<?php
namespace App\Services;

use App\Models\Therapist;

/**
 * Class WorkloadBalancer
 * Enterprise Workload Calculation & Load Balancing Service
 *
 * @package App\Services
 */
class WorkloadBalancer
{
    private Therapist $therapistModel;

    public function __construct()
    {
        $this->therapistModel = new Therapist();
    }

    /**
     * Update workload score for a therapist after queue completion or assignment
     *
     * Score Formula: (total_minutes_today / max_daily_minutes) * 10.0 + (in_progress_count * 2.0)
     */
    public function updateScore(int $therapistId): float
    {
        $therapist = $this->therapistModel->find($therapistId);
        if (!$therapist) return 0.00;

        $maxMins = (int)($therapist['max_daily_minutes'] ?? 480);
        if ($maxMins <= 0) $maxMins = 480;

        // Query today's queues for this therapist
        $db = \App\Models\Model::getDB();
        $stmt = $db->prepare("SELECT 
            COALESCE(SUM(CASE WHEN status = 'Completed' THEN COALESCE(service_time_mins, 60) ELSE 0 END), 0) as completed_mins,
            SUM(CASE WHEN status IN ('Assigned', 'In_Progress') THEN 1 ELSE 0 END) as active_queues
            FROM `queues` 
            WHERE therapist_id = :tid AND queue_date = CURDATE()");
        $stmt->execute(['tid' => $therapistId]);
        $row = $stmt->fetch();

        $completedMins = (float)($row['completed_mins'] ?? 0);
        $activeCount = (float)($row['active_queues'] ?? 0);

        // คำนวณคะแนนภาระงาน ยิ่งคะแนนต่ำยิ่งว่างและมีโอกาสได้รับคิวต่อไป
        $score = round(($completedMins / $maxMins) * 10.0 + ($activeCount * 2.5), 2);

        // อัปเดตลงตาราง
        $this->therapistModel->update($therapistId, [
            'current_workload_score' => $score,
            'is_available' => ($activeCount == 0 && $completedMins < $maxMins) ? 1 : 0,
        ]);

        return $score;
    }

    /**
     * Reset all workload scores (Called by midnight event or manually)
     */
    public function resetAll(): void
    {
        $db = \App\Models\Model::getDB();
        $db->exec("CALL sp_reset_daily_workloads()");
    }
}