using System;
using System.Collections.Generic;
using System.Linq;

namespace Implab.Automaton.RegularExpressions {
    public class RegularDFADefinition<TInput, TTag> : DFATable {

        readonly Dictionary<int,TTag[]> m_tags = new Dictionary<int, TTag[]>();
        readonly IAlphabet<TInput> m_alphabet;

        public RegularDFADefinition(IAlphabet<TInput> alphabet) {
            Safe.ArgumentNotNull(alphabet, "aplhabet");

            m_alphabet = alphabet;
        }


        public IAlphabet<TInput> InputAlphabet {
            get {
                return m_alphabet;
            }
        }

        protected override DFAStateDescriptior[] ConstructTransitionTable() {
            if (InputAlphabet.Count != m_alphabet.Count)
                throw new InvalidOperationException("The alphabet doesn't match the transition table");
            
            return base.ConstructTransitionTable();
        }

        public void MarkFinalState(int s, TTag[] tags) {
            MarkFinalState(s);
            SetStateTag(s, tags);
        }

        public void SetStateTag(int s, TTag[] tags) {
            Safe.ArgumentNotNull(tags, "tags");
            m_tags[s] = tags;
        }

        public TTag[] GetStateTag(int s) {
            TTag[] tags;
            return m_tags.TryGetValue(s, out tags) ? tags : new TTag[0];
        }

        /// <summary>
        /// Optimize the specified alphabet.
        /// </summary>
        /// <param name="alphabet">Пустой алфавит, который будет зполнен в процессе оптимизации.</param>
        public RegularDFADefinition<TInput,TTag> Optimize(IAlphabetBuilder<TInput> alphabet) {
            Safe.ArgumentNotNull(alphabet, "alphabet");

            var dfaTable = new RegularDFADefinition<TInput, TTag>(alphabet);

            var states = new DummyAlphabet(StateCount);
            var map = new MapAlphabet<int>();

            Optimize(dfaTable, InputAlphabet, alphabet, states, map); 

            foreach (var g in m_tags.Where(x => x.Key < StateCount).GroupBy(x => map.Translate(x.Key), x => x.Value ))
                dfaTable.SetStateTag(g.Key, g.SelectMany(x => x).ToArray());

            return dfaTable;
        }


    }
}