using Evergreen.Health.Application.Health.Models;

namespace Evergreen.Health.Application.Health.Policies;

public sealed record RecommendedRoomRange(int Minimum, int Maximum)
{
    public static RecommendedRoomRange Default { get; } = new(22, 25);
    public string Display => $"{Minimum}–{Maximum}℃";
    public static RecommendedRoomRange ForConstitution(string code) => code switch
    {
        "yang_deficient" => new(24, 26), "yin_deficient" or "damp_heat" => new(21, 24),
        "phlegm_damp" => new(22, 24), "blood_stasis" => new(23, 25), _ => Default
    };
}

public enum IndoorTemperatureIssue { Unavailable, Stale, Invalid }

public sealed record IndoorTemperatureSample(double? Celsius, DateTimeOffset? ObservedAt, bool Available, string Reason)
{
    public IndoorTemperatureIssue? Issue { get; init; }
}

public static class RoomTemperaturePolicy
{
    public static ClimateAdviceOutput Evaluate(IndoorTemperatureSample sample, RecommendedRoomRange range)
    {
        var mode = !sample.Available || sample.Celsius is null ? "unavailable"
            : sample.Celsius < range.Minimum ? "heat" : sample.Celsius > range.Maximum ? "cool" : "off";
        return new()
        {
            Mode = mode, RecommendedMinimumCelsius = range.Minimum, RecommendedMaximumCelsius = range.Maximum,
            Reason = mode switch
            {
                "heat" => $"室温低于建议 {range.Display}：建议空调制热",
                "cool" => $"室温高于建议 {range.Display}：建议空调制冷",
                "off" => $"室温在建议 {range.Display} 内：空调保持当前运行状态",
                _ => $"{sample.Reason}，不自动开启空调"
            },
            PendingIntegration = mode is "heat" or "cool"
        };
    }

    // 仅在启动新舒睡场景时调用，状态查询和预览不随机更改目标值。
    public static void PickTargetForSession(ClimateAdviceOutput advice)
    {
        if (advice.TargetTemperatureCelsius is null && (advice.Mode is "heat" or "cool"))
            advice.TargetTemperatureCelsius = Random.Shared.Next(advice.RecommendedMinimumCelsius,
                advice.RecommendedMaximumCelsius + 1);
    }
}