// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

#nullable disable

using Microsoft.Win32;

namespace Microsoft.DotNet.Cli.Telemetry;

internal static class DeviceIdGetter
{
    public static string GetDeviceId()
    {
        string deviceId = GetCachedDeviceId();

        // Check if the device Id is already cached
        if (string.IsNullOrEmpty(deviceId))
        {
            // Generate a new guid
            deviceId = Guid.NewGuid().ToString("D").ToLowerInvariant();

            // Cache the new device Id
            try
            {
                CacheDeviceId(deviceId);
            }
            catch
            {
                // If caching fails, return empty string to avoid sending a non-stored id
                deviceId = "";
            }
        }

        return deviceId;
    }

    private static string GetCachedDeviceId()
    {
        string deviceId = null;

        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
        {
            // Get device Id from Windows registry matching the OS architecture
            using (var key = RegistryKey.OpenBaseKey(RegistryHive.CurrentUser, RegistryView.Registry64).OpenSubKey(@"SOFTWARE\Microsoft\DeveloperTools"))
            {
                deviceId = key?.GetValue("deviceid") as string;
            }
        }
        else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
        {
            // Get device Id from Linux cache file
            string cacheFilePath;
            string xdgCacheHome = Environment.GetEnvironmentVariable("XDG_CACHE_HOME");
            if (!string.IsNullOrEmpty(xdgCacheHome))
            {
                cacheFilePath = Path.Combine(xdgCacheHome, "Microsoft", "DeveloperTools", "deviceid");
            }
            else
            {
                cacheFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".cache", "deviceid");
            }

            if (File.Exists(cacheFilePath))
            {
                deviceId = File.ReadAllText(cacheFilePath);
            }
        }
        else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
        {
            // Get device Id from macOS cache file
            string cacheFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "Library", "Application Support", "Microsoft", "DeveloperTools", "deviceid");
            if (File.Exists(cacheFilePath))
            {
                deviceId = File.ReadAllText(cacheFilePath);
            }
        }

        return deviceId;
    }

    private static void CacheDeviceId(string deviceId)
    {
        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
        {
            // Cache device Id in Windows registry matching the OS architecture
            using (RegistryKey baseKey = RegistryKey.OpenBaseKey(RegistryHive.CurrentUser, RegistryView.Registry64))
            {
                using (var key = baseKey.CreateSubKey(@"SOFTWARE\Microsoft\DeveloperTools"))
                {
                    if (key != null)
                    {
                        key.SetValue("deviceid", deviceId);
                    }
                }
            }
        }
        else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
        {
            // Cache device Id in Linux cache file
            string cacheFilePath;
            string xdgCacheHome = Environment.GetEnvironmentVariable("XDG_CACHE_HOME");
            if (!string.IsNullOrEmpty(xdgCacheHome))
            {
                cacheFilePath = Path.Combine(xdgCacheHome, "Microsoft", "DeveloperTools", "deviceId");
            }
            else
            {
                cacheFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".cache", "deviceid");
            }

            CreateDirectoryAndWriteToFile(cacheFilePath, deviceId);
        }
        else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
        {
            // Cache device Id in macOS cache file
            string cacheFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "Library", "Application Support", "Microsoft", "DeveloperTools", "deviceid");

            CreateDirectoryAndWriteToFile(cacheFilePath, deviceId);
        }
    }

    private static void CreateDirectoryAndWriteToFile(string filePath, string content)
    {
        string directory = Path.GetDirectoryName(filePath);
        if (!Directory.Exists(directory))
        {
            Directory.CreateDirectory(directory);
        }
        File.WriteAllText(filePath, content);
    }
}