CSVDatabase

import java.io.*;
import java.util.*;

public class _08CSVDatabase {
    private static final String STUDENTS_PATH = "resources/students.txt";
    private static final String GRADES_PATH = "resources/grades.txt";
    private static File studentsFile = new File(STUDENTS_PATH);
    private static File gradesFile = new File(GRADES_PATH);

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        String command;
        System.out.println("Insert one of these commands (add student,add grades, search, delete, update, exit): ");
        while (!(command = sc.nextLine().toLowerCase()).equals("exit")) {
            if (command.equals("add student")) {
                System.out.println("Insert full name,age and hometown in the following format(full name,age,hometown): ");
                command = sc.nextLine();
                String[] commandArgs = command.split(",");
                insertStudent(commandArgs[0], commandArgs[1], commandArgs[2]);
            }else if(command.equals("add grades")){
                System.out.println("Insert id of the student and what grade to insert in format(id,grade): ");
                command = sc.nextLine();
                String[] commandArgs = command.split(",");
                insertGradesById(commandArgs[0], commandArgs[1]);
            } else if (command.equals("search")) {
                System.out.println("Search by full name or id in: ");
                command = sc.nextLine();
                if (command.equals("full name")) {
                    System.out.println("Insert name: ");
                    command = sc.nextLine().toLowerCase();
                    searchByIdOrName(command, "full name");
                } else if (command.equals("id")) {
                    System.out.println("Insert id: ");
                    command = sc.nextLine();
                    searchByIdOrName(command, "id");
                } else {
                    System.out.println("No such search demand");
                }
            } else if (command.equals("delete")) {
                System.out.println("Insert id to delete: ");
                command = sc.nextLine();
                deleteById(command);
            } else if (command.equals("update")) {
                System.out.println("Insert id to update: ");
                String id = sc.nextLine();
                System.out.println("Insert what to update information or grades: ");
                String updateDemand = sc.nextLine();
                if (updateDemand.equals("information")) {
                    System.out.println("Type what information to update name,age or hometown: ");
                    String whatToUpdate = sc.nextLine();
                    String updateInfo = "";
                    if (whatToUpdate.equals("name")) {
                        System.out.println("Type first and last name separated with white space: ");
                        updateInfo = sc.nextLine();
                    } else if (whatToUpdate.equals("age")) {
                        System.out.println("Type new age: ");
                        updateInfo = sc.nextLine();
                    } else if (whatToUpdate.equals("hometown")) {
                        System.out.println("Type new hometown: ");
                        updateInfo = sc.nextLine();
                    } else {
                        System.out.println("There is no such field !");
                    }
                    updateById(id, "info", whatToUpdate + " " + updateInfo);
                } else if (updateDemand.equals("grades")) {
                    System.out.println("Type what subject and grade to update in format (subject grade):");
                    command = sc.nextLine();
                    updateById(id, "grades", command);
                } else {
                    System.out.println("You can only update student information and grades");
                }
            } else {
                System.out.println("Wrong command try again !");
            }
            System.out.println("---------------------------");
            System.out.println("Insert one of these commands (add student,add grades, search, delete, update, exit): ");

        }
//        insertStudent("Stefka Koynova" , 50 , "Ruse" );
//        insertGradesById("3", "Music 6.00");
//        searchByIdOrName("Desislava Koynova", "full name");
//        searchByIdOrName("2", "id");
//        deleteById("5");
//        updateById("2", "grades", "Math 5.59");
//        updateById("2", "grades", "Science 5.59");
//        updateById("2", "info", "name Kalin Vesov");
//        updateById("2", "info", "age 20");
//        updateById("1", "info", "hometown Sofia");

    }

    private static void insertStudent(String fullName, String age, String homeTown) {
        try (BufferedWriter bw = new BufferedWriter(new FileWriter(studentsFile, true))) {
            int studentId;
            BufferedReader br = new BufferedReader(new FileReader(studentsFile));
            String firstLine = br.readLine();
            boolean noStudents = firstLine == null || firstLine.equals("");
            if (noStudents) {
                studentId = 1;
            } else {
                String line;
                String last = firstLine;
                while ((line = br.readLine()) != null && !line.equals("")) {
                    last = line;
                }
                studentId = Integer.parseInt(last.split(",")[0]) + 1;
            }
            br.close();
            String firstName = fullName.split(" ")[0];
            String lastName = fullName.split(" ")[1];
            String currentStudent = String.format("%d,%s,%s,%s,%s"
                    , studentId, firstName, lastName, age, homeTown);
            PrintWriter pw = new PrintWriter(bw, true);
            pw.println(currentStudent);
            System.out.println("Insert completed !");

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

    private static void insertGradesById(String studentId, String grade) {
        BufferedReader br;
        try {
            br = new BufferedReader(new FileReader(studentsFile));
            boolean studentExist = false;
            String line;
            while ((line = br.readLine()) != null) {
                String id = line.split(",")[0];
                if (studentId.equals(id)) {
                    studentExist = true;
                    break;
                }
            }
            if (studentExist) {
                br = new BufferedReader(new FileReader(gradesFile));
                String currentLine;
                boolean gradesLineExist = false;

                while ((currentLine = br.readLine()) != null) {
                    String id = currentLine.split(",")[0];
                    if (studentId.equals(id)) {
                        gradesLineExist = true;
                        break;
                    }
                }

                if (gradesLineExist) {
                    Map<String, ArrayList<String>> currentGrades = new LinkedHashMap<>();
                    String[] gradesArgs = currentLine.split(",");
                    for (int i = 1; i < gradesArgs.length; i++) {
                        String[] subjectAndGrades = gradesArgs[i].split(" ");
                        String subject = subjectAndGrades[0];
                        if (!currentGrades.containsKey(subject)) {
                            currentGrades.put(subject, new ArrayList<>());
                        }
                        for (int j = 1; j < subjectAndGrades.length; j++) {
                            currentGrades.get(subject).add(subjectAndGrades[j]);
                        }
                    }
                    if (!currentGrades.containsKey(grade.split(" ")[0])) {
                        currentGrades.put(grade.split(" ")[0], new ArrayList<>());
                    }
                    currentGrades.get(grade.split(" ")[0]).add(grade.split(" ")[1]);
                    StringBuilder inputGrades = new StringBuilder();
                    inputGrades = inputGrades.append(studentId).append(",");
                    for (Map.Entry subject : currentGrades.entrySet()) {
                        inputGrades = inputGrades.append(subject.getKey()).append(" ");
                        for (String objectGrade : (ArrayList<String>) subject.getValue()) {
                            inputGrades = inputGrades.append(objectGrade).append(" ");
                        }
                        String trim = inputGrades.toString().trim();
                        inputGrades = new StringBuilder(trim);
                        inputGrades = inputGrades.append(",");
                    }
                    inputGrades = inputGrades.deleteCharAt(inputGrades.length() - 1);
                    br = new BufferedReader(new FileReader(gradesFile));
                    String readLine;
                    List<String> allGrades = new ArrayList<>();
                    while ((readLine = br.readLine()) != null) {
                        String id = readLine.split(",")[0];
                        if (studentId.equals(id)) {
                            allGrades.add(inputGrades.toString());
                        } else {
                            allGrades.add(readLine);
                        }
                    }

                    Collections.sort(allGrades);
                    BufferedWriter bw = new BufferedWriter(new FileWriter(gradesFile, false));
                    PrintWriter pw = new PrintWriter(bw, true);
                    allGrades.forEach(pw::println);
                    bw.close();
                } else {
                    BufferedWriter bw = new BufferedWriter(new FileWriter(gradesFile, true));
                    PrintWriter pw = new PrintWriter(bw, true);
                    String output = String.format("%s,%s", studentId, grade);
                    pw.println(output);
                    bw.close();
                }
                System.out.println("Insert completed !");
                br.close();
            } else {
                System.out.println("Student does not exist");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    private static void searchByIdOrName(String searchWord, String searchTerm) {
        String firstName = "";
        String lastName = "";
        String searchedId = "";
        if (searchTerm.equals("full name")) {
            firstName = searchWord.split(" ")[0];
            lastName = searchWord.split(" ")[1];
        } else {
            searchedId = searchWord;
        }
        try {
            BufferedReader br = new BufferedReader(new FileReader(studentsFile));
            String line;
            String[] searchedStudent = new String[0];
            boolean studentExist = false;
            while ((line = br.readLine()) != null) {
                String[] lineArgs = line.split(",");
                if ((lineArgs[1].toLowerCase().equals(firstName.toLowerCase())
                        && lineArgs[2].toLowerCase().equals(lastName.toLowerCase())
                        && searchTerm.equals("full name"))
                        || lineArgs[0].equals(searchedId) && searchTerm.equals("id")) {
                    studentExist = true;
                    searchedStudent = lineArgs;
                    break;
                }
            }
            if (studentExist) {
                System.out.printf("%s %s (age: %s, town: %s)\n"
                        , searchedStudent[1], searchedStudent[2], searchedStudent[3], searchedStudent[4]);
                br = new BufferedReader(new FileReader(gradesFile));
                String gradesLine;
                String[] searchedGrades = new String[0];
                boolean gradesExist = false;
                while ((gradesLine = br.readLine()) != null) {
                    if (gradesLine.split(",")[0].equals(searchedStudent[0])) {
                        searchedGrades = gradesLine.split(",");
                        gradesExist = true;
                        break;
                    }
                }
                if (gradesExist) {
                    for (int i = 1; i < searchedGrades.length; i++) {
                        String[] grades = searchedGrades[i].split(" ");
                        StringBuilder sb = new StringBuilder();
                        sb = sb.append(grades[0]).append(": ");
                        for (int j = 1; j < grades.length; j++) {
                            sb = sb.append(grades[j]).append(", ");
                        }
                        sb = sb.delete(sb.length() - 2, sb.length());
                        System.out.println("# " + sb.toString());
                    }
                } else {
                    System.out.println("There is no grades for this student");
                }
            } else {
                System.out.println("Student does not exist");
            }
            br.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void deleteById(String studentId) {
        BufferedReader br;
        try {
            br = new BufferedReader(new FileReader(studentsFile));
            String line;
            StringBuilder newStudents = new StringBuilder();
            boolean studentExist = false;
            while ((line = br.readLine()) != null) {
                if (!line.split(",")[0].equals(studentId)) {
                    newStudents = newStudents.append(line).append(System.lineSeparator());
                } else {
                    studentExist = true;
                }
            }
            newStudents = newStudents.delete(newStudents.length() - 2, newStudents.length());
            if (studentExist) {
                BufferedWriter bw = new BufferedWriter(new FileWriter(studentsFile));
                PrintWriter pw = new PrintWriter(bw, true);
                pw.println(newStudents);
                br = new BufferedReader(new FileReader(gradesFile));
                StringBuilder newGrades = new StringBuilder();
                while ((line = br.readLine()) != null) {
                    if (!line.split(",")[0].equals(studentId)) {
                        newGrades = newGrades.append(line).append(System.lineSeparator());
                    }
                }
                newGrades = newGrades.delete(newGrades.length() - 2, newGrades.length());
                bw = new BufferedWriter(new FileWriter(gradesFile));
                pw = new PrintWriter(bw, true);
                pw.println(newGrades);
                System.out.println("Delete completed !");
                bw.close();
            } else {
                System.out.println("Student does not exist");
            }
            br.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void updateById(String studentId, String whatToUpdate, String update) {
        if (whatToUpdate.equals("grades")) {
            insertGradesById(studentId, update);
        } else {
            BufferedReader br;
            try {
                br = new BufferedReader(new FileReader(studentsFile));
                String line;
                StringBuilder newStudents = new StringBuilder();
                boolean studentExist = false;
                while ((line = br.readLine()) != null) {
                    String[] lineArgs = line.split(",");
                    if (!lineArgs[0].equals(studentId)) {
                        newStudents = newStudents.append(line).append(System.lineSeparator());
                    } else {
                        String toUpdate = update.split(" ")[0];
                        if (toUpdate.equals("name")) {
                            String firstName = update.split(" ")[1];
                            String lastName = update.split(" ")[2];
                            String updatedLine = String.format("%s,%s,%s,%s,%s"
                                    , lineArgs[0], firstName, lastName, lineArgs[3], lineArgs[4]);
                            newStudents = newStudents.append(updatedLine).append(System.lineSeparator());
                        } else if (toUpdate.equals("age")) {
                            String age = update.split(" ")[1];
                            String updatedLine = String.format("%s,%s,%s,%s,%s"
                                    , lineArgs[0], lineArgs[1], lineArgs[2], age, lineArgs[4]);
                            newStudents = newStudents.append(updatedLine).append(System.lineSeparator());
                        } else if (toUpdate.equals("hometown")) {
                            String hometown = update.split(" ")[1];
                            String updatedLine = String.format("%s,%s,%s,%s,%s"
                                    , lineArgs[0], lineArgs[1], lineArgs[2], lineArgs[3], hometown);
                            newStudents = newStudents.append(updatedLine).append(System.lineSeparator());
                        }
                        studentExist = true;
                    }
                }
                newStudents = newStudents.delete(newStudents.length() - 2, newStudents.length());
                if (studentExist) {
                    BufferedWriter bw = new BufferedWriter(new FileWriter(studentsFile));
                    PrintWriter pw = new PrintWriter(bw, true);
                    pw.println(newStudents);
                    System.out.println("Update completed !");
                    bw.close();
                } else {
                    System.out.println("Student does not exist");
                }
                br.close();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}