/*
 * Author: Alex Kocharin <alex@kocharin.ru>
 * GIT: https://github.com/rlidwka/jju
 * License: WTFPL, grab your copy here: http://www.wtfpl.net/txt/copying/
 */

// RTFM: http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf

var Uni = require('./unicode')

function isHexDigit(x) {
	return (x >= '0' && x <= '9')
	    || (x >= 'A' && x <= 'F')
	    || (x >= 'a' && x <= 'f')
}

function isOctDigit(x) {
	return x >= '0' && x <= '7'
}

function isDecDigit(x) {
	return x >= '0' && x <= '9'
}

var unescapeMap = {
	'\'': '\'',
	'"' : '"',
	'\\': '\\',
	'b' : '\b',
	'f' : '\f',
	'n' : '\n',
	'r' : '\r',
	't' : '\t',
	'v' : '\v',
	'/' : '/',
}

function formatError(input, msg, position, lineno, column, json5) {
	var result = msg + ' at ' + (lineno + 1) + ':' + (column + 1)
	  , tmppos = position - column - 1
	  , srcline = ''
	  , underline = ''

	var isLineTerminator = json5 ? Uni.isLineTerminator : Uni.isLineTerminatorJSON

	// output no more than 70 characters before the wrong ones
	if (tmppos < position - 70) {
		tmppos = position - 70
	}

	while (1) {
		var chr = input[++tmppos]

		if (isLineTerminator(chr) || tmppos === input.length) {
			if (position >= tmppos) {
				// ending line error, so show it after the last char
				underline += '^'
			}
			break
		}
		srcline += chr

		if (position === tmppos) {
			underline += '^'
		} else if (position > tmppos) {
			underline += input[tmppos] === '\t' ? '\t' : ' '
		}

		// output no more than 78 characters on the string
		if (srcline.length > 78) break
	}

	return result + '\n' + srcline + '\n' + underline
}

function parse(input, options) {
	// parse as a standard JSON mode
	var json5 = !(options.mode === 'json' || options.legacy)
	var isLineTerminator = json5 ? Uni.isLineTerminator : Uni.isLineTerminatorJSON
	var isWhiteSpace = json5 ? Uni.isWhiteSpace : Uni.isWhiteSpaceJSON

	var length = input.length
	  , lineno = 0
	  , linestart = 0
	  , position = 0
	  , stack = []

	var tokenStart = function() {}
	var tokenEnd = function(v) {return v}

	/* tokenize({
	     raw: '...',
	     type: 'whitespace'|'comment'|'key'|'literal'|'separator'|'newline',
	     value: 'number'|'string'|'whatever',
	     path: [...],
	   })
	*/
	if (options._tokenize) {
		;(function() {
			var start = null
			tokenStart = function() {
				if (start !== null) throw new Error('internal error, token overlap')
				start = position
			}

			tokenEnd = function(v, type) {
				if (start != position) {
					var hash = {
						raw: input.substr(start, position-start),
						type: type,
						stack: stack.slice(0),
					}
					if (v !== undefined) hash.value = v
					options._tokenize.call(null, hash)
				}
				start = null
				return v
			}
		})()
	}

	function fail(msg) {
		var column = position - linestart

		if (!msg) {
			if (position < length) {
				var token = '\'' +
					JSON
						.stringify(input[position])
						.replace(/^"|"$/g, '')
						.replace(/'/g, "\\'")
						.replace(/\\"/g, '"')
					+ '\''

				if (!msg) msg = 'Unexpected token ' + token
			} else {
				if (!msg) msg = 'Unexpected end of input'
			}
		}

		var error = new SyntaxError(formatError(input, msg, position, lineno, column, json5))
		error.row = lineno + 1
		error.column = column + 1
		throw error
	}

	function newline(chr) {
		// account for <cr><lf>
		if (chr === '\r' && input[position] === '\n') position++
		linestart = position
		lineno++
	}

	function parseGeneric() {
		var result

		while (position < length) {
			tokenStart()
			var chr = input[position++]

			if (chr === '"' || (chr === '\'' && json5)) {
				return tokenEnd(parseString(chr), 'literal')

			} else if (chr === '{') {
				tokenEnd(undefined, 'separator')
				return parseObject()

			} else if (chr === '[') {
				tokenEnd(undefined, 'separator')
				return parseArray()

			} else if (chr === '-'
			       ||  chr === '.'
			       ||  isDecDigit(chr)
			           //           + number       Infinity          NaN
			       ||  (json5 && (chr === '+' || chr === 'I' || chr === 'N'))
			) {
				return tokenEnd(parseNumber(), 'literal')

			} else if (chr === 'n') {
				parseKeyword('null')
				return tokenEnd(null, 'literal')

			} else if (chr === 't') {
				parseKeyword('true')
				return tokenEnd(true, 'literal')

			} else if (chr === 'f') {
				parseKeyword('false')
				return tokenEnd(false, 'literal')

			} else {
				position--
				return tokenEnd(undefined)
			}
		}
	}

	function parseKey() {
		var result

		while (position < length) {
			tokenStart()
			var chr = input[position++]

			if (chr === '"' || (chr === '\'' && json5)) {
				return tokenEnd(parseString(chr), 'key')

			} else if (chr === '{') {
				tokenEnd(undefined, 'separator')
				return parseObject()

			} else if (chr === '[') {
				tokenEnd(undefined, 'separator')
				return parseArray()

			} else if (chr === '.'
			       ||  isDecDigit(chr)
			) {
				return tokenEnd(parseNumber(true), 'key')

			} else if (json5
			       &&  Uni.isIdentifierStart(chr) || (chr === '\\' && input[position] === 'u')) {
				// unicode char or a unicode sequence
				var rollback = position - 1
				var result = parseIdentifier()

				if (result === undefined) {
					position = rollback
					return tokenEnd(undefined)
				} else {
					return tokenEnd(result, 'key')
				}

			} else {
				position--
				return tokenEnd(undefined)
			}
		}
	}

	function skipWhiteSpace() {
		tokenStart()
		while (position < length) {
			var chr = input[position++]

			if (isLineTerminator(chr)) {
				position--
				tokenEnd(undefined, 'whitespace')
				tokenStart()
				position++
				newline(chr)
				tokenEnd(undefined, 'newline')
				tokenStart()

			} else if (isWhiteSpace(chr)) {
				// nothing

			} else if (chr === '/'
			       && json5
			       && (input[position] === '/' || input[position] === '*')
			) {
				position--
				tokenEnd(undefined, 'whitespace')
				tokenStart()
				position++
				skipComment(input[position++] === '*')
				tokenEnd(undefined, 'comment')
				tokenStart()

			} else {
				position--
				break
			}
		}
		return tokenEnd(undefined, 'whitespace')
	}

	function skipComment(multi) {
		while (position < length) {
			var chr = input[position++]

			if (isLineTerminator(chr)) {
				// LineTerminator is an end of singleline comment
				if (!multi) {
					// let parent function deal with newline
					position--
					return
				}

				newline(chr)

			} else if (chr === '*' && multi) {
				// end of multiline comment
				if (input[position] === '/') {
					position++
					return
				}

			} else {
				// nothing
			}
		}

		if (multi) {
			fail('Unclosed multiline comment')
		}
	}

	function parseKeyword(keyword) {
		// keyword[0] is not checked because it should've checked earlier
		var _pos = position
		var len = keyword.length
		for (var i=1; i<len; i++) {
			if (position >= length || keyword[i] != input[position]) {
				position = _pos-1
				fail()
			}
			position++
		}
	}

	function parseObject() {
		var result = options.null_prototype ? Object.create(null) : {}
		  , empty_object = {}
		  , is_non_empty = false

		while (position < length) {
			skipWhiteSpace()
			var item1 = parseKey()
			skipWhiteSpace()
			tokenStart()
			var chr = input[position++]
			tokenEnd(undefined, 'separator')

			if (chr === '}' && item1 === undefined) {
				if (!json5 && is_non_empty) {
					position--
					fail('Trailing comma in object')
				}
				return result

			} else if (chr === ':' && item1 !== undefined) {
				skipWhiteSpace()
				stack.push(item1)
				var item2 = parseGeneric()
				stack.pop()

				if (item2 === undefined) fail('No value found for key ' + item1)
				if (typeof(item1) !== 'string') {
					if (!json5 || typeof(item1) !== 'number') {
						fail('Wrong key type: ' + item1)
					}
				}

				if ((item1 in empty_object || empty_object[item1] != null) && options.reserved_keys !== 'replace') {
					if (options.reserved_keys === 'throw') {
						fail('Reserved key: ' + item1)
					} else {
						// silently ignore it
					}
				} else {
					if (typeof(options.reviver) === 'function') {
						item2 = options.reviver.call(null, item1, item2)
					}

					if (item2 !== undefined) {
						is_non_empty = true
						Object.defineProperty(result, item1, {
							value: item2,
							enumerable: true,
							configurable: true,
							writable: true,
						})
					}
				}

				skipWhiteSpace()

				tokenStart()
				var chr = input[position++]
				tokenEnd(undefined, 'separator')

				if (chr === ',') {
					continue

				} else if (chr === '}') {
					return result

				} else {
					fail()
				}

			} else {
				position--
				fail()
			}
		}

		fail()
	}

	function parseArray() {
		var result = []

		while (position < length) {
			skipWhiteSpace()
			stack.push(result.length)
			var item = parseGeneric()
			stack.pop()
			skipWhiteSpace()
			tokenStart()
			var chr = input[position++]
			tokenEnd(undefined, 'separator')

			if (item !== undefined) {
				if (typeof(options.reviver) === 'function') {
					item = options.reviver.call(null, String(result.length), item)
				}
				if (item === undefined) {
					result.length++
					item = true // hack for check below, not included into result
				} else {
					result.push(item)
				}
			}

			if (chr === ',') {
				if (item === undefined) {
					fail('Elisions are not supported')
				}

			} else if (chr === ']') {
				if (!json5 && item === undefined && result.length) {
					position--
					fail('Trailing comma in array')
				}
				return result

			} else {
				position--
				fail()
			}
		}
	}

	function parseNumber() {
		// rewind because we don't know first char
		position--

		var start = position
		  , chr = input[position++]
		  , t

		var to_num = function(is_octal) {
			var str = input.substr(start, position - start)

			if (is_octal) {
				var result = parseInt(str.replace(/^0o?/, ''), 8)
			} else {
				var result = Number(str)
			}

			if (Number.isNaN(result)) {
				position--
				fail('Bad numeric literal - "' + input.substr(start, position - start + 1) + '"')
			} else if (!json5 && !str.match(/^-?(0|[1-9][0-9]*)(\.[0-9]+)?(e[+-]?[0-9]+)?$/i)) {
				// additional restrictions imposed by json
				position--
				fail('Non-json numeric literal - "' + input.substr(start, position - start + 1) + '"')
			} else {
				return result
			}
		}

		// ex: -5982475.249875e+29384
		//     ^ skipping this
		if (chr === '-' || (chr === '+' && json5)) chr = input[position++]

		if (chr === 'N' && json5) {
			parseKeyword('NaN')
			return NaN
		}

		if (chr === 'I' && json5) {
			parseKeyword('Infinity')

			// returning +inf or -inf
			return to_num()
		}

		if (chr >= '1' && chr <= '9') {
			// ex: -5982475.249875e+29384
			//        ^^^ skipping these
			while (position < length && isDecDigit(input[position])) position++
			chr = input[position++]
		}

		// special case for leading zero: 0.123456
		if (chr === '0') {
			chr = input[position++]

			//             new syntax, "0o777"           old syntax, "0777"
			var is_octal = chr === 'o' || chr === 'O' || isOctDigit(chr)
			var is_hex = chr === 'x' || chr === 'X'

			if (json5 && (is_octal || is_hex)) {
				while (position < length
				   &&  (is_hex ? isHexDigit : isOctDigit)( input[position] )
				) position++

				var sign = 1
				if (input[start] === '-') {
					sign = -1
					start++
				} else if (input[start] === '+') {
					start++
				}

				return sign * to_num(is_octal)
			}
		}

		if (chr === '.') {
			// ex: -5982475.249875e+29384
			//                ^^^ skipping these
			while (position < length && isDecDigit(input[position])) position++
			chr = input[position++]
		}

		if (chr === 'e' || chr === 'E') {
			chr = input[position++]
			if (chr === '-' || chr === '+') position++
			// ex: -5982475.249875e+29384
			//                       ^^^ skipping these
			while (position < length && isDecDigit(input[position])) position++
			chr = input[position++]
		}

		// we have char in the buffer, so count for it
		position--
		return to_num()
	}

	function parseIdentifier() {
		// rewind because we don't know first char
		position--

		var result = ''

		while (position < length) {
			var chr = input[position++]

			if (chr === '\\'
			&&  input[position] === 'u'
			&&  isHexDigit(input[position+1])
			&&  isHexDigit(input[position+2])
			&&  isHexDigit(input[position+3])
			&&  isHexDigit(input[position+4])
			) {
				// UnicodeEscapeSequence
				chr = String.fromCharCode(parseInt(input.substr(position+1, 4), 16))
				position += 5
			}

			if (result.length) {
				// identifier started
				if (Uni.isIdentifierPart(chr)) {
					result += chr
				} else {
					position--
					return result
				}

			} else {
				if (Uni.isIdentifierStart(chr)) {
					result += chr
				} else {
					return undefined
				}
			}
		}

		fail()
	}

	function parseString(endChar) {
		// 7.8.4 of ES262 spec
		var result = ''

		while (position < length) {
			var chr = input[position++]

			if (chr === endChar) {
				return result

			} else if (chr === '\\') {
				if (position >= length) fail()
				chr = input[position++]

				if (unescapeMap[chr] && (json5 || (chr != 'v' && chr != "'"))) {
					result += unescapeMap[chr]

				} else if (json5 && isLineTerminator(chr)) {
					// line continuation
					newline(chr)

				} else if (chr === 'u' || (chr === 'x' && json5)) {
					// unicode/character escape sequence
					var off = chr === 'u' ? 4 : 2

					// validation for \uXXXX
					for (var i=0; i<off; i++) {
						if (position >= length) fail()
						if (!isHexDigit(input[position])) fail('Bad escape sequence')
						position++
					}

					result += String.fromCharCode(parseInt(input.substr(position-off, off), 16))
				} else if (json5 && isOctDigit(chr)) {
					if (chr < '4' && isOctDigit(input[position]) && isOctDigit(input[position+1])) {
						// three-digit octal
						var digits = 3
					} else if (isOctDigit(input[position])) {
						// two-digit octal
						var digits = 2
					} else {
						var digits = 1
					}
					position += digits - 1
					result += String.fromCharCode(parseInt(input.substr(position-digits, digits), 8))
					/*if (!isOctDigit(input[position])) {
						// \0 is allowed still
						result += '\0'
					} else {
						fail('Octal literals are not supported')
					}*/

				} else if (json5) {
					// \X -> x
					result += chr

				} else {
					position--
					fail()
				}

			} else if (isLineTerminator(chr)) {
				fail()

			} else {
				if (!json5 && chr.charCodeAt(0) < 32) {
					position--
					fail('Unexpected control character')
				}

				// SourceCharacter but not one of " or \ or LineTerminator
				result += chr
			}
		}

		fail()
	}

	skipWhiteSpace()
	var return_value = parseGeneric()
	if (return_value !== undefined || position < length) {
		skipWhiteSpace()

		if (position >= length) {
			if (typeof(options.reviver) === 'function') {
				return_value = options.reviver.call(null, '', return_value)
			}
			return return_value
		} else {
			fail()
		}

	} else {
		if (position) {
			fail('No data, only a whitespace')
		} else {
			fail('No data, empty input')
		}
	}
}

/*
 * parse(text, options)
 * or
 * parse(text, reviver)
 *
 * where:
 * text - string
 * options - object
 * reviver - function
 */
module.exports.parse = function parseJSON(input, options) {
	// support legacy functions
	if (typeof(options) === 'function') {
		options = {
			reviver: options
		}
	}

	if (input === undefined) {
		// parse(stringify(x)) should be equal x
		// with JSON functions it is not 'cause of undefined
		// so we're fixing it
		return undefined
	}

	// JSON.parse compat
	if (typeof(input) !== 'string') input = String(input)
	if (options == null) options = {}
	if (options.reserved_keys == null) options.reserved_keys = 'ignore'

	if (options.reserved_keys === 'throw' || options.reserved_keys === 'ignore') {
		if (options.null_prototype == null) {
			options.null_prototype = true
		}
	}

	try {
		return parse(input, options)
	} catch(err) {
		// jju is a recursive parser, so JSON.parse("{{{{{{{") could blow up the stack
		//
		// this catch is used to skip all those internal calls
		if (err instanceof SyntaxError && err.row != null && err.column != null) {
			var old_err = err
			err = new SyntaxError(old_err.message)
			err.column = old_err.column
			err.row = old_err.row
		}
		throw err
	}
}

module.exports.tokenize = function tokenizeJSON(input, options) {
	if (options == null) options = {}

	options._tokenize = function(smth) {
		if (options._addstack) smth.stack.unshift.apply(smth.stack, options._addstack)
		tokens.push(smth)
	}

	var tokens = []
	tokens.data = module.exports.parse(input, options)
	return tokens
}

