using System.Text;
using System.Collections;
using System.Collections.Generic;

namespace HeuristicLab.Problems.ProgramSynthesis {
  /// <summary>
  /// Optimized for string concatenation to reduce memory effort
  /// </summary>
  public class PrintStack : IPrintStack {
    private int lineCount = 0;
    private int length = 0;
    private IReadOnlyList<string> lines;
    private readonly StringBuilder stringBuilder = new StringBuilder();

    public PrintStack() {
      IsCurrentLineEmpty = true;
    }

    public bool IsCurrentLineEmpty { get; private set; }

    IEnumerator IEnumerable.GetEnumerator() {
      return Lines.GetEnumerator();
    }

    public void Add(string item) {
      Push(item);
    }

    public IReadOnlyList<string> Lines {
      get {
        if (lines != null && stringBuilder.Length == length)
          return lines;

        length = stringBuilder.Length;
        lines = stringBuilder.ToString().Split(PushEnvironment.NewLine);

        return lines;
      }
    }

    void IPushStack.Clear() {
      lineCount = 0;
      length = 0;
      lines = null;
      IsCurrentLineEmpty = true;
      stringBuilder.Clear();
    }

    public void NewLine() {
      stringBuilder.Append(PushEnvironment.NewLine);
      IsCurrentLineEmpty = true;
      lineCount++;
    }

    public void Push<T>(T item) {
      if (IsEmpty) lineCount = 1;
      var str = item.ToString();
      stringBuilder.Append(str);
      IsCurrentLineEmpty = IsCurrentLineEmpty && string.IsNullOrEmpty(str);
    }

    public void Push(float item) {
      if (IsEmpty) lineCount = 1;
      stringBuilder.Concat(item);
      IsCurrentLineEmpty = false;
    }

    public void Push(double item) {
      if (IsEmpty) lineCount = 1;
      stringBuilder.Concat(item);
      IsCurrentLineEmpty = false;
    }

    public void Push(long item) {
      if (IsEmpty) lineCount = 1;
      stringBuilder.Concat(item);
      IsCurrentLineEmpty = false;
    }

    public void Push(int item) {
      if (IsEmpty) lineCount = 1;
      stringBuilder.Concat(item);
      IsCurrentLineEmpty = false;
    }

    public void Push(char item) {
      if (IsEmpty) lineCount = 1;
      stringBuilder.Append(item);
      IsCurrentLineEmpty = false;
    }

    public void Push(bool item) {
      if (IsEmpty) lineCount = 1;
      stringBuilder.Append(item);
      IsCurrentLineEmpty = false;
    }

    public void Push(string item) {
      if (IsEmpty) lineCount = 1;
      stringBuilder.Append(item);
      IsCurrentLineEmpty = IsCurrentLineEmpty && string.IsNullOrEmpty(item);
    }

    public void Push(IReadOnlyList<string> items, int startIndex) {
      for (var i = startIndex; i < items.Count; i++)
        stringBuilder.Append(items[i]);

      IsCurrentLineEmpty = false;
    }

    public void Push(IReadOnlyList<string> items) {
      Push(items, 0);
    }

    public void Push(IEnumerable<string> items) {
      foreach (var item in items)
        stringBuilder.Append(item);

      IsCurrentLineEmpty = false;
    }

    public IEnumerable<string> AsStrings() {
      return Lines;
    }

    public IEnumerable<object> AsObjects() {
      return Lines;
    }

    int IPushStack.Count {
      get {
        return lineCount;
      }
    }

    public bool IsEmpty { get { return stringBuilder.Length == 0; } }

    public bool IsEnabled { get; set; }

    public bool IsReadOnly { get { return false; } }

    public override string ToString() {
      return stringBuilder.ToString();
    }
  }
}