using System;
using System.Collections.Generic;

namespace Glass.PerformanceTests
{
    /// <summary>
    /// What the command line narrows a full run to.
    /// </summary>
    public sealed class RunOptions
    {
        public const string OptionPrefix = "--";
        public const string SteadyOnlyOption = OptionPrefix + "steady-only";

        public const string Usage =
            "Usage: Glass.PerformanceTests [--x86] [--x64] [--steady-only] [text in the scenario names to run]";

        public string ScenarioFilter = "";

        /// <summary>
        /// Labels of the bitnesses to run; empty runs every one that's built.
        /// </summary>
        public readonly HashSet<string> Bitnesses = new HashSet<string>();

        public bool SteadyOnly;

        public bool Wants(string bitness)
        {
            return Bitnesses.Count == 0 || Bitnesses.Contains(bitness);
        }

        /// <summary>
        /// Null when the command line is malformed.
        /// </summary>
        public static RunOptions Parse(string[] args)
        {
            var returnMe = new RunOptions();
            bool sawFilter = false;
            foreach (string arg in args)
            {
                if (arg == SteadyOnlyOption)
                {
                    returnMe.SteadyOnly = true;
                }
                else if (arg == OptionPrefix + ProcessVariant.X86 || arg == OptionPrefix + ProcessVariant.X64)
                {
                    returnMe.Bitnesses.Add(arg.Substring(OptionPrefix.Length));
                }
                else if (arg.StartsWith(OptionPrefix, StringComparison.Ordinal) || sawFilter)
                {
                    return null;
                }
                else
                {
                    returnMe.ScenarioFilter = arg;
                    sawFilter = true;
                }
            }

            return returnMe;
        }
    }
}