src/com.example.portfolio2/com/example/portfolio2/Database.java



// SPDX-FileCopyrightText: <Alexander Marthin Klemensen stud-marthin@ruc.dk>
// SPDX-FileCopyrightText: <Ian Valentin Christensen stud-ianc@ruc.dk>
// SPDX-FileCopyrightText: <Zahed Noos zahed@ruc.dk>
// SPDX-License-Identifier: GPL-3.0-or-later

package com.example.portfolio2;

import java.util.ArrayList;

/// Bachelorizer - database model
///
/// This model handles all interaction with the database.
class Database {

    /// database singleton
    MyDB db = new MyDB();

    /// default constructor
    // (declared explicitly only to silence javadoc)
    Database() { }

    /// clear the participation database at program launch
    void initialize() {
        clearParticipation();
    }

    /// resolve activity index from name
    ///
    /// @param name  activity name
    /// @return      index of activity as integer
    int getActivityIndeks(final String name) {
        if (name == null) {
            return -1;
        }
        ArrayList<String> result = db.query("select indeks from activity a where name is '" + name + "';", "indeks");

        return Integer.parseInt(result.getFirst());
    }

    /// insert activity into participation
    ///
    /// @param activityIndex  index of activity
    void addParticipation(final int activityIndex) {
        db.cmd("insert into participation values(123, " + activityIndex + ");");
    }

    /// list currently participating activities
    ///
    /// @param program  programme name
    /// @return         names of participating activities
    ArrayList<String> getParticipation(final String program) {
        return db.query("select name from participation p inner join activity a on p.indeks = a.indeks where program is '" + program + "';", "name");
    }

    /// purge participation database
    void clearParticipation() {
        db.cmd("delete from participation");
    }

    /// list activities within a program
    ///
    /// @param program  programme name
    /// @return         names of contained activities
    ArrayList<String> selectProgram(final String program) {
        return db.query("select name from activity where program is '" + program + "';", "name");
    }

    /// sum of ECTS points under the given category
    ///
    /// @param program  programme name
    /// @return         ECTS points as String
    String getSumEcts(final String program) {
        if (program == null) {
            return "0";
        }
        ArrayList<String> result = db.query("select sum(activity.ects) as total_ects,student.name from student left outer join participation on student.studid = participation.studid inner join activity on participation.indeks = activity.indeks where program is '" + program + "' group by student.studid ;", "total_ects");
        if (result.isEmpty()) {
            return "0";
        }

        return result.getFirst();
    }

    /// sum of ECTS points under the given category
    ///
    /// @return         names of all activities as list of String
    ArrayList<String> getAllActivities() {
        return db.query("select name from activity;", "name");
    }
}