using System.Diagnostics;
using SSPCTester.Devices.Interfaces;

namespace SSPCTester.Logic.Testing;

/// <summary>基础通断测试的统一判定规则。</summary>
public static class BasicTestCriteria
{
    public const double OnVoltageThreshold = 1.0;
    public const double OffVoltageThreshold = 0.5;
    public const int SwitchSettleDelayMs = 1_000;
    public const int OffSettleTimeoutMs = 2_000;
    public const int OffInitialDelayMs = 100;
    public const int OffSampleIntervalMs = 100;
    public const int RequiredStableOffSamples = 2;

    public static bool IsOn(double voltage) => voltage > OnVoltageThreshold;

    public static bool IsOff(double voltage) => Math.Abs(voltage) < OffVoltageThreshold;

    /// <summary>
    /// 等待关断电压稳定。连续多次低于阈值才确认关断，避免旧帧和瞬时噪声造成误判。
    /// </summary>
    public static async Task<OffStateResult> WaitForStableOffAsync(
        ISspc sspc,
        int channel,
        CancellationToken ct = default)
    {
        await Task.Delay(OffInitialDelayMs, ct).ConfigureAwait(false);

        var stopwatch = Stopwatch.StartNew();
        int stableSamples = 0;
        ChannelMeasurement? latest = null;

        while (stopwatch.ElapsedMilliseconds < OffSettleTimeoutMs)
        {
            latest = await sspc.ReadMeasurementAsync(channel, ct).ConfigureAwait(false);
            stableSamples = IsOff(latest.Voltage) ? stableSamples + 1 : 0;

            if (stableSamples >= RequiredStableOffSamples)
                return new OffStateResult(true, latest, stopwatch.Elapsed);

            await Task.Delay(OffSampleIntervalMs, ct).ConfigureAwait(false);
        }

        latest ??= await sspc.ReadMeasurementAsync(channel, ct).ConfigureAwait(false);
        return new OffStateResult(false, latest, stopwatch.Elapsed);
    }
}

public sealed record OffStateResult(
    bool IsStableOff,
    ChannelMeasurement Measurement,
    TimeSpan Elapsed);