<?php

namespace App\Modules\Academic\Models;

use App\Modules\Academic\Entities\Schedule;
use CodeIgniter\Model;

/**
 * Schedule Model
 * 
 * Handles database operations for schedules.
 */
class ScheduleModel extends Model
{
    protected $table            = 'schedules';
    protected $primaryKey       = 'id';
    protected $useAutoIncrement = true;
    protected $returnType       = Schedule::class;
    protected $useSoftDeletes   = false;
    protected $protectFields    = true;
    protected $allowedFields    = [
        'class_id',
        'subject_id',
        'teacher_user_id',
        'teacher_name',
        'lesson_slot_id',
        'day_of_week',
        'start_time',
        'end_time',
        'room',
        'is_active',
    ];

    // Dates
    protected $useTimestamps = true;
    protected $dateFormat    = 'datetime';
    protected $createdField  = 'created_at';
    protected $updatedField  = 'updated_at';
    protected $deletedField  = 'deleted_at';

    // Validation
    protected $validationRules = [
        'class_id'    => 'required|integer|is_not_unique[classes.id]',
        'subject_id'  => 'required|integer|is_not_unique[subjects.id]',
        'teacher_name' => 'required|max_length[255]',
        'day_of_week' => 'required|integer|greater_than_equal_to[1]|less_than_equal_to[7]',
        'start_time'  => 'required|valid_date[H:i:s]',
        'end_time'    => 'required|valid_date[H:i:s]',
        'room'        => 'permit_empty|max_length[100]',
    ];

    protected $validationMessages = [];
    protected $skipValidation     = false;
    protected $cleanValidationRules = true;

    // Callbacks
    protected $allowCallbacks = true;
    protected $beforeInsert   = [];
    protected $afterInsert    = [];
    protected $beforeUpdate   = [];
    protected $afterUpdate    = [];
    protected $beforeFind     = [];
    protected $afterFind      = [];
    protected $beforeDelete   = [];
    protected $afterDelete    = [];

    /**
     * Find active schedule for class on specific day and time (uses schedule columns only).
     *
     * @deprecated Prefer getActiveScheduleRow() for slot/user as source of truth with fallback.
     * @param int $classId
     * @param int $dayOfWeek
     * @param string $time Time in H:i:s format
     * @return Schedule|null
     */
    public function findActiveSchedule(int $classId, int $dayOfWeek, string $time): ?Schedule
    {
        return $this->where('class_id', $classId)
            ->where('day_of_week', $dayOfWeek)
            ->where('start_time <=', $time)
            ->where('end_time >', $time)
            ->first();
    }

    /**
     * Get active schedule row with lesson_slots and users as source of truth.
     * start_time, end_time from lesson_slots; teacher_name from users; fallback to schedule columns when NULL.
     *
     * @param int $classId
     * @param int $dayOfWeek
     * @param string $time Time in H:i:s format
     * @return array{id: int, class_id: int, subject_id: int, teacher_user_id: int|null, teacher_name: string, room: string|null, start_time: string, end_time: string, day_of_week: int}|null
     */
    public function getActiveScheduleRow(int $classId, int $dayOfWeek, string $time): ?array
    {
        $db    = \Config\Database::connect();
        $sql   = 'SELECT sch.id AS id, sch.class_id, sch.subject_id, sch.teacher_user_id, '
            . 'COALESCE(u.name, sch.teacher_name) AS teacher_name, sch.room, '
            . 'COALESCE(ls.start_time, sch.start_time) AS start_time, COALESCE(ls.end_time, sch.end_time) AS end_time, sch.day_of_week '
            . 'FROM schedules sch '
            . 'LEFT JOIN lesson_slots ls ON ls.id = sch.lesson_slot_id '
            . 'LEFT JOIN users u ON u.id = sch.teacher_user_id '
            . 'WHERE sch.class_id = ? AND sch.day_of_week = ? '
            . 'AND ( COALESCE(ls.start_time, sch.start_time) ) <= ? AND ( COALESCE(ls.end_time, sch.end_time) ) > ? '
            . 'LIMIT 1';
        $row = $db->query($sql, [$classId, $dayOfWeek, $time, $time])->getRowArray();
        if ($row === null) {
            return null;
        }
        return [
            'id'              => (int) $row['id'],
            'class_id'        => (int) $row['class_id'],
            'subject_id'      => (int) $row['subject_id'],
            'teacher_user_id' => isset($row['teacher_user_id']) ? (int) $row['teacher_user_id'] : null,
            'teacher_name'    => (string) ($row['teacher_name'] ?? ''),
            'room'            => isset($row['room']) ? (string) $row['room'] : null,
            'start_time'     => (string) $row['start_time'],
            'end_time'       => (string) $row['end_time'],
            'day_of_week'    => (int) $row['day_of_week'],
        ];
    }

    /**
     * Get latest schedule for class on given day where start_time <= time (may already be ended).
     * Uses lesson_slots/users as source of truth. ORDER BY start_time DESC, LIMIT 1.
     *
     * @param int $classId
     * @param int $dayOfWeek
     * @param string $time Time in H:i:s format
     * @return array{id: int, class_id: int, subject_id: int, teacher_user_id: int|null, teacher_name: string, room: string|null, start_time: string, end_time: string, day_of_week: int}|null
     */
    public function getLatestScheduleForClassToday(int $classId, int $dayOfWeek, string $time): ?array
    {
        $db  = \Config\Database::connect();
        $sql = 'SELECT sch.id AS id, sch.class_id, sch.subject_id, sch.teacher_user_id, '
            . 'COALESCE(u.name, sch.teacher_name) AS teacher_name, sch.room, '
            . 'COALESCE(ls.start_time, sch.start_time) AS start_time, COALESCE(ls.end_time, sch.end_time) AS end_time, sch.day_of_week '
            . 'FROM schedules sch '
            . 'LEFT JOIN lesson_slots ls ON ls.id = sch.lesson_slot_id '
            . 'LEFT JOIN users u ON u.id = sch.teacher_user_id '
            . 'WHERE sch.class_id = ? AND sch.day_of_week = ? '
            . 'AND ( COALESCE(ls.start_time, sch.start_time) ) <= ? '
            . 'ORDER BY ( COALESCE(ls.start_time, sch.start_time) ) DESC '
            . 'LIMIT 1';
        $row = $db->query($sql, [$classId, $dayOfWeek, $time])->getRowArray();
        if ($row === null) {
            return null;
        }
        return [
            'id'              => (int) $row['id'],
            'class_id'        => (int) $row['class_id'],
            'subject_id'      => (int) $row['subject_id'],
            'teacher_user_id' => isset($row['teacher_user_id']) ? (int) $row['teacher_user_id'] : null,
            'teacher_name'    => (string) ($row['teacher_name'] ?? ''),
            'room'            => isset($row['room']) ? (string) $row['room'] : null,
            'start_time'     => (string) $row['start_time'],
            'end_time'       => (string) $row['end_time'],
            'day_of_week'    => (int) $row['day_of_week'],
        ];
    }

    /**
     * Get one schedule row by id with lesson_slots and users as source of truth.
     *
     * @param int $scheduleId
     * @return array{id: int, class_id: int, subject_id: int, teacher_user_id: int|null, teacher_name: string, start_time: string, end_time: string, day_of_week: int, room: string|null}|null
     */
    public function getScheduleWithSlot(int $scheduleId): ?array
    {
        $db  = \Config\Database::connect();
        $sql = 'SELECT sch.id AS id, sch.class_id, sch.subject_id, sch.teacher_user_id, '
            . 'COALESCE(u.name, sch.teacher_name) AS teacher_name, '
            . 'COALESCE(ls.start_time, sch.start_time) AS start_time, COALESCE(ls.end_time, sch.end_time) AS end_time, '
            . 'sch.day_of_week, sch.room '
            . 'FROM schedules sch '
            . 'LEFT JOIN lesson_slots ls ON ls.id = sch.lesson_slot_id '
            . 'LEFT JOIN users u ON u.id = sch.teacher_user_id '
            . 'WHERE sch.id = ? LIMIT 1';
        $row = $db->query($sql, [$scheduleId])->getRowArray();
        if ($row === null) {
            return null;
        }
        return [
            'id'              => (int) $row['id'],
            'class_id'        => (int) $row['class_id'],
            'subject_id'      => (int) $row['subject_id'],
            'teacher_user_id' => isset($row['teacher_user_id']) ? (int) $row['teacher_user_id'] : null,
            'teacher_name'    => (string) ($row['teacher_name'] ?? ''),
            'start_time'     => (string) $row['start_time'],
            'end_time'       => (string) $row['end_time'],
            'day_of_week'    => (int) $row['day_of_week'],
            'room'           => isset($row['room']) ? (string) $row['room'] : null,
        ];
    }
}