/***********************************************
 *  CS2510 Spring 2011 
 *  Lecture #11
 *  Function-Classes/Objects (2)
 ***********************************************/

import tester.*;

// Represents a Student
class Student{
    String name;
    double gpa;
    boolean graduating;
    
    Student(String name, double gpa, boolean graduating) {
        this.name = name;
        this.gpa = gpa;
        this.graduating = graduating;
    }
}

// Selects a specific student
interface ISelectStudent{
    boolean select(Student stud);
}

// Select student by name
class ByNameStudent implements ISelectStudent{
    String name;
    
    // Abstracted/convenience constructor
    ByNameStudent(String name){
        this.name = name;
    }
    
    // Default is (obviously) "Kevin"
    ByNameStudent(){
        this("Kevin");
    }
    
    // Select the given student if the name matches
    public boolean select(Student stud){
        return stud.name.equals(this.name);
    }
}

// Select students with GPA of 4.0
class ByGPAStudent implements ISelectStudent{
    // Select the given student if the GPA is a 4.0
    public boolean select(Student stud){
        return stud.gpa == 4.0;
    }
}

// Represents a List of Students
interface ILoS{
    // Is there any Student in this list that the picker likes
    boolean any(ISelectStudent picker);

    // Filter out all the graduating students
    // This can be abstracted too...
    ILoS filterGrads();
}

// Represents an empty list of Students
class MtLoS implements ILoS{
    MtLoS(){ }
    
    // Is there any Student in this empty list that the picker likes (No)
    public boolean any(ISelectStudent picker){
        return false;
    }
    // Filter out all the graduating students (Done)
    public ILoS filterGrads(){
        return this;
    }

}

// Represents a non-empty list of Students
class ConsLoS implements ILoS{
    Student first;
    ILoS rest;
    
    ConsLoS(Student first, ILoS rest) {
        this.first = first;
        this.rest = rest;
    }
    
    /** Template
     *    Fields:
     *      ... this.first ... -- Student
     *      ... this.rest ...  -- ILoS
     *      
     *    Methods:
     *      ... this.any(ISelectStudent) -- boolean
     *      ... this.filterGrads() ... -- ILoS
     *      
     *    Method of Fields:
     *      ... this.first.isGoodEnough() -- boolean
     *      ... this.rest.any(ISelectStudent) -- boolean
     *      ... this.rest.filterGrads() ... -- ILoS
     *      
     */
    
    // Is there any Student in this nonempty list that the picker likes
    public boolean any(ISelectStudent picker){
        
        // Mini template:
        //   ... picker.select(Student) ...  -- boolean
        return (picker.select(this.first) ||
                this.rest.any(picker));
    }
    // Filter out all the graduating students
    public ILoS filterGrads(){
        if(this.first.graduating)
            return this.rest.filterGrads();
        else
            return new ConsLoS(this.first, this.rest.filterGrads());
    }
}

// Examples and Tests...
class LectureExamples{
    Student stud1 = new Student("Ryan", 5.3, false);
    Student stud2 = new Student("Korbin", 4.0, true);
    Student stud3 = new Student("Kevin", 500, false);
    
    ILoS mt = new MtLoS();
    ILoS los1 = new ConsLoS(this.stud1, this.mt);
    ILoS los2 = new ConsLoS(this.stud2, this.los1);
    ILoS los3 = new ConsLoS(this.stud3, 
            new ConsLoS(this.stud2, this.los1));
    ILoS los4 = new ConsLoS(this.stud3, this.los1);
  
    ISelectStudent bygpa = new ByGPAStudent();
    ISelectStudent byname = new ByNameStudent();
    ISelectStudent bynameRyan = new ByNameStudent("Ryan");

    // Test select method in ByGPAStudent and in ByNameStudent
    boolean testSelect(Tester t){
        return (t.checkExpect(this.bygpa.select(this.stud1), false) &&
		t.checkExpect(this.bygpa.select(this.stud2), true) &&
		t.checkExpect(this.byname.select(this.stud1), false) &&
		t.checkExpect(this.byname.select(this.stud3), true) &&
		t.checkExpect(this.bynameRyan.select(this.stud1), true);
    }
    
    // Test any by GPA
    boolean testAny(Tester t){
        return (t.checkExpect(this.los2.any(new ByGPAStudent()), true) &&
                t.checkExpect(this.los1.any(new ByGPAStudent()), false));
    }
    // Test any by Name
    boolean testAny2(Tester t){
        return (t.checkExpect(this.los2.any(new ByNameStudent()), false) &&
                t.checkExpect(this.los1.any(new ByNameStudent("Ryan")), true) &&
                t.checkExpect(this.los3.any(new ByNameStudent()), true) &&
                t.checkExpect(this.los3.any(new ByNameStudent("Deniz")), false));
    }
    // Test filterGrads
    boolean testFilterGrads(Tester t){
        return (t.checkExpect(this.los2.filterGrads(), this.los1) &&
                t.checkExpect(this.los3.filterGrads(), this.los4));
    }
}