/*!
 * lunr.tokenizer
 * Copyright (C) @YEAR Oliver Nightingale
 */

/**
 * A function for splitting a string into tokens ready to be inserted into
 * the search index. Uses `lunr.tokenizer.seperator` to split strings, change
 * the value of this property to change how strings are split into tokens.
 *
 * @module
 * @param {String} obj The string to convert into tokens
 * @see lunr.tokenizer.seperator
 * @returns {Array}
 */
lunr.tokenizer = function (obj) {
  if (!arguments.length || obj == null || obj == undefined) return []
  if (Array.isArray(obj)) return obj.map(function (t) { return lunr.utils.asString(t).toLowerCase() })

  return obj.toString().trim().toLowerCase().split(lunr.tokenizer.seperator)
}

/**
 * The sperator used to split a string into tokens. Override this property to change the behaviour of
 * `lunr.tokenizer` behaviour when tokenizing strings. By default this splits on whitespace and hyphens.
 *
 * @static
 * @see lunr.tokenizer
 */
lunr.tokenizer.seperator = /[\s\-]+/

/**
 * Loads a previously serialised tokenizer.
 *
 * A tokenizer function to be loaded must already be registered with lunr.tokenizer.
 * If the serialised tokenizer has not been registered then an error will be thrown.
 *
 * @param {String} label The label of the serialised tokenizer.
 * @returns {Function}
 * @memberOf tokenizer
 */
lunr.tokenizer.load = function (label) {
  var fn = this.registeredFunctions[label]

  if (!fn) {
    throw new Error('Cannot load un-registered function: ' + label)
  }

  return fn
}

lunr.tokenizer.label = 'default'

lunr.tokenizer.registeredFunctions = {
  'default': lunr.tokenizer
}

/**
 * Register a tokenizer function.
 *
 * Functions that are used as tokenizers should be registered if they are to be used with a serialised index.
 *
 * Registering a function does not add it to an index, functions must still be associated with a specific index for them to be used when indexing and searching documents.
 *
 * @param {Function} fn The function to register.
 * @param {String} label The label to register this function with
 * @memberOf tokenizer
 */
lunr.tokenizer.registerFunction = function (fn, label) {
  if (label in this.registeredFunctions) {
    lunr.utils.warn('Overwriting existing tokenizer: ' + label)
  }

  fn.label = label
  this.registeredFunctions[label] = fn
}