<?php

namespace App\Services;

use App\Models\ClassSection;
use App\Models\Configuration;
use App\Models\Student;
use App\Models\StudentClass;
use App\Models\TeacherClass;
use App\Models\User;
use Illuminate\Support\Facades\DB;

class AssignmentService
{
    public function __construct(
        protected User $userModel,
        protected Configuration $configModel,
        protected Student $studentModel,
        protected ClassSection $classSectionModel,
        protected TeacherClass $teacherClassModel,
        protected StudentClass $studentClassModel
    ) {}

    public function buildClassAssignments(array $filters = []): array
    {
        $currentSemester   = (string) ($this->getConfigValue('semester') ?? '');
        $currentSchoolYear = (string) ($this->getConfigValue('school_year') ?? '');

        $selectedSemester = (string) ($filters['semester'] ?? $currentSemester);
        $selectedYear     = (string) ($filters['school_year'] ?? $currentSchoolYear);
        $forApi           = (bool) ($filters['for_api'] ?? false);

        // Teacher classes (year-filtered; no semester filtering like your original code)
        $teacherQ = $this->teacherClassModel->newQuery();
        if ($selectedYear !== '') {
            $teacherQ->where('school_year', $selectedYear);
        }
        $teacherClassesAll = $teacherQ->get()->toArray();

        // Student classes (active + year-filtered)
        $studentQ = method_exists($this->studentClassModel, 'active')
            ? $this->studentClassModel->active()
            : $this->studentClassModel->newQuery()->where('is_active', 1);

        if ($selectedYear !== '') {
            // If your table is aliased in scopeActive(), you can keep student_class.school_year
            $studentQ->where('school_year', $selectedYear);
        }
        $studentClassesAll = $studentQ->get()->toArray();

        // Group teacher and student classes by section
        $teacherBySection = [];
        foreach ($teacherClassesAll as $tc) {
            $secId = (int) ($tc['class_section_id'] ?? 0);
            if ($secId > 0) {
                $teacherBySection[$secId][] = $tc;
            }
        }

        $studentsBySection = [];
        foreach ($studentClassesAll as $sc) {
            $secId = (int) ($sc['class_section_id'] ?? 0);
            if ($secId > 0) {
                $studentsBySection[$secId][] = $sc;
            }
        }

        $allSectionIds = array_values(array_unique(array_merge(
            array_keys($teacherBySection),
            array_keys($studentsBySection)
        )));

        $classSections = [];

        foreach ($allSectionIds as $classSectionId) {
            $teacherClasses = $teacherBySection[$classSectionId] ?? [];
            $studentClasses = $studentsBySection[$classSectionId] ?? [];

            if (empty($teacherClasses) && empty($studentClasses)) {
                continue;
            }

            $classSectionName = $this->resolveClassSectionName($classSectionId);

            $mainTeachers       = [];
            $teacherAssistants  = [];
            $sectionSemester    = '';
            $sectionSchoolYear  = '';
            $description        = '';

            // Teacher metadata + names
            foreach ($teacherClasses as $teacherClass) {
                $teacherId = (int) ($teacherClass['teacher_id'] ?? 0);
                if ($teacherId > 0) {
                    $teacher = $this->userModel->newQuery()->find($teacherId);
                    if ($teacher) {
                        $teacherName = trim(
                            (string) ($teacher->firstname ?? '') . ' ' . (string) ($teacher->lastname ?? '')
                        );

                        if ($teacherName !== '') {
                            if (($teacherClass['position'] ?? '') === 'main') {
                                $mainTeachers[] = $teacherName;
                            } elseif (($teacherClass['position'] ?? '') === 'ta') {
                                $teacherAssistants[] = $teacherName;
                            }
                        }
                    }
                }

                if ($sectionSemester === '' && !empty($teacherClass['semester'])) {
                    $sectionSemester = (string) $teacherClass['semester'];
                }
                if ($sectionSchoolYear === '' && !empty($teacherClass['school_year'])) {
                    $sectionSchoolYear = (string) $teacherClass['school_year'];
                }
                if ($description === '' && !empty($teacherClass['description'])) {
                    $description = (string) $teacherClass['description'];
                }
            }

            // Students
            $students = [];
            foreach ($studentClasses as $studentClass) {
                if ($sectionSemester === '' && !empty($studentClass['semester'])) {
                    $sectionSemester = (string) $studentClass['semester'];
                }
                if ($sectionSchoolYear === '' && !empty($studentClass['school_year'])) {
                    $sectionSchoolYear = (string) $studentClass['school_year'];
                }
                if ($description === '' && !empty($studentClass['description'])) {
                    $description = (string) $studentClass['description'];
                }

                $studentId = (int) ($studentClass['student_id'] ?? 0);
                if ($studentId <= 0) {
                    continue;
                }

                $student = $this->studentModel->newQuery()
                    ->where('id', $studentId)
                    ->where('is_active', 1)
                    ->first();

                if (!$student) {
                    continue;
                }

                $students[] = $forApi
                    ? [
                        'id'                 => (int) $student->id,
                        'firstname'          => (string) ($student->firstname ?? ''),
                        'lastname'           => (string) ($student->lastname ?? ''),
                        'age'                => $student->age ?? null,
                        'gender'             => (string) ($student->gender ?? ''),
                        'registration_grade' => (string) ($student->registration_grade ?? ''),
                        'photo_consent'      => (bool) ($student->photo_consent ?? false),
                        'tuition_paid'       => (bool) ($student->tuition_paid ?? false),
                        'school_id'          => (string) ($student->school_id ?? ''),
                    ]
                    : [
                        'id'                 => (int) $student->id,
                        'firstname'          => e((string) ($student->firstname ?? '')),
                        'lastname'           => e((string) ($student->lastname ?? '')),
                        'age'                => e((string) ($student->age ?? '')),
                        'gender'             => e((string) ($student->gender ?? '')),
                        'registration_grade' => e((string) ($student->registration_grade ?? '')),
                        'photo_consent'      => e(((bool) ($student->photo_consent ?? false)) ? 'Yes' : 'No'),
                        'tuition_paid'       => e(((bool) ($student->tuition_paid ?? false)) ? 'Yes' : 'No'),
                        'school_id'          => e((string) ($student->school_id ?? '')),
                    ];
            }

            $classSections[] = [
                'class_section_id'   => (int) $classSectionId,
                'class_section_name' => (string) $classSectionName,
                'main_teachers'      => array_values(array_unique($mainTeachers)),
                'teacher_assistants' => array_values(array_unique($teacherAssistants)),
                'students'           => $students,
                'semester'           => $sectionSemester !== '' ? $sectionSemester : $currentSemester,
                'school_year'        => $sectionSchoolYear !== '' ? $sectionSchoolYear : $currentSchoolYear,
                'description'        => $description,
            ];
        }

        // Sort sections by name
        usort($classSections, fn ($a, $b) => strcmp(
            (string) ($a['class_section_name'] ?? ''),
            (string) ($b['class_section_name'] ?? '')
        ));

        $schoolYearsList = $this->getSchoolYearsList($currentSchoolYear);

        $payload = [
            'classSections'     => $classSections,
            'schoolYears'       => $schoolYearsList,
            'selectedYear'      => $selectedYear,
            'selectedSemester'  => $selectedSemester,
            'semester'          => $currentSemester,
            'school_year'       => $currentSchoolYear,
        ];

        // If you're using Laravel Sanctum/API only, CSRF may not be needed.
        // Keep it if your frontend still expects it:
        if (function_exists('csrf_token')) {
            $payload['csrfToken'] = csrf_token();
        }

        return $payload;
    }

    public function saveStudentAssignment(array $data, ?int $updatedBy = null): mixed
    {
        $payload = [
            'student_id'        => $data['student_id'],
            'class_section_id'  => $data['class_section_id'],
            'semester'          => $data['semester'] ?? $this->getConfigValue('semester'),
            'school_year'       => $data['school_year'] ?? $this->getConfigValue('school_year'),
            'description'       => $data['description'] ?? null,
            'updated_by'        => $updatedBy,
        ];

        // If your StudentClass model supports updateOrCreate:
        // adjust unique keys as needed (e.g. student_id + school_year + semester)
        return $this->studentClassModel->newQuery()->updateOrCreate(
            [
                'student_id'    => $payload['student_id'],
                'school_year'   => $payload['school_year'],
                'semester'      => $payload['semester'],
            ],
            $payload
        );
    }

    protected function getConfigValue(string $key): mixed
    {
        // Match your existing model API if present
        if (method_exists($this->configModel, 'getConfig')) {
            return $this->configModel->getConfig($key);
        }

        // Generic fallback
        return $this->configModel->newQuery()
            ->where('key', $key)
            ->value('value');
    }

    protected function resolveClassSectionName(int $classSectionId): string
    {
        if (method_exists($this->classSectionModel, 'getClassSectionNameBySectionId')) {
            return (string) ($this->classSectionModel->getClassSectionNameBySectionId($classSectionId) ?? '');
        }

        $section = $this->classSectionModel->newQuery()->find($classSectionId);

        // Adjust to your actual field(s)
        return (string) ($section->name ?? $section->title ?? '');
    }

    protected function getSchoolYearsList(string $fallbackYear = ''): array
    {
        try {
            $years = DB::table('teacher_class')
                ->select('school_year')
                ->whereNotNull('school_year')
                ->distinct()
                ->orderByDesc('school_year')
                ->pluck('school_year')
                ->map(fn ($y) => (string) $y)
                ->filter(fn ($y) => $y !== '')
                ->values()
                ->all();

            if (!empty($years)) {
                return $years;
            }
        } catch (\Throwable $e) {
            // fallback below
        }

        return $fallbackYear !== '' ? [$fallbackYear] : [];
    }
}