namespace KronaStaffTerminal.Services;

public static class CrashLogService
{
    private const long MaximumLogSize = 1_048_576;
    private static readonly object Gate = new();
    private static readonly string LogDirectory = Path.Combine(
        Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData),
        "Krona",
        "StaffTerminal",
        "logs");

    public static void Write(Exception exception)
    {
        try
        {
            lock (Gate)
            {
                Directory.CreateDirectory(LogDirectory);
                var path = Path.Combine(LogDirectory, "crash.log");
                RotateIfNeeded(path);
                var entry = $"[{DateTimeOffset.Now:O}]{Environment.NewLine}{exception}{Environment.NewLine}{Environment.NewLine}";
                File.AppendAllText(path, entry);
            }
        }
        catch
        {
            // Logging must never replace the original application failure.
        }
    }

    public static void WriteDiagnostic(string message)
    {
        try
        {
            lock (Gate)
            {
                Directory.CreateDirectory(LogDirectory);
                var path = Path.Combine(LogDirectory, "diagnostic.log");
                RotateIfNeeded(path);
                var entry = $"[{DateTimeOffset.Now:O}] {message}{Environment.NewLine}";
                File.AppendAllText(path, entry);
            }
        }
        catch
        {
            // Diagnostics must never throw
        }
    }

    private static void RotateIfNeeded(string path)
    {
        if (!File.Exists(path) || new FileInfo(path).Length < MaximumLogSize) return;
        for (var index = 3; index >= 1; index--)
        {
            var source = index == 1 ? path : $"{path}.{index - 1}";
            var destination = $"{path}.{index}";
            if (File.Exists(source)) File.Move(source, destination, true);
        }
    }
}