<?php

namespace App\Http\Controllers;

use App\Models\AcademicYear;
use App\Models\Department;
use App\Models\SchoolClass;
use Illuminate\Http\RedirectResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\Rule;
use Illuminate\View\View;
use RealRashid\SweetAlert\Facades\Alert;

class SchoolClassController extends Controller
{
    public function index(Request $request): View
    {
        $search = trim((string) $request->get('search'));

        $classes = SchoolClass::with(['academicYear', 'department'])
            ->withCount(['students', 'academicHistories'])
            ->when($search !== '', function ($query) use ($search) {
                $query->where('name', 'like', "%{$search}%")
                    ->orWhere('level', 'like', "%{$search}%")
                    ->orWhere('homeroom_teacher', 'like', "%{$search}%");
            })
            ->latest()
            ->paginate(10)
            ->withQueryString();

        return view('classes.index', [
            'classes' => $classes,
            'search' => $search,
            'academicYears' => AcademicYear::orderByDesc('start_year')->orderByDesc('end_year')->get(),
        ]);
    }

    public function create(): View
    {
        return view('classes.create', [
            'academicYears' => AcademicYear::where('is_active', true)->orderBy('name')->pluck('name', 'id'),
            'departments' => Department::where('is_active', true)->orderBy('name')->pluck('name', 'id'),
        ]);
    }

    public function store(Request $request): RedirectResponse
    {
        $data = $request->validate([
            'academic_year_id' => ['required', Rule::exists('academic_years', 'id')->where(fn ($query) => $query->where('is_active', true))],
            'department_id' => ['required', Rule::exists('departments', 'id')->where(fn ($query) => $query->where('is_active', true))],
            'name' => ['required', 'string', 'max:100', Rule::unique('classes', 'name')->where(fn ($query) => $query->where('academic_year_id', $request->academic_year_id))],
            'level' => ['required', 'string', 'max:10'],
            'homeroom_teacher' => ['nullable', 'string', 'max:100'],
            'capacity' => ['nullable', 'integer', 'min:1'],
            'is_active' => ['nullable', 'boolean'],
        ]);

        $data['is_active'] = $request->boolean('is_active');

        SchoolClass::create($data);

        return redirect()->route('classes.index')->with('success', 'Kelas berhasil ditambahkan.');
    }

    public function generate(Request $request): RedirectResponse
    {
        $data = $request->validate([
            'source_academic_year_id' => ['required', 'exists:academic_years,id', 'different:target_academic_year_id'],
            'target_academic_year_id' => ['required', 'exists:academic_years,id'],
            'generation_mode' => ['required', Rule::in(['same_level', 'promote_level'])],
        ]);

        $sourceClasses = SchoolClass::query()
            ->where('academic_year_id', $data['source_academic_year_id'])
            ->orderBy('department_id')
            ->orderBy('level')
            ->orderBy('name')
            ->get();

        if ($sourceClasses->isEmpty()) {
            Alert::error('Gagal', 'Tidak ada kelas pada tahun ajaran sumber yang bisa digenerate.');

            return redirect()->route('classes.index')->withErrors([
                'generate' => 'Tidak ada kelas pada tahun ajaran sumber yang bisa digenerate.',
            ]);
        }

        $created = 0;
        $skipped = 0;

        DB::transaction(function () use ($sourceClasses, $data, &$created, &$skipped) {
            foreach ($sourceClasses as $sourceClass) {
                $targetLevel = $data['generation_mode'] === 'promote_level'
                    ? $this->nextLevel($sourceClass->level)
                    : $sourceClass->level;

                if ($targetLevel === null) {
                    $skipped++;
                    continue;
                }

                $targetName = $this->transformClassName($sourceClass->name, $sourceClass->level, $targetLevel);

                $exists = SchoolClass::query()
                    ->where('academic_year_id', $data['target_academic_year_id'])
                    ->where('name', $targetName)
                    ->exists();

                if ($exists) {
                    $skipped++;
                    continue;
                }

                SchoolClass::create([
                    'academic_year_id' => $data['target_academic_year_id'],
                    'department_id' => $sourceClass->department_id,
                    'name' => $targetName,
                    'level' => $targetLevel,
                    'homeroom_teacher' => $sourceClass->homeroom_teacher,
                    'capacity' => $sourceClass->capacity,
                    'is_active' => true,
                ]);

                $created++;
            }
        });

        Alert::success('Berhasil', "Generate kelas selesai. {$created} kelas dibuat, {$skipped} dilewati.");

        return redirect()->route('classes.index')->with('success', "Generate kelas selesai. {$created} kelas dibuat, {$skipped} dilewati.");
    }

    public function show(SchoolClass $class): RedirectResponse
    {
        return redirect()->route('classes.edit', $class);
    }

    public function edit(SchoolClass $class): View
    {
        $class->loadMissing(['academicYear', 'department']);

        $academicYears = AcademicYear::query()
            ->where(function ($query) use ($class) {
                $query->where('is_active', true)
                    ->orWhere('id', $class->academic_year_id);
            })
            ->orderBy('name')
            ->pluck('name', 'id');

        $departments = Department::query()
            ->where(function ($query) use ($class) {
                $query->where('is_active', true)
                    ->orWhere('id', $class->department_id);
            })
            ->orderBy('name')
            ->pluck('name', 'id');

        return view('classes.edit', [
            'class' => $class,
            'academicYears' => $academicYears,
            'departments' => $departments,
        ]);
    }

    public function update(Request $request, SchoolClass $class): RedirectResponse
    {
        $data = $request->validate([
            'academic_year_id' => ['required', Rule::exists('academic_years', 'id')->where(fn ($query) => $query->where('is_active', true)->orWhere('id', $class->academic_year_id))],
            'department_id' => ['required', Rule::exists('departments', 'id')->where(fn ($query) => $query->where('is_active', true)->orWhere('id', $class->department_id))],
            'name' => ['required', 'string', 'max:100', Rule::unique('classes', 'name')->ignore($class->id)->where(fn ($query) => $query->where('academic_year_id', $request->academic_year_id))],
            'level' => ['required', 'string', 'max:10'],
            'homeroom_teacher' => ['nullable', 'string', 'max:100'],
            'capacity' => ['nullable', 'integer', 'min:1'],
            'is_active' => ['nullable', 'boolean'],
        ]);

        $data['is_active'] = $request->boolean('is_active');

        $class->update($data);

        return redirect()->route('classes.index')->with('success', 'Kelas berhasil diperbarui.');
    }

    public function destroy(SchoolClass $class): RedirectResponse
    {
        $class->loadCount(['students', 'academicHistories']);

        if ($class->students_count > 0) {
            Alert::error('Tidak bisa dihapus', 'Kelas ini masih digunakan oleh data siswa aktif.');

            return redirect()->route('classes.index')->withErrors([
                'delete' => 'Kelas tidak bisa dihapus karena masih digunakan oleh data siswa aktif.',
            ]);
        }

        if ($class->academic_histories_count > 0) {
            Alert::error('Tidak bisa dihapus', 'Kelas ini masih tercatat pada histori akademik siswa.');

            return redirect()->route('classes.index')->withErrors([
                'delete' => 'Kelas tidak bisa dihapus karena masih tercatat pada histori akademik siswa. Hapus atau ubah histori terkait terlebih dahulu.',
            ]);
        }

        Alert::success('Berhasil', 'Kelas berhasil dihapus.');

        $class->delete();

        return redirect()->route('classes.index')->with('success', 'Kelas berhasil dihapus.');
    }

    public function bulkDestroy(Request $request): RedirectResponse
    {
        $validated = $request->validate([
            'class_ids' => ['required', 'array', 'min:1'],
            'class_ids.*' => ['integer', 'exists:classes,id'],
        ], [
            'class_ids.required' => 'Pilih minimal satu kelas untuk dihapus.',
        ]);

        $classes = SchoolClass::withCount(['students', 'academicHistories'])
            ->whereIn('id', $validated['class_ids'])
            ->get();

        $blocked = $classes->filter(fn (SchoolClass $class) => $class->students_count > 0 || $class->academic_histories_count > 0);

        if ($blocked->isNotEmpty()) {
            Alert::error('Tidak bisa dihapus', 'Sebagian kelas masih dipakai oleh siswa aktif atau histori akademik.');

            return redirect()->route('classes.index')->withErrors([
                'delete' => 'Beberapa kelas tidak bisa dihapus karena masih dipakai oleh data siswa atau histori akademik.',
            ]);
        }

        $deletedCount = 0;

        foreach ($classes as $class) {
            $class->delete();
            $deletedCount++;
        }

        Alert::success('Berhasil', $deletedCount . ' kelas berhasil dihapus.');

        return redirect()->route('classes.index')->with('success', $deletedCount . ' kelas berhasil dihapus.');
    }

    protected function nextLevel(?string $level): ?string
    {
        return match (strtoupper((string) $level)) {
            'X' => 'XI',
            'XI' => 'XII',
            'XII' => null,
            default => $level,
        };
    }

    protected function transformClassName(string $name, ?string $fromLevel, ?string $toLevel): string
    {
        if (! $fromLevel || ! $toLevel || strtoupper($fromLevel) === strtoupper($toLevel)) {
            return $name;
        }

        return preg_replace('/^' . preg_quote($fromLevel, '/') . '\b/i', $toLevel, $name) ?: $name;
    }
}