<?php

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Models\Participant;
use App\Models\Program;
use App\Models\ProgramParticipant;
use App\Services\AuditLogService;
use App\Services\ParticipantImportService;
use Illuminate\Http\RedirectResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
use Illuminate\View\View;
use League\Csv\Writer;
use SplTempFileObject;

class ParticipantController extends Controller
{
    public function index(Program $program, Request $request): View
    {
        $query = $program->programParticipants()
            ->with('participant')
            ->latest();

        if ($request->filled('search')) {
            $query->whereHas('participant', function ($q) use ($request) {
                $q->where('name', 'like', '%' . $request->search . '%')
                  ->orWhere('agency', 'like', '%' . $request->search . '%');
            });
        }

        if ($request->filled('source')) {
            $query->where('registration_source', $request->source);
        }

        if ($request->filled('status')) {
            $query->where('status', $request->status);
        }

        $programParticipants = $query->paginate(20)->withQueryString();

        $countRow = DB::table('program_participants')
            ->where('program_id', $program->id)
            ->selectRaw("COUNT(*) as total, SUM(is_pre_registered) as pre_registered, SUM(registration_source = 'walk_in') as walk_in, SUM(status = 'checked_in') as checked_in")
            ->first();

        $counts = [
            'total'          => (int) ($countRow->total          ?? 0),
            'pre_registered' => (int) ($countRow->pre_registered ?? 0),
            'walk_in'        => (int) ($countRow->walk_in        ?? 0),
            'checked_in'     => (int) ($countRow->checked_in     ?? 0),
        ];

        return view('admin.programs.participants.index', compact('program', 'programParticipants', 'counts'));
    }

    public function create(Program $program): View
    {
        return view('admin.programs.participants.create', compact('program'));
    }

    public function store(Program $program, Request $request): RedirectResponse
    {
        $request->validate([
            'name'    => ['required', 'string', 'max:255'],
            'no_kp'   => ['required', 'string', 'regex:/^\d{6}-?\d{2}-?\d{4}$|^\d{12}$/'],
            'email'   => ['nullable', 'email', 'max:255'],
            'phone'   => ['nullable', 'string', 'max:20'],
            'agency'  => ['nullable', 'string', 'max:255'],
            'session' => ['nullable', 'in:pagi,petang,full_day'],
        ]);

        $noKp = preg_replace('/[^0-9]/', '', $request->no_kp);

        // Check duplicate in this program
        $existing = Participant::where('no_kp', $noKp)->first();
        if ($existing && $program->programParticipants()->where('participant_id', $existing->id)->exists()) {
            return back()->withInput()->with('error', 'Peserta dengan No. K/P ini sudah didaftarkan dalam program ini.');
        }

        DB::transaction(function () use ($program, $request, $noKp, $existing) {
            $participant = $existing ?? Participant::create([
                'name'             => $request->name,
                'no_kp'            => $noKp,
                'email'            => $request->email,
                'phone'            => $request->phone,
                'agency'           => $request->agency,
                'participant_type' => 'staff',
            ]);

            $program->programParticipants()->create([
                'participant_id'        => $participant->id,
                'registration_source'   => 'admin_manual',
                'is_pre_registered'     => true,
                'pre_registered_session'=> $request->session ?? $program->default_staff_session,
                'status'                => 'registered',
                'registered_at'         => now(),
            ]);

            AuditLogService::log('participant.added', $participant);
        });

        return back()->with('success', 'Peserta berjaya ditambah.');
    }

    public function destroy(Program $program, ProgramParticipant $pp): RedirectResponse
    {
        if ($pp->program_id !== $program->id) {
            abort(403);
        }

        if ($pp->attendance()->exists()) {
            return back()->with('error', 'Peserta tidak boleh dikeluarkan kerana sudah ada rekod kehadiran.');
        }

        $pp->delete();

        return back()->with('success', 'Peserta berjaya dikeluarkan daripada program.');
    }

    public function importForm(Program $program): View
    {
        return view('admin.programs.participants.import', compact('program'));
    }

    public function import(Program $program, Request $request, ParticipantImportService $importer): RedirectResponse
    {
        $request->validate([
            'csv_file' => ['required', 'file', 'mimes:csv,txt', 'max:5120'],
            'session'  => ['nullable', 'in:pagi,petang,full_day'],
        ]);

        $result = $importer->import(
            $program,
            $request->file('csv_file'),
            $request->input('session', $program->default_staff_session)
        );

        AuditLogService::log('participant.imported', $program, [], [
            'success'    => $result['success'],
            'duplicates' => $result['duplicates'],
            'failed'     => $result['failed'],
        ]);

        return back()->with('import_result', $result);
    }

    public function export(Program $program): \Symfony\Component\HttpFoundation\StreamedResponse
    {
        $headers = [
            'Content-Type'        => 'text/csv; charset=UTF-8',
            'Content-Disposition' => 'attachment; filename="peserta_' . $program->uuid . '_' . now()->format('Ymd') . '.csv"',
        ];

        return response()->stream(function () use ($program) {
            $handle = fopen('php://output', 'w');

            // UTF-8 BOM for Excel compatibility
            fputs($handle, "\xEF\xBB\xBF");

            fputcsv($handle, ['Nama', 'No K/P', 'Emel', 'Telefon', 'Agensi', 'Sesi', 'Sumber', 'Status', 'Tarikh Daftar']);

            $program->programParticipants()
                ->with('participant')
                ->lazy()
                ->each(function ($pp) use ($handle) {
                    $p = $pp->participant;
                    fputcsv($handle, [
                        $p->name,
                        $p->no_kp,
                        $p->email,
                        $p->phone,
                        $p->agency,
                        $pp->pre_registered_session ?? '—',
                        $pp->registration_source,
                        $pp->status,
                        $pp->registered_at?->format('d/m/Y H:i') ?? '—',
                    ]);
                });

            fclose($handle);
        }, 200, $headers);
    }
}