"use strict";

/**
 * filesize
 *
 * @copyright 2019 Jason Mulligan <jason.mulligan@avoidwork.com>
 * @license BSD-3-Clause
 * @version 4.0.0
 */
(function (global) {
	var b = /^(b|B)$/,
	    symbol = {
		iec: {
			bits: ["b", "Kib", "Mib", "Gib", "Tib", "Pib", "Eib", "Zib", "Yib"],
			bytes: ["B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"]
		},
		jedec: {
			bits: ["b", "Kb", "Mb", "Gb", "Tb", "Pb", "Eb", "Zb", "Yb"],
			bytes: ["B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"]
		}
	},
	    fullform = {
		iec: ["", "kibi", "mebi", "gibi", "tebi", "pebi", "exbi", "zebi", "yobi"],
		jedec: ["", "kilo", "mega", "giga", "tera", "peta", "exa", "zetta", "yotta"]
	};

	/**
  * filesize
  *
  * @method filesize
  * @param  {Mixed}   arg        String, Int or Float to transform
  * @param  {Object}  descriptor [Optional] Flags
  * @return {String}             Readable file size String
  */
	function filesize(arg) {
		var descriptor = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {};

		var result = [],
		    val = 0,
		    e = void 0,
		    base = void 0,
		    bits = void 0,
		    ceil = void 0,
		    full = void 0,
		    fullforms = void 0,
		    neg = void 0,
		    num = void 0,
		    output = void 0,
		    round = void 0,
		    unix = void 0,
		    separator = void 0,
		    spacer = void 0,
		    standard = void 0,
		    symbols = void 0;

		if (isNaN(arg)) {
			throw new Error("Invalid arguments");
		}

		bits = descriptor.bits === true;
		unix = descriptor.unix === true;
		base = descriptor.base || 2;
		round = descriptor.round !== void 0 ? descriptor.round : unix ? 1 : 2;
		separator = descriptor.separator !== void 0 ? descriptor.separator || "" : "";
		spacer = descriptor.spacer !== void 0 ? descriptor.spacer : unix ? "" : " ";
		symbols = descriptor.symbols || {};
		standard = base === 2 ? descriptor.standard || "jedec" : "jedec";
		output = descriptor.output || "string";
		full = descriptor.fullform === true;
		fullforms = descriptor.fullforms instanceof Array ? descriptor.fullforms : [];
		e = descriptor.exponent !== void 0 ? descriptor.exponent : -1;
		num = Number(arg);
		neg = num < 0;
		ceil = base > 2 ? 1000 : 1024;

		// Flipping a negative number to determine the size
		if (neg) {
			num = -num;
		}

		// Determining the exponent
		if (e === -1 || isNaN(e)) {
			e = Math.floor(Math.log(num) / Math.log(ceil));

			if (e < 0) {
				e = 0;
			}
		}

		// Exceeding supported length, time to reduce & multiply
		if (e > 8) {
			e = 8;
		}

		// Zero is now a special case because bytes divide by 1
		if (num === 0) {
			result[0] = 0;
			result[1] = unix ? "" : symbol[standard][bits ? "bits" : "bytes"][e];
		} else {
			val = num / (base === 2 ? Math.pow(2, e * 10) : Math.pow(1000, e));

			if (bits) {
				val = val * 8;

				if (val >= ceil && e < 8) {
					val = val / ceil;
					e++;
				}
			}

			result[0] = Number(val.toFixed(e > 0 ? round : 0));
			result[1] = base === 10 && e === 1 ? bits ? "kb" : "kB" : symbol[standard][bits ? "bits" : "bytes"][e];

			if (unix) {
				result[1] = standard === "jedec" ? result[1].charAt(0) : e > 0 ? result[1].replace(/B$/, "") : result[1];

				if (b.test(result[1])) {
					result[0] = Math.floor(result[0]);
					result[1] = "";
				}
			}
		}

		// Decorating a 'diff'
		if (neg) {
			result[0] = -result[0];
		}

		// Applying custom symbol
		result[1] = symbols[result[1]] || result[1];

		// Returning Array, Object, or String (default)
		if (output === "array") {
			return result;
		}

		if (output === "exponent") {
			return e;
		}

		if (output === "object") {
			return { value: result[0], symbol: result[1] };
		}

		if (full) {
			result[1] = fullforms[e] ? fullforms[e] : fullform[standard][e] + (bits ? "bit" : "byte") + (result[0] === 1 ? "" : "s");
		}

		if (separator.length > 0) {
			result[0] = result[0].toString().replace(".", separator);
		}

		return result.join(spacer);
	}

	// Partial application for functional programming
	filesize.partial = function (opt) {
		return function (arg) {
			return filesize(arg, opt);
		};
	};

	// CommonJS, AMD, script tag
	if (typeof exports !== "undefined") {
		module.exports = filesize;
	} else if (typeof define === "function" && define.amd !== void 0) {
		define(function () {
			return filesize;
		});
	} else {
		global.filesize = filesize;
	}
})(typeof window !== "undefined" ? window : global);
