<?php
header('Content-Type: application/json');
session_start();
require_once __DIR__ . '/../db/config.php';

// Authentication check
if (!isset($_SESSION['user_id'])) {
    echo json_encode(['error' => 'Unauthorized']);
    exit;
}

$user_id = $_SESSION['user_id'];
$action = $_GET['action'] ?? '';
$username = $_GET['username'] ?? '';

if (empty($username)) {
    echo json_encode(['success' => false, 'error' => 'Username required']);
    exit;
}

// Helper to check if a function is enabled
function is_enabled($func) {
    return function_exists($func) && !in_array($func, array_map('trim', explode(',', ini_get('disable_functions'))));
}

if (!is_enabled('shell_exec')) {
    echo json_encode(['success' => false, 'error' => 'PHP function shell_exec is disabled on this server. Contact your hosting provider.']);
    exit;
}

// Find node path
function get_node_path() {
    $path = trim((string)shell_exec('which node'));
    if ($path && file_exists($path)) return $path;
    
    $common_paths = ['/usr/local/bin/node', '/usr/bin/node', '/bin/node', '/opt/node/bin/node'];
    foreach ($common_paths as $p) {
        if (file_exists($p)) return $p;
    }
    return 'node'; // Fallback to PATH
}

$node = get_node_path();

// Create logs directory if not exists
$logs_dir = __DIR__ . '/../logs';
if (!is_dir($logs_dir)) {
    @mkdir($logs_dir, 0755, true);
}

$pid_file = "$logs_dir/bridge_{$username}_{$user_id}.pid";
$log_file = "$logs_dir/bridge_{$username}_{$user_id}.log";

function is_running($pid_file) {
    if (!file_exists($pid_file)) return false;
    $pid = (int)file_get_contents($pid_file);
    if ($pid <= 0) return false;
    
    // Check if process exists (posix_getpgid is safer but might be disabled)
    if (function_exists('posix_getpgid')) {
        return @posix_getpgid($pid) !== false;
    }
    
    // Fallback to pgrep or ps
    $output = shell_exec("ps -p $pid");
    return (strpos($output, (string)$pid) !== false);
}

function kill_process($pid_file, $username, $user_id) {
    if (file_exists($pid_file)) {
        $pid = (int)file_get_contents($pid_file);
        if ($pid > 0) {
            shell_exec("kill -9 $pid > /dev/null 2>&1");
        }
        @unlink($pid_file);
    }
    // Also try pkill as backup
    shell_exec("pkill -f \"node .*tiktok_bridge.js $username .* $user_id\"");
}

if ($action === 'start') {
    // 1. Kill any existing bridge
    kill_process($pid_file, $username, $user_id);
    
    // 2. Start new bridge
    $bridge_script = __DIR__ . '/../tiktok_bridge.js';
    
    // Check if node_modules exist
    if (!is_dir(__DIR__ . '/../node_modules')) {
        echo json_encode(['success' => false, 'error' => 'node_modules folder not found. Please run "npm install" on your server.']);
        exit;
    }

    $cmd = sprintf(
        "%s %s %s %s %s %s %s %s > %s 2>&1 & echo $!",
        $node,
        escapeshellarg($bridge_script),
        escapeshellarg($username),
        escapeshellarg(DB_HOST),
        escapeshellarg(DB_USER),
        escapeshellarg(DB_PASS),
        escapeshellarg(DB_NAME),
        escapeshellarg($user_id),
        escapeshellarg($log_file)
    );
    
    $pid = trim((string)shell_exec($cmd));
    
    if ($pid > 0) {
        file_put_contents($pid_file, $pid);
        echo json_encode([
            'success' => true, 
            'message' => "Bridge started for @$username",
            'pid' => $pid,
            'log' => "logs/" . basename($log_file)
        ]);
    } else {
        echo json_encode([
            'success' => false, 
            'error' => "Failed to start bridge. Check $log_file for errors.",
            'node_path' => $node
        ]);
    }

} elseif ($action === 'stop') {
    kill_process($pid_file, $username, $user_id);
    echo json_encode(['success' => true, 'message' => "Bridge stopped for @$username"]);

} elseif ($action === 'status') {
    $running = is_running($pid_file);
    
    // Check log for errors if not running but was supposed to
    $last_log = "";
    if (!$running && file_exists($log_file)) {
        $last_log = trim((string)shell_exec("tail -n 5 " . escapeshellarg($log_file)));
    }

    echo json_encode([
        'success' => true, 
        'running' => $running,
        'last_log' => $last_log
    ]);

} elseif ($action === 'debug') {
    // Special action to check environment
    $env = [
        'php_version' => PHP_VERSION,
        'shell_exec_enabled' => is_enabled('shell_exec'),
        'node_path' => $node,
        'node_version' => trim((string)shell_exec("$node -v")),
        'npm_version' => trim((string)shell_exec("npm -v")),
        'node_modules_exists' => is_dir(__DIR__ . '/../node_modules'),
        'db_host' => DB_HOST,
        'db_user' => DB_USER,
        'os' => PHP_OS,
    ];
    echo json_encode(['success' => true, 'env' => $env]);

} else {
    echo json_encode(['success' => false, 'error' => 'Invalid action']);
}