using System.Text;
using System.Security.Cryptography; // For encryption
using System.Text.Json;

namespace Blueberry.Redmine
{
    public class RedmineSettingsManager
    {
        private readonly string _filePath = Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
            "Blueberry",
            "settings.json");

        public RedmineConfig Load()
        {
            if (!File.Exists(_filePath))
                return new RedmineConfig()
                {
                    IsInitiating = true,
                };

            try
            {
                var json = File.ReadAllText(_filePath);
                var config = JsonSerializer.Deserialize<RedmineConfig>(json);
                if(config == null)
                    return new RedmineConfig();

                if (!string.IsNullOrEmpty(config.ApiKey))
                {
                    config.ApiKey = Unprotect(config.ApiKey);
                }
                return config;
            }
            catch
            {
                return new RedmineConfig();
            }
        }

        public void Save(RedmineConfig config)
        {
            Directory.CreateDirectory(Path.GetDirectoryName(_filePath) ?? throw new NullReferenceException("Config directory path creation failed."));

            var copy = new RedmineConfig
            {
                RedmineUrl = config.RedmineUrl,
                ApiKey = Protect(config.ApiKey),
                ProjectCacheDuration = config.ProjectCacheDuration,
                CacheFilePath = config.CacheFilePath,
                ConcurrencyLimit = config.ConcurrencyLimit,
                IssueCacheDuration = config.IssueCacheDuration,
                MaxRetries = config.MaxRetries,
                IsInitiating = false
            };

            var json = JsonSerializer.Serialize(copy, new JsonSerializerOptions { WriteIndented = true });
            File.WriteAllText(_filePath, json);
        }

        private string Protect(string clearText)
        {
            if (string.IsNullOrEmpty(clearText)) return "";
            byte[] clearBytes = Encoding.UTF8.GetBytes(clearText);
            byte[] encryptedBytes = ProtectedData.Protect(clearBytes, null, DataProtectionScope.CurrentUser);
            return Convert.ToBase64String(encryptedBytes);
        }

        private string Unprotect(string encryptedText)
        {
            if (string.IsNullOrEmpty(encryptedText)) return "";
            try
            {
                byte[] encryptedBytes = Convert.FromBase64String(encryptedText);
                byte[] clearBytes = ProtectedData.Unprotect(encryptedBytes, null, DataProtectionScope.CurrentUser);
                return Encoding.UTF8.GetString(clearBytes);
            }
            catch
            {
                return ""; // Decryption failed (maybe different user/machine)
            }
        }
    }
}