<?php
require_once 'db/config.php';
session_start();

if (!isset($_SESSION['user_id'])) {
    http_response_code(401);
    echo json_encode(['success' => false, 'error' => 'Unauthorized']);
    exit;
}

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    http_response_code(405);
    echo json_encode(['error' => 'Method Not Allowed']);
    exit;
}

$inputJSON = file_get_contents('php://input');
$input = json_decode($inputJSON, true);

if (json_last_error() !== JSON_ERROR_NONE) {
    http_response_code(400);
    echo json_encode(['error' => 'Invalid JSON']);
    exit;
}

$instanceId = $input['instance_id'] ?? null;
$taskCode = $input['task_code'] ?? null;
$isChecked = $input['is_checked'] ?? null;

if (!$instanceId || !$taskCode || $isChecked === null) {
    http_response_code(400);
    echo json_encode(['error' => 'Missing required parameters: instance_id, task_code, is_checked']);
    exit;
}

try {
    $pdo = db();

    // Get current data_json
    $stmt = $pdo->prepare("SELECT data_json FROM process_instances WHERE id = ?");
    $stmt->execute([$instanceId]);
    $currentDataJson = $stmt->fetchColumn();

    $data = $currentDataJson ? json_decode($currentDataJson, true) : [];

    // Update the specific task status
    $data[$taskCode] = (bool)$isChecked;
    $newDataJson = json_encode($data);

    // Save new data_json and update timestamp
    $stmt = $pdo->prepare("UPDATE process_instances SET data_json = ?, lastActivityAt = CURRENT_TIMESTAMP WHERE id = ?");
    $success = $stmt->execute([$newDataJson, $instanceId]);

    if ($success) {
        // Calculate progress
        $stmt = $pdo->prepare("SELECT pd.definition_json FROM process_definitions pd JOIN process_instances pi ON pd.id = pi.process_definition_id WHERE pi.id = ?");
        $stmt->execute([$instanceId]);
        $definitionJson = $stmt->fetchColumn();
        $definition = json_decode($definitionJson, true);
        $totalTasks = count($definition['tasks'] ?? []);
        $completedTasks = count(array_filter($data));

        echo json_encode([
            'success' => true, 
            'message' => 'Status updated successfully.',
            'progress' => [
                'completed' => $completedTasks,
                'total' => $totalTasks
            ],
            'lastActivityAt' => date('d/m/y')
        ]);
    } else {
        http_response_code(500);
        echo json_encode(['error' => 'Failed to update status.']);
    }

} catch (PDOException $e) {
    http_response_code(500);
    echo json_encode(['error' => 'Database error: ' . $e->getMessage()]);
}
?>