using System.Text.Json;
using System.Text.Json.Serialization;

namespace ChromeboxFanControl;

public sealed class AppConfig
{
    /// <summary>UI language: "auto" (system), "en", "zh-Hans", "zh-Hant". Restart to apply.</summary>
    public string Language { get; set; } = "auto";
    public string EctoolPath { get; set; } = @"C:\Program Files\crosec\ectool.exe";
    public int PollIntervalMs { get; set; } = 1500;
    /// <summary>Call ectool for RPM every N control cycles (1 = every cycle).</summary>
    public int FanRpmPollEveryNCycles { get; set; } = 1;
    public string[] FanRpmArgs { get; set; } = ["pwmgetfanrpm", "0"];
    /// <summary>Ectool args to read fan duty (0-100). Empty = skip, use commanded duty.</summary>
    public string[]? FanDutyArgs { get; set; }
    public string[] AutoFanCtrlArgs { get; set; } = ["autofanctrl"];
    public string TempSource { get; set; } = "AverageCore";
    public int RampUpSteps { get; set; } = 3;
    public int RampUpMinDeltaPercent { get; set; } = 20;
    public int FailSafeAfterConsecutiveErrors { get; set; } = 5;
    public int FailSafeFanPercent { get; set; } = 100;
    public bool FailSafeRestoreAutoFan { get; set; }
    public int ChartHistoryMinutes { get; set; } = 15;
    public int ChartMaxPoints { get; set; } = 900;
    public int[] CurvePoints { get; set; } =
    [
        0, 0, 10, 25, 40, 55, 70, 80, 90, 95, 97, 98, 99, 100
    ];

    public static JsonSerializerOptions JsonOptions { get; } = new()
    {
        WriteIndented = true,
        PropertyNameCaseInsensitive = true,
        Converters = { new JsonStringEnumConverter() }
    };

    public static string UserConfigPath =>
        Path.Combine(
            Environment.UserInteractive
                ? Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)
                : Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData),
            "ChromeboxFanControl",
            "config.json");

    public static AppConfig LoadMerged()
    {
        var cfg = new AppConfig();
        var baseDir = AppContext.BaseDirectory;
        var appSettings = Path.Combine(baseDir, "appsettings.json");
        if (File.Exists(appSettings))
            ApplyJson(File.ReadAllText(appSettings), cfg);

        if (File.Exists(UserConfigPath))
        {
            try
            {
                ApplyJson(File.ReadAllText(UserConfigPath), cfg);
            }
            catch
            {
                /* keep base */
            }
        }

        return cfg;
    }

    private static void ApplyJson(string json, AppConfig dst)
    {
        var src = JsonSerializer.Deserialize<AppConfig>(json, JsonOptions);
        if (src == null)
            return;

        if (!string.IsNullOrEmpty(src.Language))
            dst.Language = src.Language;
        dst.EctoolPath = src.EctoolPath;
        dst.PollIntervalMs = Math.Clamp(src.PollIntervalMs, 250, 60_000);
        dst.FanRpmPollEveryNCycles = Math.Max(1, src.FanRpmPollEveryNCycles);
        if (src.FanRpmArgs is { Length: > 0 })
            dst.FanRpmArgs = src.FanRpmArgs;
        dst.FanDutyArgs = src.FanDutyArgs;
        if (src.AutoFanCtrlArgs is { Length: > 0 })
            dst.AutoFanCtrlArgs = src.AutoFanCtrlArgs;
        dst.TempSource = string.Equals(src.TempSource, "MaxCore", StringComparison.OrdinalIgnoreCase) ? "MaxCore" : "AverageCore";
        dst.RampUpSteps = Math.Clamp(src.RampUpSteps, 1, 10);
        dst.RampUpMinDeltaPercent = Math.Clamp(src.RampUpMinDeltaPercent, 0, 50);
        dst.FailSafeAfterConsecutiveErrors = Math.Max(1, src.FailSafeAfterConsecutiveErrors);
        dst.FailSafeFanPercent = Math.Clamp(src.FailSafeFanPercent, 0, 100);
        dst.FailSafeRestoreAutoFan = src.FailSafeRestoreAutoFan;
        dst.ChartHistoryMinutes = Math.Clamp(src.ChartHistoryMinutes, 1, 120);
        dst.ChartMaxPoints = src.ChartMaxPoints > 0 ? src.ChartMaxPoints : 900;
        if (src.CurvePoints is { Length: 14 })
            dst.CurvePoints = (int[])src.CurvePoints.Clone();
        else if (src.CurvePoints is { Length: 13 } old13)
            dst.CurvePoints = MigrateCurveTo14(old13);
        else if (src.CurvePoints is { Length: 20 } old20)
            dst.CurvePoints = MigrateCurveTo14(old20, new[] { 0, 5, 11, 16, 21, 26, 32, 37, 42, 47, 53, 58, 63, 68, 74, 79, 84, 90, 95, 100 });
    }

    private static int[] MigrateCurveTo14(int[] oldCurve, int[]? oldTemps = null)
    {
        var temps = oldTemps ?? (oldCurve.Length == 13 ? new[] { 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 } : new[] { 0, 5, 11, 16, 21, 26, 32, 37, 42, 47, 53, 58, 63, 68, 74, 79, 84, 90, 95, 100 });
        var newTemps = FanCurve.TempBreakpoints;
        var result = new int[14];
        for (var i = 0; i < 14; i++)
        {
            var t = newTemps[i];
            if (t <= temps[0])
                result[i] = Math.Clamp(oldCurve[0], 0, 100);
            else if (t >= temps[^1])
                result[i] = Math.Clamp(oldCurve[^1], 0, 100);
            else
            {
                for (var j = 0; j < temps.Length - 1; j++)
                {
                    if (t < temps[j + 1])
                    {
                        var frac = (t - temps[j]) / (double)(temps[j + 1] - temps[j]);
                        result[i] = (int)Math.Round(Math.Clamp(oldCurve[j], 0, 100) + (Math.Clamp(oldCurve[j + 1], 0, 100) - Math.Clamp(oldCurve[j], 0, 100)) * frac);
                        break;
                    }
                }
            }
        }
        return result;
    }

    public void SaveUser()
    {
        var dir = Path.GetDirectoryName(UserConfigPath);
        if (!string.IsNullOrEmpty(dir))
            Directory.CreateDirectory(dir);
        File.WriteAllText(UserConfigPath, JsonSerializer.Serialize(this, JsonOptions));
    }
}