'use strict';

const object = {};
const hasOwnProperty = object.hasOwnProperty;
const forOwn = function(object, callback) {
	for (const key in object) {
		if (hasOwnProperty.call(object, key)) {
			callback(key, object[key]);
		}
	}
};

const extend = function(destination, source) {
	if (!source) {
		return destination;
	}
	forOwn(source, function(key, value) {
		destination[key] = value;
	});
	return destination;
};

const forEach = function(array, callback) {
	const length = array.length;
	let index = -1;
	while (++index < length) {
		callback(array[index]);
	}
};

const toString = object.toString;
const isArray = Array.isArray;
const isBuffer = Buffer.isBuffer;
const isObject = function(value) {
	// This is a very simple check, but it’s good enough for what we need.
	return toString.call(value) == '[object Object]';
};
const isString = function(value) {
	return typeof value == 'string' ||
		toString.call(value) == '[object String]';
};
const isNumber = function(value) {
	return typeof value == 'number' ||
		toString.call(value) == '[object Number]';
};
const isFunction = function(value) {
	return typeof value == 'function';
};
const isMap = function(value) {
	return toString.call(value) == '[object Map]';
};
const isSet = function(value) {
	return toString.call(value) == '[object Set]';
};

/*--------------------------------------------------------------------------*/

// https://mathiasbynens.be/notes/javascript-escapes#single
const singleEscapes = {
	'"': '\\"',
	'\'': '\\\'',
	'\\': '\\\\',
	'\b': '\\b',
	'\f': '\\f',
	'\n': '\\n',
	'\r': '\\r',
	'\t': '\\t'
	// `\v` is omitted intentionally, because in IE < 9, '\v' == 'v'.
	// '\v': '\\x0B'
};
const regexSingleEscape = /["'\\\b\f\n\r\t]/;

const regexDigit = /[0-9]/;
const regexWhitelist = /[ !#-&\(-\[\]-~]/;

const jsesc = function(argument, options) {
	const increaseIndentation = function() {
		oldIndent = indent;
		++options.indentLevel;
		indent = options.indent.repeat(options.indentLevel)
	};
	// Handle options
	const defaults = {
		'escapeEverything': false,
		'escapeEtago': false,
		'quotes': 'single',
		'wrap': false,
		'es6': false,
		'json': false,
		'compact': true,
		'lowercaseHex': false,
		'numbers': 'decimal',
		'indent': '\t',
		'indentLevel': 0,
		'__inline1__': false,
		'__inline2__': false
	};
	const json = options && options.json;
	if (json) {
		defaults.quotes = 'double';
		defaults.wrap = true;
	}
	options = extend(defaults, options);
	if (options.quotes != 'single' && options.quotes != 'double') {
		options.quotes = 'single';
	}
	const quote = options.quotes == 'double' ? '"' : '\'';
	const compact = options.compact;
	const lowercaseHex = options.lowercaseHex;
	let indent = options.indent.repeat(options.indentLevel);
	let oldIndent = '';
	const inline1 = options.__inline1__;
	const inline2 = options.__inline2__;
	const newLine = compact ? '' : '\n';
	let result;
	let isEmpty = true;
	const useBinNumbers = options.numbers == 'binary';
	const useOctNumbers = options.numbers == 'octal';
	const useDecNumbers = options.numbers == 'decimal';
	const useHexNumbers = options.numbers == 'hexadecimal';

	if (json && argument && isFunction(argument.toJSON)) {
		argument = argument.toJSON();
	}

	if (!isString(argument)) {
		if (isMap(argument)) {
			if (argument.size == 0) {
				return 'new Map()';
			}
			if (!compact) {
				options.__inline1__ = true;
				options.__inline2__ = false;
			}
			return 'new Map(' + jsesc(Array.from(argument), options) + ')';
		}
		if (isSet(argument)) {
			if (argument.size == 0) {
				return 'new Set()';
			}
			return 'new Set(' + jsesc(Array.from(argument), options) + ')';
		}
		if (isBuffer(argument)) {
			if (argument.length == 0) {
				return 'Buffer()';
			}
			return 'Buffer(' + jsesc(Array.from(argument), options) + ')';
		}
		if (isArray(argument)) {
			result = [];
			options.wrap = true;
			if (inline1) {
				options.__inline1__ = false;
				options.__inline2__ = true;
			}
			if (!inline2) {
				increaseIndentation();
			}
			forEach(argument, function(value) {
				isEmpty = false;
				if (inline2) {
					options.__inline2__ = false;
				}
				result.push(
					(compact || inline2 ? '' : indent) +
					jsesc(value, options)
				);
			});
			if (isEmpty) {
				return '[]';
			}
			if (inline2) {
				return '[' + result.join(', ') + ']';
			}
			return '[' + newLine + result.join(',' + newLine) + newLine +
				(compact ? '' : oldIndent) + ']';
		} else if (isNumber(argument)) {
			if (json) {
				// Some number values (e.g. `Infinity`) cannot be represented in JSON.
				return JSON.stringify(argument);
			}
			if (useDecNumbers) {
				return String(argument);
			}
			if (useHexNumbers) {
				let hexadecimal = argument.toString(16);
				if (!lowercaseHex) {
					hexadecimal = hexadecimal.toUpperCase();
				}
				return '0x' + hexadecimal;
			}
			if (useBinNumbers) {
				return '0b' + argument.toString(2);
			}
			if (useOctNumbers) {
				return '0o' + argument.toString(8);
			}
		} else if (!isObject(argument)) {
			if (json) {
				// For some values (e.g. `undefined`, `function` objects),
				// `JSON.stringify(value)` returns `undefined` (which isn’t valid
				// JSON) instead of `'null'`.
				return JSON.stringify(argument) || 'null';
			}
			return String(argument);
		} else { // it’s an object
			result = [];
			options.wrap = true;
			increaseIndentation();
			forOwn(argument, function(key, value) {
				isEmpty = false;
				result.push(
					(compact ? '' : indent) +
					jsesc(key, options) + ':' +
					(compact ? '' : ' ') +
					jsesc(value, options)
				);
			});
			if (isEmpty) {
				return '{}';
			}
			return '{' + newLine + result.join(',' + newLine) + newLine +
				(compact ? '' : oldIndent) + '}';
		}
	}

	const string = argument;
	// Loop over each code unit in the string and escape it
	let index = -1;
	const length = string.length;
	result = '';
	while (++index < length) {
		const character = string.charAt(index);
		if (options.es6) {
			const first = string.charCodeAt(index);
			if ( // check if it’s the start of a surrogate pair
				first >= 0xD800 && first <= 0xDBFF && // high surrogate
				length > index + 1 // there is a next code unit
			) {
				const second = string.charCodeAt(index + 1);
				if (second >= 0xDC00 && second <= 0xDFFF) { // low surrogate
					// https://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
					const codePoint = (first - 0xD800) * 0x400 + second - 0xDC00 + 0x10000;
					let hexadecimal = codePoint.toString(16);
					if (!lowercaseHex) {
						hexadecimal = hexadecimal.toUpperCase();
					}
					result += '\\u{' + hexadecimal + '}';
					++index;
					continue;
				}
			}
		}
		if (!options.escapeEverything) {
			if (regexWhitelist.test(character)) {
				// It’s a printable ASCII character that is not `"`, `'` or `\`,
				// so don’t escape it.
				result += character;
				continue;
			}
			if (character == '"') {
				result += quote == character ? '\\"' : character;
				continue;
			}
			if (character == '\'') {
				result += quote == character ? '\\\'' : character;
				continue;
			}
		}
		if (
			character == '\0' &&
			!json &&
			!regexDigit.test(string.charAt(index + 1))
		) {
			result += '\\0';
			continue;
		}
		if (regexSingleEscape.test(character)) {
			// no need for a `hasOwnProperty` check here
			result += singleEscapes[character];
			continue;
		}
		const charCode = character.charCodeAt(0);
		let hexadecimal = charCode.toString(16);
		if (!lowercaseHex) {
			hexadecimal = hexadecimal.toUpperCase();
		}
		const longhand = hexadecimal.length > 2 || json;
		const escaped = '\\' + (longhand ? 'u' : 'x') +
			('0000' + hexadecimal).slice(longhand ? -4 : -2);
		result += escaped;
		continue;
	}
	if (options.wrap) {
		result = quote + result + quote;
	}
	if (options.escapeEtago) {
		// https://mathiasbynens.be/notes/etago
		return result.replace(/<\/(script|style)/gi, '<\\/$1');
	}
	return result;
};

jsesc.version = '2.1.0';

module.exports = jsesc;