using System.Net.Http.Json;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace IronServices.Client;

/// <summary>
/// Client for IronServices APIs with session-based authentication.
/// Handles login, token storage, and automatic bearer token attachment across multiple services.
/// </summary>
public class IronServicesClient : IDisposable
{
    private readonly HttpClient _httpClient;
    private readonly ITokenStorage _tokenStorage;
    private readonly JsonSerializerOptions _jsonOptions;
    private readonly IronServicesClientOptions _options;
    private string? _sessionToken;
    private DateTime? _expiresAt;
    private bool _disposed;

    // Lazy-initialized API services
    private LicensingApi? _licensing;
    private NotifyApi? _notify;
    private TelemetryApi? _telemetry;

    /// <summary>
    /// IronLicensing API operations.
    /// </summary>
    public LicensingApi Licensing => _licensing ??= new LicensingApi(this, _options.LicensingUrl);

    /// <summary>
    /// IronNotify API operations.
    /// </summary>
    public NotifyApi Notify => _notify ??= new NotifyApi(this, _options.NotifyUrl);

    /// <summary>
    /// IronTelemetry API operations.
    /// </summary>
    public TelemetryApi Telemetry => _telemetry ??= new TelemetryApi(this, _options.TelemetryUrl);

    /// <summary>
    /// Creates a new IronServices client with multiple service URLs.
    /// </summary>
    public IronServicesClient(IronServicesClientOptions options, ITokenStorage? tokenStorage = null)
    {
        _options = options ?? throw new ArgumentNullException(nameof(options));

        _httpClient = new HttpClient();
        _httpClient.DefaultRequestHeaders.Add("Accept", "application/json");

        _tokenStorage = tokenStorage ?? new InMemoryTokenStorage();
        _jsonOptions = new JsonSerializerOptions
        {
            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
            Converters = { new JsonStringEnumConverter() }
        };

        // Try to restore session from storage
        RestoreSession();
    }

    /// <summary>
    /// Creates a new IronServices client with a single base URL (legacy compatibility).
    /// All services will use this URL.
    /// </summary>
    public IronServicesClient(string baseUrl, ITokenStorage? tokenStorage = null)
        : this(new IronServicesClientOptions
        {
            LicensingUrl = baseUrl,
            NotifyUrl = baseUrl,
            TelemetryUrl = baseUrl
        }, tokenStorage)
    {
    }

    /// <summary>
    /// Whether the client has a valid session token.
    /// </summary>
    public bool IsAuthenticated => !string.IsNullOrEmpty(_sessionToken) &&
                                    (_expiresAt == null || _expiresAt > DateTime.UtcNow);

    /// <summary>
    /// Current session expiration time (UTC).
    /// </summary>
    public DateTime? SessionExpiresAt => _expiresAt;

    /// <summary>
    /// The current session token (for advanced scenarios).
    /// </summary>
    public string? SessionToken => _sessionToken;

    /// <summary>
    /// Login with email and password.
    /// </summary>
    public async Task<LoginResult> LoginAsync(string email, string password, CancellationToken cancellationToken = default)
    {
        var request = new { email, password };
        var url = BuildUrl(_options.LicensingUrl, "api/v1/users/login");

        var response = await _httpClient.PostAsJsonAsync(url, request, _jsonOptions, cancellationToken);

        if (!response.IsSuccessStatusCode)
        {
            var error = await ReadErrorAsync(response, cancellationToken);
            return new LoginResult { Success = false, Error = error };
        }

        var result = await response.Content.ReadFromJsonAsync<LoginResponse>(_jsonOptions, cancellationToken);

        if (result == null || string.IsNullOrEmpty(result.SessionToken))
        {
            return new LoginResult { Success = false, Error = "Invalid response from server" };
        }

        // Store session
        await SetSessionAsync(result.SessionToken, result.ExpiresAt);

        return new LoginResult
        {
            Success = true,
            UserId = result.UserId,
            Email = result.Email,
            DisplayName = result.DisplayName,
            Role = result.Role,
            ExpiresAt = result.ExpiresAt
        };
    }

    /// <summary>
    /// Register a new account.
    /// </summary>
    public async Task<RegisterResult> RegisterAsync(string email, string password, string? displayName = null, CancellationToken cancellationToken = default)
    {
        var request = new { email, password, displayName };
        var url = BuildUrl(_options.LicensingUrl, "api/v1/users/register");

        var response = await _httpClient.PostAsJsonAsync(url, request, _jsonOptions, cancellationToken);

        if (!response.IsSuccessStatusCode)
        {
            var error = await ReadErrorAsync(response, cancellationToken);
            return new RegisterResult { Success = false, Error = error };
        }

        var result = await response.Content.ReadFromJsonAsync<RegisterResponse>(_jsonOptions, cancellationToken);

        return new RegisterResult
        {
            Success = true,
            UserId = result?.User?.Id,
            Email = result?.User?.Email,
            ApiKey = result?.ApiKey
        };
    }

    /// <summary>
    /// Logout and clear session.
    /// </summary>
    public async Task LogoutAsync(CancellationToken cancellationToken = default)
    {
        if (IsAuthenticated)
        {
            try
            {
                var url = BuildUrl(_options.LicensingUrl, "api/v1/users/logout");
                await _httpClient.PostAsync(url, null, cancellationToken);
            }
            catch
            {
                // Ignore logout errors
            }
        }

        await ClearSessionAsync();
    }

    /// <summary>
    /// Get current user profile.
    /// </summary>
    public async Task<UserProfile?> GetProfileAsync(CancellationToken cancellationToken = default)
    {
        EnsureAuthenticated();

        var url = BuildUrl(_options.LicensingUrl, "api/v1/users/me");
        var response = await _httpClient.GetAsync(url, cancellationToken);

        if (!response.IsSuccessStatusCode)
        {
            if (response.StatusCode == System.Net.HttpStatusCode.Unauthorized)
            {
                await ClearSessionAsync();
            }
            return null;
        }

        return await response.Content.ReadFromJsonAsync<UserProfile>(_jsonOptions, cancellationToken);
    }

    /// <summary>
    /// Verify email with 6-digit code.
    /// </summary>
    public async Task<VerifyEmailResult> VerifyEmailAsync(string email, string code, CancellationToken cancellationToken = default)
    {
        var request = new { email, code };
        var url = BuildUrl(_options.LicensingUrl, "api/v1/users/verify-email");

        var response = await _httpClient.PostAsJsonAsync(url, request, _jsonOptions, cancellationToken);

        if (!response.IsSuccessStatusCode)
        {
            var error = await ReadErrorAsync(response, cancellationToken);
            return new VerifyEmailResult { Success = false, Error = error };
        }

        var result = await response.Content.ReadFromJsonAsync<VerifyEmailResponse>(_jsonOptions, cancellationToken);

        if (result?.SessionToken != null)
        {
            await SetSessionAsync(result.SessionToken, null);
        }

        return new VerifyEmailResult
        {
            Success = true,
            Message = result?.Message ?? "Email verified"
        };
    }

    /// <summary>
    /// Request password reset email.
    /// </summary>
    public async Task<bool> RequestPasswordResetAsync(string email, CancellationToken cancellationToken = default)
    {
        var request = new { email };
        var url = BuildUrl(_options.LicensingUrl, "api/v1/users/forgot-password");
        var response = await _httpClient.PostAsJsonAsync(url, request, _jsonOptions, cancellationToken);
        return response.IsSuccessStatusCode;
    }

    /// <summary>
    /// Reset password with token.
    /// </summary>
    public async Task<ResetPasswordResult> ResetPasswordAsync(string token, string newPassword, CancellationToken cancellationToken = default)
    {
        var request = new { token, newPassword };
        var url = BuildUrl(_options.LicensingUrl, "api/v1/users/reset-password");

        var response = await _httpClient.PostAsJsonAsync(url, request, _jsonOptions, cancellationToken);

        if (!response.IsSuccessStatusCode)
        {
            var error = await ReadErrorAsync(response, cancellationToken);
            return new ResetPasswordResult { Success = false, Error = error };
        }

        return new ResetPasswordResult { Success = true };
    }

    /// <summary>
    /// Make an authenticated GET request to a specific URL.
    /// </summary>
    public async Task<T?> GetAsync<T>(string fullUrl, CancellationToken cancellationToken = default)
    {
        EnsureAuthenticated();
        var response = await _httpClient.GetAsync(fullUrl, cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            var errorContent = await response.Content.ReadAsStringAsync(cancellationToken);
            throw new HttpRequestException($"GET {fullUrl} failed with {(int)response.StatusCode} {response.ReasonPhrase}: {errorContent}");
        }
        return await response.Content.ReadFromJsonAsync<T>(_jsonOptions, cancellationToken);
    }

    /// <summary>
    /// Make an authenticated POST request to a specific URL.
    /// </summary>
    public async Task<TResponse?> PostAsync<TRequest, TResponse>(string fullUrl, TRequest data, CancellationToken cancellationToken = default)
    {
        EnsureAuthenticated();
        var response = await _httpClient.PostAsJsonAsync(fullUrl, data, _jsonOptions, cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            var errorContent = await response.Content.ReadAsStringAsync(cancellationToken);
            throw new HttpRequestException($"POST {fullUrl} failed with {(int)response.StatusCode} {response.ReasonPhrase}: {errorContent}");
        }
        return await response.Content.ReadFromJsonAsync<TResponse>(_jsonOptions, cancellationToken);
    }

    /// <summary>
    /// Make an authenticated PUT request to a specific URL.
    /// </summary>
    public async Task<TResponse?> PutAsync<TRequest, TResponse>(string fullUrl, TRequest data, CancellationToken cancellationToken = default)
    {
        EnsureAuthenticated();
        var response = await _httpClient.PutAsJsonAsync(fullUrl, data, _jsonOptions, cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            var errorContent = await response.Content.ReadAsStringAsync(cancellationToken);
            throw new HttpRequestException($"PUT {fullUrl} failed with {(int)response.StatusCode} {response.ReasonPhrase}: {errorContent}");
        }
        return await response.Content.ReadFromJsonAsync<TResponse>(_jsonOptions, cancellationToken);
    }

    /// <summary>
    /// Make an authenticated DELETE request to a specific URL.
    /// </summary>
    public async Task DeleteAsync(string fullUrl, CancellationToken cancellationToken = default)
    {
        EnsureAuthenticated();
        var response = await _httpClient.DeleteAsync(fullUrl, cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            var errorContent = await response.Content.ReadAsStringAsync(cancellationToken);
            throw new HttpRequestException($"DELETE {fullUrl} failed with {(int)response.StatusCode} {response.ReasonPhrase}: {errorContent}");
        }
    }

    /// <summary>
    /// Build a full URL from a base URL and endpoint.
    /// </summary>
    internal static string BuildUrl(string baseUrl, string endpoint)
    {
        return baseUrl.TrimEnd('/') + "/" + endpoint.TrimStart('/');
    }

    private async Task SetSessionAsync(string token, DateTime? expiresAt)
    {
        _sessionToken = token;
        _expiresAt = expiresAt;
        _httpClient.DefaultRequestHeaders.Authorization =
            new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", _sessionToken);
        await _tokenStorage.SaveTokenAsync(_sessionToken, _expiresAt);
    }

    private void RestoreSession()
    {
        var (token, expiresAt) = _tokenStorage.GetTokenAsync().GetAwaiter().GetResult();

        if (!string.IsNullOrEmpty(token) && (expiresAt == null || expiresAt > DateTime.UtcNow))
        {
            _sessionToken = token;
            _expiresAt = expiresAt;
            _httpClient.DefaultRequestHeaders.Authorization =
                new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", _sessionToken);
        }
    }

    private async Task ClearSessionAsync()
    {
        _sessionToken = null;
        _expiresAt = null;
        _httpClient.DefaultRequestHeaders.Authorization = null;
        await _tokenStorage.ClearTokenAsync();
    }

    private void EnsureAuthenticated()
    {
        if (!IsAuthenticated)
        {
            throw new InvalidOperationException("Not authenticated. Call LoginAsync first.");
        }
    }

    private async Task<string> ReadErrorAsync(HttpResponseMessage response, CancellationToken cancellationToken)
    {
        try
        {
            var content = await response.Content.ReadAsStringAsync(cancellationToken);
            var error = JsonSerializer.Deserialize<ErrorResponse>(content, _jsonOptions);
            return error?.Error ?? $"Request failed with status {response.StatusCode}";
        }
        catch
        {
            return $"Request failed with status {response.StatusCode}";
        }
    }

    public void Dispose()
    {
        if (!_disposed)
        {
            _httpClient.Dispose();
            _disposed = true;
        }
    }
}

/// <summary>
/// Configuration options for IronServicesClient.
/// </summary>
public class IronServicesClientOptions
{
    /// <summary>
    /// Base URL for IronLicensing API (also used for auth/user operations).
    /// Default: https://ironlicensing.com
    /// </summary>
    public string LicensingUrl { get; set; } = "https://ironlicensing.com";

    /// <summary>
    /// Base URL for IronNotify API.
    /// Default: https://ironnotify.com
    /// </summary>
    public string NotifyUrl { get; set; } = "https://ironnotify.com";

    /// <summary>
    /// Base URL for IronTelemetry API.
    /// Default: https://irontelemetry.com
    /// </summary>
    public string TelemetryUrl { get; set; } = "https://irontelemetry.com";
}