<?php

namespace App\Modules\Dashboard\Services;

use App\Modules\Auth\Entities\Role;

/**
 * Dashboard Realtime Service
 *
 * Fetches latest attendance records for SSE stream (by id > afterId).
 * Role-aware filtering: ADMIN (all), WALI_KELAS (by assigned class), GURU_MAPEL (by teacher), ORANG_TUA (by own children).
 */
class DashboardRealtimeService
{
    /** Scope type: no filter */
    public const SCOPE_ADMIN = 'admin';

    /** Scope type: filter by class_id(s) where user is wali */
    public const SCOPE_WALI_KELAS = 'wali_kelas';

    /** Scope type: filter by schedules taught by this teacher (teacher_user_id) */
    public const SCOPE_GURU_MAPEL = 'guru_mapel';

    /** Scope type: filter by student_ids linked to parent */
    public const SCOPE_ORANG_TUA = 'orang_tua';

    /**
     * Resolve user scope for realtime filtering from current user (with roles).
     *
     * @param array $user { id, name, email, roles: [ { role_code, role_name } ] }
     * @return array{ type: string, class_ids?: int[], teacher_user_id?: int, student_ids?: int[] }
     */
    public function resolveUserScope(array $user): array
    {
        $roles = $user['roles'] ?? [];
        $roleCodes = array_column($roles, 'role_code');

        if (in_array(Role::CODE_ADMIN, $roleCodes, true)) {
            return ['type' => self::SCOPE_ADMIN];
        }

        if (in_array(Role::CODE_WALI_KELAS, $roleCodes, true)) {
            $classIds = $this->getClassIdsForWali($user['id']);
            if ($classIds !== []) {
                return ['type' => self::SCOPE_WALI_KELAS, 'class_ids' => $classIds];
            }
        }

        if (in_array(Role::CODE_GURU_MAPEL, $roleCodes, true)) {
            return ['type' => self::SCOPE_GURU_MAPEL, 'teacher_user_id' => (int) ($user['id'] ?? 0)];
        }

        if (in_array(Role::CODE_ORANG_TUA, $roleCodes, true)) {
            $studentIds = $this->getStudentIdsForParent($user['id']);
            if ($studentIds !== []) {
                return ['type' => self::SCOPE_ORANG_TUA, 'student_ids' => $studentIds];
            }
        }

        return ['type' => self::SCOPE_ADMIN];
    }

    /**
     * Get class IDs where user is wali (classes.wali_user_id = userId).
     */
    protected function getClassIdsForWali(int $userId): array
    {
        $db   = \Config\Database::connect();
        $rows = $db->table('classes')->select('id')->where('wali_user_id', $userId)->get()->getResultArray();
        return array_map('intval', array_column($rows, 'id'));
    }

    /**
     * Get student IDs linked to parent (parent.user_id = userId via student_parents).
     */
    protected function getStudentIdsForParent(int $userId): array
    {
        $db   = \Config\Database::connect();
        $rows = $db->table('student_parents AS sp')
            ->select('sp.student_id')
            ->join('parents AS p', 'p.id = sp.parent_id', 'inner')
            ->where('p.user_id', $userId)
            ->get()
            ->getResultArray();
        return array_map('intval', array_column($rows, 'student_id'));
    }

    /**
     * Get attendance sessions after a given ID (for SSE incremental feed), with optional role scope.
     *
     * @param int $afterId Only return rows with id > afterId
     * @param int $limit Max rows to return
     * @param array|null $userContext Current user from session (id, name, email, roles). If null, no scope filter.
     * @return array<int, array{id: int, student_name: string, class_name: string, subject: string, checkin_at: string, status: string}>
     */
    public function getAttendanceSinceId(int $afterId = 0, int $limit = 100, ?array $userContext = null): array
    {
        $db      = \Config\Database::connect();
        $builder = $db->table('attendance_sessions AS a');
        $builder->select('
            a.id,
            s.name AS student_name,
            c.name AS class_name,
            COALESCE(sub.name, "-") AS subject,
            a.checkin_at,
            a.status
        ');
        $builder->join('students AS s', 's.id = a.student_id', 'left');
        $builder->join('classes AS c', 'c.id = s.class_id', 'left');
        $builder->join('schedules AS sch', 'sch.id = a.schedule_id', 'left');
        $builder->join('subjects AS sub', 'sub.id = sch.subject_id', 'left');
        $builder->where('a.id >', $afterId);

        if ($userContext !== null) {
            $this->applyScopeToBuilder($builder, $this->resolveUserScope($userContext));
        }

        $builder->orderBy('a.id', 'ASC');
        $builder->limit($limit);

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

        $out = [];
        foreach ($rows as $row) {
            $out[] = [
                'id'           => (int) $row['id'],
                'student_name' => (string) ($row['student_name'] ?? '-'),
                'class_name'   => (string) ($row['class_name'] ?? '-'),
                'subject'      => (string) ($row['subject'] ?? '-'),
                'checkin_at'   => (string) $row['checkin_at'],
                'status'       => (string) $row['status'],
            ];
        }

        return $out;
    }

    /**
     * Apply scope conditions to the attendance query builder (no duplicate query).
     *
     * @param \CodeIgniter\Database\BaseBuilder $builder
     * @param array $scope From resolveUserScope()
     */
    protected function applyScopeToBuilder($builder, array $scope): void
    {
        switch ($scope['type'] ?? '') {
            case self::SCOPE_WALI_KELAS:
                $classIds = $scope['class_ids'] ?? [];
                if ($classIds !== []) {
                    $builder->whereIn('s.class_id', $classIds);
                } else {
                    $builder->where('1 =', 0);
                }
                break;
            case self::SCOPE_GURU_MAPEL:
                $teacherUserId = (int) ($scope['teacher_user_id'] ?? 0);
                if ($teacherUserId > 0) {
                    $builder->where('sch.teacher_user_id', $teacherUserId);
                } else {
                    $builder->where('1 =', 0);
                }
                break;
            case self::SCOPE_ORANG_TUA:
                $studentIds = $scope['student_ids'] ?? [];
                if ($studentIds !== []) {
                    $builder->whereIn('a.student_id', $studentIds);
                } else {
                    $builder->where('1 =', 0);
                }
                break;
            case self::SCOPE_ADMIN:
            default:
                break;
        }
    }
}