'use strict';

const LetterGuessResult = Object.freeze({
    MATCH:     Symbol("match"),
    UNUSED:    Symbol("unused"),
    ELSEWHERE: Symbol("elsewhere")
});
function getLetterGuessResultClass(result) {
    return result.toString().slice(7, -1);
}
class GuessResult {
    constructor(guess, correct, letters) {
        this.guess = guess;
        this.correct = correct;
        this.letters = letters;
    }
}
class LetterInfo {
    constructor(letter, wordLength) {
        this.letter = letter;
        this.min = 0;
        this.max = wordLength;
        this.knownMatches = new Set();
        this.knownElsewheres = new Set();
        this.knownNotHere = new Set();
    }
}
class Bagels {
    constructor(word, availableLetters) {
        this.word = word;
        this.numLetters = word.length;

        this.availableLetters = word.split('');
        for (var i = 0; i < availableLetters.length; i++) {
            this.availableLetters = this.availableLetters
                                   .concat(availableLetters[i].split(''));
        }
        this.availableLetters = [...new Set(this.availableLetters)].sort();

        this.guesses = new Array();

        this.knownInformation = {};
        this.availableLetters.forEach(letter => {
            this.knownInformation[letter] = new LetterInfo(letter, word.length);
        });
        this.knownMatches = new Set();
    }

    static generateRandom(settings) {
        if (settings === null) return null;

        let maxIters = 100;
        let iters = 0;

        let regExp = new RegExp('^[a-z]{' + settings.min_word_length + ','
            + settings.max_word_length + '}$');
        let word;
        do {
            word = topWords[1000+getRandomInt(30000)].word;
            if (iters++ > maxIters) return null;
        } while (!regExp.test(word) || !isValidWord(word));

        let numLetters = settings.num_random_letters;
        let availableLetters;
        let availableLettersValid = false;
        do {
            availableLetters = new Set(word.split(''));
            for (let i = 0; i < numLetters; i++) {
                let newLetter;
                do {
                    newLetter = getRandomLetter();
                } while (availableLetters.has(newLetter));
                availableLetters.add(newLetter);
            }
            availableLetters = [...availableLetters];

            if (settings.min_matches <= 1 && settings.max_matches >= topWords.length) {
                availableLettersValid = true;
            } else {
                let preciseRegExp = new RegExp('^[' + availableLetters.join('')
                    + ']{' + word.length + '}$');
                let matchingTopWords = topWords.filter(w => preciseRegExp.test(w.word)).length;
                availableLettersValid = matchingTopWords >= settings.min_matches && matchingTopWords <= settings.max_matches;
            }

            if (!availableLettersValid && iters++ > maxIters) return null;
        } while (!availableLettersValid);

        return new Bagels(word, availableLetters);
    }

    static fromFragment(fragment) {
        try {
            if (!fragment.includes(',')) {
                return null;
            }

            var parts = fragment.split(',');
            var word = parts[0];
            var availableLetters = parts[1];

            // TODO more checks?
            if (!isValidWord(word)) return null;
            if (word.length < 2) return null;

            return new Bagels(word, availableLetters);
        }
        catch(e) {
            return null;
        }
    }

    get fragment() {
        return this.word + ',' + this.availableLetters.sort().join('');
    }

    isValidGuess(guess) {
        var availableLetters = this.availableLetters;
        return guess.length == this.numLetters
            && guess.split('')
                    .every(letter => availableLetters.includes(letter))
            && isValidWord(guess);
    }

    computeGuessResult(guess) {
        if (!this.isValidGuess(guess)) return null;

        var guessArr = guess.split('');
        // Don't compute ELSEWHERE results yet.
        var unmatchedLetters = this.word.split('');

        // From https://blog.mariusschulz.com/2016/07/16/removing-elements-from-javascript-arrays
        function remove(array, element) {
            const index = array.indexOf(element);

            if (index !== -1) {
                array.splice(index, 1);
            }
        }

        var word = this.word;
        var result = guessArr.map(function(guessedLetter, idx) {
            if (word[idx] == guessedLetter) {
                remove(unmatchedLetters, guessedLetter);
                return LetterGuessResult.MATCH;
            }
            return LetterGuessResult.UNUSED;
        });

        if (guess == word) {
            return new GuessResult(guess, true, result);
        }

        for (var i = 0; i < this.numLetters; i++) {
            if (result[i] == LetterGuessResult.UNUSED) {
                if (unmatchedLetters.includes(guessArr[i])) {
                    remove(unmatchedLetters, guessArr[i]);
                    result[i] = LetterGuessResult.ELSEWHERE;
                }
            }
        }

        return new GuessResult(guess, false, result);
    }

    makeGuess(guess) {
        var result = this.computeGuessResult(guess);
        if (result !== null) {
            this.guesses.push(result);
            this.updateKnownInformation(result);
        }
        return result;
    }

    updateKnownInformation(guess) {
        let minTotal = 0;
        for (var letter in this.knownInformation) {
            let info = this.knownInformation[letter];
            let min = 0;
            let timesGuessed = 0;
            let anyUnused = false;
            for (let i=0; i < this.numLetters; i++) {
                if (guess.guess[i] != letter) continue;
                timesGuessed++;

                let res = guess.letters[i];
                if (res == LetterGuessResult.MATCH) {
                    min++;
                    info.knownMatches.add(i);
                    this.knownMatches.add(i);
                } else if (res == LetterGuessResult.ELSEWHERE) {
                    min++;
                    info.knownElsewheres.add(i);
                } else if (res == LetterGuessResult.UNUSED) {
                    info.knownNotHere.add(i);
                    anyUnused = true;
                }
            }
            if (anyUnused) {
                info.max = min;
            }
            info.min = Math.max(info.min, min);

            minTotal += info.min;
        }

        if (minTotal > 0) {
            for (let letter in this.knownInformation) {
                let info = this.knownInformation[letter];
                info.max = Math.min(info.max,
                                    this.numLetters - (minTotal - info.min));
            }
        }
    }
}