<?php

namespace App\Services;

use App\Models\Course;
use App\Models\CourseSign;
use App\Models\User;
use Illuminate\Support\Facades\DB;

class SchoolmateEnrollmentService
{
    /**
     * 仅选择未删除、尚未成为校友且有有效审核通过报名的学员。
     * 多门课程取最早开课日期；指定课程补齐不受自动入库开关限制。
     */
    public function pendingUsers($courses)
    {
        $sources = CourseSign::query()
            ->join('courses', 'courses.id', '=', 'course_signs.course_id')
            ->whereNull('courses.deleted_at')
            ->whereIn('courses.id', (clone $courses)->select('courses.id'))
            ->where('course_signs.status', 1)
            ->select('course_signs.user_id')
            ->selectRaw('MIN(courses.start_date) as source_start_date')
            ->groupBy('course_signs.user_id');

        return User::query()
            ->joinSub($sources, 'schoolmate_sources', function ($join) {
                $join->on('users.id', '=', 'schoolmate_sources.user_id');
            })
            ->whereRaw('COALESCE(users.is_schoolmate, 0) != 1')
            ->select('users.*', 'schoolmate_sources.source_start_date');
    }

    public function automaticCourses()
    {
        // 保留开课前一天入库的原行为，同时补查历史及开课后审核通过的学员。
        return Course::where('auto_schoolmate', 1)
            ->whereNotNull('start_date')
            ->whereDate('start_date', '<=', now()->addDay()->toDateString());
    }

    public function promote(int $userId, string $startDate): int
    {
        return DB::transaction(function () use ($userId, $startDate) {
            // 手工补齐和自动任务同时运行时，不覆盖已有校友的入库时间。
            $user = User::whereKey($userId)->lockForUpdate()->first();
            if (!$user || $user->is_schoolmate == 1) {
                return 0;
            }

            return User::batchUpdateToSchoolmate([$userId], $startDate);
        });
    }
}