namespace MAF1.Decisions;

/// <summary>
/// CLI 版确认框。回车 / 1 = 结束查询；2 = 再输入城市；也可以直接打「成都」。
/// ReadLine 和超时赛跑：到期返回 TimedOut，走默认方案。
/// MAF1 工作流 CLI 与 MAF1.Route 共用。
/// </summary>
public static class ConsoleDecisionPrompt
{
    public static async Task<DecisionAnswer> WaitAsync(DecisionRequest request)
    {
        Console.WriteLine();
        Console.WriteLine("[需要确认]");
        Console.WriteLine(request.Prompt);
        if (!string.IsNullOrWhiteSpace(request.Reason))
        {
            Console.WriteLine($"原因：{request.Reason}");
        }

        Console.WriteLine($"未及时确认将使用默认方案。等待 {request.TimeoutSeconds} 秒。");
        for (int i = 0; i < request.Options.Count; i++)
        {
            DecisionOption option = request.Options[i];
            string mark = option.IsDefault ? " ← 默认" : "";
            Console.WriteLine($"  {i + 1}) {option.Label}{mark}");
            if (!string.IsNullOrWhiteSpace(option.Description))
            {
                Console.WriteLine($"     {option.Description}");
            }
        }

        Console.Write("输入序号，或直接回车采用默认：");
        string? line = await ReadLineOrTimeoutAsync(request.Deadline);
        if (line is null)
        {
            Console.WriteLine();
            Console.WriteLine("未及时确认，采用默认方案：结束查询。");
            return new DecisionAnswer { OptionId = request.DefaultOptionId, TimedOut = true };
        }

        line = line.Trim();
        if (line.Length == 0 || line is "1" || line.Equals("stop", StringComparison.OrdinalIgnoreCase))
        {
            return new DecisionAnswer { OptionId = DecisionOptionIds.Stop };
        }

        if (line is "2" || line.Equals(DecisionOptionIds.QueryCities, StringComparison.OrdinalIgnoreCase))
        {
            Console.Write("请输入城市名（例如 成都、北京）：");
            string? cities = await ReadLineOrTimeoutAsync(request.Deadline);
            if (cities is null)
            {
                Console.WriteLine();
                Console.WriteLine("未及时输入城市，采用默认方案：结束查询。");
                return new DecisionAnswer { OptionId = DecisionOptionIds.Stop, TimedOut = true };
            }

            if (EmptyCityDecision.ParseCities(cities).Count == 0)
            {
                Console.WriteLine("没有有效城市名，采用默认方案：结束查询。");
                return new DecisionAnswer { OptionId = DecisionOptionIds.Stop };
            }

            return new DecisionAnswer { OptionId = DecisionOptionIds.QueryCities, Text = cities };
        }

        if (EmptyCityDecision.ParseCities(line).Count > 0)
        {
            return new DecisionAnswer { OptionId = DecisionOptionIds.QueryCities, Text = line };
        }

        Console.WriteLine("无法识别输入，采用默认方案：结束查询。");
        return new DecisionAnswer { OptionId = DecisionOptionIds.Stop };
    }

    /// <summary>超时返回 null。注意：超时后后台的 ReadLine 仍可能阻塞，学习项目可接受。</summary>
    private static async Task<string?> ReadLineOrTimeoutAsync(DateTimeOffset deadline)
    {
        TimeSpan remain = deadline - DateTimeOffset.UtcNow;
        if (remain <= TimeSpan.Zero)
        {
            return null;
        }

        Task<string?> read = Task.Run(() => Console.ReadLine());
        Task delay = Task.Delay(remain);
        Task finished = await Task.WhenAny(read, delay);
        if (finished == delay)
        {
            return null;
        }

        return await read;
    }
}