using System;
using System.Text;

namespace LibHacBuild.CodeGen
{
    public class IndentingStringBuilder
    {
        public int LevelSize { get; set; } = 4;
        public int Level { get; private set; }

        private StringBuilder _sb = new StringBuilder();
        private string _indentation = string.Empty;
        private bool _hasIndentedCurrentLine;

        public IndentingStringBuilder() { }
        public IndentingStringBuilder(int levelSize) => LevelSize = levelSize;

        public void SetLevel(int level)
        {
            Level = Math.Max(level, 0);
            _indentation = new string(' ', Level * LevelSize);
        }

        public void IncreaseLevel() => SetLevel(Level + 1);
        public void DecreaseLevel() => SetLevel(Level - 1);

        public IndentingStringBuilder AppendLine()
        {
            _sb.AppendLine();
            _hasIndentedCurrentLine = false;
            return this;
        }

        public IndentingStringBuilder AppendLine(string value)
        {
            IndentIfNeeded();
            _sb.AppendLine(value);
            _hasIndentedCurrentLine = false;
            return this;
        }

        public IndentingStringBuilder Append(string value)
        {
            IndentIfNeeded();
            _sb.Append(value);
            return this;
        }

        public IndentingStringBuilder AppendLineAndIncrease(string value)
        {
            AppendLine(value);
            IncreaseLevel();
            return this;
        }

        public IndentingStringBuilder DecreaseAndAppendLine(string value)
        {
            DecreaseLevel();
            AppendLine(value);
            return this;
        }

        private void IndentIfNeeded()
        {
            if (!_hasIndentedCurrentLine)
            {
                _sb.Append(_indentation);
                _hasIndentedCurrentLine = true;
            }
        }

        public override string ToString() => _sb.ToString();
    }
}