DataLoader.java

import java.io.FileReader;
import java.util.ArrayList;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;


public class DataLoader extends DataConstants {
    public static ArrayList<User> user = new ArrayList<User>();

    public static ArrayList<User> getUsers(){
        try {
            FileReader reader = new FileReader(USER_FILE_NAME);
            JSONParser parser = new JSONParser(); 
            JSONArray usersJSON = (JSONArray) parser.parse(reader);

            for(int i = 0; i < usersJSON.size(); i++ ){
                JSONObject userJSON = (JSONObject) usersJSON.get(i);

                String userID = (String) userJSON.get(USER_ID);
                String uFirstName = (String) userJSON.get(USER_FIRST_NAME);
                String uLastName = (String) userJSON.get(USER_LAST_NAME);
                String userEmail = (String) userJSON.get(USER_EMAIL);
                String uPhoneNumber = (String) userJSON.get(USER_PHONENUMBER);
                String userName = (String) userJSON.get(USER_USERNAME);
                String uPassword = (String) userJSON.get(USER_PASSWORD);
                String isUser = (String) userJSON.get(IS_AUTHOR);

                User userObj = new User(uFirstName, uLastName, userEmail, uPhoneNumber,userName,uPassword,userID,isUser);
                user.add(userObj);
                //public boolean validUser(String firstname, String lastname, String email, String phonenumber, String username,
                //String password, String userID, String isAuthor)
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return user;
    }

  
    public ArrayList<Course> getCourses() {
        ArrayList<Course> courses = new ArrayList<Course>();
        try {
            FileReader reader = new FileReader(COURSE_FILE_NAME);
            JSONParser parser = new JSONParser();
            JSONObject coursesJSON = (JSONObject) parser.parse(reader);
            JSONArray coursesArray = (JSONArray) coursesJSON.get("courses");
    
            for(int i = 0; i < coursesArray.size(); i++ ){
                JSONObject courseJSON = (JSONObject) coursesArray.get(i);
    
                String courseId = (String) courseJSON.get(COURSE_ID);
                String title = (String) courseJSON.get(COURSE_TITLE);
                String description = (String) courseJSON.get(COURSE_DESCRIPTION);
                String user_Id = (String) courseJSON.get(USER_ID);
                String difficulty = (String) courseJSON.get(DIFFICULTY);
                String author = (String) courseJSON.get(IS_AUTHOR);
                ModuleGrade moduleGrades = (ModuleGrade) courseJSON.get("modulegrade");
                
                JSONArray modulesJSON = (JSONArray) courseJSON.get(COURSE_MODULE);
            ArrayList<Module> modules = new ArrayList<Module>();
            for(int j = 0; j < modulesJSON.size(); j++) {
                JSONObject moduleJSON = (JSONObject) modulesJSON.get(j);
                String moduleTitle = (String) moduleJSON.get("title");
                String moduleDescription = (String) moduleJSON.get("description");

                JSONArray topicsJSON = (JSONArray) moduleJSON.get(COURSE_TOPIC);
                ArrayList<Topic> topics = new ArrayList<Topic>();
                for(int k = 0; k < topicsJSON.size(); k++) {
                    JSONObject topicJSON = (JSONObject) topicsJSON.get(k);
                    String topicTitle = (String) topicJSON.get("title");
                    String topicDescription = (String) topicJSON.get("description");
                    topics.add(new Topic(topicTitle, topicDescription));
                }
                JSONArray questionsJSON = (JSONArray) moduleJSON.get(COURSE_QUESTIONS);
                        ArrayList<Question> questions = new ArrayList<Question>();
                        for(int k = 0; k < questionsJSON.size(); k++) {
                            JSONObject questionJSON = (JSONObject) questionsJSON.get(k);
                            String questionText = (String) questionJSON.get("questionText");
                            JSONArray choicesJSON = (JSONArray) questionJSON.get("choices");
                            ArrayList<String> choices = new ArrayList<String>();
                            for(int l = 0; l < choicesJSON.size(); l++) {
                                String choice = (String) choicesJSON.get(l);
                                choices.add(choice);
                            }
                            int correctChoice = (int) questionJSON.get("correctChoice");
                            Question question = new Question(questionText, choices, correctChoice);
                            questions.add(question);
                        }

            JSONArray commentsJSON = (JSONArray) moduleJSON.get(COMMENTS);
            ArrayList<Comment> comments = new ArrayList<Comment>();
            for(int g = 0; g < commentsJSON.size(); g++) {
                JSONObject commentJSON = (JSONObject) commentsJSON.get(g);
                String userId = (String) commentJSON.get("user_id");
                String text = (String) commentJSON.get("text");
                comments.add(new Comment(userId, text));
            }
            

            
            Module module = new Module(moduleTitle, moduleDescription, topics, questions, comments, moduleGrades);
           
            modules.add(module);
        
            
        }
        JSONArray reviewJSON = (JSONArray) courseJSON.get(REVIEW);
        ArrayList<Review> reviews = new ArrayList<Review>();
        for(int m = 0; m < reviewJSON.size(); m++) {
            JSONObject reviewObj = (JSONObject) reviewJSON.get(m);
            String userId = (String) reviewObj.get("user_id");
            String text = (String) reviewObj.get("text");
            String rating = (String) reviewObj.get("rating");
            String date = (String) reviewObj.get("date");
            reviews.add(new Review(userId, text, rating, date));
        }
        JSONArray courgradeJSON = (JSONArray) courseJSON.get("courgrade");
                ArrayList<CourseGrade> courseGrades = new ArrayList<CourseGrade>();
                for(int n=0;n<courgradeJSON.size();n++){
                    JSONObject courGradObject = (JSONObject) courgradeJSON.get(n);
                    String userID = (String) courGradObject.get("user_id");
                    double totalGrade = (Double) courGradObject.get("totalGrade");
                    Course course = (Course) courGradObject.get("course");
                    courseGrades.add(new CourseGrade(course,totalGrade,userID));
                }


                //Course course = new Course(courseId, title, description,user_Id, modules, reviews, courseGrades, difficulty);
                Course course = new Course(author, title, description, user_Id, courseId, difficulty, modules, reviews);
                courses.add(course);
 
            }
            
            }catch (Exception e) {
            e.printStackTrace();
        }
        return courses;
    }
}