using System.Globalization;
using System.Text.Json;
using System.Text.Json.Serialization;
using Fleet.Core;

namespace MoShiro.Protocol;

/// <summary>Task = { id, scope, kind, target, params, schedule, enabled }。参数已经按 ParamSpec 校验并补全默认值。</summary>
public sealed class TaskSpec
{
    [JsonPropertyName("id")]
    public TaskId Id { get; set; }

    /// <summary>line | target</summary>
    [JsonPropertyName("scope")]
    public string Scope { get; set; } = "line";

    [JsonPropertyName("kind")]
    public string Kind { get; set; } = "";

    [JsonPropertyName("target")]
    public string? Target { get; set; }

    [JsonPropertyName("params")]
    public Dictionary<string, JsonElement> Params { get; set; } = [];

    /// <summary>continuous | every:&lt;分钟&gt; | once</summary>
    [JsonPropertyName("schedule")]
    public string Schedule { get; set; } = TaskSchedule.Continuous;

    [JsonPropertyName("enabled")]
    public bool Enabled { get; set; } = true;
}

public sealed class PeerSpec
{
    [JsonPropertyName("probe_id")]
    public ProbeId ProbeId { get; set; }

    /// <summary>Probe 的身份公钥（SPKI，base64）。</summary>
    [JsonPropertyName("pubkey")]
    public string PublicKey { get; set; } = "";
}

/// <summary>期望状态文档（Fleet state type = <c>task_set</c>）：Backend 为每个 Agent 计算的有效任务集。</summary>
public sealed class TaskSet
{
    public const string StateType = "task_set";

    [JsonPropertyName("version")]
    public long Version { get; set; }

    [JsonPropertyName("tasks")]
    public List<TaskSpec> Tasks { get; set; } = [];

    /// <summary>允许连接到这个 Agent 的 Probe 公钥。</summary>
    [JsonPropertyName("peers")]
    public List<PeerSpec> Peers { get; set; } = [];
}

public static class TaskSchedule
{
    public const string Continuous = "continuous";
    public const string Once = "once";
    public const string EveryPrefix = "every:";

    public static string Every(int minutes) => EveryPrefix + minutes.ToString(CultureInfo.InvariantCulture);

    /// <summary>校验调度字符串：<c>every:N</c> 的 N ≥ 60（适用于重负载 Kind）。</summary>
    public static Result<int?> Validate(string schedule)
    {
        if (schedule is Continuous or Once)
        {
            return Result<int?>.Ok(null);
        }

        if (schedule.StartsWith(EveryPrefix, StringComparison.Ordinal)
            && int.TryParse(schedule.AsSpan(EveryPrefix.Length), NumberStyles.None, CultureInfo.InvariantCulture, out int minutes))
        {
            return minutes >= 60
                ? Result<int?>.Ok(minutes)
                : Result<int?>.Fail(MoShiroErrors.ValidationFailed, "every:N requires N >= 60 minutes");
        }

        return Result<int?>.Fail(MoShiroErrors.ValidationFailed, "schedule must be continuous, once or every:<minutes>");
    }
}