using System.IO;
using System.Text.Json;
using CloudPrint.Client.Models;
using CloudPrint.Client.Services.Abstractions;

namespace CloudPrint.Client.Services;

public sealed class JsonSettingsService : ISettingsService
{
    private static readonly JsonSerializerOptions SerializerOptions = new()
    {
        WriteIndented = true
    };

    private readonly string _settingsPath;
    private readonly ISecretProtector _secretProtector;

    public JsonSettingsService()
        : this(new DpapiSecretProtector())
    {
    }

    public JsonSettingsService(ISecretProtector secretProtector)
        : this(secretProtector, Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "CloudPrint.Client", "settings.json"))
    {
    }

    public JsonSettingsService(ISecretProtector secretProtector, string settingsPath)
    {
        if (string.IsNullOrWhiteSpace(settingsPath))
        {
            throw new ArgumentException("设置文件路径不能为空", nameof(settingsPath));
        }

        _secretProtector = secretProtector;
        _settingsPath = settingsPath;
    }

    public ClientSettings Load()
    {
        if (!File.Exists(_settingsPath))
        {
            return new ClientSettings();
        }

        try
        {
            var json = File.ReadAllText(_settingsPath);
            var dto = JsonSerializer.Deserialize<SettingsFileDto>(json, SerializerOptions);
            return dto?.ToSettings(_secretProtector) ?? new ClientSettings();
        }
        catch
        {
            return new ClientSettings();
        }
    }

    public void Save(ClientSettings settings)
    {
        ArgumentNullException.ThrowIfNull(settings);

        var directory = Path.GetDirectoryName(_settingsPath);
        if (!string.IsNullOrWhiteSpace(directory))
        {
            Directory.CreateDirectory(directory);
        }

        var json = JsonSerializer.Serialize(SettingsFileDto.FromSettings(settings, _secretProtector), SerializerOptions);
        File.WriteAllText(_settingsPath, json);
    }

    private sealed class SettingsFileDto
    {
        public string ServerAddress { get; set; } = "http://localhost:8080";
        public string ApiKey { get; set; } = string.Empty; // Legacy plaintext field.
        public string ProtectedApiKey { get; set; } = string.Empty;
        public string AdminUsername { get; set; } = string.Empty;
        public string AdminAccessToken { get; set; } = string.Empty; // Legacy plaintext field.
        public string ProtectedAdminAccessToken { get; set; } = string.Empty;
        public string StoreName { get; set; } = "默认打印店";
        public bool AllowInsecureGrpc { get; set; } = true;
        public string LibraryRoot { get; set; } = string.Empty;
        public string PrintCacheRoot { get; set; } = string.Empty;
        public int MaxUploadSizeMb { get; set; } = 50;
        public int HeartbeatIntervalSeconds { get; set; } = 15;

        public ClientSettings ToSettings(ISecretProtector protector)
        {
            return new ClientSettings
            {
                ServerAddress = ServerAddress,
                ApiKey = ReadSecret(ProtectedApiKey, ApiKey, protector),
                AdminUsername = AdminUsername,
                AdminAccessToken = ReadSecret(ProtectedAdminAccessToken, AdminAccessToken, protector),
                StoreName = StoreName,
                AllowInsecureGrpc = AllowInsecureGrpc,
                LibraryRoot = LibraryRoot,
                PrintCacheRoot = PrintCacheRoot,
                MaxUploadSizeMb = MaxUploadSizeMb,
                HeartbeatIntervalSeconds = HeartbeatIntervalSeconds
            };
        }

        public static SettingsFileDto FromSettings(ClientSettings settings, ISecretProtector protector)
        {
            return new SettingsFileDto
            {
                ServerAddress = settings.ServerAddress,
                ProtectedApiKey = protector.Protect(settings.ApiKey),
                AdminUsername = settings.AdminUsername,
                ProtectedAdminAccessToken = protector.Protect(settings.AdminAccessToken),
                StoreName = settings.StoreName,
                AllowInsecureGrpc = settings.AllowInsecureGrpc,
                LibraryRoot = settings.LibraryRoot,
                PrintCacheRoot = settings.PrintCacheRoot,
                MaxUploadSizeMb = settings.MaxUploadSizeMb,
                HeartbeatIntervalSeconds = settings.HeartbeatIntervalSeconds
            };
        }

        private static string ReadSecret(string protectedValue, string legacyPlainText, ISecretProtector protector)
        {
            if (string.IsNullOrWhiteSpace(protectedValue))
            {
                return legacyPlainText;
            }

            try
            {
                return protector.Unprotect(protectedValue);
            }
            catch
            {
                return legacyPlainText;
            }
        }
    }
}