# All files / lib/helpers DFHelper.js

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90% Branches 18/20
77.78% Functions 7/9
98% Lines 49/50

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     'use strict'

    var _ = require('underscore')

    function DFHelper() {}

    _.extend(DFHelper, {
        noop: function() {},
        parse: function(stdout, options) {
            Iif (!stdout) {
                return void 0
            }

            var multiplier = DFHelper.getMultiplierByPrefix(options.prefixMultiplier)
            var isDisplayPrefixMultiplier = !!options.isDisplayPrefixMultiplier
            var displayedPrefixMultiplier = isDisplayPrefixMultiplier ? options.prefixMultiplier : null
            var precision = options.precision
            var format = DFHelper.format
            var response = _(
                stdout
                    .trim()

                    // split into rows
                    .split(/\r|\n|\r\n/)

                    // strip column headers away
                    .slice(1)
            ).map(function(row) {
                var columns = row

                    // one or more whitespaces followed by one or more digits
                    // must be interpreted as column delimiter
                    .replace(/\s+(\d+)/g, '\t$1')

                    // one or more whitespaces followed by a slash
                    // must be interpreted as the last column delimiter
                    .replace(/\s+\//g, '\t/')

                    // split into columns
                    .split(/\t/)

                var filesystem = columns[0]
                var size = format(columns[1], multiplier, precision, displayedPrefixMultiplier)
                var used = format(columns[2], multiplier, precision, displayedPrefixMultiplier)
                var available = format(columns[3], multiplier, precision, displayedPrefixMultiplier)
                var capacity = format(columns[4], 0.01)
                var mount = _.rest(columns, 5).join(' ')

                return {
                    filesystem: filesystem,
                    size: size,
                    used: used,
                    available: available,
                    capacity: capacity,
                    mount: mount,
                }
            })

            return response
        },
        format: function(s, multiplier, precision, displayedPrefixMultiplier) {
            multiplier = multiplier || 1

            var tmp = parseInt(s, 10) * multiplier
            var amount = Math.pow(10, precision)
            var hasPrecision = _.isNumber(precision)

            if (hasPrecision) {
                tmp = Math.round(tmp * amount) / amount
            }

            if (displayedPrefixMultiplier) {
                if (hasPrecision) {
                    tmp = tmp.toFixed(precision)
                }
                tmp = tmp + displayedPrefixMultiplier
            }

            return tmp
        },
        getMultiplierByPrefix: function(prefix) {
            var prefixMultipliers = DFHelper.getPrefixMultipliers()

            var defaultPrefix = 'KiB'
            var defaultMultiplier = 1024
            var multiplier = 1

            // prefixes are case insensitive
            prefix = (prefix || defaultPrefix).toLowerCase()

            // invalid prefix multipliers are ignored
            if (!prefixMultipliers[prefix]) {
                prefix = defaultPrefix
            }

            // df outputs sizes in KiB
            // nothing to do
            if (prefix === defaultPrefix) {
                return multiplier
            }

            // convert to bytes then convert to unit of choice
            multiplier = defaultMultiplier / prefixMultipliers[prefix]

            return multiplier
        },
        getPrefixMultipliers: function() {
            if (DFHelper._prefixMultipliers) {
                return DFHelper._prefixMultipliers
            }

            var pow2 = DFHelper._pow2
            var pow10 = DFHelper._pow10

            DFHelper._prefixMultipliers = {
                kib: pow2(10),
                mib: pow2(20),
                gib: pow2(30),
                tib: pow2(40),
                pib: pow2(50),
                eib: pow2(60),
                zib: pow2(70),
                yib: pow2(80),

                kb: pow10(3),
                mb: pow10(6),
                gb: pow10(9),
                tb: pow10(12),
                pb: pow10(15),
                eb: pow10(18),
                zb: pow10(21),
                yb: pow10(24),
            }

            return DFHelper._prefixMultipliers
        },
        _pow2: function(exponent) {
            return Math.pow(2, exponent)
        },
        _pow10: function(exponent) {
            return Math.pow(10, exponent)
        },
        _prefixMultipliers: null,
    })

    module.exports = DFHelper