<?php

namespace App\Http\Controllers;

use App\Models\Branch;
use App\Models\ThirteenthMonthRun;
use App\Models\ThirteenthMonthEntry;
use App\Services\ThirteenthMonthService;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;
use Inertia\Inertia;

class ThirteenthMonthController extends Controller
{
    protected $service;

    public function __construct(ThirteenthMonthService $service)
    {
        $this->service = $service;
    }

    /**
     * Display the 13th Month Pay management index page.
     */
    public function index(Request $request)
    {
        $currentYear = (int) date('Y');
        
        $startYear = $request->input('start_year') ? (int) $request->input('start_year') : $currentYear;
        $startMonth = $request->input('start_month') ? (int) $request->input('start_month') : 1;
        $endYear = $request->input('end_year') ? (int) $request->input('end_year') : $currentYear;
        $endMonth = $request->input('end_month') ? (int) $request->input('end_month') : 12;

        $selectedBranchId = $request->input('branch_id') ? (int) $request->input('branch_id') : null;

        // Available years for back-year filtering (last 5 years up to next year)
        $availableYears = range($currentYear - 5, $currentYear + 1);
        $branches = Branch::all(['id', 'name']);

        // Check if an existing run matches these range parameters
        $existingRun = ThirteenthMonthRun::where('start_year', $startYear)
            ->where('start_month', $startMonth)
            ->where('end_year', $endYear)
            ->where('end_month', $endMonth)
            ->when($selectedBranchId, function ($q) use ($selectedBranchId) {
                $q->where('branch_id', $selectedBranchId);
            }, function ($q) {
                $q->whereNull('branch_id');
            })
            ->with(['entries.employee.user', 'entries.employee.designation', 'entries.employee.department', 'branch', 'creator'])
            ->first();

        if (!$existingRun) {
            // Generate dynamic run preview on the fly
            $existingRun = $this->service->generateRun($startYear, $startMonth, $endYear, $endMonth, $selectedBranchId, null, Auth::id());
        }

        // Fetch historical runs list
        $pastRuns = ThirteenthMonthRun::with(['branch', 'creator'])
            ->orderBy('year', 'desc')
            ->orderBy('created_at', 'desc')
            ->get();

        return Inertia::render('hr/thirteenth-month/index', [
            'activeRun' => $existingRun,
            'pastRuns' => $pastRuns,
            'branches' => $branches,
            'availableYears' => array_values($availableYears),
            'filters' => [
                'start_year' => $startYear,
                'start_month' => $startMonth,
                'end_year' => $endYear,
                'end_month' => $endMonth,
                'branch_id' => $selectedBranchId,
            ],
        ]);
    }

    /**
     * Generate or recalculate a 13th month batch run with custom date ranges.
     */
    public function store(Request $request)
    {
        $request->validate([
            'start_year' => 'required|integer|min:2020|max:2035',
            'start_month' => 'required|integer|min:1|max:12',
            'end_year' => 'required|integer|min:2020|max:2035',
            'end_month' => 'required|integer|min:1|max:12',
            'branch_id' => 'nullable|exists:branches,id',
        ]);

        $startYear = (int) $request->start_year;
        $startMonth = (int) $request->start_month;
        $endYear = (int) $request->end_year;
        $endMonth = (int) $request->end_month;
        $branchId = $request->branch_id ? (int) $request->branch_id : null;

        $run = $this->service->generateRun($startYear, $startMonth, $endYear, $endMonth, $branchId, null, Auth::id());

        return redirect()->back()->with('success', '13th Month Pay range calculated successfully!');
    }

    /**
     * Update an individual employee's adjustment or note.
     */
    public function updateEntry(Request $request, $id)
    {
        $request->validate([
            'adjustment_amount' => 'required|numeric',
            'notes' => 'nullable|string|max:255',
        ]);

        $entry = ThirteenthMonthEntry::findOrFail($id);
        $adjustment = (float) $request->adjustment_amount;

        $entry->adjustment_amount = $adjustment;
        $entry->final_payout = round($entry->computed_amount + $adjustment, 2);
        if ($request->has('notes')) {
            $entry->notes = $request->notes;
        }
        $entry->save();

        // Recalculate parent run totals
        $run = $entry->run;
        if ($run) {
            $run->total_payout = round($run->entries()->sum('final_payout'), 2);
            $run->save();
        }

        return redirect()->back()->with('success', '13th Month entry updated successfully.');
    }

    /**
     * Approve and lock the 13th Month Pay run.
     */
    public function approveRun(Request $request, $id)
    {
        $run = ThirteenthMonthRun::findOrFail($id);
        $run->status = 'approved';
        $run->save();

        return redirect()->back()->with('success', '13th Month Pay run has been approved!');
    }

    /**
     * Export 13th Month Payout Schedule as Bank CSV.
     */
    public function exportCsv($id)
    {
        $run = ThirteenthMonthRun::with(['entries.employee.user', 'entries.employee.department', 'branch'])->findOrFail($id);

        $filename = "13th_Month_Pay_{$run->start_year}_{$run->start_month}_to_{$run->end_year}_{$run->end_month}_Export.csv";
        $headers = [
            'Content-Type' => 'text/csv',
            'Content-Disposition' => "attachment; filename=\"{$filename}\"",
        ];

        $callback = function () use ($run) {
            $file = fopen('php://output', 'w');
            fputcsv($file, ['Employee Code', 'Employee Name', 'Department', 'Total Base Earned', 'Computed 13th Month', 'Adjustment', 'Final Net Payout']);

            foreach ($run->entries as $entry) {
                $empCode = $entry->employee->employee_code ?? "EMP-{$entry->employee_id}";
                $empName = $entry->employee->user->name ?? 'Staff';
                $dept = $entry->employee->department->name ?? 'General';

                fputcsv($file, [
                    $empCode,
                    $empName,
                    $dept,
                    number_format($entry->total_base_earned, 2, '.', ''),
                    number_format($entry->computed_amount, 2, '.', ''),
                    number_format($entry->adjustment_amount, 2, '.', ''),
                    number_format($entry->final_payout, 2, '.', ''),
                ]);
            }

            fclose($file);
        };

        return response()->stream($callback, 200, $headers);
    }
}