/* 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/. */

/*
 * Defines a handler object to represent forms that autofill can handle.
 */

"use strict";

this.EXPORTED_SYMBOLS = ["FormAutofillHandler"];

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

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

Cu.import("resource://formautofill/FormAutofillUtils.jsm");

XPCOMUtils.defineLazyModuleGetter(this, "FormAutofillHeuristics",
                                  "resource://formautofill/FormAutofillHeuristics.jsm");

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

/**
 * Handles profile autofill for a DOM Form element.
 * @param {FormLike} form Form that need to be auto filled
 */
function FormAutofillHandler(form) {
  this.form = form;
  this.fieldDetails = [];
  this.winUtils = this.form.rootElement.ownerGlobal.QueryInterface(Ci.nsIInterfaceRequestor)
    .getInterface(Ci.nsIDOMWindowUtils);
}

FormAutofillHandler.prototype = {
  /**
   * DOM Form element to which this object is attached.
   */
  form: null,

  /**
   * Array of collected data about relevant form fields.  Each item is an object
   * storing the identifying details of the field and a reference to the
   * originally associated element from the form.
   *
   * The "section", "addressType", "contactType", and "fieldName" values are
   * used to identify the exact field when the serializable data is received
   * from the backend.  There cannot be multiple fields which have
   * the same exact combination of these values.
   *
   * A direct reference to the associated element cannot be sent to the user
   * interface because processing may be done in the parent process.
   */
  fieldDetails: null,

  /**
   * String of the filled profile's guid.
   */
  filledProfileGUID: null,

  /**
   * A WindowUtils reference of which Window the form belongs
   */
  winUtils: null,

  /**
   * Enum for form autofill MANUALLY_MANAGED_STATES values
   */
  fieldStateEnum: {
    // not themed
    NORMAL: null,
    // highlighted
    AUTO_FILLED: "-moz-autofill",
    // highlighted && grey color text
    PREVIEW: "-moz-autofill-preview",
  },

  /**
   * Set fieldDetails from the form about fields that can be autofilled.
   */
  collectFormFields() {
    let fieldDetails = FormAutofillHeuristics.getFormInfo(this.form);
    this.fieldDetails = fieldDetails ? fieldDetails : [];
    log.debug("Collected details on", this.fieldDetails.length, "fields");
  },

  /**
   * Processes form fields that can be autofilled, and populates them with the
   * profile provided by backend.
   *
   * @param {Object} profile
   *        A profile to be filled in.
   * @param {Object} focusedInput
   *        A focused input element which is skipped for filling.
   */
  autofillFormFields(profile, focusedInput) {
    log.debug("profile in autofillFormFields:", profile);

    this.filledProfileGUID = profile.guid;
    for (let fieldDetail of this.fieldDetails) {
      // Avoid filling field value in the following cases:
      // 1. the focused input which is filled in FormFillController.
      // 2. a non-empty input field
      // 3. the invalid value set
      // 4. value already chosen in select element

      let element = fieldDetail.elementWeakRef.get();
      if (!element) {
        continue;
      }

      let value = profile[fieldDetail.fieldName];
      if (element instanceof Ci.nsIDOMHTMLInputElement && !element.value && value) {
        if (element !== focusedInput) {
          element.setUserInput(value);
        }
        this.changeFieldState(fieldDetail, "AUTO_FILLED");
      } else if (element instanceof Ci.nsIDOMHTMLSelectElement) {
        for (let option of element.options) {
          if (value === option.textContent || value === option.value) {
            // Do not change value if the option is already selected.
            // Use case for multiple select is not considered here.
            if (option.selected) {
              break;
            }
            // TODO: Using dispatchEvent does not 100% simulate select change.
            //       Should investigate further in Bug 1365895.
            option.selected = true;
            element.dispatchEvent(new Event("input", {"bubbles": true}));
            element.dispatchEvent(new Event("change", {"bubbles": true}));
            this.changeFieldState(fieldDetail, "AUTO_FILLED");
            break;
          }
        }
      }

      // Unlike using setUserInput directly, FormFillController dispatches an
      // asynchronous "DOMAutoComplete" event with an "input" event follows right
      // after. So, we need to suppress the first "input" event fired off from
      // focused input to make sure the latter change handler won't be affected
      // by auto filling.
      if (element === focusedInput) {
        const suppressFirstInputHandler = e => {
          if (e.isTrusted) {
            e.stopPropagation();
            element.removeEventListener("input", suppressFirstInputHandler);
          }
        };

        element.addEventListener("input", suppressFirstInputHandler);
      }
      element.previewValue = "";
    }

    // Handle the highlight style resetting caused by user's correction afterward.
    log.debug("register change handler for filled form:", this.form);
    const onChangeHandler = e => {
      let hasFilledFields;

      if (!e.isTrusted) {
        return;
      }

      for (let fieldDetail of this.fieldDetails) {
        let element = fieldDetail.elementWeakRef.get();

        if (!element) {
          return;
        }

        if (e.target == element || (e.target == element.form && e.type == "reset")) {
          this.changeFieldState(fieldDetail, "NORMAL");
        }

        hasFilledFields |= (fieldDetail.state == "AUTO_FILLED");
      }

      // Unregister listeners once no field is in AUTO_FILLED state.
      if (!hasFilledFields) {
        this.form.rootElement.removeEventListener("input", onChangeHandler);
        this.form.rootElement.removeEventListener("reset", onChangeHandler);
      }
    };

    this.form.rootElement.addEventListener("input", onChangeHandler);
    this.form.rootElement.addEventListener("reset", onChangeHandler);
  },

  /**
   * Populates result to the preview layers with given profile.
   *
   * @param {Object} profile
   *        A profile to be previewed with
   */
  previewFormFields(profile) {
    log.debug("preview profile in autofillFormFields:", profile);

    for (let fieldDetail of this.fieldDetails) {
      let element = fieldDetail.elementWeakRef.get();
      let value = profile[fieldDetail.fieldName] || "";

      // Skip the field that is null or already has text entered
      if (!element || element.value) {
        continue;
      }

      element.previewValue = value;
      this.changeFieldState(fieldDetail, value ? "PREVIEW" : "NORMAL");
    }
  },

  /**
   * Clear preview text and background highlight of all fields.
   */
  clearPreviewedFormFields() {
    log.debug("clear previewed fields in:", this.form);

    for (let fieldDetail of this.fieldDetails) {
      let element = fieldDetail.elementWeakRef.get();
      if (!element) {
        log.warn(fieldDetail.fieldName, "is unreachable");
        continue;
      }

      element.previewValue = "";

      // We keep the state if this field has
      // already been auto-filled.
      if (fieldDetail.state === "AUTO_FILLED") {
        continue;
      }

      this.changeFieldState(fieldDetail, "NORMAL");
    }
  },

  /**
   * Change the state of a field to correspond with different presentations.
   *
   * @param {Object} fieldDetail
   *        A fieldDetail of which its element is about to update the state.
   * @param {string} nextState
   *        Used to determine the next state
   */
  changeFieldState(fieldDetail, nextState) {
    let element = fieldDetail.elementWeakRef.get();

    if (!element) {
      log.warn(fieldDetail.fieldName, "is unreachable while changing state");
      return;
    }
    if (!(nextState in this.fieldStateEnum)) {
      log.warn(fieldDetail.fieldName, "is trying to change to an invalid state");
      return;
    }

    for (let [state, mmStateValue] of Object.entries(this.fieldStateEnum)) {
      // The NORMAL state is simply the absence of other manually
      // managed states so we never need to add or remove it.
      if (!mmStateValue) {
        continue;
      }

      if (state == nextState) {
        this.winUtils.addManuallyManagedState(element, mmStateValue);
      } else {
        this.winUtils.removeManuallyManagedState(element, mmStateValue);
      }
    }

    fieldDetail.state = nextState;
  },

  /**
   * Return the profile that is converted from fieldDetails and only non-empty fields
   * are included.
   *
   * @returns {Object} The new profile that convert from details with trimmed result.
   */
  createProfile() {
    let profile = {};

    this.fieldDetails.forEach(detail => {
      let element = detail.elementWeakRef.get();
      // Remove the unnecessary spaces
      let value = element && element.value.trim();
      if (!value) {
        return;
      }

      profile[detail.fieldName] = value;
    });

    return profile;
  },
};