Add delete function without tests

src/main/java/seedu/duke/controllers/ModulePlannerController.java

@@ -144,6 +144,12 @@ public void start() {
                     view.handleAddMessage(isSuccessful);
                     break;
                 }
+                case "delete": {
+                    String module = words[1].toUpperCase();
+                    String deleteMessage = student.getSchedule().deleteModule(module);
+                    view.handleDeleteMessage(deleteMessage);
+                    break;
+                }
                 case "schedule": {
                     student.getSchedule().printMainModuleList();
                     break;

src/main/java/seedu/duke/models/logic/Api.java

@@ -207,6 +207,12 @@ public static ArrayList<String> getModulePrereqBasedOnCourse(String moduleCode,
 
     }
 
+    /**
+     * Checks if a module with the given module code exists in the NUSMods database.
+     *
+     * @param moduleCode The module code to check for existence.
+     * @return `true` if the module exists, `false` if the module does not exist.
+     */
     public static boolean doesModuleExist(String moduleCode) {
         JSONObject moduleInfo = getFullModuleInfo(moduleCode);
         return (!(moduleInfo == null));

src/main/java/seedu/duke/models/schema/ModuleList.java

@@ -103,5 +103,15 @@ public int getNumberOfModules() {
         return numberOfModules;
     }
 
+    /**
+     * Changes the number of modules by the specified difference.
+     *
+     * @param difference The difference by which to change the number of modules.
+     *                   A positive value increases the number, while a negative value decreases it.
+     */
+    public void changeNumberOfModules(int difference) {
+        numberOfModules += difference;
+    }
+
 
 }

src/main/java/seedu/duke/models/schema/Schedule.java

@@ -1,28 +1,58 @@
 package seedu.duke.models.schema;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import static seedu.duke.models.logic.Api.satisfiesAllPrereq;
 
+/**
+ * The `Schedule` class represents a student's course schedule and extends the `ModuleList` class.
+ * It allows a student to manage and manipulate their enrolled modules across multiple semesters.
+ */
 public class Schedule extends ModuleList {
 
     private static final int MAXIMUM_SEMESTERS = 8;
+    private static final String MISSING_MODULE = "Module is not in schedule.";
+    private static final String DEPENDENT_MODULE = "Unable to delete module. This module is a prerequisite for ";
+    private static final String INVALID_MODULE = "Please select a valid module";
+    private static final String DELETE_MODULE = "Module Successfully Deleted";
     protected int[] modulesPerSem;
 
+    /**
+     * Constructs a new `Schedule` with the provided modules and distribution across semesters.
+     *
+     * @param modules      A string containing module codes representing the student's schedule.
+     * @param modulesPerSem An array indicating the distribution of modules across semesters.
+     */
     public Schedule(String modules, int[] modulesPerSem) {
         super(modules);
         this.modulesPerSem = modulesPerSem;
     }
 
+    /**
+     * Constructs a new, empty `Schedule` with no modules and a default semester distribution.
+     */
     public Schedule() {
         super();
         this.modulesPerSem = new int[]{0, 0, 0, 0, 0, 0, 0, 0};
     }
 
+    /**
+     * Retrieves the maximum number of semesters allowed in a student's course schedule.
+     *
+     * @return The maximum number of semesters allowed.
+     */
     public static int getMaximumSemesters() {
         return MAXIMUM_SEMESTERS;
     }
 
+    /**
+     * Adds a module to the student's course schedule at the specified target semester.
+     *
+     * @param module     The module code to be added.
+     * @param targetSem  The target semester for adding the module.
+     * @return `true` if the module is successfully added, `false` if the addition is not possible.
+     */
     public boolean addModule(String module, int targetSem)  {
 
         if (targetSem < 1 || targetSem > MAXIMUM_SEMESTERS) {
@@ -41,6 +71,7 @@ public boolean addModule(String module, int targetSem)  {
             if (satisfiesAllPrereq(module, completedModules)) {
                 this.getMainModuleList().add(indexToAdd, module);
                 modulesPerSem[targetSem - 1] += 1;
+                changeNumberOfModules(1);
                 printMainModuleList();
                 return true;
             }
@@ -51,6 +82,68 @@ public boolean addModule(String module, int targetSem)  {
         return false;
     }
 
+    /**
+     * Deletes a module from the student's course schedule.
+     *
+     * @param module The module code to be deleted from the schedule.
+     * @return One of the following strings:
+     *     - If the module is successfully deleted: {@value #DELETE_MODULE}
+     *     - If the specified module does not exist in the schedule: {@value #MISSING_MODULE}
+     *     - If another module is dependent on the specified module:
+     *       {@value #DEPENDENT_MODULE} followed by the dependent module's code.
+     *     - If the specified module is invalid: {@value #INVALID_MODULE}
+     */
+    public String deleteModule(String module) {
+
+        int targetIndex = getMainModuleList().indexOf(module);
+
+        if (targetIndex == -1) {
+            return MISSING_MODULE;
+        }
+
+        int targetSem = 1;
+        int moduleCount = modulesPerSem[0];
+
+        while ((moduleCount - 1) < targetIndex) {
+            moduleCount += modulesPerSem[targetSem];
+            targetSem += 1;
+        }
+
+        int nextSemStartingIndex = moduleCount;
+
+        int lastModuleIndex = getNumberOfModules() - 1;
+
+        List<String> completedModulesArray = getMainModuleList().subList(0, nextSemStartingIndex);
+        ModuleList completedModules = new ModuleList(String.join(" ", completedModulesArray));
+        completedModules.getMainModuleList().remove(module);
+
+        List<String> modulesAheadArray;
+        try {
+            modulesAheadArray = getMainModuleList().subList(nextSemStartingIndex, lastModuleIndex + 1);
+        } catch (IndexOutOfBoundsException | IllegalArgumentException e) {
+            modulesAheadArray = new ArrayList<>();
+        }
+
+        try {
+            for (String moduleAhead : modulesAheadArray){
+                if (!satisfiesAllPrereq(moduleAhead, completedModules)) {
+                    return DEPENDENT_MODULE + moduleAhead;
+                }
+            }
+        } catch (IllegalArgumentException e) {
+            return INVALID_MODULE;
+        }
+
+        getMainModuleList().remove(module);
+        modulesPerSem[targetSem - 1] -= 1;
+        changeNumberOfModules(-1);
+
+        return DELETE_MODULE;
+    }
+
+    /**
+     * Prints the student's course schedule, displaying modules organized by semesters.
+     */
     @Override
     public void printMainModuleList() {
         int moduleCounter = 0;

src/main/java/seedu/duke/utils/Parser.java

@@ -116,6 +116,17 @@ public static boolean isValidInput(String command, String[] words) {
             }
             break;
         }
+        case "delete": {
+            if (words.length != 2) {
+                ErrorHandler.invalidDeleteFormat();
+                return false;
+            }
+            if (!doesModuleExist(words[1].toUpperCase())) {
+                ErrorHandler.invalidModule();
+                return false;
+            }
+            break;
+        }
         case "test2": {
             if (words.length < 21) {
                 return false;

src/main/java/seedu/duke/views/CommandLineView.java

@@ -34,6 +34,10 @@ public void handleMajorMessage(int userInputLength, Major major) {
         displayMessage("Major " + major + " selected!");
     }
 
+    public void handleDeleteMessage(String deleteMessage) {
+        displayMessage(deleteMessage);
+    }
+
     public void handleAddMessage(boolean isSuccessful) {
         if (isSuccessful) {
             displayMessage("Module Successfully Added");

src/main/java/seedu/duke/views/ErrorHandler.java

@@ -25,4 +25,8 @@ public static void invalidSemester() {
     public static void invalidModule() {
         System.out.println("Please select a valid module");
     }
+
+    public static void invalidDeleteFormat() {
+        System.out.println("Please delete a module using this format: delete [module code]");
+    }
 }