<?php

require_once __DIR__ . '/auth_check.php';

/**
 * Cumulative calendar feed: deadlines + trainings + maintenances.
 * Each layer is returned only if the user may see that module, and only
 * if the layer is requested via ?layers=deadlines,trainings,maintenances
 */
try {
    $pdo = mnt_pdo();

    $start = substr((string)($_GET['start'] ?? date('Y-m-01', strtotime('-6 months'))), 0, 10);
    $end   = substr((string)($_GET['end'] ?? date('Y-m-t', strtotime('+12 months'))), 0, 10);

    $requested = array_filter(explode(',', (string)($_GET['layers'] ?? 'deadlines,trainings,maintenances')));
    $wants = fn(string $layer): bool => in_array($layer, $requested, true);

    $events = [];

    // ---- Maintenances --------------------------------------------------
    if ($wants('maintenances') && mnt_user_can('maintenance.calendar.view')) {
        $stmt = $pdo->prepare("
            SELECT m.id, m.title, m.code, m.next_due_date, m.alert_days, m.is_critical,
                   e.id AS equipment_id, e.name AS equipment_name
            FROM maint_maintenances m
            INNER JOIN inv_equipment e ON e.id = m.equipment_id
            WHERE m.is_active = 1
              AND e.status = 'active'
              AND m.next_due_date BETWEEN ? AND ?
        ");
        $stmt->execute([$start, $end]);

        foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $row) {
            $state = mnt_due_state($row['next_due_date'], (int)$row['alert_days']);
            $color = $state === 'overdue' ? '#dc3545' : '#2f7d8f';

            $events[] = [
                'id' => 'maint-' . $row['id'],
                'title' => '🔧 ' . $row['equipment_name'] . ': ' . $row['title'],
                'start' => $row['next_due_date'],
                'allDay' => true,
                'backgroundColor' => $color,
                'borderColor' => $color,
                'extendedProps' => [
                    'layer' => 'maintenances',
                    'url' => 'manutenzioni/equipment.php?id=' . (int)$row['equipment_id'],
                    'state' => $state,
                ],
            ];
        }
    }

    // ---- Deadlines (scadenzario) --------------------------------------
    if ($wants('deadlines') && mnt_user_can('deadlines.view')) {
        $stmt = $pdo->prepare("
            SELECT d.id, d.topic, d.due_date, d.status, d.notification_days, s.name AS subject_name
            FROM scad_deadlines d
            LEFT JOIN scad_subjects s ON s.id = d.subject_id
            WHERE d.due_date BETWEEN ? AND ?
        ");
        $stmt->execute([$start, $end]);

        foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $row) {
            $isCompleted = $row['status'] === 'completed';
            $state = $isCompleted ? 'ok' : mnt_due_state($row['due_date'], (int)$row['notification_days']);
            $color = $isCompleted ? '#6c757d' : ($state === 'overdue' ? '#b02a37' : '#6f42c1');

            $events[] = [
                'id' => 'scad-' . $row['id'],
                'title' => '📅 ' . $row['topic'],
                'start' => $row['due_date'],
                'allDay' => true,
                'backgroundColor' => $color,
                'borderColor' => $color,
                'extendedProps' => [
                    'layer' => 'deadlines',
                    'url' => 'scadenzario/detail.php?id=' . (int)$row['id'],
                    'state' => $state,
                ],
            ];
        }
    }

    // ---- Trainings (formazione) ---------------------------------------
    if ($wants('trainings') && mnt_user_can('hr.trainings.view')) {
        $stmt = $pdo->prepare("
            SELECT t.id, t.next_due_date, t.reminder_days,
                   tt.name AS topic_name,
                   CONCAT(e.first_name, ' ', e.last_name) AS employee_name
            FROM employee_trainings t
            INNER JOIN training_topics tt ON tt.id = t.training_topic_id
            INNER JOIN employees e ON e.id = t.employee_id
            WHERE t.next_due_date IS NOT NULL AND t.next_due_date BETWEEN ? AND ?
        ");
        $stmt->execute([$start, $end]);

        foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $row) {
            $state = mnt_due_state($row['next_due_date'], (int)($row['reminder_days'] ?? 0));
            $color = $state === 'overdue' ? '#a94442' : '#198754';

            $events[] = [
                'id' => 'train-' . $row['id'],
                'title' => '🎓 ' . $row['topic_name'] . ' — ' . $row['employee_name'],
                'start' => $row['next_due_date'],
                'allDay' => true,
                'backgroundColor' => $color,
                'borderColor' => $color,
                'extendedProps' => [
                    'layer' => 'trainings',
                    'url' => 'trainings.php',
                    'state' => $state,
                ],
            ];
        }
    }

    echo json_encode($events);
} catch (Throwable $e) {
    http_response_code(500);
    echo json_encode(['error' => $e->getMessage()]);
}