using System;
using System.Collections.Generic;
using System.Threading.Tasks;

/// <summary>
/// Brisk 认证模块。
/// </summary>
public sealed class BriskAuthModule
    : BriskModuleBase
{
    /// <summary>
    /// 通过稳定的第三方用户 ID 换取 Brisk 登录态。
    /// </summary>
    public async Task<BriskLoginResult> LoginWithUserIdAsync(string loginProvider, string loginUserId, BriskProfile profile = null)
    {
        RequireNotEmpty(loginProvider, nameof(loginProvider));
        RequireNotEmpty(loginUserId, nameof(loginUserId));

        return await LoginInternalAsync(CreateLoginBody(loginProvider, profile, loginUserId, null), loginProvider, loginUserId);
    }

    /// <summary>
    /// 通过第三方返回的 code 换取 Brisk 登录态。
    /// </summary>
    public async Task<BriskLoginResult> LoginWithCodeAsync(string loginProvider, string code, BriskProfile profile = null)
    {
        RequireNotEmpty(loginProvider, nameof(loginProvider));
        RequireNotEmpty(code, nameof(code));

        return await LoginInternalAsync(CreateLoginBody(loginProvider, profile, null, code), loginProvider, null);
    }

    /// <summary>
    /// 登出当前账号并清理本地会话。
    /// </summary>
    public async Task LogoutAsync()
    {
        var context = GetContext();

        try
        {
            if (context.Session.HasAccessToken)
            {
                await context.HttpClient.PostJsonAsync("/auth/logout", new Dictionary<string, object>(), true);
            }
        }
        catch (BriskAuthExpiredException)
        {
            // Local logout should still succeed even if the remote token has already expired.
        }
        catch (BriskBlockingException exception)
        {
            Brisk.NotifyBlockingError(exception);
            throw;
        }
        finally
        {
            context.Session.Clear();
            await context.TokenStore.ClearAsync();
            Brisk.NotifyLoggedOut();
        }
    }

    private async Task<BriskLoginResult> LoginInternalAsync(Dictionary<string, object> body, string requestedLoginProvider, string requestedLoginUserId)
    {
        return await ExecutePublicAsync(async context =>
        {
            var data = await context.HttpClient.PostJsonAsync("/auth/login/exchange", body, false);
            var result = BriskModelMapper.ToLoginResult(data);
            if (string.IsNullOrWhiteSpace(result.LoginProvider))
            {
                result.LoginProvider = requestedLoginProvider;
            }

            if (string.IsNullOrWhiteSpace(result.LoginUserId))
            {
                result.LoginUserId = requestedLoginUserId;
            }

            await UpdateSessionAsync(context, result);
            Brisk.NotifyLoggedIn();
            return result;
        });
    }

    private Dictionary<string, object> CreateLoginBody(string loginProvider, BriskProfile profile, string loginUserId, string code)
    {
        var context = GetContext();
        var body = new Dictionary<string, object>
        {
            { "game_key", context.Options.GameKey },
            { "login_provider", loginProvider }
        };

        AddIfNotEmpty(body, "login_user_id", loginUserId);
        AddIfNotEmpty(body, "code", code);
        AddIfNotEmpty(body, "device_id", context.Options.DeviceId);
        AddIfNotEmpty(body, "client_version", context.Options.ClientVersion);

        if (profile != null)
        {
            AddIfNotEmpty(body, "nickname", profile.Nickname);
            AddIfNotEmpty(body, "avatar_url", profile.AvatarUrl);
            if (profile.ProfileJson != null)
            {
                body["profile_json"] = profile.ProfileJson;
            }
        }

        return body;
    }

    private static void AddIfNotEmpty(Dictionary<string, object> body, string key, string value)
    {
        if (!string.IsNullOrWhiteSpace(value))
        {
            body[key] = value;
        }
    }

    private async Task UpdateSessionAsync(BriskContext context, BriskLoginResult result)
    {
        var expiresAt = result.ExpiresIn > 0
            ? DateTimeOffset.UtcNow.AddSeconds(result.ExpiresIn)
            : (DateTimeOffset?)null;

        context.Session.Update(
            result.AccessToken,
            expiresAt,
            result.PlayerId,
            result.ProjectAccountId,
            result.LoginProvider,
            result.LoginUserId);

        var storedSession = new BriskStoredSession
        {
            AccessToken = result.AccessToken,
            ExpiresAt = expiresAt,
            PlayerId = result.PlayerId,
            ProjectAccountId = result.ProjectAccountId,
            LoginProvider = result.LoginProvider,
            LoginUserId = result.LoginUserId
        };

        await context.TokenStore.SaveAsync(storedSession);
    }
}