import {reservedWords, keywords} from "./identifier"
import {types as tt} from "./tokentype"
import {lineBreak} from "./whitespace"

export function Parser(options, input, startPos) {
  this.options = options
  this.sourceFile = this.options.sourceFile || null
  this.isKeyword = keywords[this.options.ecmaVersion >= 6 ? 6 : 5]
  this.isReservedWord = reservedWords[this.options.ecmaVersion]
  this.input = input

  // Load plugins
  this.loadPlugins(this.options.plugins)

  // Set up token state

  // The current position of the tokenizer in the input.
  if (startPos) {
    this.pos = startPos
    this.lineStart = Math.max(0, this.input.lastIndexOf("\n", startPos))
    this.curLine = this.input.slice(0, this.lineStart).split(lineBreak).length
  } else {
    this.pos = this.lineStart = 0
    this.curLine = 1
  }

  // Properties of the current token:
  // Its type
  this.type = tt.eof
  // For tokens that include more information than their type, the value
  this.value = null
  // Its start and end offset
  this.start = this.end = this.pos
  // And, if locations are used, the {line, column} object
  // corresponding to those offsets
  this.startLoc = this.endLoc = null

  // Position information for the previous token
  this.lastTokEndLoc = this.lastTokStartLoc = null
  this.lastTokStart = this.lastTokEnd = this.pos

  // The context stack is used to superficially track syntactic
  // context to predict whether a regular expression is allowed in a
  // given position.
  this.context = this.initialContext()
  this.exprAllowed = true

  // Figure out if it's a module code.
  this.strict = this.inModule = this.options.sourceType === "module"

  // Used to signify the start of a potential arrow function
  this.potentialArrowAt = -1

  // Flags to track whether we are in a function, a generator.
  this.inFunction = this.inGenerator = false
  // Labels in scope.
  this.labels = []

  // If enabled, skip leading hashbang line.
  if (this.pos === 0 && this.options.allowHashBang && this.input.slice(0, 2) === '#!')
    this.skipLineComment(2)
}

Parser.prototype.extend = function(name, f) {
  this[name] = f(this[name])
}

// Registered plugins

export const plugins = {}

Parser.prototype.loadPlugins = function(plugins) {
  for (let name in plugins) {
    let plugin = exports.plugins[name]
    if (!plugin) throw new Error("Plugin '" + name + "' not found")
    plugin(this, plugins[name])
  }
}