/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * Form Autofill field heuristics.
 */

"use strict";

this.EXPORTED_SYMBOLS = ["FormAutofillHeuristics", "LabelUtils"];

const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;

Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://formautofill/FormAutofillUtils.jsm");

this.log = null;
FormAutofillUtils.defineLazyLogGetter(this, this.EXPORTED_SYMBOLS[0]);

const PREF_HEURISTICS_ENABLED = "extensions.formautofill.heuristics.enabled";

/**
 * A scanner for traversing all elements in a form and retrieving the field
 * detail with FormAutofillHeuristics.getInfo function. It also provides a
 * cursor (parsingIndex) to indicate which element is waiting for parsing.
 */
class FieldScanner {
  /**
   * Create a FieldScanner based on form elements with the existing
   * fieldDetails.
   *
   * @param {Array.DOMElement} elements
   *        The elements from a form for each parser.
   */
  constructor(elements) {
    this._elementsWeakRef = Cu.getWeakReference(elements);
    this.fieldDetails = [];
    this._parsingIndex = 0;
  }

  get _elements() {
    return this._elementsWeakRef.get();
  }

  /**
   * This cursor means the index of the element which is waiting for parsing.
   *
   * @returns {number}
   *          The index of the element which is waiting for parsing.
   */
  get parsingIndex() {
    return this._parsingIndex;
  }

  /**
   * Move the parsingIndex to the next elements. Any elements behind this index
   * means the parsing tasks are finished.
   *
   * @param {number} index
   *        The latest index of elements waiting for parsing.
   */
  set parsingIndex(index) {
    if (index > this.fieldDetails.length) {
      throw new Error("The parsing index is out of range.");
    }
    this._parsingIndex = index;
  }

  /**
   * Retrieve the field detail by the index. If the field detail is not ready,
   * the elements will be traversed until matching the index.
   *
   * @param {number} index
   *        The index of the element that you want to retrieve.
   * @returns {Object}
   *          The field detail at the specific index.
   */
  getFieldDetailByIndex(index) {
    if (index >= this._elements.length) {
      throw new Error(`The index ${index} is out of range.(${this._elements.length})`);
    }

    if (index < this.fieldDetails.length) {
      return this.fieldDetails[index];
    }

    for (let i = this.fieldDetails.length; i < (index + 1); i++) {
      this.pushDetail();
    }

    return this.fieldDetails[index];
  }

  get parsingFinished() {
    return this.parsingIndex >= this._elements.length;
  }

  /**
   * This function will prepare an autocomplete info object with getInfo
   * function and push the detail to fieldDetails property. Any duplicated
   * detail will be marked as _duplicated = true for the parser.
   *
   * Any element without the related detail will be used for adding the detail
   * to the end of field details.
   */
  pushDetail() {
    let elementIndex = this.fieldDetails.length;
    if (elementIndex >= this._elements.length) {
      throw new Error("Try to push the non-existing element info.");
    }
    let element = this._elements[elementIndex];
    let info = FormAutofillHeuristics.getInfo(element);
    if (!info) {
      info = {};
    }
    let fieldInfo = {
      section: info.section,
      addressType: info.addressType,
      contactType: info.contactType,
      fieldName: info.fieldName,
      elementWeakRef: Cu.getWeakReference(element),
    };

    if (info._reason) {
      fieldInfo._reason = info._reason;
    }

    // Store the association between the field metadata and the element.
    if (this.findSameField(info) != -1) {
      // A field with the same identifier already exists.
      log.debug("Not collecting a field matching another with the same info:", info);
      fieldInfo._duplicated = true;
    }

    this.fieldDetails.push(fieldInfo);
  }

  /**
   * When a field detail should be changed its fieldName after parsing, use
   * this function to update the fieldName which is at a specific index.
   *
   * @param {number} index
   *        The index indicates a field detail to be updated.
   * @param {string} fieldName
   *        The new fieldName
   */
  updateFieldName(index, fieldName) {
    if (index >= this.fieldDetails.length) {
      throw new Error("Try to update the non-existing field detail.");
    }
    this.fieldDetails[index].fieldName = fieldName;

    delete this.fieldDetails[index]._duplicated;
    let indexSame = this.findSameField(this.fieldDetails[index]);
    if (indexSame != index && indexSame != -1) {
      this.fieldDetails[index]._duplicated = true;
    }
  }

  findSameField(info) {
    return this.fieldDetails.findIndex(f => f.section == info.section &&
                                       f.addressType == info.addressType &&
                                       f.contactType == info.contactType &&
                                       f.fieldName == info.fieldName);
  }

  /**
   * Provide the field details without invalid field name and duplicated fields.
   *
   * @returns {Array<Object>}
   *          The array with the field details without invalid field name and
   *          duplicated fields.
   */
  get trimmedFieldDetail() {
    return this.fieldDetails.filter(f => f.fieldName && !f._duplicated);
  }

  elementExisting(index) {
    return index < this._elements.length;
  }
}

this.LabelUtils = {
  // The tag name list is from Chromium except for "STYLE":
  // eslint-disable-next-line max-len
  // https://cs.chromium.org/chromium/src/components/autofill/content/renderer/form_autofill_util.cc?l=216&rcl=d33a171b7c308a64dc3372fac3da2179c63b419e
  EXCLUDED_TAGS: ["SCRIPT", "NOSCRIPT", "OPTION", "STYLE"],

  // A map object, whose keys are the id's of form fields and each value is an
  // array consisting of label elements correponding to the id.
  // @type {Map<string, array>}
  _mappedLabels: null,

  // An array consisting of label elements whose correponding form field doesn't
  // have an id attribute.
  // @type {Array.<HTMLLabelElement>}
  _unmappedLabels: null,

  /**
   * Extract all strings of an element's children to an array.
   * "element.textContent" is a string which is merged of all children nodes,
   * and this function provides an array of the strings contains in an element.
   *
   * @param  {Object} element
   *         A DOM element to be extracted.
   * @returns {Array}
   *          All strings in an element.
   */
  extractLabelStrings(element) {
    let strings = [];
    let _extractLabelStrings = (el) => {
      if (this.EXCLUDED_TAGS.includes(el.tagName)) {
        return;
      }

      if (el.nodeType == Ci.nsIDOMNode.TEXT_NODE || el.childNodes.length == 0) {
        let trimmedText = el.textContent.trim();
        if (trimmedText) {
          strings.push(trimmedText);
        }
        return;
      }

      for (let node of el.childNodes) {
        let nodeType = node.nodeType;
        if (nodeType != Ci.nsIDOMNode.ELEMENT_NODE && nodeType != Ci.nsIDOMNode.TEXT_NODE) {
          continue;
        }
        _extractLabelStrings(node);
      }
    };
    _extractLabelStrings(element);
    return strings;
  },

  generateLabelMap(doc) {
    let mappedLabels = new Map();
    let unmappedLabels = [];

    for (let label of doc.querySelectorAll("label")) {
      let id = label.htmlFor;
      if (!id) {
        let control = label.control;
        if (!control) {
          continue;
        }
        id = control.id;
      }
      if (id) {
        let labels = mappedLabels.get(id);
        if (labels) {
          labels.push(label);
        } else {
          mappedLabels.set(id, [label]);
        }
      } else {
        unmappedLabels.push(label);
      }
    }

    this._mappedLabels = mappedLabels;
    this._unmappedLabels = unmappedLabels;
  },

  clearLabelMap() {
    this._mappedLabels = null;
    this._unmappedLabels = null;
  },

  findLabelElements(element) {
    if (!this._mappedLabels) {
      this.generateLabelMap(element.ownerDocument);
    }

    let id = element.id;
    if (!id) {
      return this._unmappedLabels.filter(label => label.control == element);
    }
    return this._mappedLabels.get(id) || [];
  },
};

/**
 * Returns the autocomplete information of fields according to heuristics.
 */
this.FormAutofillHeuristics = {
  RULES: null,

  /**
   * Try to match the telephone related fields to the grammar
   * list to see if there is any valid telephone set and correct their
   * field names.
   *
   * @param {FieldScanner} fieldScanner
   *        The current parsing status for all elements
   * @returns {boolean}
   *          Return true if there is any field can be recognized in the parser,
   *          otherwise false.
   */
  _parsePhoneFields(fieldScanner) {
    let matchingResult;

    const GRAMMARS = this.PHONE_FIELD_GRAMMARS;
    for (let i = 0; i < GRAMMARS.length; i++) {
      let detailStart = fieldScanner.parsingIndex;
      let ruleStart = i;
      for (; i < GRAMMARS.length && GRAMMARS[i][0] && fieldScanner.elementExisting(detailStart); i++, detailStart++) {
        let detail = fieldScanner.getFieldDetailByIndex(detailStart);
        if (!detail || GRAMMARS[i][0] != detail.fieldName || detail._reason == "autocomplete") {
          break;
        }
        let element = detail.elementWeakRef.get();
        if (!element) {
          break;
        }
        if (GRAMMARS[i][2] && (!element.maxLength || GRAMMARS[i][2] < element.maxLength)) {
          break;
        }
      }
      if (i >= GRAMMARS.length) {
        break;
      }

      if (!GRAMMARS[i][0]) {
        matchingResult = {
          ruleFrom: ruleStart,
          ruleTo: i,
        };
        break;
      }

      // Fast rewinding to the next rule.
      for (; i < GRAMMARS.length; i++) {
        if (!GRAMMARS[i][0]) {
          break;
        }
      }
    }

    let parsedField = false;
    if (matchingResult) {
      let {ruleFrom, ruleTo} = matchingResult;
      let detailStart = fieldScanner.parsingIndex;
      for (let i = ruleFrom; i < ruleTo; i++) {
        fieldScanner.updateFieldName(detailStart, GRAMMARS[i][1]);
        fieldScanner.parsingIndex++;
        detailStart++;
        parsedField = true;
      }
    }

    if (fieldScanner.parsingFinished) {
      return parsedField;
    }

    let nextField = fieldScanner.getFieldDetailByIndex(fieldScanner.parsingIndex);
    if (nextField && nextField.fieldName == "tel-extension") {
      fieldScanner.parsingIndex++;
      parsedField = true;
    }

    return parsedField;
  },

  /**
   * Try to find the correct address-line[1-3] sequence and correct their field
   * names.
   *
   * @param {FieldScanner} fieldScanner
   *        The current parsing status for all elements
   * @returns {boolean}
   *          Return true if there is any field can be recognized in the parser,
   *          otherwise false.
   */
  _parseAddressFields(fieldScanner) {
    let parsedFields = false;
    let addressLines = ["address-line1", "address-line2", "address-line3"];
    for (let i = 0; !fieldScanner.parsingFinished && i < addressLines.length; i++) {
      let detail = fieldScanner.getFieldDetailByIndex(fieldScanner.parsingIndex);
      if (!detail || !addressLines.includes(detail.fieldName)) {
        // When the field is not related to any address-line[1-3] fields, it
        // means the parsing process can be terminated.
        break;
      }
      fieldScanner.updateFieldName(fieldScanner.parsingIndex, addressLines[i]);
      fieldScanner.parsingIndex++;
      parsedFields = true;
    }

    return parsedFields;
  },

  /**
   * This function should provide all field details of a form. The details
   * contain the autocomplete info (e.g. fieldName, section, etc).
   *
   * `allowDuplicates` is used for the xpcshell-test purpose currently because
   * the heuristics should be verified that some duplicated elements still can
   * be predicted correctly.
   *
   * @param {HTMLFormElement} form
   *        the elements in this form to be predicted the field info.
   * @param {boolean} allowDuplicates
   *        true to remain any duplicated field details otherwise to remove the
   *        duplicated ones.
   * @returns {Array<Object>}
   *        all field details in the form.
   */
  getFormInfo(form, allowDuplicates = false) {
    if (form.elements.length <= 0) {
      return [];
    }

    let fieldScanner = new FieldScanner(form.elements);
    while (!fieldScanner.parsingFinished) {
      let parsedPhoneFields = this._parsePhoneFields(fieldScanner);
      let parsedAddressFields = this._parseAddressFields(fieldScanner);

      // If there is no any field parsed, the parsing cursor can be moved
      // forward to the next one.
      if (!parsedPhoneFields && !parsedAddressFields) {
        fieldScanner.parsingIndex++;
      }
    }

    LabelUtils.clearLabelMap();

    if (allowDuplicates) {
      return fieldScanner.fieldDetails;
    }

    return fieldScanner.trimmedFieldDetail;
  },

  getInfo(element) {
    if (!FormAutofillUtils.isFieldEligibleForAutofill(element)) {
      return null;
    }

    let info = element.getAutocompleteInfo();
    // An input[autocomplete="on"] will not be early return here since it stll
    // needs to find the field name.
    if (info && info.fieldName && info.fieldName != "on" && info.fieldName != "off") {
      info._reason = "autocomplete";
      return info;
    }

    if (!this._prefEnabled) {
      return null;
    }

    let isAutoCompleteOff = element.autocomplete == "off" ||
      (element.form && element.form.autocomplete == "off");

    // "email" type of input is accurate for heuristics to determine its Email
    // field or not. However, "tel" type is used for ZIP code for some web site
    // (e.g. HomeDepot, BestBuy), so "tel" type should be not used for "tel"
    // prediction.
    if (element.type == "email" && !isAutoCompleteOff) {
      return {
        fieldName: "email",
        section: "",
        addressType: "",
        contactType: "",
      };
    }

    const FIELDNAMES_IGNORING_AUTOCOMPLETE_OFF = [
      "cc-name",
      "cc-number",
      "cc-exp-month",
      "cc-exp-year",
      "cc-exp",
    ];
    let regexps = isAutoCompleteOff ? FIELDNAMES_IGNORING_AUTOCOMPLETE_OFF : Object.keys(this.RULES);

    if (!FormAutofillUtils.isAutofillCreditCardsAvailable) {
      if (isAutoCompleteOff) {
        if (!this._regexpListOf_CcUnavailable_AcOff) {
          this._regexpListOf_CcUnavailable_AcOff = regexps.filter(name => !FormAutofillUtils.isCreditCardField(name));
        }
        regexps = this._regexpListOf_CcUnavailable_AcOff;
      } else {
        if (!this._regexpListOf_CcUnavailable_AcOn) {
          this._regexpListOf_CcUnavailable_AcOn = regexps.filter(name => !FormAutofillUtils.isCreditCardField(name));
        }
        regexps = this._regexpListOf_CcUnavailable_AcOn;
      }
    }
    if (regexps.length == 0) {
      return null;
    }

    let labelStrings;
    let getElementStrings = {};
    getElementStrings[Symbol.iterator] = function* () {
      yield element.id;
      yield element.name;
      if (!labelStrings) {
        labelStrings = [];
        let labels = LabelUtils.findLabelElements(element);
        for (let label of labels) {
          labelStrings.push(...LabelUtils.extractLabelStrings(label));
        }
      }
      yield *labelStrings;
    };

    for (let regexp of regexps) {
      for (let string of getElementStrings) {
        // The original regexp "(?<!united )state|county|region|province" for
        // "address-line1" wants to exclude any "united state" string, so the
        // following code is to remove all "united state" string before applying
        // "addess-level1" regexp.
        //
        // Since "united state" string matches to the regexp of address-line2&3,
        // the two regexps should be excluded here.
        if (["address-level1", "address-line2", "address-line3"].includes(regexp)) {
          string = string.toLowerCase().split("united state").join("");
        }
        if (this.RULES[regexp].test(string)) {
          return {
            fieldName: regexp,
            section: "",
            addressType: "",
            contactType: "",
          };
        }
      }
    }

    return null;
  },

/**
 * Phone field grammars - first matched grammar will be parsed. Grammars are
 * separated by { REGEX_SEPARATOR, FIELD_NONE, 0 }. Suffix and extension are
 * parsed separately unless they are necessary parts of the match.
 * The following notation is used to describe the patterns:
 * <cc> - country code field.
 * <ac> - area code field.
 * <phone> - phone or prefix.
 * <suffix> - suffix.
 * <ext> - extension.
 * :N means field is limited to N characters, otherwise it is unlimited.
 * (pattern <field>)? means pattern is optional and matched separately.
 *
 * This grammar list from Chromium will be enabled partially once we need to
 * support more cases of Telephone fields.
 */
  PHONE_FIELD_GRAMMARS: [
    // Country code: <cc> Area Code: <ac> Phone: <phone> (- <suffix>

    // (Ext: <ext>)?)?
      // {REGEX_COUNTRY, FIELD_COUNTRY_CODE, 0},
      // {REGEX_AREA, FIELD_AREA_CODE, 0},
      // {REGEX_PHONE, FIELD_PHONE, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // \( <ac> \) <phone>:3 <suffix>:4 (Ext: <ext>)?
      // {REGEX_AREA_NOTEXT, FIELD_AREA_CODE, 3},
      // {REGEX_PREFIX_SEPARATOR, FIELD_PHONE, 3},
      // {REGEX_PHONE, FIELD_SUFFIX, 4},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <cc> <ac>:3 - <phone>:3 - <suffix>:4 (Ext: <ext>)?
      // {REGEX_PHONE, FIELD_COUNTRY_CODE, 0},
      // {REGEX_PHONE, FIELD_AREA_CODE, 3},
      // {REGEX_PREFIX_SEPARATOR, FIELD_PHONE, 3},
      // {REGEX_SUFFIX_SEPARATOR, FIELD_SUFFIX, 4},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <cc>:3 <ac>:3 <phone>:3 <suffix>:4 (Ext: <ext>)?
    ["tel", "tel-country-code", 3],
    ["tel", "tel-area-code", 3],
    ["tel", "tel-local-prefix", 3],
    ["tel", "tel-local-suffix", 4],
    [null, null, 0],

    // Area Code: <ac> Phone: <phone> (- <suffix> (Ext: <ext>)?)?
      // {REGEX_AREA, FIELD_AREA_CODE, 0},
      // {REGEX_PHONE, FIELD_PHONE, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <ac> <phone>:3 <suffix>:4 (Ext: <ext>)?
      // {REGEX_PHONE, FIELD_AREA_CODE, 0},
      // {REGEX_PHONE, FIELD_PHONE, 3},
      // {REGEX_PHONE, FIELD_SUFFIX, 4},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <cc> \( <ac> \) <phone> (- <suffix> (Ext: <ext>)?)?
      // {REGEX_PHONE, FIELD_COUNTRY_CODE, 0},
      // {REGEX_AREA_NOTEXT, FIELD_AREA_CODE, 0},
      // {REGEX_PREFIX_SEPARATOR, FIELD_PHONE, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: \( <ac> \) <phone> (- <suffix> (Ext: <ext>)?)?
      // {REGEX_PHONE, FIELD_COUNTRY_CODE, 0},
      // {REGEX_AREA_NOTEXT, FIELD_AREA_CODE, 0},
      // {REGEX_PREFIX_SEPARATOR, FIELD_PHONE, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <cc> - <ac> - <phone> - <suffix> (Ext: <ext>)?
      // {REGEX_PHONE, FIELD_COUNTRY_CODE, 0},
      // {REGEX_PREFIX_SEPARATOR, FIELD_AREA_CODE, 0},
      // {REGEX_PREFIX_SEPARATOR, FIELD_PHONE, 0},
      // {REGEX_SUFFIX_SEPARATOR, FIELD_SUFFIX, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Area code: <ac>:3 Prefix: <prefix>:3 Suffix: <suffix>:4 (Ext: <ext>)?
      // {REGEX_AREA, FIELD_AREA_CODE, 3},
      // {REGEX_PREFIX, FIELD_PHONE, 3},
      // {REGEX_SUFFIX, FIELD_SUFFIX, 4},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <ac> Prefix: <phone> Suffix: <suffix> (Ext: <ext>)?
      // {REGEX_PHONE, FIELD_AREA_CODE, 0},
      // {REGEX_PREFIX, FIELD_PHONE, 0},
      // {REGEX_SUFFIX, FIELD_SUFFIX, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <ac> - <phone>:3 - <suffix>:4 (Ext: <ext>)?
    ["tel", "tel-area-code", 0],
    ["tel", "tel-local-prefix", 3],
    ["tel", "tel-local-suffix", 4],
    [null, null, 0],

    // Phone: <cc> - <ac> - <phone> (Ext: <ext>)?
      // {REGEX_PHONE, FIELD_COUNTRY_CODE, 0},
      // {REGEX_PREFIX_SEPARATOR, FIELD_AREA_CODE, 0},
      // {REGEX_SUFFIX_SEPARATOR, FIELD_PHONE, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <ac> - <phone> (Ext: <ext>)?
      // {REGEX_AREA, FIELD_AREA_CODE, 0},
      // {REGEX_PHONE, FIELD_PHONE, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <cc>:3 - <phone>:10 (Ext: <ext>)?
      // {REGEX_PHONE, FIELD_COUNTRY_CODE, 3},
      // {REGEX_PHONE, FIELD_PHONE, 10},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Ext: <ext>
      // {REGEX_EXTENSION, FIELD_EXTENSION, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},

    // Phone: <phone> (Ext: <ext>)?
      // {REGEX_PHONE, FIELD_PHONE, 0},
      // {REGEX_SEPARATOR, FIELD_NONE, 0},
  ],
};

XPCOMUtils.defineLazyGetter(this.FormAutofillHeuristics, "RULES", () => {
  let sandbox = {};
  let scriptLoader = Cc["@mozilla.org/moz/jssubscript-loader;1"]
                       .getService(Ci.mozIJSSubScriptLoader);
  const HEURISTICS_REGEXP = "chrome://formautofill/content/heuristicsRegexp.js";
  scriptLoader.loadSubScript(HEURISTICS_REGEXP, sandbox, "utf-8");
  return sandbox.HeuristicsRegExp.RULES;
});

XPCOMUtils.defineLazyGetter(this.FormAutofillHeuristics, "_prefEnabled", () => {
  return Services.prefs.getBoolPref(PREF_HEURISTICS_ENABLED);
});

Services.prefs.addObserver(PREF_HEURISTICS_ENABLED, () => {
  this.FormAutofillHeuristics._prefEnabled = Services.prefs.getBoolPref(PREF_HEURISTICS_ENABLED);
});