<?php
require_once(__DIR__ . '/auth_check.php');
header('Content-Type: application/json');
require_once(__DIR__ . '/../../class/db-functions.php');

try {
    if (!isset($_GET['id']) || !is_numeric($_GET['id'])) {
        echo json_encode(['success' => false, 'message' => 'ID non valido.']);
        exit;
    }

    $id = (int)$_GET['id'];

    $db = DBHandlerSelect::getInstance();
    $pdo = $db->getConnection();

    $stmt = $pdo->prepare("SELECT * FROM scad_deadlines WHERE id = ? AND status = 'active'");
    $stmt->execute([$id]);
    $deadline = $stmt->fetch(PDO::FETCH_ASSOC);

    if (!$deadline) {
        echo json_encode(['success' => false, 'message' => 'Scadenza non trovata o già completata.']);
        exit;
    }

    $pdo->beginTransaction();

    // Mark as completed
    $pdo->prepare("UPDATE scad_deadlines SET status = 'completed', completed_at = NOW(), completed_by = ? WHERE id = ?")
        ->execute([$currentUserId, $id]);

    // History
    $pdo->prepare("INSERT INTO scad_deadline_histories (deadline_id, user_id, action) VALUES (?, ?, 'completed')")
        ->execute([$id, $currentUserId]);

    $newId = null;

    // If recurring, create next deadline
    if ($deadline['recurrence_type'] !== 'once') {
        $dueDate = new DateTime($deadline['due_date']);
        $checkDate = $deadline['check_date'] ? new DateTime($deadline['check_date']) : null;

        switch ($deadline['recurrence_type']) {
            case 'monthly':     $interval = new DateInterval('P1M'); break;
            case 'quarterly':   $interval = new DateInterval('P3M'); break;
            case 'semiannual':  $interval = new DateInterval('P6M'); break;
            case 'annual':       $interval = new DateInterval('P1Y'); break;
            case 'biennial':    $interval = new DateInterval('P2Y'); break;
            case 'triennial':   $interval = new DateInterval('P3Y'); break;
            case 'quadriennial':  $interval = new DateInterval('P4Y'); break;
            case 'quinquennial':  $interval = new DateInterval('P5Y'); break;
            case 'decennial':     $interval = new DateInterval('P10Y'); break;
            case 'quindecennial': $interval = new DateInterval('P15Y'); break;
            default:            $interval = null;
        }

        if ($interval) {
            $dueDate->add($interval);
            if ($checkDate) $checkDate->add($interval);

            $ins = $pdo->prepare("
                INSERT INTO scad_deadlines
                    (subject_id, topic, law_regulation, recurrence_type, due_date, check_date,
                     document_date, notification_days, storage_location, notes, created_by, departments)
                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
            ");
            $ins->execute([
                $deadline['subject_id'], $deadline['topic'], $deadline['law_regulation'],
                $deadline['recurrence_type'], $dueDate->format('Y-m-d'),
                $checkDate ? $checkDate->format('Y-m-d') : null,
                $deadline['document_date'],
                $deadline['notification_days'], $deadline['storage_location'],
                $deadline['notes'], $deadline['created_by'], $deadline['departments']
            ]);

            $newId = $pdo->lastInsertId();

            // Copy employee assignments
            $empStmt = $pdo->prepare("SELECT employee_id FROM scad_deadline_employee WHERE deadline_id = ?");
            $empStmt->execute([$id]);
            $empIds = $empStmt->fetchAll(PDO::FETCH_COLUMN);

            if (!empty($empIds)) {
                $insertEmp = $pdo->prepare("INSERT INTO scad_deadline_employee (deadline_id, employee_id) VALUES (?, ?)");
                foreach ($empIds as $empId) {
                    $insertEmp->execute([$newId, $empId]);
                }
            }

            // History for new
            $pdo->prepare("INSERT INTO scad_deadline_histories (deadline_id, user_id, action, notes) VALUES (?, ?, 'created', ?)")
                ->execute([$newId, $currentUserId, 'Creata automaticamente dalla scadenza #' . $id]);
        }
    }

    $pdo->commit();

    $msg = 'Scadenza completata con successo.';
    if ($newId) {
        $msg .= ' Nuova scadenza creata con data ' . $dueDate->format('d/m/Y') . '.';
    }

    echo json_encode(['success' => true, 'message' => $msg, 'new_id' => $newId]);

} catch (Exception $e) {
    if (isset($pdo) && $pdo->inTransaction()) {
        $pdo->rollBack();
    }
    echo json_encode(['success' => false, 'message' => 'Errore: ' . $e->getMessage()]);
}