import std.stdio;
import std.string;

class School {
    Classroom[] classes;

    void addClass(ref Classroom classroom) {
        //classroom.school = this;
        this.classes ~= classroom;
    }

    void invite(string className, ref Teacher teacher) {
        Classroom classroom = getClassByName(className);
        if (classroom !is null)
            classroom.teachers ~= teacher;
    }

    void invite(string className, ref Student student) {
        Classroom classroom = getClassByName(className);
        if (classroom !is null)
            classroom.students ~= student;
    }

    void invite(string className, Teacher[] teachers) {
        foreach(ref teacher; teachers) {
            invite(className, teacher);
        }
    }

    void invite(string className, Student[] students) {
        foreach(ref student; students) {
            invite(className, student);
        }
    }

    Classroom getClassByName(string className) {
        if (isDefined(className)) {
            foreach(classroom; this.classes) {
                if (classroom.name == className)
                    return classroom;
            }
        }
        return null;
    }

    Classroom newClassroom(string name, ref Teacher teacher) {
        auto classroom = new Classroom(name, teacher);
        addClass(classroom);
        return classroom;
    }

    bool isDefined(string className) {
        foreach(classroom; this.classes) {
            if (classroom.name == className)
                return true;
        }
        return false;
    }

    void printClasses() {
        foreach(classroom; this.classes) {
            writeln(classroom);
        }
    }
}

class Teacher: User {
    string lesson;

    this(string firstName, string lastName, short age, string lesson) {
        super(firstName, lastName, age);
        this.role = "Teacher";
        this.lesson = lesson;
    }
}

class Student: User {
    this(string firstName, string lastName, short age) {
        super(firstName, lastName, age);
        this.role = "Student";
    }
}

class Classroom {
    private School _school;
    string name;

    Teacher formMaster;
    Teacher[] teachers;
    Student[] students;

    this(string name, ref Teacher teacher) {
        this.name = name;
        this.formMaster = teacher;
    }

    @property void school(ref School school) {
        this._school = school;
    }

    override string toString() const {
        string text = format("Class %s. Teacher %s. %d students: \n", this.name, this.formMaster.name, this.students.length);
        foreach(student; this.students) {
            text ~= "\t" ~ student.toString() ~ "\n";
        }
        return text;
    }
}

class User {
    Classroom classroom;
    string firstName;
    string lastName;
    string role;
    short age;

    this(string firstName, string lastName, short age) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }

    @property string name() const {
            return format("%s %s", this.firstName, this.lastName);
    }

    override string toString() const {
        return format("%s %s. Age %d.", this.role, this.name, this.age);
    }
}

void main() {
    auto students = [
        new Student("Henry", "El", 16),
        new Student("Nicol", "Mi", 16),
        new Student("Leo", "Ef", 11)
    ];

    auto teacher = new Teacher("Marry", "Elezabet", 43, "Russian Language");

    auto school = new School();
    school.newClassroom("10A", teacher);
    school.newClassroom("6B", teacher);

    school.invite("10A", students[0..2]);
    school.invite("6B", students[2]);

    school.printClasses();
}