using System.Diagnostics;
using System.Text.RegularExpressions;

namespace ChromeboxFanControl;

public sealed class EctoolRunner
{
    private static readonly Regex NumberRegex = new(@"\d+", RegexOptions.Compiled);

    public static (bool ok, string stdout, string stderr) RunSync(
        string exePath,
        IReadOnlyList<string> args,
        int timeoutMs = 15_000) =>
        RunAsync(exePath, args, CancellationToken.None, timeoutMs).GetAwaiter().GetResult();

    public static async Task<(bool ok, string stdout, string stderr)> RunAsync(
        string exePath,
        IReadOnlyList<string> args,
        CancellationToken ct = default,
        int timeoutMs = 15_000)
    {
        if (string.IsNullOrWhiteSpace(exePath) || !File.Exists(exePath))
            return (false, "", "ectool executable not found.");

        var psi = new ProcessStartInfo
        {
            FileName = exePath,
            UseShellExecute = false,
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            CreateNoWindow = true,
        };
        foreach (var a in args)
            psi.ArgumentList.Add(a);

        using var proc = new Process { StartInfo = psi };
        try
        {
            proc.Start();
        }
        catch (Exception ex)
        {
            return (false, "", ex.Message);
        }

        var stdoutTask = proc.StandardOutput.ReadToEndAsync(ct);
        var stderrTask = proc.StandardError.ReadToEndAsync(ct);
        var waitTask = proc.WaitForExitAsync(ct);
        var completed = await Task.WhenAny(waitTask, Task.Delay(timeoutMs, ct)).ConfigureAwait(false);
        if (completed != waitTask)
        {
            try
            {
                proc.Kill(entireProcessTree: true);
            }
            catch
            {
                /* ignore */
            }

            return (false, "", "ectool timed out.");
        }

        await waitTask.ConfigureAwait(false);
        var stdout = await stdoutTask.ConfigureAwait(false);
        var stderr = await stderrTask.ConfigureAwait(false);
        var ok = proc.ExitCode == 0;
        return (ok, stdout, stderr);
    }

    /// <summary>Pick the most plausible RPM (typically 500–20000) from ectool text output.</summary>
    public static int? TryParseFanRpm(string stdout)
    {
        if (string.IsNullOrWhiteSpace(stdout))
            return null;

        int? best = null;
        foreach (Match m in NumberRegex.Matches(stdout))
        {
            if (!int.TryParse(m.Value, out var n))
                continue;
            if (n is < 400 or > 50_000)
                continue;
            // Prefer larger numbers in typical fan range (avoid fan index "0")
            if (n >= 800 && (best == null || n > best))
                best = n;
        }

        if (best != null)
            return best;

        foreach (Match m in NumberRegex.Matches(stdout))
        {
            if (int.TryParse(m.Value, out var n) && n is >= 0 and <= 50_000)
                return n;
        }

        return null;
    }

    /// <summary>Pick duty percent (0-100) from ectool text output.</summary>
    public static int? TryParseFanDuty(string stdout)
    {
        if (string.IsNullOrWhiteSpace(stdout))
            return null;

        foreach (Match m in NumberRegex.Matches(stdout))
        {
            if (int.TryParse(m.Value, out var n) && n is >= 0 and <= 100)
                return n;
        }

        return null;
    }
}