/**
 * @file
 * A Backbone Model for the state of an in-place editable field in the DOM.
 */

(function(_, Backbone, Drupal) {
  Drupal.quickedit.FieldModel = Drupal.quickedit.BaseModel.extend(
    /** @lends Drupal.quickedit.FieldModel# */ {
      /**
       * @type {object}
       */
      defaults: /** @lends Drupal.quickedit.FieldModel# */ {
        /**
         * The DOM element that represents this field. It may seem bizarre to have
         * a DOM element in a Backbone Model, but we need to be able to map fields
         * in the DOM to FieldModels in memory.
         */
        el: null,

        /**
         * A field ID, of the form
         * `<entity type>/<id>/<field name>/<language>/<view mode>`
         *
         * @example
         * "node/1/field_tags/und/full"
         */
        fieldID: null,

        /**
         * The unique ID of this field within its entity instance on the page, of
         * the form `<entity type>/<id>/<field name>/<language>/<view
         * mode>[entity instance ID]`.
         *
         * @example
         * "node/1/field_tags/und/full[0]"
         */
        id: null,

        /**
         * A {@link Drupal.quickedit.EntityModel}. Its "fields" attribute, which
         * is a FieldCollection, is automatically updated to include this
         * FieldModel.
         */
        entity: null,

        /**
         * This field's metadata as returned by the
         * QuickEditController::metadata().
         */
        metadata: null,

        /**
         * Callback function for validating changes between states. Receives the
         * previous state, new state, context, and a callback.
         */
        acceptStateChange: null,

        /**
         * A logical field ID, of the form
         * `<entity type>/<id>/<field name>/<language>`, i.e. the fieldID without
         * the view mode, to be able to identify other instances of the same
         * field on the page but rendered in a different view mode.
         *
         * @example
         * "node/1/field_tags/und".
         */
        logicalFieldID: null,

        // The attributes below are stateful. The ones above will never change
        // during the life of a FieldModel instance.

        /**
         * In-place editing state of this field. Defaults to the initial state.
         * Possible values: {@link Drupal.quickedit.FieldModel.states}.
         */
        state: 'inactive',

        /**
         * The field is currently in the 'changed' state or one of the following
         * states in which the field is still changed.
         */
        isChanged: false,

        /**
         * Is tracked by the EntityModel, is mirrored here solely for decorative
         * purposes: so that FieldDecorationView.renderChanged() can react to it.
         */
        inTempStore: false,

        /**
         * The full HTML representation of this field (with the element that has
         * the data-quickedit-field-id as the outer element). Used to propagate
         * changes from this field to other instances of the same field storage.
         */
        html: null,

        /**
         * An object containing the full HTML representations (values) of other
         * view modes (keys) of this field, for other instances of this field
         * displayed in a different view mode.
         */
        htmlForOtherViewModes: null,
      },

      /**
       * State of an in-place editable field in the DOM.
       *
       * @constructs
       *
       * @augments Drupal.quickedit.BaseModel
       *
       * @param {object} options
       *   Options for the field model.
       */
      initialize(options) {
        // Store the original full HTML representation of this field.
        this.set('html', options.el.outerHTML);

        // Enlist field automatically in the associated entity's field collection.
        this.get('entity')
          .get('fields')
          .add(this);

        // Automatically generate the logical field ID.
        this.set(
          'logicalFieldID',
          this.get('fieldID')
            .split('/')
            .slice(0, 4)
            .join('/'),
        );

        // Call Drupal.quickedit.BaseModel's initialize() method.
        Drupal.quickedit.BaseModel.prototype.initialize.call(this, options);
      },

      /**
       * Destroys the field model.
       *
       * @param {object} options
       *   Options for the field model.
       */
      destroy(options) {
        if (this.get('state') !== 'inactive') {
          throw new Error(
            'FieldModel cannot be destroyed if it is not inactive state.',
          );
        }
        Drupal.quickedit.BaseModel.prototype.destroy.call(this, options);
      },

      /**
       * @inheritdoc
       */
      sync() {
        // We don't use REST updates to sync.
      },

      /**
       * Validate function for the field model.
       *
       * @param {object} attrs
       *   The attributes changes in the save or set call.
       * @param {object} options
       *   An object with the following option:
       * @param {string} [options.reason]
       *   A string that conveys a particular reason to allow for an exceptional
       *   state change.
       * @param {Array} options.accept-field-states
       *   An array of strings that represent field states that the entities must
       *   be in to validate. For example, if `accept-field-states` is
       *   `['candidate', 'highlighted']`, then all the fields of the entity must
       *   be in either of these two states for the save or set call to
       *   validate and proceed.
       *
       * @return {string}
       *   A string to say something about the state of the field model.
       */
      validate(attrs, options) {
        const current = this.get('state');
        const next = attrs.state;
        if (current !== next) {
          // Ensure it's a valid state.
          if (_.indexOf(this.constructor.states, next) === -1) {
            return `"${next}" is an invalid state`;
          }
          // Check if the acceptStateChange callback accepts it.
          if (!this.get('acceptStateChange')(current, next, options, this)) {
            return 'state change not accepted';
          }
        }
      },

      /**
       * Extracts the entity ID from this field's ID.
       *
       * @return {string}
       *   An entity ID: a string of the format `<entity type>/<id>`.
       */
      getEntityID() {
        return this.get('fieldID')
          .split('/')
          .slice(0, 2)
          .join('/');
      },

      /**
       * Extracts the view mode ID from this field's ID.
       *
       * @return {string}
       *   A view mode ID.
       */
      getViewMode() {
        return this.get('fieldID')
          .split('/')
          .pop();
      },

      /**
       * Find other instances of this field with different view modes.
       *
       * @return {Array}
       *   An array containing view mode IDs.
       */
      findOtherViewModes() {
        const currentField = this;
        const otherViewModes = [];
        Drupal.quickedit.collections.fields
          // Find all instances of fields that display the same logical field
          // (same entity, same field, just a different instance and maybe a
          // different view mode).
          .where({ logicalFieldID: currentField.get('logicalFieldID') })
          .forEach(field => {
            // Ignore the current field and other fields with the same view mode.
            if (
              field !== currentField &&
              field.get('fieldID') !== currentField.get('fieldID')
            ) {
              otherViewModes.push(field.getViewMode());
            }
          });
        return otherViewModes;
      },
    },
    /** @lends Drupal.quickedit.FieldModel */ {
      /**
       * Sequence of all possible states a field can be in during quickediting.
       *
       * @type {Array.<string>}
       */
      states: [
        // The field associated with this FieldModel is linked to an EntityModel;
        // the user can choose to start in-place editing that entity (and
        // consequently this field). No in-place editor (EditorView) is associated
        // with this field, because this field is not being in-place edited.
        // This is both the initial (not yet in-place editing) and the end state
        // (finished in-place editing).
        'inactive',
        // The user is in-place editing this entity, and this field is a
        // candidate
        // for in-place editing. In-place editor should not
        // - Trigger: user.
        // - Guarantees: entity is ready, in-place editor (EditorView) is
        //   associated with the field.
        // - Expected behavior: visual indicators
        //   around the field indicate it is available for in-place editing, no
        //   in-place editor presented yet.
        'candidate',
        // User is highlighting this field.
        // - Trigger: user.
        // - Guarantees: see 'candidate'.
        // - Expected behavior: visual indicators to convey highlighting, in-place
        //   editing toolbar shows field's label.
        'highlighted',
        // User has activated the in-place editing of this field; in-place editor
        // is activating.
        // - Trigger: user.
        // - Guarantees: see 'candidate'.
        // - Expected behavior: loading indicator, in-place editor is loading
        //   remote data (e.g. retrieve form from back-end). Upon retrieval of
        //   remote data, the in-place editor transitions the field's state to
        //   'active'.
        'activating',
        // In-place editor has finished loading remote data; ready for use.
        // - Trigger: in-place editor.
        // - Guarantees: see 'candidate'.
        // - Expected behavior: in-place editor for the field is ready for use.
        'active',
        // User has modified values in the in-place editor.
        // - Trigger: user.
        // - Guarantees: see 'candidate', plus in-place editor is ready for use.
        // - Expected behavior: visual indicator of change.
        'changed',
        // User is saving changed field data in in-place editor to
        // PrivateTempStore. The save mechanism of the in-place editor is called.
        // - Trigger: user.
        // - Guarantees: see 'candidate' and 'active'.
        // - Expected behavior: saving indicator, in-place editor is saving field
        //   data into PrivateTempStore. Upon successful saving (without
        //   validation errors), the in-place editor transitions the field's state
        //   to 'saved', but to 'invalid' upon failed saving (with validation
        //   errors).
        'saving',
        // In-place editor has successfully saved the changed field.
        // - Trigger: in-place editor.
        // - Guarantees: see 'candidate' and 'active'.
        // - Expected behavior: transition back to 'candidate' state because the
        //   deed is done. Then: 1) transition to 'inactive' to allow the field
        //   to be rerendered, 2) destroy the FieldModel (which also destroys
        //   attached views like the EditorView), 3) replace the existing field
        //   HTML with the existing HTML and 4) attach behaviors again so that the
        //   field becomes available again for in-place editing.
        'saved',
        // In-place editor has failed to saved the changed field: there were
        // validation errors.
        // - Trigger: in-place editor.
        // - Guarantees: see 'candidate' and 'active'.
        // - Expected behavior: remain in 'invalid' state, let the user make more
        //   changes and then save it again, without validation errors.
        'invalid',
      ],

      /**
       * Indicates whether the 'from' state comes before the 'to' state.
       *
       * @param {string} from
       *   One of {@link Drupal.quickedit.FieldModel.states}.
       * @param {string} to
       *   One of {@link Drupal.quickedit.FieldModel.states}.
       *
       * @return {bool}
       *   Whether the 'from' state comes before the 'to' state.
       */
      followsStateSequence(from, to) {
        return _.indexOf(this.states, from) < _.indexOf(this.states, to);
      },
    },
  );

  /**
   * @constructor
   *
   * @augments Backbone.Collection
   */
  Drupal.quickedit.FieldCollection = Backbone.Collection.extend(
    /** @lends Drupal.quickedit.FieldCollection */ {
      /**
       * @type {Drupal.quickedit.FieldModel}
       */
      model: Drupal.quickedit.FieldModel,
    },
  );
})(_, Backbone, Drupal);
