using System.Text.Json;

using MoShiro.Protocol;

namespace MoShiro.Backend.Application;

public sealed record PhaseSpec(string Kind, IReadOnlyDictionary<string, JsonElement> Overrides, int DurationSeconds);

/// <summary>
/// 测试方案：业务层的概念，只在 Backend。方案只是若干采集原语（Kind）阶段的编排，采集层（Agent、Measurement）不认识它。
/// 测试方案：多个阶段的 once 任务组合（例如 hy2_ladder 在 10、25、50、100 Mbps 下各跑 10 秒）。</summary>
public sealed record PlanSpec(string Id, string Title, string Description, IReadOnlyList<PhaseSpec> Phases);

public static class Plans
{
    private static JsonElement N(double value) => JsonSerializer.SerializeToElement(value, PlanJson.Default.Double);

    private static JsonElement S(string value) => JsonSerializer.SerializeToElement(value, PlanJson.Default.String);

    private static PhaseSpec Train(double mbps) =>
        new("quic_stream", new Dictionary<string, JsonElement> { ["mbps"] = N(mbps), ["duration_s"] = N(10) }, 10);

    public static readonly PlanSpec Hy2Ladder = new(
        "hy2_ladder",
        "Hysteria2 ladder",
        "UDP train at 10, 25, 50 and 100 Mbit/s for 10 s each; models Brutal fixed-rate congestion control.",
        [Train(10), Train(25), Train(50), Train(100)]);

    public static readonly PlanSpec RealitySession = new(
        "reality_session",
        "REALITY session",
        "Connection establishment, a short (4 s) bulk transfer for the peak throughput and a held connection.",
        [
            new PhaseSpec("tcp_connect", new Dictionary<string, JsonElement> { ["per_minute"] = N(20) }, 30),
            new PhaseSpec("tcp_transfer", new Dictionary<string, JsonElement> { ["duration_s"] = N(4), ["direction"] = S("rev") }, 4),
            new PhaseSpec("tls_hold", new Dictionary<string, JsonElement> { ["heartbeat_s"] = N(5) }, 30),
        ]);

    public static readonly IReadOnlyList<PlanSpec> All = [Hy2Ladder, RealitySession];

    public static PlanSpec? Find(string id)
    {
        foreach (PlanSpec plan in All)
        {
            if (plan.Id == id)
            {
                return plan;
            }
        }

        return null;
    }
}

[System.Text.Json.Serialization.JsonSerializable(typeof(double))]
[System.Text.Json.Serialization.JsonSerializable(typeof(string))]
internal sealed partial class PlanJson : System.Text.Json.Serialization.JsonSerializerContext;