/**
 * @file
 * A Backbone View that controls the overall "in-place editing application".
 *
 * @see Drupal.quickedit.AppModel
 */

(function($, _, Backbone, Drupal) {
  // Indicates whether the page should be reloaded after in-place editing has
  // shut down. A page reload is necessary to re-instate the original HTML of
  // the edited fields if in-place editing has been canceled and one or more of
  // the entity's fields were saved to PrivateTempStore: one of them may have
  // been changed to the empty value and hence may have been rerendered as the
  // empty string, which makes it impossible for Quick Edit to know where to
  // restore the original HTML.
  let reload = false;

  Drupal.quickedit.AppView = Backbone.View.extend(
    /** @lends Drupal.quickedit.AppView# */ {
      /**
       * @constructs
       *
       * @augments Backbone.View
       *
       * @param {object} options
       *   An object with the following keys:
       * @param {Drupal.quickedit.AppModel} options.model
       *   The application state model.
       * @param {Drupal.quickedit.EntityCollection} options.entitiesCollection
       *   All on-page entities.
       * @param {Drupal.quickedit.FieldCollection} options.fieldsCollection
       *   All on-page fields
       */
      initialize(options) {
        // AppView's configuration for handling states.
        // @see Drupal.quickedit.FieldModel.states
        this.activeFieldStates = ['activating', 'active'];
        this.singleFieldStates = ['highlighted', 'activating', 'active'];
        this.changedFieldStates = ['changed', 'saving', 'saved', 'invalid'];
        this.readyFieldStates = ['candidate', 'highlighted'];

        // Track app state.
        this.listenTo(
          options.entitiesCollection,
          'change:state',
          this.appStateChange,
        );
        this.listenTo(
          options.entitiesCollection,
          'change:isActive',
          this.enforceSingleActiveEntity,
        );

        // Track app state.
        this.listenTo(
          options.fieldsCollection,
          'change:state',
          this.editorStateChange,
        );
        // Respond to field model HTML representation change events.
        this.listenTo(
          options.fieldsCollection,
          'change:html',
          this.renderUpdatedField,
        );
        this.listenTo(
          options.fieldsCollection,
          'change:html',
          this.propagateUpdatedField,
        );
        // Respond to addition.
        this.listenTo(
          options.fieldsCollection,
          'add',
          this.rerenderedFieldToCandidate,
        );
        // Respond to destruction.
        this.listenTo(options.fieldsCollection, 'destroy', this.teardownEditor);
      },

      /**
       * Handles setup/teardown and state changes when the active entity changes.
       *
       * @param {Drupal.quickedit.EntityModel} entityModel
       *   An instance of the EntityModel class.
       * @param {string} state
       *   The state of the associated field. One of
       *   {@link Drupal.quickedit.EntityModel.states}.
       */
      appStateChange(entityModel, state) {
        const app = this;
        let entityToolbarView;
        switch (state) {
          case 'launching':
            reload = false;
            // First, create an entity toolbar view.
            entityToolbarView = new Drupal.quickedit.EntityToolbarView({
              model: entityModel,
              appModel: this.model,
            });
            entityModel.toolbarView = entityToolbarView;
            // Second, set up in-place editors.
            // They must be notified of state changes, hence this must happen
            // while the associated fields are still in the 'inactive' state.
            entityModel.get('fields').each(fieldModel => {
              app.setupEditor(fieldModel);
            });
            // Third, transition the entity to the 'opening' state, which will
            // transition all fields from 'inactive' to 'candidate'.
            _.defer(() => {
              entityModel.set('state', 'opening');
            });
            break;

          case 'closed':
            entityToolbarView = entityModel.toolbarView;
            // First, tear down the in-place editors.
            entityModel.get('fields').each(fieldModel => {
              app.teardownEditor(fieldModel);
            });
            // Second, tear down the entity toolbar view.
            if (entityToolbarView) {
              entityToolbarView.remove();
              delete entityModel.toolbarView;
            }
            // A page reload may be necessary to re-instate the original HTML of
            // the edited fields.
            if (reload) {
              reload = false;
              window.location.reload();
            }
            break;
        }
      },

      /**
       * Accepts or reject editor (Editor) state changes.
       *
       * This is what ensures that the app is in control of what happens.
       *
       * @param {string} from
       *   The previous state.
       * @param {string} to
       *   The new state.
       * @param {null|object} context
       *   The context that is trying to trigger the state change.
       * @param {Drupal.quickedit.FieldModel} fieldModel
       *   The fieldModel to which this change applies.
       *
       * @return {bool}
       *   Whether the editor change was accepted or rejected.
       */
      acceptEditorStateChange(from, to, context, fieldModel) {
        let accept = true;

        // If the app is in view mode, then reject all state changes except for
        // those to 'inactive'.
        if (
          context &&
          (context.reason === 'stop' || context.reason === 'rerender')
        ) {
          if (from === 'candidate' && to === 'inactive') {
            accept = true;
          }
        }
        // Handling of edit mode state changes is more granular.
        else {
          // In general, enforce the states sequence. Disallow going back from a
          // "later" state to an "earlier" state, except in explicitly allowed
          // cases.
          if (!Drupal.quickedit.FieldModel.followsStateSequence(from, to)) {
            accept = false;
            // Allow: activating/active -> candidate.
            // Necessary to stop editing a field.
            if (
              _.indexOf(this.activeFieldStates, from) !== -1 &&
              to === 'candidate'
            ) {
              accept = true;
            }
            // Allow: changed/invalid -> candidate.
            // Necessary to stop editing a field when it is changed or invalid.
            else if (
              (from === 'changed' || from === 'invalid') &&
              to === 'candidate'
            ) {
              accept = true;
            }
            // Allow: highlighted -> candidate.
            // Necessary to stop highlighting a field.
            else if (from === 'highlighted' && to === 'candidate') {
              accept = true;
            }
            // Allow: saved -> candidate.
            // Necessary when successfully saved a field.
            else if (from === 'saved' && to === 'candidate') {
              accept = true;
            }
            // Allow: invalid -> saving.
            // Necessary to be able to save a corrected, invalid field.
            else if (from === 'invalid' && to === 'saving') {
              accept = true;
            }
            // Allow: invalid -> activating.
            // Necessary to be able to correct a field that turned out to be
            // invalid after the user already had moved on to the next field
            // (which we explicitly allow to have a fluent UX).
            else if (from === 'invalid' && to === 'activating') {
              accept = true;
            }
          }

          // If it's not against the general principle, then here are more
          // disallowed cases to check.
          if (accept) {
            let activeField;
            let activeFieldState;
            // Ensure only one field (editor) at a time is active … but allow a
            // user to hop from one field to the next, even if we still have to
            // start saving the field that is currently active: assume it will be
            // valid, to allow for a fluent UX. (If it turns out to be invalid,
            // this block of code also handles that.)
            if (
              (this.readyFieldStates.indexOf(from) !== -1 ||
                from === 'invalid') &&
              this.activeFieldStates.indexOf(to) !== -1
            ) {
              activeField = this.model.get('activeField');
              if (activeField && activeField !== fieldModel) {
                activeFieldState = activeField.get('state');
                // Allow the state change. If the state of the active field is:
                // - 'activating' or 'active': change it to 'candidate'
                // - 'changed' or 'invalid': change it to 'saving'
                // - 'saving' or 'saved': don't do anything.
                if (this.activeFieldStates.indexOf(activeFieldState) !== -1) {
                  activeField.set('state', 'candidate');
                } else if (
                  activeFieldState === 'changed' ||
                  activeFieldState === 'invalid'
                ) {
                  activeField.set('state', 'saving');
                }

                // If the field that's being activated is in fact already in the
                // invalid state (which can only happen because above we allowed
                // the user to move on to another field to allow for a fluent UX;
                // we assumed it would be saved successfully), then we shouldn't
                // allow the field to enter the 'activating' state, instead, we
                // simply change the active editor. All guarantees and
                // assumptions for this field still hold!
                if (from === 'invalid') {
                  this.model.set('activeField', fieldModel);
                  accept = false;
                }
                // Do not reject: the field is either in the 'candidate' or
                // 'highlighted' state and we allow it to enter the 'activating'
                // state!
              }
            }
            // Reject going from activating/active to candidate because of a
            // mouseleave.
            else if (
              _.indexOf(this.activeFieldStates, from) !== -1 &&
              to === 'candidate'
            ) {
              if (context && context.reason === 'mouseleave') {
                accept = false;
              }
            }
            // When attempting to stop editing a changed/invalid property, ask for
            // confirmation.
            else if (
              (from === 'changed' || from === 'invalid') &&
              to === 'candidate'
            ) {
              if (context && context.reason === 'mouseleave') {
                accept = false;
              }
              // Check whether the transition has been confirmed?
              else if (context && context.confirmed) {
                accept = true;
              }
            }
          }
        }

        return accept;
      },

      /**
       * Sets up the in-place editor for the given field.
       *
       * Must happen before the fieldModel's state is changed to 'candidate'.
       *
       * @param {Drupal.quickedit.FieldModel} fieldModel
       *   The field for which an in-place editor must be set up.
       */
      setupEditor(fieldModel) {
        // Get the corresponding entity toolbar.
        const entityModel = fieldModel.get('entity');
        const entityToolbarView = entityModel.toolbarView;
        // Get the field toolbar DOM root from the entity toolbar.
        const fieldToolbarRoot = entityToolbarView.getToolbarRoot();
        // Create in-place editor.
        const editorName = fieldModel.get('metadata').editor;
        const editorModel = new Drupal.quickedit.EditorModel();
        const editorView = new Drupal.quickedit.editors[editorName]({
          el: $(fieldModel.get('el')),
          model: editorModel,
          fieldModel,
        });

        // Create in-place editor's toolbar for this field — stored inside the
        // entity toolbar, the entity toolbar will position itself appropriately
        // above (or below) the edited element.
        const toolbarView = new Drupal.quickedit.FieldToolbarView({
          el: fieldToolbarRoot,
          model: fieldModel,
          $editedElement: $(editorView.getEditedElement()),
          editorView,
          entityModel,
        });

        // Create decoration for edited element: padding if necessary, sets
        // classes on the element to style it according to the current state.
        const decorationView = new Drupal.quickedit.FieldDecorationView({
          el: $(editorView.getEditedElement()),
          model: fieldModel,
          editorView,
        });

        // Track these three views in FieldModel so that we can tear them down
        // correctly.
        fieldModel.editorView = editorView;
        fieldModel.toolbarView = toolbarView;
        fieldModel.decorationView = decorationView;
      },

      /**
       * Tears down the in-place editor for the given field.
       *
       * Must happen after the fieldModel's state is changed to 'inactive'.
       *
       * @param {Drupal.quickedit.FieldModel} fieldModel
       *   The field for which an in-place editor must be torn down.
       */
      teardownEditor(fieldModel) {
        // Early-return if this field was not yet decorated.
        if (typeof fieldModel.editorView === 'undefined') {
          return;
        }

        // Unbind event handlers; remove toolbar element; delete toolbar view.
        fieldModel.toolbarView.remove();
        delete fieldModel.toolbarView;

        // Unbind event handlers; delete decoration view. Don't remove the element
        // because that would remove the field itself.
        fieldModel.decorationView.remove();
        delete fieldModel.decorationView;

        // Unbind event handlers; delete editor view. Don't remove the element
        // because that would remove the field itself.
        fieldModel.editorView.remove();
        delete fieldModel.editorView;
      },

      /**
       * Asks the user if they want to stop editing via a modal.
       *
       * @param {Drupal.quickedit.EntityModel} entityModel
       *   An instance of the EntityModel class.
       *
       * @see Drupal.quickedit.AppView#acceptEditorStateChange
       */
      confirmEntityDeactivation(entityModel) {
        const that = this;
        let discardDialog;

        function closeDiscardDialog(action) {
          discardDialog.close(action);
          // The active modal has been removed.
          that.model.set('activeModal', null);

          // If the targetState is saving, the field must be saved, then the
          // entity must be saved.
          if (action === 'save') {
            entityModel.set('state', 'committing', { confirmed: true });
          } else {
            entityModel.set('state', 'deactivating', { confirmed: true });
            // Editing has been canceled and the changes will not be saved. Mark
            // the page for reload if the entityModel declares that it requires
            // a reload.
            if (entityModel.get('reload')) {
              reload = true;
              entityModel.set('reload', false);
            }
          }
        }

        // Only instantiate if there isn't a modal instance visible yet.
        if (!this.model.get('activeModal')) {
          const $unsavedChanges = $(
            `<div>${Drupal.t('You have unsaved changes')}</div>`,
          );
          discardDialog = Drupal.dialog($unsavedChanges.get(0), {
            title: Drupal.t('Discard changes?'),
            dialogClass: 'quickedit-discard-modal',
            resizable: false,
            buttons: [
              {
                text: Drupal.t('Save'),
                click() {
                  closeDiscardDialog('save');
                },
                primary: true,
              },
              {
                text: Drupal.t('Discard changes'),
                click() {
                  closeDiscardDialog('discard');
                },
              },
            ],
            // Prevent this modal from being closed without the user making a
            // choice as per http://stackoverflow.com/a/5438771.
            closeOnEscape: false,
            create() {
              $(this)
                .parent()
                .find('.ui-dialog-titlebar-close')
                .remove();
            },
            beforeClose: false,
            close(event) {
              // Automatically destroy the DOM element that was used for the
              // dialog.
              $(event.target).remove();
            },
          });
          this.model.set('activeModal', discardDialog);

          discardDialog.showModal();
        }
      },

      /**
       * Reacts to field state changes; tracks global state.
       *
       * @param {Drupal.quickedit.FieldModel} fieldModel
       *   The `fieldModel` holding the state.
       * @param {string} state
       *   The state of the associated field. One of
       *   {@link Drupal.quickedit.FieldModel.states}.
       */
      editorStateChange(fieldModel, state) {
        const from = fieldModel.previous('state');
        const to = state;

        // Keep track of the highlighted field in the global state.
        if (
          _.indexOf(this.singleFieldStates, to) !== -1 &&
          this.model.get('highlightedField') !== fieldModel
        ) {
          this.model.set('highlightedField', fieldModel);
        } else if (
          this.model.get('highlightedField') === fieldModel &&
          to === 'candidate'
        ) {
          this.model.set('highlightedField', null);
        }

        // Keep track of the active field in the global state.
        if (
          _.indexOf(this.activeFieldStates, to) !== -1 &&
          this.model.get('activeField') !== fieldModel
        ) {
          this.model.set('activeField', fieldModel);
        } else if (
          this.model.get('activeField') === fieldModel &&
          to === 'candidate'
        ) {
          // Discarded if it transitions from a changed state to 'candidate'.
          if (from === 'changed' || from === 'invalid') {
            fieldModel.editorView.revert();
          }
          this.model.set('activeField', null);
        }
      },

      /**
       * Render an updated field (a field whose 'html' attribute changed).
       *
       * @param {Drupal.quickedit.FieldModel} fieldModel
       *   The FieldModel whose 'html' attribute changed.
       * @param {string} html
       *   The updated 'html' attribute.
       * @param {object} options
       *   An object with the following keys:
       * @param {bool} options.propagation
       *   Whether this change to the 'html' attribute occurred because of the
       *   propagation of changes to another instance of this field.
       */
      renderUpdatedField(fieldModel, html, options) {
        // Get data necessary to rerender property before it is unavailable.
        const $fieldWrapper = $(fieldModel.get('el'));
        const $context = $fieldWrapper.parent();

        const renderField = function() {
          // Destroy the field model; this will cause all attached views to be
          // destroyed too, and removal from all collections in which it exists.
          fieldModel.destroy();

          // Replace the old content with the new content.
          $fieldWrapper.replaceWith(html);

          // Attach behaviors again to the modified piece of HTML; this will
          // create a new field model and call rerenderedFieldToCandidate() with
          // it.
          Drupal.attachBehaviors($context.get(0));
        };

        // When propagating the changes of another instance of this field, this
        // field is not being actively edited and hence no state changes are
        // necessary. So: only update the state of this field when the rerendering
        // of this field happens not because of propagation, but because it is
        // being edited itself.
        if (!options.propagation) {
          // Deferred because renderUpdatedField is reacting to a field model
          // change event, and we want to make sure that event fully propagates
          // before making another change to the same model.
          _.defer(() => {
            // First set the state to 'candidate', to allow all attached views to
            // clean up all their "active state"-related changes.
            fieldModel.set('state', 'candidate');

            // Similarly, the above .set() call's change event must fully
            // propagate before calling it again.
            _.defer(() => {
              // Set the field's state to 'inactive', to enable the updating of
              // its DOM value.
              fieldModel.set('state', 'inactive', { reason: 'rerender' });

              renderField();
            });
          });
        } else {
          renderField();
        }
      },

      /**
       * Propagates changes to an updated field to all instances of that field.
       *
       * @param {Drupal.quickedit.FieldModel} updatedField
       *   The FieldModel whose 'html' attribute changed.
       * @param {string} html
       *   The updated 'html' attribute.
       * @param {object} options
       *   An object with the following keys:
       * @param {bool} options.propagation
       *   Whether this change to the 'html' attribute occurred because of the
       *   propagation of changes to another instance of this field.
       *
       * @see Drupal.quickedit.AppView#renderUpdatedField
       */
      propagateUpdatedField(updatedField, html, options) {
        // Don't propagate field updates that themselves were caused by
        // propagation.
        if (options.propagation) {
          return;
        }

        const htmlForOtherViewModes = updatedField.get('htmlForOtherViewModes');
        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: updatedField.get('logicalFieldID') })
          .forEach(field => {
            if (field === updatedField) {
              // Ignore the field that was already updated.
            }
            // If this other instance of the field has the same view mode, we can
            // update it easily.
            else if (field.getViewMode() === updatedField.getViewMode()) {
              field.set('html', updatedField.get('html'));
            }
            // If this other instance of the field has a different view mode, and
            // that is one of the view modes for which a re-rendered version is
            // available (and that should be the case unless this field was only
            // added to the page after editing of the updated field began), then
            // use that view mode's re-rendered version.
            else if (field.getViewMode() in htmlForOtherViewModes) {
              field.set('html', htmlForOtherViewModes[field.getViewMode()], {
                propagation: true,
              });
            }
          });
      },

      /**
       * If the new in-place editable field is for the entity that's currently
       * being edited, then transition it to the 'candidate' state.
       *
       * This happens when a field was modified, saved and hence rerendered.
       *
       * @param {Drupal.quickedit.FieldModel} fieldModel
       *   A field that was just added to the collection of fields.
       */
      rerenderedFieldToCandidate(fieldModel) {
        const activeEntity = Drupal.quickedit.collections.entities.findWhere({
          isActive: true,
        });

        // Early-return if there is no active entity.
        if (!activeEntity) {
          return;
        }

        // If the field's entity is the active entity, make it a candidate.
        if (fieldModel.get('entity') === activeEntity) {
          this.setupEditor(fieldModel);
          fieldModel.set('state', 'candidate');
        }
      },

      /**
       * EntityModel Collection change handler.
       *
       * Handler is called `change:isActive` and enforces a single active entity.
       *
       * @param {Drupal.quickedit.EntityModel} changedEntityModel
       *   The entityModel instance whose active state has changed.
       */
      enforceSingleActiveEntity(changedEntityModel) {
        // When an entity is deactivated, we don't need to enforce anything.
        if (changedEntityModel.get('isActive') === false) {
          return;
        }

        // This entity was activated; deactivate all other entities.
        changedEntityModel.collection
          .chain()
          .filter(
            entityModel =>
              entityModel.get('isActive') === true &&
              entityModel !== changedEntityModel,
          )
          .each(entityModel => {
            entityModel.set('state', 'deactivating');
          });
      },
    },
  );
})(jQuery, _, Backbone, Drupal);
