namespace Yuuna.Contracts.Patterns
{
    using System;
    using System.Collections;
    using System.Collections.Concurrent;
    using System.Collections.Generic;
    using System.Collections.Immutable;
    using System.Diagnostics;
    using System.Diagnostics.CodeAnalysis;
    using System.Linq;
    using System.Text;
    using Yuuna.Contracts.Interaction;
    using Yuuna.Contracts.Optimization;
    using Yuuna.Contracts.Semantics;



    internal sealed class PatternBuilder :  IGrammarSet, IPatternBuilder 
    {
        private readonly ImmutableDictionary<IGrammar, Behaviour>.Builder _rules;
        internal PatternBuilder() 
        {
            this._rules = ImmutableDictionary.CreateBuilder<IGrammar, Behaviour>(EqualityComparer<IGrammar>.Default); 
        }
        public IImmutableList<IGrammar> ToImmutable()
        {
            return this._rules.Keys.ToImmutableArray();
        }
        public bool TryGet(IGrammar grammar, out Behaviour behaviour)
        {
            return this._rules.TryGetValue(grammar, out behaviour);
        } 
        IBehaviourBuilder IPatternBuilder.Build(IGroup group, params IGroup[] rest)
        {
            if (group is null)
                throw new ArgumentNullException(nameof(group));
            var g = new Grammar();
            g.Add(group);
            if (rest != null)
                foreach (var item in rest)
                {
                    g.Add(item);
                }
            g.Immute();
            return new BehaviourBuilder(this._rules.Add, g);
        }

    }

}