package resources.instructor;

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


/**
 * This class represents the Database of all Instructors. The administrator is
 * allowed to add Instructors and get Instructors to make modifications to
 * their preferences.
 * 
 * @author sbayley
 */
public abstract class InstructorDB {
   public Collection<Instructor> instructors; //collection of Instructors
   
   /**
    * Adds a new Instructor to the DB
    * 
    * @param i
    *       new instructor to add to InstructorDB
    */
    /*
    pre:
      //
      // There is no Instructor in the input DB with the same Name
      // as the Instructor to be added.
      //
       !exists (Instructor other;
          instructors.contains(other);
             i.name.first.equals(other.name.first) 
                && i.name.last.equals(other.name.last))
        
        &&
        
        //
        // The instructors name is not null
        //
        (i.name.first != null && i.name.last != null)
        
        &&
       
       //
       // The employeeId is not empty and greater than 0
       //
        (i.employeeId != null && i.employeeId > 0)
        
    post:
        //    
        // An Instructor is in output DB if and only if it is the Instructor
        // to be added or it is in the input DB.
        //
        forall (Instructor other; 
           instructors'.contains(i) iff
           other.equals(i) || instructors.contains(other));
    
    */
   
   public abstract void add(Instructor i);

   /**
    * Removes an instructor from the DB.
    * 
    * @param i
    *       instructor to remove

    */
   /*
   pre:
      //
      // Delete the given instructor record from the given InstructorDB. The given 
      // instructor must already be in the input db.
      //
      instructors.contains(i);

   post:
      //
      // A course is in the output data if and only if it is the new
      // course to be added or it is in the input data.
      //
      forall ( Instructor i_other ;
         (instructors'.contains(i_other)) iff
            !i_other.equals(i) && instructors.contains(i_other));
  */

   public abstract void removeInstructor(Instructor i);
   
   
   /**
   * Returns sorted list of Instructors.
   */
     /*@
   * post:
   *    // The output list is sorted lexicographically by name of 
   *    // Instructor, according to the semantics of 
   *    // java.lang.String.compareto().
   *    //
   *    
   *    forall (int i; (i>=0) && (i < return.size() - 1);
   *       return.get(i).name.first.compareTo(return.get(i + 1).name.first) < 0);
   * 
   @*/
  public abstract List<Instructor> viewInstructors();
}