/**
 * Brute force the string
 * @param {Number} len
 * @param {Function} checkFunc that return Promise resolved to boolean if bruted value is matching
 * @returns {Promise} Result of brute force
 */
const bruteString = (len, checkFunc) => {
    const startTime = Date.now();
    const symbols = [..."0123456789qwertyuiopasdfghjklzzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM!@#$%^&*()_-=+{}[]\\|?/.>,<;:'\"`~"];
    const limit = Math.pow(symbols.length, len) - 1;
    const loopLimit = 32767;
    const loopDelay = 10;
    const infoIntervalDelay = 1000;

    const wordIndexArray = [];
    for (let i = 0; i < len; i++) wordIndexArray.push(0);

    let totalIterations = 0;
    let finished = false;

    const updateIndexes = () => {
        let changingSymbol = 0;
        let shift = true;
        while (shift) {
          if (changingSymbol > wordIndexArray.length - 1) {
            finished = true;
            shift = false;
          } else if (wordIndexArray[changingSymbol] < symbols.length - 1) {
            wordIndexArray[changingSymbol]++;
            shift = false;
          } else {
            wordIndexArray[changingSymbol] = 0;
            changingSymbol++;
          }
        }
      };

      const nextWord = () => {
        totalIterations++;
        let word = "";
        for (let i = 0; i < len; i++) word += symbols[wordIndexArray[i]];
        updateIndexes();
        return word;
      };

      function* brute() {
        while (true) {
            let guess = nextWord();
            if (finished) return null;
            let match = yield checkFunc(guess);
            if (match) return guess;
            yield null;
      }
    }

    const getTimeString = (time) => {
        const seconds = Math.floor(time / 1000)
        const minutes = Math.floor(seconds / 60)
        const hours = Math.floor(minutes / 60)
        const days = Math.floor(hours / 24)
        switch (true) {
            case days >= 1:
                return `${days} days`
            case hours >= 1:
                return `${hours} hours ${minutes % 60} minutes`
            case minutes >= 1:
                return `${minutes} minutes ${seconds % 60} seconds`
            default:
                return `${seconds} seconds`
                break;
        }
    }

    // Spams info on bruteforce process
    const infoInterval = setInterval(() => {
        let doneCoef = totalIterations / limit;
        let intPrs = Math.round(doneCoef * 100);
        const durationTime = Date.now() - startTime;
        const timeLeft = Math.round(durationTime / doneCoef) - durationTime;
        console.info(`Progress: ${(intPrs * 100) / 100}% (${totalIterations} / ${limit})\nTime running: ${getTimeString(durationTime)}\nTime left: ${getTimeString(timeLeft)}`)
       }, infoIntervalDelay);

    return new Promise((resolve, reject) => {
        const generatorInstance = brute();
        const generatorRunner = (result) => {
            const nextIteration = () => {
                if (result.value !== null && typeof result.value.then === "function") {
                    result.value.then((check) => {
                        generatorRunner(generatorInstance.next(check));
                    })
                } else {
                    generatorRunner(generatorInstance.next());
                }
            };

            if (result.done) {
                clearTimeout(infoInterval);
                if (result.value !== null) {
                    resolve(result.value);
                }
                else reject("No match found")
            } else {
                if (totalIterations % loopLimit === 0) {
                    setTimeout(() => {
                        nextIteration();
                    }, loopDelay)
                } else {
                    nextIteration();
                }
            }
        };
        generatorRunner(generatorInstance.next())
    });
  };

  // exemple of usage

  const correctCheck = (value) => {
    return Promise.resolve(value === "pass")
  }

  bruteString(4, correctCheck)
    .then((res) => {
        console.log("Match found:", res);
    })
    .catch((err) => {
        console.error(err);
    });