<?php

namespace App\Http\Controllers\Api;

use App\Models\Configuration;
use App\Models\MidtermExam;
use App\Models\StudentClass;
use App\Models\Student;
use App\Models\TeacherClass;
use App\Services\SemesterScoreService;
use Illuminate\Support\Facades\DB;
use RuntimeException;
use Symfony\Component\HttpFoundation\Response;

class MidtermController extends BaseApiController
{
    protected Configuration $config;
    protected Student $student;
    protected TeacherClass $teacherClass;
    protected MidtermExam $midtermExam;
    protected SemesterScoreService $semesterScoreService;
    protected string $schoolYear;
    protected string $semester;

    public function __construct()
    {
        parent::__construct();
        $this->config = model(Configuration::class);
        $this->student = model(Student::class);
        $this->teacherClass = model(TeacherClass::class);
        $this->midtermExam = model(MidtermExam::class);
        $this->semesterScoreService = app(SemesterScoreService::class);

        $this->schoolYear = (string) ($this->config->getConfig('school_year') ?? '');
        $this->semester = (string) ($this->config->getConfig('semester') ?? '');
    }

    /**
     * GET /api/v1/midterm
     * Get midterm exam data for a class section
     */
    public function index()
    {
        // Get class_section_id from POST -> GET -> session
        $incoming = $this->request->getPost('class_section_id')
            ?? $this->request->getGet('class_section_id')
            ?? session()->get('class_section_id');

        $classSectionId = (int) ($incoming ?: 0);

        if ($classSectionId <= 0) {
            return $this->respondError('Missing class section.', Response::HTTP_BAD_REQUEST);
        }

        // Persist for downstream use
        session()->put('class_section_id', $classSectionId);

        try {
            $result = $this->getSavedScores($classSectionId, $this->semester, $this->schoolYear);

            return $this->success([
                'students' => $result['students'],
                'semester' => $result['semester'],
                'school_year' => $result['schoolYear'],
                'class_section_id' => $classSectionId,
            ], 'Midterm exam data retrieved successfully');
        } catch (\Throwable $e) {
            log_message('error', 'Midterm index error: ' . $e->getMessage());
            return $this->respondError($e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * POST /api/v1/midterm
     * Update midterm exam scores (teacher endpoint)
     */
    public function update()
    {
        $updatedBy = $this->getCurrentUserId();
        if (!$updatedBy) {
            return $this->respondError('Authentication required', Response::HTTP_UNAUTHORIZED);
        }

        $payload = $this->payloadData();
        $scores = $payload['final_score'] ?? null;
        $classSectionId = (int) ($payload['class_section_id'] ?? session()->get('class_section_id') ?? 0);

        if (!is_array($scores)) {
            return $this->respondError('No scores submitted.', Response::HTTP_BAD_REQUEST);
        }

        if ($classSectionId <= 0) {
            return $this->respondError('Missing class section.', Response::HTTP_BAD_REQUEST);
        }

        try {
            $this->saveExamScores('midterm_exam', $scores, $updatedBy, $classSectionId, $this->semester, $this->schoolYear);

            $studentTeacherInfo = $this->student->getStudentInfoByClassSectionId($classSectionId, $this->semester, $this->schoolYear);
            
            // Add semester and school_year to each student info for the service
            foreach ($studentTeacherInfo as &$student) {
                $student['semester'] = $this->semester;
                $student['school_year'] = $this->schoolYear;
            }
            unset($student);

            // Call the updateScoresForStudents method
            try {
                $this->semesterScoreService->updateScoresForStudents($studentTeacherInfo);
            } catch (RuntimeException $e) {
                log_message('error', 'SemesterScoreService error: ' . $e->getMessage());
            }

            return $this->success([
                'class_section_id' => $classSectionId,
                'updated_count' => count($scores),
            ], 'Midterm exam scores updated successfully');
        } catch (\Throwable $e) {
            log_message('error', 'Midterm update error: ' . $e->getMessage());
            return $this->respondError('Failed to update midterm exam scores: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * POST /api/v1/midterm/management
     * Update midterm exam scores (management endpoint)
     */
    public function updateManagement()
    {
        $payload = $this->payloadData();
        $scores = $payload['final_score'] ?? null;
        $updatedBy = (int) ($payload['teacher_id'] ?? $this->getCurrentUserId() ?? 0);
        $classSectionId = (int) ($payload['class_section_id'] ?? session()->get('class_section_id') ?? 0);

        if (!is_array($scores)) {
            return $this->respondError('No scores submitted.', Response::HTTP_BAD_REQUEST);
        }

        if ($classSectionId <= 0) {
            return $this->respondError('Missing class section.', Response::HTTP_BAD_REQUEST);
        }

        if ($updatedBy <= 0) {
            return $this->respondError('Missing teacher ID.', Response::HTTP_BAD_REQUEST);
        }

        try {
            $this->saveExamScores('midterm_exam', $scores, $updatedBy, $classSectionId, $this->semester, $this->schoolYear);

            $studentTeacherInfo = $this->student->getStudentInfoByClassSectionId($classSectionId, $this->semester, $this->schoolYear);
            
            // Add semester and school_year to each student info for the service
            foreach ($studentTeacherInfo as &$student) {
                $student['semester'] = $this->semester;
                $student['school_year'] = $this->schoolYear;
            }
            unset($student);

            // Call the updateScoresForStudents method
            try {
                $this->semesterScoreService->updateScoresForStudents($studentTeacherInfo);
            } catch (RuntimeException $e) {
                log_message('error', 'SemesterScoreService error: ' . $e->getMessage());
            }

            // Return the same data structure as index for consistency
            $result = $this->getSavedScores($classSectionId, $this->semester, $this->schoolYear);

            return $this->success([
                'students' => $result['students'],
                'semester' => $result['semester'],
                'school_year' => $result['schoolYear'],
                'class_section_id' => $classSectionId,
                'updated_count' => count($scores),
            ], 'Midterm exam scores updated successfully');
        } catch (\Throwable $e) {
            log_message('error', 'Midterm updateManagement error: ' . $e->getMessage());
            return $this->respondError('Failed to update midterm exam scores: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * GET /api/v1/midterm/management
     * Get midterm exam data for management view
     */
    public function showManagement()
    {
        // Get class_section_id from POST -> GET -> session
        $incoming = $this->request->getPost('class_section_id')
            ?? $this->request->getGet('class_section_id')
            ?? session()->get('class_section_id');

        $classSectionId = (int) ($incoming ?: 0);

        if ($classSectionId <= 0) {
            return $this->respondError('Missing class section.', Response::HTTP_BAD_REQUEST);
        }

        try {
            // Load roster + saved scores for this class/term
            $result = $this->getSavedScores($classSectionId, $this->semester, $this->schoolYear);

            return $this->success([
                'students' => $result['students'],
                'semester' => $result['semester'],
                'school_year' => $result['schoolYear'],
                'class_section_id' => $classSectionId,
            ], 'Midterm exam management data retrieved successfully');
        } catch (\Throwable $e) {
            log_message('error', 'Midterm showManagement error: ' . $e->getMessage());
            return $this->respondError($e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Save exam scores to the database
     */
    private function saveExamScores(string $table, array $scores, int $updatedBy, int $classSectionId, string $semester, string $schoolYear): void
    {
        $now = utc_now();

        foreach ($scores as $studentId => $data) {
            if (!is_numeric($studentId) || !isset($data['score'])) {
                continue;
            }

            $score = $data['score'];

            $existing = DB::table($table)
                ->where('student_id', $studentId)
                ->where('class_section_id', $classSectionId)
                ->where('semester', $semester)
                ->where('school_year', $schoolYear)
                ->first();

            $dataToSave = [
                'student_id' => (int) $studentId,
                'class_section_id' => $classSectionId,
                'updated_by' => $updatedBy,
                'score' => is_numeric($score) ? (float) $score : null,
                'semester' => $semester,
                'school_year' => $schoolYear,
                'updated_at' => $now,
            ];

            if ($existing) {
                DB::table($table)
                    ->where('id', $existing->id)
                    ->update($dataToSave);
            } else {
                $dataToSave['created_at'] = $now;
                DB::table($table)->insert($dataToSave);
            }
        }
    }

    /**
     * Get roster + saved midterm scores for a specific classSection/term.
     */
    private function getSavedScores(int $classSectionId, string $semester, string $schoolYear): array
    {
        if ($classSectionId <= 0) {
            throw new \InvalidArgumentException('Invalid class section id.');
        }

        session()->put('class_section_id', $classSectionId);

        // Subquery: pick ONE midterm row per student (latest by id).
        $latestMidtermSub = DB::table('midterm_exam')
            ->select('student_id', DB::raw('MAX(id) AS max_id'))
            ->where('class_section_id', $classSectionId)
            ->where('semester', $semester)
            ->where('school_year', $schoolYear)
            ->groupBy('student_id');

        // Main query: roster for this class/term + LEFT JOIN the single midterm row
        $rows = DB::table('students as s')
            ->select([
                's.id AS student_id',
                's.school_id',
                's.firstname',
                's.lastname',
                'me.score',
            ])
            ->join('student_class as sc', function ($join) use ($classSectionId, $semester, $schoolYear) {
                $join->on('sc.student_id', '=', 's.id')
                    ->where('sc.class_section_id', '=', $classSectionId)
                    ->where('sc.semester', '=', $semester)
                    ->where('sc.school_year', '=', $schoolYear);
            })
            ->leftJoinSub($latestMidtermSub, 'ml', function ($join) {
                $join->on('ml.student_id', '=', 's.id');
            })
            ->leftJoin('midterm_exam as me', 'me.id', '=', 'ml.max_id')
            ->distinct()
            ->orderBy('s.lastname', 'ASC')
            ->orderBy('s.firstname', 'ASC')
            ->get()
            ->toArray();

        // Final safety net: ensure one row per student_id
        $unique = [];
        foreach ($rows as $r) {
            $rArray = (array) $r;
            $unique[(int) $rArray['student_id']] = $rArray;
        }

        $students = array_values($unique);

        return [
            'students' => $students,
            'semester' => $semester,
            'schoolYear' => $schoolYear,
        ];
    }
}