const { Glib } = require('../../lib');

const calculateChecksum = (string) => {
  return Array.from(string.characterFrequencies.entries())
    .sort(([a, af], [b, bf]) => {
      if (af > bf) {
        return -1;
      } else if (af < bf) {
        return 1;
      }
      return a.charCodeAt(0) - b.charCodeAt(0);
    })
    .glib.take(5)
    .map(([a]) => a).string;
};

const START_CHAR_CODE = 'a'.charCodeAt(0);
const decrypt = (name, sectorId) => {
  let outputString = '';
  for (let i = 0; i < name.length; i++) {
    const letterNum = name.charCodeAt(i) - START_CHAR_CODE;
    const decryptedLetterNum = (letterNum + sectorId) % 26;
    outputString += String.fromCharCode(decryptedLetterNum + START_CHAR_CODE);
  }
  return outputString;
};

const parse = (input) =>
  Glib.fromLines(input)
    .map((room) => {
      let [first, checksum] = room.split('[');
      checksum = checksum.slice(0, -1);
      const splits = first.split('-');
      const name = splits.slice(0, -1).join('-');
      const sectorId = parseInt(splits.slice(-1), 10);
      return { name, sectorId, checksum };
    })
    .filter(({ name, checksum }) => {
      const cleanName = name.split('-').join('');
      return calculateChecksum(cleanName) === checksum;
    });

module.exports = {
  '1': (input) =>
    parse(input)
      .map(({ sectorId }) => sectorId)
      .toInts()
      .sum(),
  '2': (input) =>
    parse(input)
      .filter(
        ({ name, sectorId }) =>
          name
            .split('-')
            .map((component) => decrypt(component, sectorId))
            .join('-') === 'northpole-object-storage',
      )
      .first().sectorId,
};