phorge-phorge/src/applications/differential/field/specification/base/DifferentialFieldSpecification.php

<?php

/*
 * Copyright 2011 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Describes and implements the behavior for a custom field on Differential
 * revisions. Along with other configuration, you can extend this class to add
 * custom fields to Differential revisions and commit messages.
 *
 * Generally, you should implement all methods from the storage task and then
 * the methods from one or more interface tasks.
 *
 * @task storage Field Storage
 * @task edit Extending the Revision Edit Interface
 * @task view Extending the Revision View Interface
 * @task conduit Extending the Conduit View Interface
 * @task commit Extending Commit Messages
 * @task load Loading Additional Data
 * @task context Contextual Data
 */
abstract class DifferentialFieldSpecification {

  private $revision;
  private $diff;
  private $handles;
  private $diffProperties;
  private $user;


/* -(  Storage  )------------------------------------------------------------ */


  /**
   * Return a unique string used to key storage of this field's value, like
   * "mycompany.fieldname" or similar. You can return null (the default) to
   * indicate that this field does not use any storage. This is appropriate for
   * display fields, like @{class:DifferentialLinesFieldSpecification}. If you
   * implement this, you must also implement @{method:getValueForStorage} and
   * @{method:setValueFromStorage}.
   *
   * @return string|null  Unique key which identifies this field in auxiliary
   *                      field storage. Maximum length is 32. Alternatively,
   *                      null (default) to indicate that this field does not
   *                      use auxiliary field storage.
   * @task storage
   */
  public function getStorageKey() {
    return null;
  }


  /**
   * Return a serialized representation of the field value, appropriate for
   * storing in auxiliary field storage. You must implement this method if
   * you implement @{method:getStorageKey}.
   *
   * @return string Serialized field value.
   * @task storage
   */
  public function getValueForStorage() {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }


  /**
   * Set the field's value given a serialized storage value. This is called
   * when the field is loaded; if no data is available, the value will be
   * null. You must implement this method if you implement
   * @{method:getStorageKey}.
   *
   * @param string|null Serialized field representation (from
   *                    @{method:getValueForStorage}) or null if no value has
   *                    ever been stored.
   * @return this
   * @task storage
   */
  public function setValueFromStorage($value) {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }


/* -(  Extending the Revision Edit Interface  )------------------------------ */


  /**
   * Determine if this field should appear on the "Edit Revision" interface. If
   * you return true from this method, you must implement
   * @{method:setValueFromRequest}, @{method:renderEditControl} and
   * @{method:validateField}.
   *
   * For a concrete example of a field which implements an edit interface, see
   * @{class:DifferentialRevertPlanFieldSpecification}.
   *
   * @return bool True to indicate that this field implements an edit interface.
   * @task edit
   */
  public function shouldAppearOnEdit() {
    return false;
  }


  /**
   * Set the field's value from an HTTP request. Generally, you should read
   * the value of some field name you emitted in @{method:renderEditControl}
   * and save it into the object, e.g.:
   *
   *   $this->value = $request->getStr('my-custom-field');
   *
   * If you have some particularly complicated field, you may need to read
   * more data; this is why you have access to the entire request.
   *
   * You must implement this if you implement @{method:shouldAppearOnEdit}.
   *
   * You should not perform field validation here; instead, you should implement
   * @{method:validateField}.
   *
   * @param AphrontRequest HTTP request representing a user submitting a form
   *                       with this field in it.
   * @return this
   * @task edit
   */
  public function setValueFromRequest(AphrontRequest $request) {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }


  /**
   * Build a renderable object (generally, some @{class:AphrontFormControl})
   * which can be appended to a @{class:AphrontFormView} and represents the
   * interface the user sees on the "Edit Revision" screen when interacting
   * with this field.
   *
   * For example:
   *
   *   return id(new AphrontFormTextControl())
   *     ->setLabel('Custom Field')
   *     ->setName('my-custom-key')
   *     ->setValue($this->value);
   *
   * You must implement this if you implement @{method:shouldAppearOnEdit}.
   *
   * @return AphrontView|string Something renderable.
   * @task edit
   */
  public function renderEditControl() {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }


  /**
   * This method will be called after @{method:setValueFromRequest} but before
   * the field is saved. It gives you an opportunity to inspect the field value
   * and throw a @{class:DifferentialFieldValidationException} if there is a
   * problem with the value the user has provided (for example, the value the
   * user entered is not correctly formatted).
   *
   * By default, fields are not validated.
   *
   * @return void
   * @task edit
   */
  public function validateField() {
    return;
  }

  /**
   * Hook for applying revision changes via the editor. Normally, you should
   * not implement this, but a number of builtin fields use the revision object
   * itself as storage. If you need to do something similar for whatever reason,
   * this method gives you an opportunity to interact with the editor or
   * revision before changes are saved (for example, you can write the field's
   * value into some property of the revision).
   *
   * @param DifferentialRevisionEditor  Active editor which is applying changes
   *                                    to the revision.
   * @return void
   * @task edit
   */
  public function willWriteRevision(DifferentialRevisionEditor $editor) {
    return;
  }

  /**
   * Hook after an edit operation has completed. This allows you to update
   * link tables or do other write operations which should happen after the
   * revision is saved. Normally you don't need to implement this.
   *
   *
   * @param DifferentialRevisionEditor  Active editor which has just applied
   *                                    changes to the revision.
   * @return void
   * @task edit
   */
  public function didWriteRevision(DifferentialRevisionEditor $editor) {
    return;
  }


/* -(  Extending the Revision View Interface  )------------------------------ */


  /**
   * Determine if this field should appear on the revision detail view
   * interface. One use of this interface is to add purely informational
   * fields to the revision view, without any sort of backing storage.
   *
   * If you return true from this method, you must implement the methods
   * @{method:renderLabelForRevisionView} and
   * @{method:renderValueForRevisionView}.
   *
   * @return bool True if this field should appear when viewing a revision.
   * @task view
   */
  public function shouldAppearOnRevisionView() {
    return false;
  }


  /**
   * Return a string field label which will appear in the revision detail
   * table.
   *
   * You must implement this method if you return true from
   * @{method:shouldAppearOnRevisionView}.
   *
   * @return string Label for field in revision detail view.
   * @task view
   */
  public function renderLabelForRevisionView() {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }


  /**
   * Return a markup block representing the field for the revision detail
   * view. Note that you can return null to suppress display (for instance,
   * if the field shows related objects of some type and the revision doesn't
   * have any related objects).
   *
   * You must implement this method if you return true from
   * @{method:shouldAppearOnRevisionView}.
   *
   * @return string|null Display markup for field value, or null to suppress
   *                     field rendering.
   * @task view
   */
  public function renderValueForRevisionView() {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }


/* -(  Extending the Conduit Interface  )------------------------------------ */


  /**
   * @task conduit
   */
  public function shouldAppearOnConduitView() {
    return false;
  }

  /**
   * @task conduit
   */
  public function getValueForConduit() {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }

  /**
   * @task conduit
   */
  public function getKeyForConduit() {
    $key = $this->getStorageKey();
    if ($key === null) {
      throw new DifferentialFieldSpecificationIncompleteException($this);
    }
    return $key;
  }


/* -(  Extending Commit Messages  )------------------------------------------ */


  /**
   * Determine if this field should appear in commit messages. You should return
   * true if this field participates in any part of the commit message workflow,
   * even if it is not rendered by default.
   *
   * If you implement this method, you must implement
   * @{method:getCommitMessageKey} and
   * @{method:setValueFromParsedCommitMessage}.
   *
   * @return bool True if this field appears in commit messages in any capacity.
   * @task commit
   */
  public function shouldAppearOnCommitMessage() {
    return false;
  }

  /**
   * Key which identifies this field in parsed commit messages. Commit messages
   * exist in two forms: raw textual commit messages and parsed dictionaries of
   * fields. This method must return a unique string which identifies this field
   * in dictionaries. Principally, this dictionary is shipped to and from arc
   * over Conduit. Keys should be appropriate property names, like "testPlan"
   * (not "Test Plan") and must be globally unique.
   *
   * You must implement this method if you return true from
   * @{method:shouldAppearOnCommitMessage}.
   *
   * @return string Key which identifies the field in dictionaries.
   * @task commit
   */
  public function getCommitMessageKey() {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }

  /**
   * Set this field's value from a value in a parsed commit message dictionary.
   * Afterward, this field will go through the normal write workflows and the
   * change will be permanently stored via either the storage mechanisms (if
   * your field implements them), revision write hooks (if your field implements
   * them) or discarded (if your field implements neither, e.g. is just a
   * display field).
   *
   * You must implement this method if you return true from
   * @{method:shouldAppearOnCommitMessage}.
   *
   * @param mixed Field value from a parsed commit message dictionary.
   * @return this
   * @task commit
   */
  public function setValueFromParsedCommitMessage($value) {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }

  /**
   * In revision control systems which read revision information from the
   * working copy, the user may edit the commit message outside of invoking
   * "arc diff --edit". When they do this, only some fields (those fields which
   * can not be edited by other users) are safe to overwrite. For instance, it
   * is fine to overwrite "Summary" because no one else can edit it, but not
   * to overwrite "Reviewers" because reviewers may have been added or removed
   * via the web interface.
   *
   * If a field is safe to overwrite when edited in a working copy commit
   * message, return true. If the authoritative value should always be used,
   * return false. By default, fields can not be overwritten.
   *
   * @return bool True to indicate the field is save to overwrite.
   * @task commit
   */
  public function shouldOverwriteWhenCommitMessageIsEdited() {
    return false;
  }

  /**
   * Return true if this field should be suggested to the user during
   * "arc diff --edit". Basicially, return true if the field is something the
   * user might want to fill out (like "Summary"), and false if it's a
   * system/display/readonly field (like "Differential Revision"). If this
   * method returns true, the field will be rendered even if it has no value
   * during edit and update operations.
   *
   * @return bool True to indicate the field should appear in the edit template.
   * @task commit
   */
  public function shouldAppearOnCommitMessageTemplate() {
    return true;
  }

  /**
   * Render a human-readable label for this field, like "Summary" or
   * "Test Plan". This is distinct from the commit message key, but generally
   * they should be similar.
   *
   * @return string Human-readable field label for commit messages.
   * @task commit
   */
  public function renderLabelForCommitMessage() {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }

  /**
   * Render a human-readable value for this field when it appears in commit
   * messages (for instance, lists of users should be rendered as user names).
   *
   * The ##$is_edit## parameter allows you to distinguish between commit
   * messages being rendered for editing and those being rendered for amending
   * or commit. Some fields may decline to render a value in one mode (for
   * example, "Reviewed By" appears only when doing commit/amend, not while
   * editing).
   *
   * @param bool True if the message is being edited.
   * @return string Human-readable field value.
   * @task commit
   */
  public function renderValueForCommitMessage($is_edit) {
    throw new DifferentialFieldSpecificationIncompleteException($this);
  }


/* -(  Loading Additional Data  )-------------------------------------------- */


  /**
   * Specify which @{class:PhabricatorObjectHandles} need to be loaded for your
   * field to render correctly.
   *
   * This is a convenience method which makes the handles available on all
   * interfaces where the field appears. If your field needs handles on only
   * some interfaces (or needs different handles on different interfaces) you
   * can overload the more specific methods to customize which interfaces you
   * retrieve handles for. Requesting only the handles you need will improve
   * the performance of your field.
   *
   * You can later retrieve these handles by calling @{method:getHandle}.
   *
   * @return list List of PHIDs to load handles for.
   * @task load
   */
  protected function getRequiredHandlePHIDs() {
    return array();
  }

  /**
   * Specify which @{class:PhabricatorObjectHandles} need to be loaded for your
   * field to render correctly on the view interface.
   *
   * This is a more specific version of @{method:getRequiredHandlePHIDs} which
   * can be overridden to improve field performance by loading only data you
   * need.
   *
   * @return list List of PHIDs to load handles for.
   * @task load
   */
  public function getRequiredHandlePHIDsForRevisionView() {
    return $this->getRequiredHandlePHIDs();
  }

  /**
   * Specify which @{class:PhabricatorObjectHandles} need to be loaded for your
   * field to render correctly on the edit interface.
   *
   * This is a more specific version of @{method:getRequiredHandlePHIDs} which
   * can be overridden to improve field performance by loading only data you
   * need.
   *
   * @return list List of PHIDs to load handles for.
   * @task load
   */
  public function getRequiredHandlePHIDsForRevisionEdit() {
    return $this->getRequiredHandlePHIDs();
  }

  /**
   * Specify which @{class:PhabricatorObjectHandles} need to be loaded for your
   * field to render correctly on the commit message interface.
   *
   * This is a more specific version of @{method:getRequiredHandlePHIDs} which
   * can be overridden to improve field performance by loading only data you
   * need.
   *
   * @return list List of PHIDs to load handles for.
   * @task load
   */
  public function getRequiredHandlePHIDsForCommitMessage() {
    return $this->getRequiredHandlePHIDs();
  }


  /**
   * Specify which diff properties this field needs to load.
   *
   * @return list List of diff property keys this field requires.
   * @task load
   */
  public function getRequiredDiffProperties() {
    return array();
  }


/* -(  Contextual Data  )---------------------------------------------------- */


  /**
   * @task context
   */
  final public function setRevision(DifferentialRevision $revision) {
    $this->revision = $revision;
    $this->didSetRevision();
    return $this;
  }

  /**
   * @task context
   */
  protected function didSetRevision() {
    return;
  }


  /**
   * @task context
   */
  final public function setDiff(DifferentialDiff $diff) {
    $this->diff = $diff;
    return $this;
  }

  /**
   * @task context
   */
  final public function setHandles(array $handles) {
    $this->handles = $handles;
    return $this;
  }

  /**
   * @task context
   */
  final public function setDiffProperties(array $diff_properties) {
    $this->diffProperties = $diff_properties;
    return $this;
  }

  /**
   * @task context
   */
  final public function setUser(PhabricatorUser $user) {
    $this->user = $user;
    return $this;
  }

  /**
   * @task context
   */
  final protected function getRevision() {
    if (empty($this->revision)) {
      throw new DifferentialFieldDataNotAvailableException($this);
    }
    return $this->revision;
  }

  /**
   * @task context
   */
  final protected function getDiff() {
    if (empty($this->diff)) {
      throw new DifferentialFieldDataNotAvailableException($this);
    }
    return $this->diff;
  }

  /**
   * @task context
   */
  final protected function getUser() {
    if (empty($this->user)) {
      throw new DifferentialFieldDataNotAvailableException($this);
    }
    return $this->user;
  }

  /**
   * Get the handle for an object PHID. You must overload
   * @{method:getRequiredHandlePHIDs} (or a more specific version thereof)
   * and include the PHID you want in the list for it to be available here.
   *
   * @return PhabricatorObjectHandle Handle to the object.
   * @task context
   */
  final protected function getHandle($phid) {
    if ($this->handles === null) {
      throw new DifferentialFieldDataNotAvailableException($this);
    }
    if (empty($this->handles[$phid])) {
      $class = get_class($this);
      throw new Exception(
        "A differential field (of class '{$class}') is attempting to retrieve ".
        "a handle ('{$phid}') which it did not request. Return all handle ".
        "PHIDs you need from getRequiredHandlePHIDs().");
    }
    return $this->handles[$phid];
  }

  /**
   * Get a diff property which this field previously requested by returning
   * the key from @{method:getRequiredDiffProperties}.
   *
   * @param  string      Diff property key.
   * @return string|null Diff property, or null if the property does not have
   *                     a value.
   * @task context
   */
  final public function getDiffProperty($key) {
    if ($this->diffProperties === null) {
      // This will be set to some (possibly empty) array if we've loaded
      // properties, so null means diff properties aren't available in this
      // context.
      throw new DifferentialFieldDataNotAvailableException($this);
    }
    if (!array_key_exists($key, $this->diffProperties)) {
      $class = get_class($this);
      throw new Exception(
        "A differential field (of class '{$class}') is attempting to retrieve ".
        "a diff property ('{$key}') which it did not request. Return all ".
        "diff property keys you need from getRequiredDiffProperties().");
    }
    return $this->diffProperties[$key];
  }

}