let fs = require('fs');
let { logger } = require('./logging');

function getShortestPrefix(radixTree, key, sliceSize) {
    let shortKey = key.substring(0, sliceSize);
    let keyCount = radixTree.countPrefix(shortKey);
    if (keyCount < 1) {
        return null;
    }
    if (key.length === sliceSize && radixTree.getPrefix(shortKey).includes(key)) {
        return null;
    }
    if (keyCount === 1) {
        return shortKey;
    }
    return getShortestPrefix(radixTree, key, sliceSize + 1);
}

function toISODateString(d) {
    function pad(n) { return n < 10 ? '0' + n : n }
    return d.getUTCFullYear() + '-'
        + pad(d.getUTCMonth() + 1) + '-'
        + pad(d.getUTCDate()) + 'T'
        + pad(d.getUTCHours()) + ':'
        + pad(d.getUTCMinutes()) + ':'
        + pad(d.getUTCSeconds()) + 'Z'
}

function getBuildInfo() {
    let buildInfoPath = process.env.NODE_PATH + '/build.info';
    try {
        return fs.readFileSync(buildInfoPath, "utf8");
    } catch (err) {
        if (err.code === 'ENOENT') {
            return "UNKNOWN_" + toISODateString(new Date());
        } else {
            logger.error("Unexpected Error!", err);
        }
    }
}

function sleep(ms) {
    return new Promise(resolve => {
        setTimeout(resolve, ms)
    })
}

function isString(s) {
    return typeof (s) === 'string' || s instanceof String;
}

function isFunction(f) {
    return f && {}.toString.call(f) === '[object Function]';
}

/**
 * Parse the prototype tree to return all accessible properties till
 * reaching a sentinelPrototype. 
 * 
 * Optionally provide a filtering function to return only the names that match.
 * 
 * @param {*} initialObj The starting object to derive the from
 * @param {*} sentinelPrototype The prototype that represents the end of the line
 * @param {*} filterFunc A fioltering function for the return names
 */
function getObjectKeysToPrototype(initialObj, sentinelPrototype, filterFunc = (e) => true) {
    let prototypeChain = []
    var targetPrototype = initialObj;
    while (Object.getPrototypeOf(targetPrototype) && targetPrototype !== sentinelPrototype) {
        targetPrototype = Object.getPrototypeOf(targetPrototype);
        prototypeChain.push(targetPrototype);
    }
    // console.log("Prototype chain: %s", prototypeChain);
    let completePropertyNames = prototypeChain.map((obj) => {
        return Object.getOwnPropertyNames(obj);
    })
    return [Object.getOwnPropertyNames(initialObj)].concat.apply([], completePropertyNames).filter(filterFunc);
}

exports.getShortestPrefix = getShortestPrefix;
exports.toISODateString = toISODateString;
exports.getBuildInfo = getBuildInfo;
exports.sleep = sleep;
exports.isString = isString;
exports.isFunction = isFunction;
exports.getObjectKeysToPrototype = getObjectKeysToPrototype;