<?php
require_once 'lib/ErrorHandler.php';
register_error_handler();

require_once 'db/config.php';
require_once 'WorkflowEngine.php';

if (session_status() == PHP_SESSION_NONE) {
    session_start();
}

header('Content-Type: application/json');

if (!isset($_SESSION['user_id'])) {
    http_response_code(401);
    echo json_encode(['error' => ['message' => 'Authentication required.']]);
    exit;
}

$userId = $_SESSION['user_id'];
$personId = filter_input(INPUT_POST, 'person_id', FILTER_VALIDATE_INT);
$processDefinitionId = filter_input(INPUT_POST, 'process_id', FILTER_VALIDATE_INT);

$subjectType = filter_input(INPUT_POST, 'subject_type', FILTER_SANITIZE_STRING);
$subjectId = filter_input(INPUT_POST, 'subject_id', FILTER_VALIDATE_INT);
$processCode = filter_input(INPUT_POST, 'process_code', FILTER_SANITIZE_STRING);
$mode = filter_input(INPUT_POST, 'mode', FILTER_SANITIZE_STRING) ?: 'resume_or_create';

if ($personId && !$subjectType) {
    $subjectType = 'person';
    $subjectId = $personId;
}

$pdo = db();

if ($processDefinitionId && !$processCode) {
    $stmt = $pdo->prepare("SELECT code FROM process_definitions WHERE id = ?");
    $stmt->execute([$processDefinitionId]);
    $processCode = $stmt->fetchColumn();
}

if (!$subjectId || !$subjectType || !$processCode) {
    throw new InvalidArgumentException('Invalid or missing subject_type, subject_id, or process_code.');
}

$engine = new WorkflowEngine();
$instance = $engine->getOrCreateInstanceBySubject($subjectType, $subjectId, $processCode, $userId, $mode);

if ($instance && isset($instance['instance_id'])) {
    echo json_encode(['success' => true, 'message' => 'Process initialized successfully.', 'instance_id' => $instance['instance_id']]);
} else {
    throw new Exception("Failed to initialize process for an unknown reason.");
}