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

namespace Language.Lua
{
    public class TextInput : ParserInput<char>
    {
        string InputText;

        List<int> LineBreaks;

        public TextInput(string text)
        {
            InputText = text;

            LineBreaks = new List<int>();
            LineBreaks.Add(0);
            for (int index = 0; index < InputText.Length; index++)
            {
                if (InputText[index] == '\n')
                {
                    LineBreaks.Add(index + 1);
                }
            }
            LineBreaks.Add(InputText.Length);
        }

        #region ParserInput<char> Members

        public int Length
        {
            get { return InputText.Length; }
        }

        public bool HasInput(int pos)
        {
            return pos < InputText.Length;
        }

        public char GetInputSymbol(int pos)
        {
            return InputText[pos];
        }

        public char[] GetSubSection(int position, int length)
        {
            return InputText.Substring(position, length).ToCharArray();
        }

        public string FormErrorMessage(int position, string message)
        {
            int line;
            int col;
            GetLineColumnNumber(position, out line, out col);
            string ch = HasInput(position) ? "'" + GetInputSymbol(position) + "'" : null;
            return String.Format("Line {0}, Col {1} {2}: {3}", line, col, ch, message);
        }

        #endregion

        public void GetLineColumnNumber(int pos, out int line, out int col)
        {
            col = 1;
            for (line = 1; line < LineBreaks.Count; line++)
            {
                if (LineBreaks[line] > pos)
                {
                    for (int p = LineBreaks[line - 1]; p < pos; p++)
                    {
                        if (InputText[p] == '\t')
                        {
                            col += 4;
                        }
                        else
                        {
                            col++;
                        }
                    }
                    break;
                }
            }
        }

        public string GetSubString(int start, int length)
        {
            return InputText.Substring(start, length);
        }
    }
}