namespace ScreenJob.WindowsServiceHost;

internal sealed record ServiceOptions(
    string BackendScriptPath,
    string WorkingDirectory,
    string LogDirectory)
{
    public static ServiceOptions Parse(string[] args)
    {
        var map = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);

        for (var i = 0; i < args.Length; i++)
        {
            var raw = args[i];
            if (!raw.StartsWith("--", StringComparison.Ordinal))
            {
                continue;
            }

            var key = raw[2..];
            if (string.IsNullOrWhiteSpace(key))
            {
                continue;
            }

            if (i + 1 < args.Length && !args[i + 1].StartsWith("--", StringComparison.Ordinal))
            {
                map[key] = args[++i];
            }
            else
            {
                map[key] = "true";
            }
        }

        if (!map.TryGetValue("backend-script", out var backendScript) || string.IsNullOrWhiteSpace(backendScript))
        {
            throw new ArgumentException("Missing required argument: --backend-script <absolute-path-to-start_backend.ps1>.");
        }

        if (!Path.IsPathRooted(backendScript))
        {
            throw new ArgumentException("The --backend-script value must be an absolute path.");
        }

        if (!File.Exists(backendScript))
        {
            throw new FileNotFoundException("Backend script not found.", backendScript);
        }

        if (!map.TryGetValue("working-dir", out var workingDir) || string.IsNullOrWhiteSpace(workingDir))
        {
            workingDir = Path.GetDirectoryName(backendScript)
                ?? throw new ArgumentException("Could not resolve working directory from backend script path.");
        }

        if (!Path.IsPathRooted(workingDir))
        {
            throw new ArgumentException("The --working-dir value must be an absolute path.");
        }

        if (!map.TryGetValue("log-dir", out var logDir) || string.IsNullOrWhiteSpace(logDir))
        {
            logDir = Path.Combine(workingDir, "screenjob_runs", "service");
        }

        if (!Path.IsPathRooted(logDir))
        {
            throw new ArgumentException("The --log-dir value must be an absolute path.");
        }

        return new ServiceOptions(
            Path.GetFullPath(backendScript),
            Path.GetFullPath(workingDir),
            Path.GetFullPath(logDir));
    }
}