var assert = require('assert')
var tokenize = require('./parse').tokenize
var stringify = require('./stringify').stringify
var analyze = require('./analyze').analyze

function isObject(x) {
  return typeof(x) === 'object' && x !== null
}

function value_to_tokenlist(value, stack, options, is_key, indent) {
  options = Object.create(options)
  options._stringify_key = !!is_key

  if (indent) {
    options._prefix = indent.prefix.map(function(x) {
      return x.raw
    }).join('')
  }

  if (options._splitMin == null) options._splitMin = 0
  if (options._splitMax == null) options._splitMax = 0

  var stringified = stringify(value, options)

  if (is_key) {
    return [ { raw: stringified, type: 'key', stack: stack, value: value } ]
  }

  options._addstack = stack
  var result = tokenize(stringified, {
    _addstack: stack,
  })
  result.data = null
  return result
}

// '1.2.3' -> ['1','2','3']
function arg_to_path(path) {
  // array indexes
  if (typeof(path) === 'number') path = String(path)

  if (path === '') path = []
  if (typeof(path) === 'string') path = path.split('.')

  if (!Array.isArray(path)) throw Error('Invalid path type, string or array expected')
  return path
}

// returns new [begin, end] or false if not found
//
//          {x:3, xxx: 111, y: [111,  {q: 1, e: 2}  ,333]  }
// f('y',0) returns this       B^^^^^^^^^^^^^^^^^^^^^^^^E
// then f('1',1) would reduce it to   B^^^^^^^^^^E
function find_element_in_tokenlist(element, lvl, tokens, begin, end) {
  while(tokens[begin].stack[lvl] != element) {
    if (begin++ >= end) return false
  }
  while(tokens[end].stack[lvl] != element) {
    if (end-- < begin) return false
  }
  return [begin, end]
}

function is_whitespace(token_type) {
  return token_type === 'whitespace'
      || token_type === 'newline'
      || token_type === 'comment'
}

function find_first_non_ws_token(tokens, begin, end) {
  while(is_whitespace(tokens[begin].type)) {
    if (begin++ >= end) return false
  }
  return begin
}

function find_last_non_ws_token(tokens, begin, end) {
  while(is_whitespace(tokens[end].type)) {
    if (end-- < begin) return false
  }
  return end
}

/*
 * when appending a new element of an object/array, we are trying to
 * figure out the style used on the previous element
 *
 * return {prefix, sep1, sep2, suffix}
 *
 *      '    "key" :  "element"    \r\n'
 * prefix^^^^ sep1^ ^^sep2     ^^^^^^^^suffix
 *
 * begin - the beginning of the object/array
 * end - last token of the last element (value or comma usually)
 */
function detect_indent_style(tokens, is_array, begin, end, level) {
  var result = {
    sep1: [],
    sep2: [],
    suffix: [],
    prefix: [],
    newline: [],
  }

  if (tokens[end].type === 'separator' && tokens[end].stack.length !== level+1 && tokens[end].raw !== ',') {
    // either a beginning of the array (no last element) or other weird situation
    //
    // just return defaults
    return result
  }

  //                              ' "key"  : "value"  ,'
  // skipping last separator, we're now here        ^^
  if (tokens[end].type === 'separator')
    end = find_last_non_ws_token(tokens, begin, end - 1)
  if (end === false) return result

  //                              ' "key"  : "value"  ,'
  // skipping value                          ^^^^^^^
  while(tokens[end].stack.length > level) end--

  if (!is_array) {
    while(is_whitespace(tokens[end].type)) {
      if (end < begin) return result
      if (tokens[end].type === 'whitespace') {
        result.sep2.unshift(tokens[end])
      } else {
        // newline, comment or other unrecognized codestyle
        return result
      }
      end--
    }

    //                              ' "key"  : "value"  ,'
    // skipping separator                    ^
    assert.equal(tokens[end].type, 'separator')
    assert.equal(tokens[end].raw, ':')
    while(is_whitespace(tokens[--end].type)) {
      if (end < begin) return result
      if (tokens[end].type === 'whitespace') {
        result.sep1.unshift(tokens[end])
      } else {
        // newline, comment or other unrecognized codestyle
        return result
      }
    }

    assert.equal(tokens[end].type, 'key')
    end--
  }

  //                              ' "key"  : "value"  ,'
  // skipping key                   ^^^^^
  while(is_whitespace(tokens[end].type)) {
    if (end < begin) return result
    if (tokens[end].type === 'whitespace') {
      result.prefix.unshift(tokens[end])
    } else if (tokens[end].type === 'newline') {
      result.newline.unshift(tokens[end])
      return result
    } else {
      // comment or other unrecognized codestyle
      return result
    }
    end--
  }

  return result
}

function Document(text, options) {
  var self = Object.create(Document.prototype)

  if (options == null) options = {}
  //options._structure = true
  var tokens = self._tokens = tokenize(text, options)
  self._data = tokens.data
  tokens.data = null
  self._options = options

  var stats = analyze(text, options)
  if (options.indent == null) {
    options.indent = stats.indent
  }
  if (options.quote == null) {
    options.quote = stats.quote
  }
  if (options.quote_keys == null) {
    options.quote_keys = stats.quote_keys
  }
  if (options.no_trailing_comma == null) {
    options.no_trailing_comma = !stats.has_trailing_comma
  }
  return self
}

// return true if it's a proper object
//        throw otherwise
function check_if_can_be_placed(key, object, is_unset) {
  //if (object == null) return false
  function error(add) {
    return Error("You can't " + (is_unset ? 'unset' : 'set') + " key '" + key + "'" + add)
  }

  if (!isObject(object)) {
    throw error(' of an non-object')
  }
  if (Array.isArray(object)) {
    // array, check boundary
    if (String(key).match(/^\d+$/)) {
      key = Number(String(key))
      if (object.length < key || (is_unset && object.length === key)) {
        throw error(', out of bounds')
      } else if (is_unset && object.length !== key+1) {
        throw error(' in the middle of an array')
      } else {
        return true
      }
    } else {
      throw error(' of an array')
    }
  } else {
    // object
    return true
  }
}

// usage: document.set('path.to.something', 'value')
//    or: document.set(['path','to','something'], 'value')
Document.prototype.set = function(path, value) {
  path = arg_to_path(path)

  // updating this._data and check for errors
  if (path.length === 0) {
    if (value === undefined) throw Error("can't remove root document")
    this._data = value
    var new_key = false

  } else {
    var data = this._data

    for (var i=0; i<path.length-1; i++) {
      check_if_can_be_placed(path[i], data, false)
      data = data[path[i]]
    }
    if (i === path.length-1) {
      check_if_can_be_placed(path[i], data, value === undefined)
    }

    var new_key = !(path[i] in data)

    if (value === undefined) {
      if (Array.isArray(data)) {
        data.pop()
      } else {
        delete data[path[i]]
      }
    } else {
      data[path[i]] = value
    }
  }

  // for inserting document
  if (!this._tokens.length)
    this._tokens = [ { raw: '', type: 'literal', stack: [], value: undefined } ]

  var position = [
    find_first_non_ws_token(this._tokens, 0, this._tokens.length - 1),
    find_last_non_ws_token(this._tokens, 0, this._tokens.length - 1),
  ]
  for (var i=0; i<path.length-1; i++) {
    position = find_element_in_tokenlist(path[i], i, this._tokens, position[0], position[1])
    if (position == false) throw Error('internal error, please report this')
  }
  // assume that i == path.length-1 here

  if (path.length === 0) {
    var newtokens = value_to_tokenlist(value, path, this._options)
    // all good

  } else if (!new_key) {
    // replace old value with a new one (or deleting something)
    var pos_old = position
    position = find_element_in_tokenlist(path[i], i, this._tokens, position[0], position[1])

    if (value === undefined && position !== false) {
      // deleting element (position !== false ensures there's something)
      var newtokens = []

      if (!Array.isArray(data)) {
        // removing element from an object, `{x:1, key:CURRENT} -> {x:1}`
        // removing sep, literal and optional sep
        // ':'
        var pos2 = find_last_non_ws_token(this._tokens, pos_old[0], position[0] - 1)
        assert.equal(this._tokens[pos2].type, 'separator')
        assert.equal(this._tokens[pos2].raw, ':')
        position[0] = pos2

        // key
        var pos2 = find_last_non_ws_token(this._tokens, pos_old[0], position[0] - 1)
        assert.equal(this._tokens[pos2].type, 'key')
        assert.equal(this._tokens[pos2].value, path[path.length-1])
        position[0] = pos2
      }

      // removing comma in arrays and objects
      var pos2 = find_last_non_ws_token(this._tokens, pos_old[0], position[0] - 1)
      assert.equal(this._tokens[pos2].type, 'separator')
      if (this._tokens[pos2].raw === ',') {
        position[0] = pos2
      } else {
        // beginning of the array/object, so we should remove trailing comma instead
        pos2 = find_first_non_ws_token(this._tokens, position[1] + 1, pos_old[1])
        assert.equal(this._tokens[pos2].type, 'separator')
        if (this._tokens[pos2].raw === ',') {
          position[1] = pos2
        }
      }

    } else {
      var indent = pos2 !== false
                 ? detect_indent_style(this._tokens, Array.isArray(data), pos_old[0], position[1] - 1, i)
                 : {}
      var newtokens = value_to_tokenlist(value, path, this._options, false, indent)
    }

  } else {
    // insert new key, that's tricky
    var path_1 = path.slice(0, i)

    //  find a last separator after which we're inserting it
    var pos2 = find_last_non_ws_token(this._tokens, position[0] + 1, position[1] - 1)
    assert(pos2 !== false)

    var indent = pos2 !== false
               ? detect_indent_style(this._tokens, Array.isArray(data), position[0] + 1, pos2, i)
               : {}

    var newtokens = value_to_tokenlist(value, path, this._options, false, indent)

    // adding leading whitespaces according to detected codestyle
    var prefix = []
    if (indent.newline && indent.newline.length)
      prefix = prefix.concat(indent.newline)
    if (indent.prefix && indent.prefix.length)
      prefix = prefix.concat(indent.prefix)

    // adding '"key":' (as in "key":"value") to object values
    if (!Array.isArray(data)) {
      prefix = prefix.concat(value_to_tokenlist(path[path.length-1], path_1, this._options, true))
      if (indent.sep1 && indent.sep1.length)
        prefix = prefix.concat(indent.sep1)
      prefix.push({raw: ':', type: 'separator', stack: path_1})
      if (indent.sep2 && indent.sep2.length)
        prefix = prefix.concat(indent.sep2)
    }

    newtokens.unshift.apply(newtokens, prefix)

    // check if prev token is a separator AND they're at the same level
    if (this._tokens[pos2].type === 'separator' && this._tokens[pos2].stack.length === path.length-1) {
      // previous token is either , or [ or {
      if (this._tokens[pos2].raw === ',') {
        // restore ending comma
        newtokens.push({raw: ',', type: 'separator', stack: path_1})
      }
    } else {
      // previous token isn't a separator, so need to insert one
      newtokens.unshift({raw: ',', type: 'separator', stack: path_1})
    }

    if (indent.suffix && indent.suffix.length)
      newtokens.push.apply(newtokens, indent.suffix)

    assert.equal(this._tokens[position[1]].type, 'separator')
    position[0] = pos2+1
    position[1] = pos2
  }

  newtokens.unshift(position[1] - position[0] + 1)
  newtokens.unshift(position[0])
  this._tokens.splice.apply(this._tokens, newtokens)

  return this
}

// convenience method
Document.prototype.unset = function(path) {
  return this.set(path, undefined)
}

Document.prototype.get = function(path) {
  path = arg_to_path(path)

  var data = this._data
  for (var i=0; i<path.length; i++) {
    if (!isObject(data)) return undefined
    data = data[path[i]]
  }
  return data
}

Document.prototype.has = function(path) {
  path = arg_to_path(path)

  var data = this._data
  for (var i=0; i<path.length; i++) {
    if (!isObject(data)) return false
    data = data[path[i]]
  }
  return data !== undefined
}

// compare old object and new one, and change differences only
Document.prototype.update = function(value) {
  var self = this
  change([], self._data, value)
  return self

  function change(path, old_data, new_data) {
    if (!isObject(new_data) || !isObject(old_data)) {
      // if source or dest is primitive, just replace
      if (new_data !== old_data)
        self.set(path, new_data)

    } else if (Array.isArray(new_data) != Array.isArray(old_data)) {
      // old data is an array XOR new data is an array, replace as well
      self.set(path, new_data)

    } else if (Array.isArray(new_data)) {
      // both values are arrays here

      if (new_data.length > old_data.length) {
        // adding new elements, so going forward
        for (var i=0; i<new_data.length; i++) {
          path.push(String(i))
          change(path, old_data[i], new_data[i])
          path.pop()
        }

      } else {
        // removing something, so going backward
        for (var i=old_data.length-1; i>=0; i--) {
          path.push(String(i))
          change(path, old_data[i], new_data[i])
          path.pop()
        }
      }

    } else {
      // both values are objects here
      for (var i in new_data) {
        path.push(String(i))
        change(path, old_data[i], new_data[i])
        path.pop()
      }

      for (var i in old_data) {
        if (i in new_data) continue
        path.push(String(i))
        change(path, old_data[i], new_data[i])
        path.pop()
      }
    }
  }
}

Document.prototype.toString = function() {
  return this._tokens.map(function(x) {
    return x.raw
  }).join('')
}

module.exports.Document = Document

module.exports.update = function updateJSON(source, new_value, options) {
  return Document(source, options).update(new_value).toString()
}