namespace Sdt.Cli;

public static class CliParser
{
    private static readonly HashSet<string> SubcommandRoots = new(StringComparer.OrdinalIgnoreCase)
    {
        "workspace",
        "bridge",
        "setup",
        "doctor",
        "env",
        "favorite",
        "config",
    };

    public static CliInvocation Parse(IReadOnlyList<string> args)
    {
        if (args.Count == 0)
            return new CliInvocation("interactive", null, [], new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase));

        if (args.Any(a => string.Equals(a, "--plain", StringComparison.OrdinalIgnoreCase)))
            ApplyPlainOutputMode();

        if (args.Count == 1 &&
            (string.Equals(args[0], "--help", StringComparison.OrdinalIgnoreCase) ||
             string.Equals(args[0], "-h", StringComparison.OrdinalIgnoreCase) ||
             string.Equals(args[0], "help", StringComparison.OrdinalIgnoreCase)))
        {
            return new CliInvocation("help", null, [], new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase));
        }

        if (args.Count == 1 &&
            (string.Equals(args[0], "init", StringComparison.OrdinalIgnoreCase) ||
             string.Equals(args[0], "--init", StringComparison.OrdinalIgnoreCase)))
        {
            return new CliInvocation("init", null, [], new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase));
        }

        var command = args[0];
        string? subcommand = null;
        var optionStart = args.Count;

        if (SubcommandRoots.Contains(command) &&
            args.Count > 1 &&
            !args[1].StartsWith("-", StringComparison.Ordinal))
        {
            subcommand = args[1];
            optionStart = 2;
        }
        else
        {
            optionStart = 1;
        }

        var tail = args.Skip(optionStart).ToArray();
        var options = ParseOptions(tail, out var positional);

        return new CliInvocation(command, subcommand, positional, options);
    }

    private static Dictionary<string, string?> ParseOptions(string[] args, out List<string> positional)
    {
        var options = new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase);
        positional = [];
        for (var i = 0; i < args.Length; i++)
        {
            var token = args[i];
            if (!token.StartsWith("-", StringComparison.Ordinal))
            {
                positional.Add(token);
                continue;
            }

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

        return options;
    }

    private static void ApplyPlainOutputMode()
    {
        Environment.SetEnvironmentVariable("NO_COLOR", "1");
        Environment.SetEnvironmentVariable("SDT_NO_COLOR", "1");
        Environment.SetEnvironmentVariable("SDT_NO_UNICODE", "1");
    }
}