package presentation;

import java.util.Collection;
import java.util.List;

/**
 * A Topic is the most important unit of the content of a presentation
 * and is identified by a name and (usually) a number. Topics are
 * related to each other in a tree structure.
 * <p>
 * A Topic's name and any associated content appear
 * entirely on one slide of the presentation.
 */
abstract class Topic {
    /** Name displayed in the slide. */
    FormattedText name;

    /** Plain-text name displayed in the outline. */
    String outlineName;

    /** Topic number. */
    String number;

    /** Content associated with the topic. */
    List<ContentElement> content;

    /** Child topics, forming a tree structure. */
    List<Topic> children;

    /** Topic that has this as a child. */
    Topic parent;

    /** Slide that contains this topic. */
    Slide slide;

    /**
     * True if the topic's content and subtopics are initially
     * collapsed but can be expanded inside the slide.
     */
    boolean expandable;

    /** Whether an 'expandable' topic is expanded inside the slide. */
    boolean expandedInSlide;

    /** Whether a topic is expanded within the outline navigator. */
    boolean expandedInOutline;

   /**
    * Expands the current topic in the outline.
    */
   /*@
     requires
      //
      //The topic is currently collapsed
      //
         (expandedInOutline == false);


      ensures
      //
      //If the topic is expandable and not already expanded, it gets expanded in the outline
      //
         (expandedInOutline == true);
   */
   abstract void expand();

   /**
    * Collapses the current topic in the outline.
    */
   /*@
     requires
      //
      //The topic is already expanded
      //
         (expandedInOutline == true);


      ensures
      //
      //If the topic is expandable and already expanded, it gets collapsed in the outline
      //
         (expandedInOutline == false);
   */
   abstract void collapse();


   /**
    * Inserts a topic as a sibling of this topic.
    */
   /*@
     ensures
     // The topic's parent has the new topic as a new child,
     // immediately following the current topic.
     (\exists int i; parent.children.get(i) == this && parent.children.get(i+1) == newTopic
      && (\forall int j; (j >= 0 && j < i) || (j > i+1 && j < parent.children.size());
          parent.children.get(i) == \old(parent.children).get(i)));
    */
    abstract void addSiblingTopic(Topic newTopic);

    /**
     * Inserts a topic as the last child of this topic.
     */
    /*@
      ensures
      // The new topic is the first child
      (newTopic == children.get(children.size() - 1))
      &&
      // All other topics are unchanged
      (children.size() == \old(children).size() - 1)
      &&
      (\forall int i; i < \old(children).size(); children.get(i) == \old(children).get(i));
     */
    abstract void addSubTopic(Topic newTopic);

    /**
     * Inserts content to be associated with this topic, after all
     * existing associated content.
     */
    abstract void addContent(ContentElement content);
}

/**
 * ContentElements are optionally attached to topics to provide
 * richer and more detailed exposition.
 */
abstract class ContentElement {}

/**
 * A paragraph inserted into the presentation.
 */
class Paragraph extends ContentElement {
    FormattedText content;
}

/**
 * An image inserted into the presentation. Contains dimensions
 * of the image plus some representation of the image data.
 */
class Image extends ContentElement {
    int width;
    int height;
    /* */
}

/**
 * Text including bold and italic portions.
 */
class FormattedText { /* */ }