<?php

namespace App\Http\Controllers\Api;

use App\Models\AttendanceRecord;
use App\Models\ClassSection;
use App\Models\Configuration;
use App\Models\FinalExam;
use App\Models\Homework;
use App\Models\MidtermExam;
use App\Models\Project;
use App\Models\Quiz;
use App\Models\ScoreComment;
use App\Models\SemesterScore;
use App\Models\StudentClass;
use App\Models\Student;
use App\Models\TeacherClass;
use App\Models\User;
use Illuminate\Support\Facades\DB;
use RuntimeException;
use Symfony\Component\HttpFoundation\Response;

class GradingController extends BaseApiController
{
    protected Configuration $config;
    protected Homework $homework;
    protected User $user;
    protected StudentClass $studentClass;
    protected Student $student;
    protected TeacherClass $teacherClass;
    protected ClassSection $classSection;
    protected string $schoolYear;
    protected string $semester;
    protected $semesterScoreService;

    public function __construct()
    {
        parent::__construct();
        $this->config = model(Configuration::class);
        $this->homework = model(Homework::class);
        $this->user = model(User::class);
        $this->studentClass = model(StudentClass::class);
        $this->student = model(Student::class);
        $this->teacherClass = model(TeacherClass::class);
        $this->classSection = model(ClassSection::class);
        $this->schoolYear = (string) ($this->config->getConfig('school_year') ?? '');
        $this->semester = (string) ($this->config->getConfig('semester') ?? '');
        $this->semesterScoreService = \Config\Services::semesterScoreService();
    }

    /**
     * Show scores for a specific type, class section, and student
     */
    public function show($type, $classSectionId = null, $studentId = null)
    {
        $model = $this->getModelByType($type);
        if (!$model) {
            return $this->respondError('Invalid type', Response::HTTP_BAD_REQUEST);
        }

        $student = model(Student::class);
        $student = null;
        if ($studentId) {
            $student = $student->find($studentId);
            if (!$student) {
                return $this->respondError('Student not found', Response::HTTP_NOT_FOUND);
            }
        }

        try {
            $scores = $model->where([
                'student_id' => $studentId,
                'semester' => $this->semester,
                'school_year' => $this->schoolYear
            ])->findAll();

            return $this->success([
                'student' => $student,
                'scores' => $scores,
                'type' => $type,
                'class_section_id' => $classSectionId,
                'semester' => $this->semester,
                'school_year' => $this->schoolYear,
            ], 'Scores retrieved successfully');
        } catch (\Throwable $e) {
            log_message('error', 'Grading show error: ' . $e->getMessage());
            return $this->respondError('Failed to retrieve scores', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Update scores for various types
     */
    public function update()
    {
        $data = $this->payloadData();
        $type = $data['type'] ?? null;
        $studentId = (int) ($data['student_id'] ?? 0);
        $classSectionId = (int) ($data['class_section_id'] ?? 0);

        if (!$type) {
            return $this->respondError('Type is required', Response::HTTP_BAD_REQUEST);
        }

        $model = $this->getModelByType($type);
        if (!$model) {
            return $this->respondError('Invalid type', Response::HTTP_BAD_REQUEST);
        }

        try {
            if (in_array($type, ['homework', 'quiz', 'project'])) {
                $scoreIds = $data['score_ids'] ?? [];
                $scores = $data['scores'] ?? [];
                $comments = $data['comments'] ?? [];

                foreach ($scoreIds as $i => $id) {
                    $updateData = [
                        'score' => $scores[$i] ?? null,
                        'updated_at' => utc_now()
                    ];
                    if (isset($comments[$i])) {
                        $updateData['comment'] = $comments[$i];
                    }
                    $model->update($id, $updateData);
                }
            } elseif (in_array($type, ['midterm', 'final', 'test'])) {
                $score = $data['score'] ?? null;
                $updateData = [
                    'score' => $score,
                    'updated_at' => utc_now()
                ];

                $existing = $model->where([
                    'student_id' => $studentId,
                    'class_section_id' => $classSectionId,
                    'semester' => $this->semester,
                    'school_year' => $this->schoolYear
                ])->first();

                if ($existing) {
                    $model->update($existing['id'], $updateData);
                } else {
                    $insertData = array_merge($updateData, [
                        'student_id' => $studentId,
                        'class_section_id' => $classSectionId,
                        'semester' => $this->semester,
                        'school_year' => $this->schoolYear,
                        'created_at' => utc_now()
                    ]);
                    $model->insert($insertData);
                }
            } elseif ($type === 'comments') {
                $comment = $data['comment'] ?? null;
                
                // Remove existing comments for this student/semester/year
                $model->where([
                    'student_id' => $studentId,
                    'semester' => $this->semester,
                    'school_year' => $this->schoolYear
                ])->delete();

                // Insert new comment
                $model->insert([
                    'student_id' => $studentId,
                    'score_type' => 'general',
                    'semester' => $this->semester,
                    'school_year' => $this->schoolYear,
                    'comment' => $comment,
                    'commented_by' => $this->getCurrentUserId(),
                    'created_at' => utc_now()
                ]);
            }

            // Update semester scores for students in the class section
            if ($classSectionId > 0) {
                $studentTeacherInfo = $this->student->getStudentInfoByClassSectionId(
                    $classSectionId,
                    $this->semester,
                    $this->schoolYear
                );

                try {
                    foreach ($studentTeacherInfo as $studentInfo) {
                        $this->semesterScoreService->updateStudentScores([
                            'student_id' => $studentInfo['student_id'],
                            'school_id' => $studentInfo['school_id'] ?? null,
                            'class_section_id' => $studentInfo['class_section_id'],
                            'updated_by' => $studentInfo['updated_by'] ?? $this->getCurrentUserId(),
                        ], $this->semester, $this->schoolYear);
                    }
                } catch (RuntimeException $e) {
                    log_message('error', 'Failed to update semester scores: ' . $e->getMessage());
                }
            }

            return $this->success(null, 'Scores updated successfully');
        } catch (\Throwable $e) {
            log_message('error', 'Grading update error: ' . $e->getMessage());
            return $this->respondError('Failed to update scores: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Get grading main view data - all students grouped by class sections
     */
    public function grading()
    {
        $schoolYear = (string) $this->schoolYear;
        $semester = (string) $this->semester;

        // Roster + dual-join to semester_scores:
        //   ss_b: match when semester_scores.class_section_id = BUSINESS ID (student_class.class_section_id)
        //   ss_p: match when semester_scores.class_section_id = PK (classSection.id)
        $rows = DB::table('student_class as sc')
            ->select([
                'cs.id as section_pk',
                'cs.class_section_id as section_id',
                'cs.class_id',
                'cs.class_section_name',
                's.id as student_id',
                's.school_id',
                's.firstname',
                's.lastname',
                DB::raw('COALESCE(ss_b.ptap_score, ss_p.ptap_score) as ss_ptap_score'),
                DB::raw('COALESCE(ss_b.semester_score, ss_p.semester_score) as ss_semester_score'),
                'ss_b.class_section_id as matched_biz_csid',
                'ss_p.class_section_id as matched_pk_csid'
            ])
            ->leftJoin('classSection as cs', 'cs.class_section_id', '=', 'sc.class_section_id')
            ->join('students as s', 's.id', '=', 'sc.student_id')
            ->leftJoin('semester_scores as ss_b', function($join) use ($semester, $schoolYear) {
                $join->on('ss_b.student_id', '=', 's.id')
                     ->on('ss_b.class_section_id', '=', 'sc.class_section_id')
                     ->whereRaw('LOWER(ss_b.semester) = LOWER(?)', [$semester])
                     ->where('ss_b.school_year', '=', $schoolYear);
            })
            ->leftJoin('semester_scores as ss_p', function($join) use ($semester, $schoolYear) {
                $join->on('ss_p.student_id', '=', 's.id')
                     ->on('ss_p.class_section_id', '=', 'cs.id')
                     ->whereRaw('LOWER(ss_p.semester) = LOWER(?)', [$semester])
                     ->where('ss_p.school_year', '=', $schoolYear);
            })
            ->where('sc.school_year', $schoolYear)
            ->orderBy('cs.class_id', 'ASC')
            ->orderBy('cs.class_section_name', 'ASC')
            ->orderBy('s.lastname', 'ASC')
            ->orderBy('s.firstname', 'ASC')
            ->get()
            ->toArray();

        // Build structures keyed by BUSINESS section id
        $grades = []; // class_id => [ ['class_section_id','class_section_name'], ... ]
        $studentsBySection = []; // section_id => [ students... ]

        foreach ($rows as $r) {
            $sectionId = (int) ($r->section_id ?? 0);
            $classId = (int) ($r->class_id ?? 0);
            $sectionName = (string) ($r->class_section_name ?? '');

            if ($sectionId <= 0 || $classId <= 0) continue;

            if (!isset($grades[$classId])) {
                $grades[$classId] = [];
            }

            $exists = false;
            foreach ($grades[$classId] as $s) {
                if ((int)$s['class_section_id'] === $sectionId) {
                    $exists = true;
                    break;
                }
            }

            if (!$exists) {
                $grades[$classId][] = [
                    'class_section_id' => $sectionId,
                    'class_section_name' => $sectionName,
                ];
            }

            $sid = (int) ($r->student_id ?? 0);
            if ($sid <= 0) continue;

            $ptapScore = $r->ss_ptap_score ?? null;
            $semesterScore = $r->ss_semester_score ?? null;

            if (!isset($studentsBySection[$sectionId])) {
                $studentsBySection[$sectionId] = [];
            }

            $studentsBySection[$sectionId][] = [
                'id' => $sid,
                'school_id' => $r->school_id ?? null,
                'firstname' => $r->firstname ?? null,
                'lastname' => $r->lastname ?? null,
                'ptap' => is_null($ptapScore) ? null : (float) $ptapScore,
                'semester_score' => is_null($semesterScore) ? null : (float) $semesterScore,
            ];
        }

        return $this->success([
            'grades' => $grades,
            'students_by_section' => $studentsBySection,
            'semester' => $semester,
            'school_year' => $schoolYear,
        ], 'Grading data retrieved successfully');
    }

    /**
     * Get all scores and comments for students
     */
    public function getScoreComment()
    {
        // Get all students for the current semester and school year
        $studentClassEntries = $this->studentClass
            ->where('semester', $this->semester)
            ->where('school_year', $this->schoolYear)
            ->findAll();

        // Group student IDs
        $studentIds = array_map(fn($entry) => $entry['student_id'], $studentClassEntries);

        if (empty($studentIds)) {
            return $this->success([], 'No students found');
        }

        // Fetch all scores and comments for the students
        $scoresAndComments = $this->getAllScoresAndComments($studentIds, $this->semester, $this->schoolYear);

        return $this->success($scoresAndComments, 'Scores and comments retrieved successfully');
    }

    /**
     * Fetch all scores and comments for a list of students based on semester and school year.
     *
     * @param array $studentIds List of student IDs.
     * @param string $semester Current semester (e.g., 'fall', 'spring').
     * @param string $schoolYear Current school year (e.g., '2025-2026').
     * @return array
     */
    private function getAllScoresAndComments($studentIds, $semester, $schoolYear)
    {
        // Validate input parameters
        if (empty($studentIds) || !is_array($studentIds)) {
            return [];
        }

        if (empty($semester) || empty($schoolYear)) {
            throw new \InvalidArgumentException('Semester and school year must be provided');
        }

        // Initialize models
        $models = [
            'final_exam' => model(FinalExam::class),
            'homework' => model(Homework::class),
            'midterm' => model(MidtermExam::class),
            'project' => model(Project::class),
            'quiz' => model(Quiz::class),
            'comments' => model(ScoreComment::class),
            'semester_scores' => model(SemesterScore::class),
            'student' => model(Student::class),
            'student_class' => model(StudentClass::class),
            'teacher_class' => model(TeacherClass::class),
            'config' => model(Configuration::class),
            'attendance' => model(AttendanceRecord::class)
        ];

        // Get semester days configuration
        $semesterKey = strtolower($semester) === 'fall' ? 'total_semester1_days' : 'total_semester2_days';
        $totalSemesterDays = $models['config']->getConfig($semesterKey) ?? 0;

        // Common query conditions
        $conditions = [
            'semester' => $semester,
            'school_year' => $schoolYear
        ];

        // Fetch all student data first
        $students = $models['student']->whereIn('id', $studentIds)
            ->where('school_year', $schoolYear)
            ->findAll();

        if (empty($students)) {
            return [];
        }

        // Initialize result array with student data
        $allScores = [];

        foreach ($students as $student) {
            $className = $models['student_class']->getClassSectionsByStudentId($student['id'], $schoolYear);
            $updatedBy = $models['teacher_class']->getTeacherIdByClassSection($className, $semester, $schoolYear);

            $allScores[$student['id']] = [
                'school_id' => $student['school_id'],
                'firstname' => $student['firstname'],
                'lastname' => $student['lastname'],
                'class_name' => $className,
                'comments' => []
            ];
        }

        // Fetch and process attendance data
        foreach ($studentIds as $studentId) {
            if (!isset($allScores[$studentId])) continue;

            $absences = $models['attendance']->getTotalAbsences($studentId, $semester, $schoolYear);
            $attendance = min((($totalSemesterDays - $absences + 1) / $totalSemesterDays) * 100, 100);

            $allScores[$studentId]['attendance'] = [
                'score' => round($attendance, 2),
                'absences' => $absences,
                'total_days' => $totalSemesterDays
            ];
        }

        // Fetch and process all score types
        $scoreTypes = [
            'final_exam' => $models['final_exam'],
            'homework' => $models['homework'],
            'midterm' => $models['midterm'],
            'project' => $models['project'],
            'quiz' => $models['quiz'],
            'semester_score' => $models['semester_scores']
        ];

        foreach ($scoreTypes as $type => $model) {
            $scores = $model->whereIn('student_id', $studentIds)
                ->where($conditions)
                ->findAll();

            foreach ($scores as $score) {
                if ($type === 'semester_score') {
                    $allScores[$score['student_id']][$type] = [
                        'homework_avg' => $score['homework_avg'],
                        'quiz_avg' => $score['quiz_avg'],
                        'project_avg' => $score['project_avg'],
                        'midterm_exam_score' => $score['midterm_exam_score'],
                        'final_exam_score' => $score['final_exam_score'],
                        'attendance_score' => $score['attendance_score'],
                        'participation_score' => $score['participation_score'],
                        'ptap_score' => $score['ptap_score'],
                        'test_avg' => $score['test_avg'],
                        'semester_score' => $score['semester_score'],
                        'semester' => $score['semester'],
                        'school_year' => $score['school_year']
                    ];
                } else {
                    $allScores[$score['student_id']][$type] = $score;
                }
            }
        }

        // Fetch and process comments
        $comments = $models['comments']->whereIn('student_id', $studentIds)
            ->where($conditions)
            ->findAll();

        foreach ($comments as $comment) {
            $allScores[$comment['student_id']]['comments'][] = $comment;
        }

        return $allScores;
    }

    /**
     * Get model instance by type
     */
    private function getModelByType(?string $type)
    {
        return match ($type) {
            'homework' => model(Homework::class),
            'quiz' => model(Quiz::class),
            'project' => model(Project::class),
            'midterm' => model(MidtermExam::class),
            'final' => model(FinalExam::class),
            'test' => model(SemesterScore::class),
            'comments' => model(ScoreComment::class),
            default => null,
        };
    }
}