using System;
using System.Collections.Generic;
using static DDD.SpawnScheduleUtils;

namespace DDD
{
    public class RegularSpawnScheduleBuilder : ISpawnScheduleBuilder
    {
        public SpawnSchedule Build(SpawnScheduleBuildArgs args)
        {
            int normalQuota  = Math.Max(0, args.NormalQuota);
            int specialQuota = Math.Max(0, args.SpecialQuota);
            if (args.NormalIds  == null || args.NormalIds.Count  == 0) normalQuota  = 0;
            if (args.SpecialIds == null || args.SpecialIds.Count == 0) specialQuota = 0;

            var kinds = BuildProportionalKinds(normalQuota, specialQuota);

            int normalIndex = 0, specialIndex = 0;
            var result = new List<string>(kinds.Count);

            foreach (var kind in kinds)
            {
                if (kind == CustomerType.Special)
                {
                    var id = NextRoundRobin(args.SpecialIds, ref specialIndex);
                    if (!string.IsNullOrEmpty(id)) result.Add(id);
                }
                else
                {
                    var id = NextRoundRobin(args.NormalIds, ref normalIndex);
                    if (!string.IsNullOrEmpty(id)) result.Add(id);
                }
            }

            return new SpawnSchedule(result);
        }
    }
}