import { allowed, words } from './words.server'

export class Game {
  index: number
  guesses: string[]
  answers: string[]
  answer: string

  /**
   * Create a game object from the player's cookie, or initialise a new game
   */
  constructor(serialized: string | undefined = undefined) {
    if (serialized) {
      const [index, guesses, answers] = serialized.split('-')

      this.index = +index
      this.guesses = guesses ? guesses.split(' ') : []
      this.answers = answers ? answers.split(' ') : []
    } else {
      this.index = Math.floor(Math.random() * words.length)
      this.guesses = ['', '', '', '', '', '']
      this.answers = []
    }

    this.answer = words[this.index]
  }

  /**
   * Update game state based on a guess of a five-letter word. Returns
   * true if the guess was valid, false otherwise
   */
  enter(letters: string[]) {
    const word = letters.join('')
    const valid = allowed.has(word)

    if (!valid) return false

    this.guesses[this.answers.length] = word

    const available = Array.from(this.answer)
    const answer = Array(5).fill('_')

    // first, find exact matches
    for (let i = 0; i < 5; i += 1) {
      if (letters[i] === available[i]) {
        answer[i] = 'x'
        available[i] = ' '
      }
    }

    // then find close matches (this has to happen
    // in a second step, otherwise an early close
    // match can prevent a later exact match)
    for (let i = 0; i < 5; i += 1) {
      if (answer[i] === '_') {
        const index = available.indexOf(letters[i])
        if (index !== -1) {
          answer[i] = 'c'
          available[index] = ' '
        }
      }
    }

    this.answers.push(answer.join(''))

    return true
  }

  /**
   * Serialize game state so it can be set as a cookie
   */
  toString() {
    return `${this.index}-${this.guesses.join(' ')}-${this.answers.join(' ')}`
  }
}