse($validated['start_date']);
            $endDate = \Carbon\Carbon::parse($validated['end_date']);
            
            $period = \Carbon\CarbonPeriod::create($startDate, $endDate);

            foreach ($period as $date) {
                \App\Models\AttendanceRecord::updateOrCreate(
                    [
                        'employee_id' => $validated['employee_id'],
                        'date' => $date->format('Y-m-d'),
                    ],
                    [
                        'shift_id' => $validated['is_rest_day'] ? null : $validated['shift_id'],
                        'is_rest_day' => $validated['is_rest_day'] ?? false,
                        'status' => $validated['is_rest_day'] ? 'absent' : 'present', // Default status for scheduled shift
                        'created_by' => creatorId(),
                    ]
                );
            }

            return redirect()->back()->with('success', __('Shifts assigned successfully.'));
        }

        return redirect()->back()->with('error', __('Permission Denied.'));
    }
}