Server.java

import java.io.*;
import java.net.*;
import java.nio.file.*;
import java.util.*;
import java.util.stream.Collectors;

public class Server {
    public static void main(String[] args) throws IOException {
        System.out.println("Welcome to the server");
        ServerSocket serverSocket = new ServerSocket(8080);
        while (true){
            System.out.println("Waiting for client...");
            new ClientHandler(serverSocket.accept()).start();
        }
    }
}
class ClientHandler extends Thread {
    Socket socket;
    DataOutputStream dos;
    DataInputStream dis;

    public ClientHandler(Socket socket) throws IOException {
        this.socket = socket;
        dos = new DataOutputStream(socket.getOutputStream());
        dis = new DataInputStream(socket.getInputStream());
        System.out.println("Connected to server");
    }

    public String listener() throws IOException {
        System.out.println("listener");
        StringBuilder sb = new StringBuilder();
        int index = dis.read();
        while (index != 0) {
            sb.append((char) index);
            index = dis.read();
        }
        System.out.println("listener2");
        return sb.toString();
    }

    public void writer(String text) throws IOException {
        dos.writeBytes(text);
        dos.flush();
        dos.close();
        dis.close();
        socket.close();
        System.out.println(text);
        System.out.println("command finished and response sent to server");
    }

    @Override
    public void run() {
        super.run();
        String command;
        try {
            command = listener();
            System.out.println("command received: { " + command + " }");
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        String[] split = command.split("~");//login$402243000$fg1999
        for (String s : split) {
            System.out.println(s);
        }
        try {
            switch (split[0]) {
                case "login": //login~studentID~password
                    logJava(split); //Enter the student
                    break;
                case "sign in": //sign in~studentID~password~fullName
                    signJava(split); //Student registration
                    break;
                case "viewProf": //viewProf~ID
                    viewProf(split); //Display full name, number of units and average
                    break;
                case "delete account": //deleteAccount~ID
                    deleteAccount(split); //Delete the student from the database
                    break;
                case "changePass": //changePass~ID~newPass
                    changePass(split); //Change the password in the file
                    break;
                case "viewSara": //viewSara~ID
                    sara(split); //Display number of assignments, maximum and minimum grade
                    break;
                case "myCourses": //myCourses~ID
                    myCourses(split); // Display courseName, teacherName, numberOfUnits, numberOfAssignments
                    break;
                case "takeCourse": // takeCourse~ID~courseName
                    takeCourse(split); //Adding student to a course and sending course details
                    break;
                case "viewCourses": //viewCourses~ID
                    viewCourses(split); //View every course in the database
                    break;
                case "assignments"://assignments~ID
                    seeAssignments(split); //View assignments (courseName~assignmentName~deadline~activeOrNot)
                    break;
                case "doAssignment": //doAssignment~ID~courseName
                    doAssignment(split); // Change the status to "not active" in assignmentFile
                    break;
                case "addWork": //addWork~ID~workName~workDate
                    addWork(split); //Add work in the database
                    break;
                case "doWork": //doWork~ID~workName
                    doWork(split); // Change "active" to "not active"
                    break;
                case "deleteWork": //deleteWork~ID~workName
                    deleteWork(split); // Remove the work from database and application
                    break;
                case "viewWorks": // viewWorks~ID
                    viewWorks(split); // read works from database
                    break;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }



    public void logJava(String[] split) {
        boolean logIn = false;
        int responseOfDatabase = 100;
        try {
            responseOfDatabase = Database.loginChecker(split[1], split[2]);
        } catch (Exception e) {
            e.printStackTrace();
        }
        if (responseOfDatabase == 2) {
            logIn = true;
            System.out.println("status code is 200");
            System.out.println("Successfully logged in!");
            try {
                writer("200");
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (responseOfDatabase == 1) {
            System.out.println("status code is 401");
            System.out.println("Password is incorrect!");
            try {
                writer("401");
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            System.out.println("status code is 404");
            System.out.println("username not found!");
            try {
                writer("404");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (logIn) {
            long l = Long.parseLong(split[1]);
            Student student = null;
            try {
                student = new Student(l);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
    }

    public void signJava(String[] split) throws IOException {
        boolean signIn = false;
        int responseOfDatabase = 100;
        String fullName = split[3];
        responseOfDatabase = Database.signInChecker(split[1], split[2]);

        if (responseOfDatabase == 2) {
            signIn = true;
            System.out.println("status code is 200");
            System.out.println("Successfully signed in!");
            try {
                Student st = new Student(Long.parseLong(split[1]));
                FileWriter fw = new FileWriter("D:\\University\\AP\\project\\project files\\students\\studentInfos\\"
                        + split[1] + "_info.txt", true);
                fw.write("Full Name: " + fullName + "\n");
                fw.flush();
                fw.close();
                writer("200");
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (responseOfDatabase == 1) {
            System.out.println("status code is 401");
            System.out.println("Password is incorrect!");
            try {
                writer("401");
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            System.out.println("status code is 404");
            System.out.println("username is incorrect");
            try {
                writer("404");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public void viewProf (String[] split) throws IOException {
        String studentId = split[1];
        String filePath = "D:\\University\\AP\\project\\project files\\students\\studentInfos\\"
                + studentId + "_info.txt";
        Scanner scanner = new Scanner(new File(filePath));
        String units = null;
        String fullName = null;
        double average = 0;

        while (scanner.hasNextLine()){
            String line = scanner.nextLine();
            if (line.startsWith("Number")){
                units = line.substring(17);
            }
            if (line.startsWith("Full")){
                fullName = line.substring(11);
            }
        }

        BufferedReader reader2 = new BufferedReader(new FileReader("D:\\University\\AP\\project\\project files\\students\\studentCourses\\"
                + studentId + "_courses.txt"));
        String line;
        double totalGrade = 0.0;
        int courseCount = 0;

        while ((line = reader2.readLine()) != null) {
            if (line.contains("grade:")) {
                String gradeString = line.split("grade: ")[1].trim();
                double grade = Double.parseDouble(gradeString);
                totalGrade += grade;
                courseCount++;
            }
        }
        reader2.close();
        if (courseCount > 0) {
            average = totalGrade / courseCount;
        }

        writer(fullName + "~" + units + "~" + average);

    }

    public void deleteAccount(String[] split) throws IOException {
        String studentId = split[1];
        File stInfo = new File("D:\\University\\AP\\project\\project files\\students\\studentInfos\\"
                + studentId + "_info.txt");
        File stCourses = new File("D:\\University\\AP\\project\\project files\\students\\studentCourses\\"
                + studentId + "_courses.txt");
        String courseStudentsFolderPath = "D:\\University\\AP\\project\\project files\\courses\\courseStudents\\";
        String line;

        try {
            BufferedReader reader = new BufferedReader(new FileReader(stCourses));
            while ((line = reader.readLine()) != null ) {
                String courseName = reader.readLine().split(", ")[0].substring(8).trim();
                String courseFilePath = courseStudentsFolderPath + courseName + "_students.txt";

                File courseFile = new File(courseFilePath);
                if (courseFile.exists()) {
                    StringBuilder content = new StringBuilder();
                    Scanner courseScanner = new Scanner(courseFile);
                    while (courseScanner.hasNextLine()) {
                        String lineX = courseScanner.nextLine();
                        if (!lineX.contains(studentId)) {
                            content.append(lineX).append("\n");
                        }
                    }
                    courseScanner.close();

                    FileWriter writer = new FileWriter(courseFile);
                    writer.write(content.toString());
                    writer.close();
                }
            }
            reader.close();
            System.out.println("Student data removed successfully.");
        } catch (IOException e) {
            e.printStackTrace();
        }

        stInfo.delete();
        stCourses.delete();

        String filePath = "D:\\University\\AP\\project\\project files\\Student info.txt";
        String fileContent = Files.readString(Paths.get(filePath));
        // Java 8 is coming!
        List<String> lines = fileContent.lines()
                .filter(lineXX -> !lineXX.contains(studentId))
                .collect(Collectors.toList());

        Files.write(Paths.get(filePath), lines);
        writer("200");
    }

    public void changePass(String [] split) throws IOException {
        String studentId = split[1];
        String newPass = split[2];
        String filePath = "D:\\University\\AP\\project\\project files\\Student info.txt";
        if (!cli.passwordValidator(newPass)){
            writer("404");
            return;
        }
        try {
            File file = new File(filePath);
            FileReader fileReader = new FileReader(file);
            BufferedReader bufferedReader = new BufferedReader(fileReader);

            String line;
            StringBuilder fileContent = new StringBuilder();

            while ((line = bufferedReader.readLine()) != null) {
                if (line.contains("Username: " + studentId)) {
                    line = line.replaceFirst("Password: .*", "Password: " + newPass);
                }
                fileContent.append(line).append("\n");
            }

            bufferedReader.close();

            FileWriter fileWriter = new FileWriter(file);
            fileWriter.write(fileContent.toString());
            fileWriter.close();
            writer("200");

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void sara(String[] split) {
        String studentId = split[1];

        String filePath = "D:\\University\\AP\\project\\project files\\students\\studentCourses\\"
                + studentId + "_courses.txt";
        try {
            BufferedReader reader = new BufferedReader(new FileReader(filePath));
            String line;
            double highestGrade = 0;
            double lowestGrade = 20;

            while ((line = reader.readLine()) != null) {
                if (line.contains("grade:")) {
                    String gradeString = line.split(": ")[2].trim();
                    double grade = Double.parseDouble(gradeString);

                    highestGrade = Math.max(highestGrade, grade);
                    lowestGrade = Math.min(lowestGrade, grade);
                }
            }
            reader.close();


            String courseInformationsPath = "D:\\University\\AP\\project\\project files\\courses\\courseInformations\\";
            BufferedReader reader2= new BufferedReader(new FileReader(filePath));
            int asNum = 0;
            String courseName;
            String lineX;
            while ((lineX = reader2.readLine()) != null) {
                String[] parts = lineX.split(",");
                courseName = parts[0].substring(8).trim();


                String assignmentFilePath = courseInformationsPath + courseName + "_info.txt";
                BufferedReader assignmentReader = new BufferedReader(new FileReader(assignmentFilePath));
                String assignmentLine;
                while ((assignmentLine = assignmentReader.readLine()) != null) {
                    if (assignmentLine.contains("Assignment")) {
                        asNum++;
                    }
                }
                assignmentReader.close();
            }
            reader2.close();

            writer(asNum + "~" + highestGrade + "~" + lowestGrade);

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void myCourses(String[] split) throws IOException {
        List<String> studentCourses = new ArrayList<>();
        String studentId = split[1];
        StringBuilder result = new StringBuilder();
        int asses = 0;

        try {
            File file = new File("D:\\University\\AP\\project\\project files\\students\\studentCourses\\"
                    + studentId + "_courses.txt");
            Scanner reader = new Scanner(file);
            while (reader.hasNextLine()) {
                String line = reader.nextLine();
                String courseName = line.split(": ")[1];
                if (courseName.contains(", grade")) {
                    courseName = courseName.split(",")[0];
                }
                studentCourses.add(courseName);
            }
            reader.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        String courseInfosPath = "D:\\University\\AP\\project\\project files\\courses\\courseInformations\\";
        String teachersPath = "D:\\University\\AP\\project\\project files\\teachers\\teacherInfo\\";
        for (String course : studentCourses) {
            try {
                result.append(course).append("~");
                File courseFile = new File(courseInfosPath + course + "_info.txt");
                Scanner courseReader = new Scanner(courseFile);
                while (courseReader.hasNextLine()) {
                    String line = courseReader.nextLine();
                    if (line.startsWith("Teacher")){
                        String teacherId = line.substring(12, 21);
                        File teacherFile = new File(teachersPath + teacherId + "_info.txt");
                        Scanner scanner = new Scanner(teacherFile);
                        while (scanner.hasNextLine()){
                            String scLine = scanner.nextLine();
                            if (scLine.startsWith("Fullname: ")){
                                String teacherName = scLine.substring(10);
                                result.append(teacherName).append("~");
                            }
                        }
                        //result.append(line, 12, 21).append("~");
                    }
                    if (line.startsWith("number")){
                        result.append(line.charAt(21)).append("~");
                    }
                    if (line.startsWith("Assignment: ")){
                        asses++;
                    }
                }
                courseReader.close();
                result.append(asses).append("~");

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        writer(result.substring(0,result.length()-1));
    }

    public void takeCourse(String[] split) throws IOException {
        boolean done = false;
        int responseOfDatabase = 100;
        String courseInfosPath = "D:\\University\\AP\\project\\project files\\courses\\courseInformations\\";
        String teachersPath = "D:\\University\\AP\\project\\project files\\teachers\\teacherInfo\\";
        StringBuilder result = new StringBuilder();
        int assignmets = 0;

        responseOfDatabase = Database.takeCourseChecker(split[1], split[2]);
        if (responseOfDatabase == 0){
            System.out.println("this course does not exist");
            writer("404");
        } else if (responseOfDatabase == 1) {
            done = true;
            System.out.println("status code is 200");
            System.out.println("Successfully take course");
            try {
                result.append(split[2]).append("~");
                File courseFile = new File(courseInfosPath + split[2] + "_info.txt");
                Scanner courseReader = new Scanner(courseFile);
                while (courseReader.hasNextLine()) {
                    String line = courseReader.nextLine();
                    if (line.startsWith("Teacher")){
                        String teacherId = line.substring(12, 21);
                        File teacherFile = new File(teachersPath + teacherId + "_info.txt");
                        Scanner scanner = new Scanner(teacherFile);
                        while (scanner.hasNextLine()){
                            String scLine = scanner.nextLine();
                            if (scLine.startsWith("Fullname: ")){
                                String teacherName = scLine.substring(10);
                                result.append(teacherName).append("~");
                            }
                        }
                    }
                    if (line.startsWith("number")){
                        result.append(line.charAt(21)).append("~");
                    }
                    if (line.startsWith("Assignment: ")){
                        assignmets++;
                    }
                }
                courseReader.close();
                result.append(assignmets).append("~");

            } catch (IOException e) {
                e.printStackTrace();
            }
            writer(result.substring(0,result.length()-1));
        }
    }

    public void viewCourses (String[] split) throws IOException {
        List<String> studentCourses = new ArrayList<>();
        String studentId = split[1];

        try {
            File file = new File("D:\\University\\AP\\project\\project files\\students\\studentCourses\\"
                    + studentId + "_courses.txt");
            Scanner reader = new Scanner(file);
            while (reader.hasNextLine()) {
                String line = reader.nextLine();
                String courseName = line.split(": ")[1];
                if (courseName.contains(", grade")) {
                    courseName = courseName.split(",")[0];
                }
                studentCourses.add(courseName);
            }
            reader.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        String courseInfosPath = "D:\\University\\AP\\project\\project files\\courses\\courseInformations\\";
        for (String course : studentCourses) {
            try {
                System.out.println(course + ":");
                File courseFile = new File(courseInfosPath + course + "_info.txt");
                Scanner courseReader = new Scanner(courseFile);
                while (courseReader.hasNextLine()) {
                    String line = courseReader.nextLine();
                    writer(line);
                }
                courseReader.close();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
    }

    public void doAssignment(String[] split) throws IOException {
        String studentId = split[1];
        String courseName = split[2];
        String assignmentName = null;

        String line;
        BufferedReader courseReader = new BufferedReader(new FileReader("D:\\University\\AP\\project\\project files\\courses\\courseInformations\\"
                + courseName + "_info.txt"));
        while ((line = courseReader.readLine()) != null){
            if (line.contains("Assignment")){
                assignmentName = line.split(",")[0].substring(12);
            }
        }

        File assignmentFile = new File("D:\\University\\AP\\project\\project files\\assignments\\" +
                assignmentName + ".txt");
        FileWriter assignmentWriter = new FileWriter(assignmentFile , true);
        assignmentWriter.write(studentId + "\n");
        assignmentWriter.flush();
        assignmentWriter.close();
        writer("200");
    }


    public void seeAssignments(String[] split) {
        String studentId = split[1];
        String studentCoursesFilePath = "D:\\University\\AP\\project\\project files\\students\\studentCourses\\"
                + studentId + "_courses.txt";
        String courseInformationsPath = "D:\\University\\AP\\project\\project files\\courses\\courseInformations\\";
        StringBuilder stringBuilder = new StringBuilder();

        try {
            BufferedReader studentCoursesReader = new BufferedReader(new FileReader(studentCoursesFilePath));
            String line;
            while ((line = studentCoursesReader.readLine()) != null) {
                String[] parts = line.split(",");
                String courseName = parts[0].substring(8).trim();

                String assignmentFilePath = courseInformationsPath + courseName + "_info.txt";
                BufferedReader assignmentReader = new BufferedReader(new FileReader(assignmentFilePath));
                String assignmentLine;
                while ((assignmentLine = assignmentReader.readLine()) != null) {
                    if (assignmentLine.contains("Assignment")) {
                        stringBuilder.append("Course: ").append(courseName).append("\n");
                        stringBuilder.append(assignmentLine).append("\n");
                    }
                }
                assignmentReader.close();
            }
            studentCoursesReader.close();


            String result = convertToDesiredFormat(String.valueOf(stringBuilder), studentId);
            writer(result);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public String convertToDesiredFormat(String input, String id) throws IOException {
        String[] lines = input.split("\n");
        StringBuilder output = new StringBuilder();

        for (int i = 0; i < lines.length; i += 2) {
            String course = lines[i].split(": ")[1];
            String[] assignmentParts = lines[i + 1].split(", ");

            String assignment = assignmentParts[0].substring(12);
            String deadline = assignmentParts[1].split(": ")[1];
            String status = assignmentParts[2];

            BufferedReader br = new BufferedReader(new FileReader("D:\\University\\AP\\project\\project files\\assignments\\"
                    + assignment + ".txt"));
            String line;

            while ((line = br.readLine()) != null){
                if (line.contains(id)){
                    status = "not active";
                }
            }
            br.close();

            output.append(course).append("~").append(deadline).append("~").append(status);
            if (i < lines.length - 2) {
                output.append("~");
            }
        }

        return output.toString();
    }

    public void addWork(String[] split) throws IOException {
        String studentId = split[1];
        String workName = split[2];
        String workDate = split[3];

        FileWriter workWriter = new FileWriter("D:\\University\\AP\\project\\project files\\students\\studentWorks\\"
                + studentId + "_works.txt", true);
        workWriter.write(workName + "~" + workDate + "~" + "active" + "\n");
        workWriter.flush();
        workWriter.close();

        System.out.println("200");
        writer("200");
    }

    public void doWork(String[] split) throws IOException {
        String studentId = split[1];
        String workName = split[2];
        String path = "D:\\University\\AP\\project\\project files\\students\\studentWorks\\"
                + studentId + "_works.txt";
        String tempPath = "D:\\University\\AP\\project\\project files\\students\\studentWorks\\"
                + studentId + "_works_temp.txt";

        try (BufferedReader reader = new BufferedReader(new FileReader(path));
             BufferedWriter writer = new BufferedWriter(new FileWriter(tempPath))) {

            String line;
            while ((line = reader.readLine()) != null) {
                if (line.startsWith(workName)) {
                    line = line.replace("active", "not active");
                }
                writer.write(line);
                writer.newLine();
            }
            reader.close();
            writer.close();

            System.out.println("200");
            writer("200");
        } catch (IOException e) {
            e.printStackTrace();
        }

        Files.move(Paths.get(tempPath), Paths.get(path), StandardCopyOption.REPLACE_EXISTING);

    }

    public void deleteWork(String[] split){
        String studentId = split[1];
        String workName = split[2];
        String filePath = "D:\\University\\AP\\project\\project files\\students\\studentWorks\\"
                + studentId + "_works.txt";

        try {
            String fileContent = new String(Files.readAllBytes(Paths.get(filePath)));
            String[] works = fileContent.split("\n");
            StringBuilder updatedContent = new StringBuilder();
            for(String work : works){
                if (!work.contains(workName)){
                    updatedContent.append(work);
                }
            }
            Files.write(Paths.get(filePath), updatedContent.toString().getBytes());
            System.out.println("200");
            writer("200");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void viewWorks(String[] split) throws IOException {
        String studentId = split[1];
        StringBuilder sb = new StringBuilder();
        File workFile = new File("D:\\University\\AP\\project\\project files\\students\\studentWorks\\"
                + studentId + "_works.txt");
        Scanner workScanner = new Scanner(workFile);
        String line;

        while (workScanner.hasNextLine()){
            line = workScanner.nextLine();
            sb.append(line).append("~");
        }

        String result = sb.toString().substring(0, sb.length()-1);
        System.out.println("200");
        writer(result);
        workScanner.close();
    }





}