AOC2021/AOC2021/Models/Day10/ChunkReader.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace AOC2021.Models.Day10
{
    public class ChunkReader
    {
        private Stack<char> _stack;
        private string _inputLine;
        public ChunkReader(string line)
        {
            this._inputLine = line;
            this._stack = new Stack<char>();
        }

        public ChunkReaderResult Process()
        {
            var result = new ChunkReaderResult() { Line = this._inputLine };
            foreach (char c in this._inputLine)
            {
                //Implies its an opening char so we sent to stack
                if (isOpeningChar(c))
                {
                    _stack.Push(c);
                    continue;
                }
                if (_stack.Peek() == GetCorrespondingChar(c))
                {
                    _stack.Pop();
                }
                else
                {
                    result.CorruptedChar = c;
                    result.ExpectedChar = GetCorrespondingChar(_stack.Peek());
                    result.isCorrupted = true;
                    break;
                }
            }
            if (!result.isCorrupted)
            {
                if (this._stack.Count == 0)
                    result.isValid = true;
                else
                {
                    result.isIncomplete = true;
                    while (_stack.Count() > 0)
                    {
                        result.CompletionString += GetCorrespondingChar(_stack.Pop());
                    }
                }
            }
            return result;
        }

        private bool isOpeningChar(char c)
        {
            if (c == '(' || c == '[' || c == '{' || c == '<')
                return true;
            return false;
        }

        private char GetCorrespondingChar(char c)
        {
            switch (c)
            {
                case '(':
                    return ')';
                case '[':
                    return ']';
                case '{':
                    return '}';
                case '<':
                    return '>';
                case ')':
                    return '(';
                case ']':
                    return '[';
                case '}':
                    return '{';
                case '>':
                    return '<';
            }
            throw new Exception("Invalid char given, no corresponing char found for: " + c);
        }
    }
}