using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using HeuristicLab.Common;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Algorithms.DataAnalysis.SymRegGrammarEnumeration.GrammarEnumeration {
  [StorableClass]
  public class SymbolString : DeepCloneable, IEnumerable<Symbol> {
    [Storable]
    private readonly Symbol[] symbols;

    public Symbol this[int index] {
      get { return symbols[index]; }
    }

    public SymbolString(IEnumerable<Symbol> s) {
      symbols = s.ToArray();
    }

    public SymbolString(params Symbol[] s) {
      symbols = s;
    }

    [StorableConstructor]
    protected SymbolString(bool deserializing) { }

    protected SymbolString(SymbolString original, Cloner cloner) : base(original, cloner) {
      symbols = original.symbols.Select(cloner.Clone).ToArray();
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new SymbolString(this, cloner);
    }

    public bool IsSentence() {
      return !this.Any(sym => sym is NonterminalSymbol);
    }

    public int[] GetNonterminalSymbolIndexes() {
      return Enumerable.Range(0, symbols.Length)
        .Where(i => symbols[i] is NonterminalSymbol)
        .ToArray();
    }

    public int NextNonterminalIndex() {
      Debug.Assert(!IsSentence());
      int firstNonTerminalIndex = 0;
      while (firstNonTerminalIndex < symbols.Length && symbols[firstNonTerminalIndex] is TerminalSymbol) {
        firstNonTerminalIndex++;
      }
      return firstNonTerminalIndex;
    }

    public SymbolString DerivePhrase(int nonterminalSymbolIndex, Production production) {
      int productionLength = production.Count;
      int newStringLength = Count() + productionLength - 1;
      Symbol[] newPhrase = new Symbol[newStringLength];

      // Copy "left" part of the phrase
      Array.Copy(symbols, 0, newPhrase, 0, nonterminalSymbolIndex);
      // Copy production and overwrite nonterminalsymbol
      production.CopyTo(0, newPhrase, nonterminalSymbolIndex, productionLength);
      // Copy "right" part of the original phrase
      Array.Copy(symbols, nonterminalSymbolIndex + 1, newPhrase, nonterminalSymbolIndex + productionLength, symbols.Length - nonterminalSymbolIndex - 1);

      return new SymbolString(newPhrase);
    }

    public override string ToString() {
      return string.Join<Symbol>(" ", symbols);
    }

    #region Enumerable interface
    IEnumerator IEnumerable.GetEnumerator() {
      return GetEnumerator();
    }

    public IEnumerator<Symbol> GetEnumerator() {
      return ((IEnumerable<Symbol>)symbols).GetEnumerator();
    }

    public int Count() {
      return symbols.Length;
    }
    #endregion
  }
}