var Uni = require('./unicode')

// Fix Function#name on browsers that do not support it (IE)
// http://stackoverflow.com/questions/6903762/function-name-not-supported-in-ie
if (!(function f(){}).name) {
  Object.defineProperty((function(){}).constructor.prototype, 'name', {
    get: function() {
      var name = this.toString().match(/^\s*function\s*(\S*)\s*\(/)[1]
      // For better performance only parse once, and then cache the
      // result through a new accessor for repeated access.
      Object.defineProperty(this, 'name', { value: name })
      return name
    }
  })
}

var special_chars = {
  0: '\\0', // this is not an octal literal
  8: '\\b',
  9: '\\t',
  10: '\\n',
  11: '\\v',
  12: '\\f',
  13: '\\r',
  92: '\\\\',
}

// for oddballs
var hasOwnProperty = Object.prototype.hasOwnProperty

// some people escape those, so I'd copy this to be safe
var escapable = /[\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/

function _stringify(object, options, recursiveLvl, currentKey) {
  var json5 = (options.mode === 'json5' || !options.mode)
  /*
   * Opinionated decision warning:
   *
   * Objects are serialized in the following form:
   * { type: 'Class', data: DATA }
   *
   * Class is supposed to be a function, and new Class(DATA) is
   * supposed to be equivalent to the original value
   */
  /*function custom_type() {
    return stringify({
      type: object.constructor.name,
      data: object.toString()
    })
  }*/

  // if add, it's an internal indentation, so we add 1 level and a eol
  // if !add, it's an ending indentation, so we just indent
  function indent(str, add) {
    var prefix = options._prefix ? options._prefix : ''
    if (!options.indent) return prefix + str
    var result = ''
    var count = recursiveLvl + (add || 0)
    for (var i=0; i<count; i++) result += options.indent
    return prefix + result + str + (add ? '\n' : '')
  }

  function _stringify_key(key) {
    if (options.quote_keys) return _stringify_str(key)
    if (String(Number(key)) == key && key[0] != '-') return key
    if (key == '') return _stringify_str(key)

    var result = ''
    for (var i=0; i<key.length; i++) {
      if (i > 0) {
        if (!Uni.isIdentifierPart(key[i]))
          return _stringify_str(key)

      } else {
        if (!Uni.isIdentifierStart(key[i]))
          return _stringify_str(key)
      }

      var chr = key.charCodeAt(i)

      if (options.ascii) {
        if (chr < 0x80) {
          result += key[i]

        } else {
          result += '\\u' + ('0000' + chr.toString(16)).slice(-4)
        }

      } else {
        if (escapable.exec(key[i])) {
          result += '\\u' + ('0000' + chr.toString(16)).slice(-4)

        } else {
          result += key[i]
        }
      }
    }

    return result
  }

  function _stringify_str(key) {
    var quote = options.quote
    var quoteChr = quote.charCodeAt(0)

    var result = ''
    for (var i=0; i<key.length; i++) {
      var chr = key.charCodeAt(i)

      if (chr < 0x10) {
        if (chr === 0 && json5) {
          result += '\\0'
        } else if (chr >= 8 && chr <= 13 && (json5 || chr !== 11)) {
          result += special_chars[chr]
        } else if (json5) {
          result += '\\x0' + chr.toString(16)
        } else {
          result += '\\u000' + chr.toString(16)
        }

      } else if (chr < 0x20) {
        if (json5) {
          result += '\\x' + chr.toString(16)
        } else {
          result += '\\u00' + chr.toString(16)
        }

      } else if (chr >= 0x20 && chr < 0x80) {
        // ascii range
        if (chr === 47 && i && key[i-1] === '<') {
          // escaping slashes in </script>
          result += '\\' + key[i]

        } else if (chr === 92) {
          result += '\\\\'

        } else if (chr === quoteChr) {
          result += '\\' + quote

        } else {
          result += key[i]
        }

      } else if (options.ascii || Uni.isLineTerminator(key[i]) || escapable.exec(key[i])) {
        if (chr < 0x100) {
          if (json5) {
            result += '\\x' + chr.toString(16)
          } else {
            result += '\\u00' + chr.toString(16)
          }

        } else if (chr < 0x1000) {
          result += '\\u0' + chr.toString(16)

        } else if (chr < 0x10000) {
          result += '\\u' + chr.toString(16)

        } else {
          throw Error('weird codepoint')
        }
      } else {
        result += key[i]
      }
    }
    return quote + result + quote
  }

  function _stringify_object() {
    if (object === null) return 'null'
    var result = []
      , len = 0
      , braces

    if (Array.isArray(object)) {
      braces = '[]'
      for (var i=0; i<object.length; i++) {
        var s = _stringify(object[i], options, recursiveLvl+1, String(i))
        if (s === undefined) s = 'null'
        len += s.length + 2
        result.push(s + ',')
      }

    } else {
      braces = '{}'
      var fn = function(key) {
        var t = _stringify(object[key], options, recursiveLvl+1, key)
        if (t !== undefined) {
          t = _stringify_key(key) + ':' + (options.indent ? ' ' : '') + t + ','
          len += t.length + 1
          result.push(t)
        }
      }

      if (Array.isArray(options.replacer)) {
        for (var i=0; i<options.replacer.length; i++)
          if (hasOwnProperty.call(object, options.replacer[i]))
            fn(options.replacer[i])
      } else {
        var keys = Object.keys(object)
        if (options.sort_keys)
          keys = keys.sort(typeof(options.sort_keys) === 'function'
                           ? options.sort_keys : undefined)
        keys.forEach(fn)
      }
    }

    // objects shorter than 30 characters are always inlined
    // objects longer than 60 characters are always splitted to multiple lines
    // anything in the middle depends on indentation level
    len -= 2
    if (options.indent && (len > options._splitMax - recursiveLvl * options.indent.length || len > options._splitMin) ) {
      // remove trailing comma in multiline if asked to
      if (options.no_trailing_comma && result.length) {
        result[result.length-1] = result[result.length-1].substring(0, result[result.length-1].length-1)
      }

      var innerStuff = result.map(function(x) {return indent(x, 1)}).join('')
      return braces[0]
          + (options.indent ? '\n' : '')
          + innerStuff
          + indent(braces[1])
    } else {
      // always remove trailing comma in one-lined arrays
      if (result.length) {
        result[result.length-1] = result[result.length-1].substring(0, result[result.length-1].length-1)
      }

      var innerStuff = result.join(options.indent ? ' ' : '')
      return braces[0]
          + innerStuff
          + braces[1]
    }
  }

  function _stringify_nonobject(object) {
    if (typeof(options.replacer) === 'function') {
      object = options.replacer.call(null, currentKey, object)
    }

    switch(typeof(object)) {
      case 'string':
        return _stringify_str(object)

      case 'number':
        if (object === 0 && 1/object < 0) {
          // Opinionated decision warning:
          //
          // I want cross-platform negative zero in all js engines
          // I know they're equal, but why lose that tiny bit of
          // information needlessly?
          return '-0'
        }
        if (!json5 && !Number.isFinite(object)) {
          // json don't support infinity (= sucks)
          return 'null'
        }
        return object.toString()

      case 'boolean':
        return object.toString()

      case 'undefined':
        return undefined

      case 'function':
//        return custom_type()

      default:
        // fallback for something weird
        return JSON.stringify(object)
    }
  }

  if (options._stringify_key) {
    return _stringify_key(object)
  }

  if (typeof(object) === 'object') {
    if (object === null) return 'null'

    var str
    if (typeof(str = object.toJSON5) === 'function' && options.mode !== 'json') {
      object = str.call(object, currentKey)

    } else if (typeof(str = object.toJSON) === 'function') {
      object = str.call(object, currentKey)
    }

    if (object === null) return 'null'
    if (typeof(object) !== 'object') return _stringify_nonobject(object)

    if (object.constructor === Number || object.constructor === Boolean || object.constructor === String) {
      object = object.valueOf()
      return _stringify_nonobject(object)

    } else if (object.constructor === Date) {
      // only until we can't do better
      return _stringify_nonobject(object.toISOString())

    } else {
      if (typeof(options.replacer) === 'function') {
        object = options.replacer.call(null, currentKey, object)
        if (typeof(object) !== 'object') return _stringify_nonobject(object)
      }

      return _stringify_object(object)
    }
  } else {
    return _stringify_nonobject(object)
  }
}

/*
 * stringify(value, options)
 * or
 * stringify(value, replacer, space)
 *
 * where:
 * value - anything
 * options - object
 * replacer - function or array
 * space - boolean or number or string
 */
module.exports.stringify = function stringifyJSON(object, options, _space) {
  // support legacy syntax
  if (typeof(options) === 'function' || Array.isArray(options)) {
    options = {
      replacer: options
    }
  } else if (typeof(options) === 'object' && options !== null) {
    // nothing to do
  } else {
    options = {}
  }
  if (_space != null) options.indent = _space

  if (options.indent == null) options.indent = '\t'
  if (options.quote == null) options.quote = "'"
  if (options.ascii == null) options.ascii = false
  if (options.mode == null) options.mode = 'json5'

  if (options.mode === 'json' || options.mode === 'cjson') {
    // json only supports double quotes (= sucks)
    options.quote = '"'

    // json don't support trailing commas (= sucks)
    options.no_trailing_comma = true

    // json don't support unquoted property names (= sucks)
    options.quote_keys = true
  }

  // why would anyone use such objects?
  if (typeof(options.indent) === 'object') {
    if (options.indent.constructor === Number
    ||  options.indent.constructor === Boolean
    ||  options.indent.constructor === String)
      options.indent = options.indent.valueOf()
  }

  // gap is capped at 10 characters
  if (typeof(options.indent) === 'number') {
    if (options.indent >= 0) {
      options.indent = Array(Math.min(~~options.indent, 10) + 1).join(' ')
    } else {
      options.indent = false
    }
  } else if (typeof(options.indent) === 'string') {
    options.indent = options.indent.substr(0, 10)
  }

  if (options._splitMin == null) options._splitMin = 50
  if (options._splitMax == null) options._splitMax = 70

  return _stringify(object, options, 0, '')
}