<?php

namespace App\Http\Controllers\Api;

use App\Models\Configuration;
use App\Models\FinalExam;
use App\Models\Student;
use Symfony\Component\HttpFoundation\Response;

class FinalController extends BaseApiController
{
    protected FinalExam $final;
    protected Configuration $config;
    protected Student $student;

    public function __construct()
    {
        parent::__construct();
        $this->final  = model(FinalExam::class);
        $this->config = model(Configuration::class);
        $this->student = model(Student::class);
    }

    public function getByStudent($id = null)
    {
        $schoolYear = $this->config->getConfig('school_year');
        $semester = $this->config->getConfig('semester');

        $final = $this->final->newQuery()
            ->when($id, fn($q) => $q->where('student_id', $id))
            ->when($schoolYear, fn($q) => $q->where('school_year', $schoolYear))
            ->when($semester, fn($q) => $q->where('semester', $semester))
            ->first();

        return $this->success($final ?: null, 'Final exam retrieved successfully');
    }

    public function create()
    {
        $user = $this->getCurrentUser();
        $data = $this->payloadData();
        if (empty($data)) {
            return $this->respondError('Invalid request data', Response::HTTP_BAD_REQUEST);
        }

        $rules = [
            'student_id'     => 'required|integer',
            'class_section_id' => 'required|integer',
        ];
        $errors = $this->validateRequest($data, $rules);
        if (!empty($errors)) {
            return $this->respondValidationError($errors);
        }

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

        $query = $this->final->newQuery()
            ->where('student_id', $data['student_id'])
            ->where('class_section_id', $data['class_section_id']);
        if ($schoolYear) {
            $query->where('school_year', $schoolYear);
        }
        if ($semester) {
            $query->where('semester', $semester);
        }
        $existing = $query->first();

        $finalData = [
            'student_id'       => $data['student_id'],
            'class_section_id' => $data['class_section_id'],
            'score'            => $data['score'] ?? null,
            'comment'          => $data['comment'] ?? null,
            'school_year'      => $schoolYear,
            'semester'         => $semester,
            'updated_by'       => $user->id ?? null,
        ];

        try {
            if ($existing) {
                $existing->fill($finalData);
                $existing->save();
                $final = $existing->fresh();
            } else {
                $final = $this->final->create($finalData);
            }
            return $this->success($final, 'Final exam saved successfully', Response::HTTP_CREATED);
        } catch (\Throwable $e) {
            log_message('error', 'Final exam save error: ' . $e->getMessage());
            return $this->respondError('Failed to save final exam', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    public function update($id = null)
    {
        $final = $this->final->find($id);
        if (!$final) {
            return $this->respondError('Final exam not found', Response::HTTP_NOT_FOUND);
        }

        $data = $this->payloadData();
        if (empty($data)) {
            return $this->respondError('Invalid request data', Response::HTTP_BAD_REQUEST);
        }

        $allowed = ['score', 'comment'];
        $updateData = [];
        foreach ($allowed as $field) {
            if (array_key_exists($field, $data)) {
                $updateData[$field] = $data[$field];
            }
        }

        if (empty($updateData)) {
            return $this->respondError('No valid fields to update', Response::HTTP_BAD_REQUEST);
        }

        $updateData['updated_by'] = $this->getCurrentUser()->id ?? null;

        try {
            $final->fill($updateData);
            $final->save();
            return $this->success($final->fresh(), 'Final exam updated successfully');
        } catch (\Throwable $e) {
            log_message('error', 'Final exam update error: ' . $e->getMessage());
            return $this->respondError('Failed to update final exam', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Get students with their final exam scores for a class section
     * 
     * @param int|null $classSectionId
     * @return \Illuminate\Http\JsonResponse
     */
    public function getByClassSection($classSectionId = null)
    {
        // Get class_section_id from route parameter, query param, or request body
        $incoming = $classSectionId 
            ?? $this->request->getGet('class_section_id')
            ?? $this->request->getPost('class_section_id')
            ?? null;

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

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

        try {
            $result = $this->getSavedScores($classSectionId);
            return $this->success($result, 'Students with final exam scores retrieved successfully');
        } catch (\InvalidArgumentException $e) {
            return $this->respondError($e->getMessage(), Response::HTTP_BAD_REQUEST);
        } catch (\Throwable $e) {
            log_message('error', 'Final exam getByClassSection error: ' . $e->getMessage());
            return $this->respondError('Failed to retrieve students with final exam scores', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Get students with their final exam scores for a class section
     * 
     * @param int $classSectionId
     * @return array
     * @throws \InvalidArgumentException
     */
    protected function getSavedScores(int $classSectionId): array
    {
        if ($classSectionId <= 0) {
            throw new \InvalidArgumentException('Invalid class section id.');
        }

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

        $db = \Config\Database::connect();

        // Subquery: pick ONE final exam row per student (latest by id)
        $latestFinalSub = $db->table('final_exam')
            ->select('student_id, MAX(id) AS max_id')
            ->where('class_section_id', $classSectionId)
            ->where('semester', $semester)
            ->where('school_year', $schoolYear)
            ->groupBy('student_id')
            ->getCompiledSelect();

        // Main query: roster + LEFT JOIN the single final exam row
        $builder = $this->student->builder();
        
        $builder
            ->select('
                s.id AS student_id,
                s.school_id,
                s.firstname,
                s.lastname,
                fe.score
            ')
            ->from('students s')
            ->join(
                'student_class sc',
                'sc.student_id = s.id
                 AND sc.class_section_id = ' . (int) $classSectionId . '
                 AND sc.school_year = ' . $db->escape($schoolYear),
                'inner',
                false
            )
            ->join('(' . $latestFinalSub . ') fl', 'fl.student_id = s.id', 'left', false)
            ->join('final_exam fe', 'fe.id = fl.max_id', 'left')
            ->orderBy('s.lastname', 'ASC')
            ->orderBy('s.firstname', 'ASC');

        $builder->distinct();
        $rows = $builder->get()->getResultArray();

        // Ensure one row per student
        $unique = [];
        foreach ($rows as $r) {
            $unique[(int)$r['student_id']] = $r;
        }
        $students = array_values($unique);

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