<?php
// api/executive.php
session_start();
require_once dirname(__DIR__) . '/config/database.php';
require_once dirname(__DIR__) . '/models/Job.php';

header('Content-Type: application/json; charset=utf-8');

if (!isset($_SESSION['user_id'])) {
    echo json_encode(['success' => false, 'message' => 'Unauthorized']);
    exit;
}

$conn = Database::getInstance();
$period = $_GET['period'] ?? 'today';

try {
    $start_date = '';
    $end_date = date('Y-m-d') . ' 23:59:59';
    
    if ($period === 'week') {
        $start_date = date('Y-m-d', strtotime('-7 days')) . ' 00:00:00';
    } elseif ($period === 'month') {
        $start_date = date('Y-m-01') . ' 00:00:00';
    } else { // today
        $start_date = date('Y-m-d') . ' 00:00:00';
    }

    // 1. SLA & Times
    $sla_target = 15;

    $query_times = "SELECT 
                        TIMESTAMPDIFF(MINUTE, created_at, accepted_at) as wait_time,
                        TIMESTAMPDIFF(MINUTE, accepted_at, completed_at) as service_time
                    FROM jobs 
                    WHERE status = 'completed' AND created_at BETWEEN :start AND :end";
    $stmt_times = $conn->prepare($query_times);
    $stmt_times->bindParam(':start', $start_date);
    $stmt_times->bindParam(':end', $end_date);
    $stmt_times->execute();
    
    $completed_jobs = $stmt_times->fetchAll(PDO::FETCH_ASSOC);
    
    $total_wait = 0;
    $total_service = 0;
    $sla_met = 0;

    foreach ($completed_jobs as $job) {
        $w = max(0, (int)$job['wait_time']);
        $s = max(0, (int)$job['service_time']);
        
        $total_wait += $w;
        $total_service += $s;
        
        if ($w <= $sla_target) {
            $sla_met++;
        }
    }

    $completed_count = count($completed_jobs);
    $avg_wait = $completed_count > 0 ? round($total_wait / $completed_count) : 0;
    $avg_service = $completed_count > 0 ? round($total_service / $completed_count) : 0;
    $sla_percent = $completed_count > 0 ? round(($sla_met / $completed_count) * 100) : 100;

    // 2. Trend Data (7 days)
    $trend_data = [];
    $trend_labels = [];
    for ($i = 6; $i >= 0; $i--) {
        $d = date('Y-m-d', strtotime("-$i days"));
        $thai_days = ['อา.', 'จ.', 'อ.', 'พ.', 'พฤ.', 'ศ.', 'ส.'];
        $day_index = date('w', strtotime($d));
        
        $trend_labels[] = $thai_days[$day_index];
        
        $q = "SELECT COUNT(*) as cnt FROM jobs WHERE DATE(created_at) = :d";
        $s = $conn->prepare($q);
        $s->bindParam(':d', $d);
        $s->execute();
        $trend_data[] = $s->fetch(PDO::FETCH_ASSOC)['cnt'];
    }

    // 3. Department Workload
    $query_dept = "SELECT d.name, COUNT(j.id) as count
                   FROM jobs j
                   JOIN departments d ON j.from_department_id = d.id
                   WHERE j.created_at BETWEEN :start AND :end
                   GROUP BY d.id
                   ORDER BY count DESC
                   LIMIT 5";
    $stmt_dept = $conn->prepare($query_dept);
    $stmt_dept->bindParam(':start', $start_date);
    $stmt_dept->bindParam(':end', $end_date);
    $stmt_dept->execute();
    
    $dept_labels = [];
    $dept_data = [];
    while ($row = $stmt_dept->fetch(PDO::FETCH_ASSOC)) {
        $name = mb_strlen($row['name'], 'UTF-8') > 15 ? mb_substr($row['name'], 0, 15, 'UTF-8') . '...' : $row['name'];
        $dept_labels[] = $name;
        $dept_data[] = (int)$row['count'];
    }

    $jobModel = new Job();
    $staffPerformance = $jobModel->getStaffPerformance($period);

    echo json_encode([
        'success' => true,
        'kpi' => [
            'sla_percent' => $sla_percent,
            'avg_wait_time' => $avg_wait,
            'avg_service_time' => $avg_service
        ],
        'charts' => [
            'trend' => [
                'labels' => $trend_labels,
                'data' => $trend_data
            ],
            'departments' => [
                'labels' => $dept_labels,
                'data' => $dept_data
            ]
        ],
        'staff_performance' => $staffPerformance
    ]);
    exit;

} catch (Exception $e) {
    echo json_encode(['success' => false, 'message' => $e->getMessage()]);
}