Modify Ui to be responsible to format exceptions

To be consistent across operating systems, Ui now checks for the
operating system's line separator and standardises all tabbing
to 4 spaces.

src/main/java/earl/logic/DeadlineHandler.java

@@ -1,6 +1,7 @@
 package earl.logic;
 
 import earl.exceptions.EarlException;
+import earl.tasks.Task;
 import earl.tasks.TaskType;
 import earl.util.TaskList;
 import earl.util.Ui;
@@ -20,18 +21,21 @@ public DeadlineHandler(String args) {
     public void handle(TaskList tasks, Ui ui) throws EarlException {
         try {
             String[] data = args.split("\\s+/by\\s+");
-            tasks.add(TaskType.DEADLINE.createTask(data));
-            ui.makeResponse("Added new deadline.",
-                    "\t" + tasks.get(tasks.getSize() - 1),
-                    "There are " + tasks.getSize() + " task(s) tracked.");
+            Task added = tasks.add(TaskType.DEADLINE.createTask(data));
+            ui.buildResponse("Added new deadline.");
+            ui.buildResponse(ui.leftPad(added.toString()));
+            ui.buildResponse("There are " + tasks.getSize()
+                    + " task(s) tracked.");
+            ui.completeResponse();
         } catch (IndexOutOfBoundsException e) {
             throw new EarlException(
-                    "Error, invalid deadline format.\n"
-                            + "\tExample use:\n\t"
-                            + "\tdeadline <task_name> /by <end>");
+                    ui.appendNewline("Error, invalid deadline format.")
+                            + ui.appendNewline("Example use:")
+                            + ui.leftPad("deadline <name> /by <due>"));
         } catch (Exception e) {
-            throw new EarlException("Error, unknown use of deadline.\n"
-                    + e.getMessage());
+            throw new EarlException(
+                    ui.appendNewline("Error, unknown use of deadline.")
+                            + ui.leftPad(e.getMessage()));
         }
     }
 }

src/main/java/earl/logic/DeleteHandler.java

@@ -30,8 +30,9 @@ public void handle(TaskList tasks, Ui ui) throws EarlException {
         } catch (EarlException e) {
             throw e;
         } catch (Exception e) {
-            throw new EarlException("Error, unknown use of delete.\n"
-                    + "\t" + e.getMessage());
+            throw new EarlException(
+                    ui.appendNewline("Error, unknown use of delete.")
+                            + ui.leftPad(e.getMessage()));
         }
     }
 }

src/main/java/earl/logic/EventHandler.java

@@ -1,6 +1,7 @@
 package earl.logic;
 
 import earl.exceptions.EarlException;
+import earl.tasks.Task;
 import earl.tasks.TaskType;
 import earl.util.TaskList;
 import earl.util.Ui;
@@ -19,17 +20,22 @@ public EventHandler(String args) {
     public void handle(TaskList tasks, Ui ui) throws EarlException {
         try {
             String[] data = args.split("\\s+/(from|to)\\s+");
-            tasks.add(TaskType.EVENT.createTask(data));
-            ui.makeResponse("Added new event.",
-                    "\t" + tasks.get(tasks.getSize() - 1),
-                    "There are " + tasks.getSize() + " task(s) tracked.");
+            Task added = tasks.add(TaskType.EVENT.createTask(data));
+            ui.buildResponse("Added new event.");
+            ui.buildResponse(ui.leftPad(added.toString()));
+            ui.buildResponse("There are " + tasks.getSize()
+                    + " task(s) tracked.");
+            ui.completeResponse();
         } catch (IndexOutOfBoundsException e) {
-            throw new EarlException("Error, invalid event format.\n"
-                    + "\tExample use:\n\t"
-                    + "\tevent <task_name> /from <start> /to <end>");
+            throw new EarlException(
+                    ui.appendNewline("Error, invalid event format.")
+                            + ui.appendNewline("Example use:")
+                            + ui.leftPad("event <name>"
+                                    + " /from <start> /to <end>"));
         } catch (Exception e) {
-            throw new EarlException("Error, unknown use of event.\n"
-                    + e.getMessage());
+            throw new EarlException(
+                    ui.appendNewline("Error, unknown use of event.")
+                            + ui.leftPad(e.getMessage()));
         }
     }
 }

src/main/java/earl/logic/MarkHandler.java

@@ -26,20 +26,20 @@ public void handle(TaskList tasks, Ui ui) throws EarlException {
             }
             for (int idx : indices) {
                 boolean success = tasks.get(idx).markAsDone();
+                String feedback = idx + 1 + "." + tasks.get(idx);
                 if (!success) {
-                    addDisplayEntry(idx + 1 + "." + tasks.get(idx)
-                            + " already marked as done.");
-                    continue;
+                    feedback = feedback + " already marked as done.";
                 }
-                addDisplayEntry(idx + 1 + "." + tasks.get(idx));
+                addDisplayEntry(feedback);
             }
             addDisplayEntry("Item(s) marked as done.");
             ui.makeResponse(getDisplay());
         } catch (EarlException e) {
             throw e;
         } catch (Exception e) {
-            throw new EarlException("Error, unknown use of mark.\n"
-                    + "\t" + e.getMessage());
+            throw new EarlException(
+                    ui.appendNewline("Error, unknown use of mark.")
+                            + ui.leftPad(e.getMessage()));
         }
     }
 }

src/main/java/earl/logic/TodoHandler.java

@@ -1,6 +1,7 @@
 package earl.logic;
 
 import earl.exceptions.EarlException;
+import earl.tasks.Task;
 import earl.tasks.TaskType;
 import earl.util.TaskList;
 import earl.util.Ui;
@@ -18,16 +19,20 @@ public TodoHandler(String args) {
     @Override
     public void handle(TaskList tasks, Ui ui) throws EarlException {
         try {
-            tasks.add(TaskType.TODO.createTask(args));
-            ui.makeResponse("Added new todo.",
-                    "\t" + tasks.get(tasks.getSize() - 1),
-                    "There are " + tasks.getSize() + " task(s) tracked.");
+            Task added = tasks.add(TaskType.TODO.createTask(args));
+            ui.buildResponse("Added new todo.");
+            ui.buildResponse(ui.leftPad(added.toString()));
+            ui.buildResponse("There are " + tasks.getSize()
+                    + " task(s) tracked.");
+            ui.completeResponse();
         } catch (IndexOutOfBoundsException e) {
-            throw new EarlException("Error, missing task name.\n"
-                    + "\tExample use:\n\ttodo <task_name>");
+            throw new EarlException(
+                    ui.appendNewline("Error, missing task name. Example use:")
+                            + ui.leftPad("todo <name>"));
         } catch (Exception e) {
-            throw new EarlException("Error, unknown use of todo.\n"
-                    + e.getMessage());
+            throw new EarlException(
+                    ui.appendNewline("Error, unknown use of todo.")
+                            + ui.leftPad(e.getMessage()));
         }
     }
 }

src/main/java/earl/logic/UnmarkHandler.java

@@ -24,20 +24,20 @@ public void handle(TaskList tasks, Ui ui) throws EarlException {
             }
             for (int idx : indices) {
                 boolean success = tasks.get(idx).markUndone();
+                String feedback = idx + 1 + "." + tasks.get(idx);
                 if (!success) {
-                    addDisplayEntry(idx + 1 + "." + tasks.get(idx)
-                            + " already marked as not done.");
-                    continue;
+                    feedback = feedback + " already marked as not done.";
                 }
-                addDisplayEntry(idx + 1 + "." + tasks.get(idx));
+                addDisplayEntry(feedback);
             }
             addDisplayEntry("Item(s) marked as not done.");
             ui.makeResponse(getDisplay());
         } catch (EarlException e) {
             throw e;
         } catch (Exception e) {
-            throw new EarlException("Error, unknown use of mark.\n"
-                    + "\t" + e.getMessage());
+            throw new EarlException(
+                    ui.appendNewline("Error, unknown use of unmark.")
+                            + ui.leftPad(e.getMessage()));
         }
     }
 }

src/main/java/earl/util/TaskList.java

@@ -41,8 +41,9 @@ public Task get(int i) {
         return tasks.get(i);
     }
 
-    public void add(Task task) {
+    public Task add(Task task) {
         tasks.add(task);
+        return task;
     }
 
     public Task delete(int idx) {

src/main/java/earl/util/Ui.java

@@ -1,5 +1,7 @@
 package earl.util;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Scanner;
 
 /**
@@ -9,19 +11,23 @@ public class Ui {
 
     private static final String PADDING = " ".repeat(4);
     private static final String DIVIDER = "_".repeat(60);
-    private static final String GREETING_MESSAGE = "Hello! I'm Earl\n"
+    private static final String NEWLINE = System.lineSeparator();
+    private static final String GREETING_MESSAGE = "Hello! I'm Earl" + NEWLINE
             + PADDING + "What can I do for you?";
 
     private static final String GOODBYE_MESSAGE = "Goodbye! See you soon.";
 
     private final Scanner sc;
+    private final List<String> delayedResponse;
 
-    private String[] prevResponse;
+    private String[] response;
 
     /** Class constructor. */
     public Ui() {
         sc = new Scanner(System.in);
-        prevResponse = new String[0];
+        response = new String[1];
+        response[0] = GREETING_MESSAGE;
+        delayedResponse = new ArrayList<>();
     }
 
     /** Displays horizontal divider. */
@@ -36,6 +42,21 @@ private static void printStrings(String... arr) {
         }
     }
 
+    private void setPrevResponse(String... arr) {
+        response = arr;
+    }
+
+    /** Adds strings to be displayed later. */
+    public void buildResponse(String... arr) {
+        delayedResponse.addAll(List.of(arr));
+    }
+
+    /** Formats and prints the built response for the user to read. */
+    public void completeResponse() {
+        makeResponse(delayedResponse.toArray(String[]::new));
+        delayedResponse.clear();
+    }
+
     /**
      * Formats and prints the arguments for the user to read.
      * <p>
@@ -52,14 +73,19 @@ public void makeResponse(String... arr) {
         printDivider();
     }
 
-    private void setPrevResponse(String... arr) {
-        prevResponse = arr;
-    }
-
     public String getUserInput() {
         return sc.nextLine();
     }
 
+    /** Left pads the input string with the class's set padding. */
+    public String leftPad(String line) {
+        return PADDING + line;
+    }
+
+    public String appendNewline(String line) {
+        return line + NEWLINE;
+    }
+
     public void showGreeting() {
         makeResponse(GREETING_MESSAGE);
     }
@@ -75,11 +101,11 @@ public void showGoodbye() {
      *          text based UI
      */
     public String getResponse() {
-        StringBuilder res = new StringBuilder(PADDING + DIVIDER + "\n");
-        for (String line: prevResponse) {
-            res.append(PADDING).append(line).append("\n");
+        StringBuilder res = new StringBuilder(PADDING + DIVIDER + NEWLINE);
+        for (String line: response) {
+            res.append(PADDING).append(line).append(NEWLINE);
         }
-        res.append(PADDING).append(DIVIDER).append("\n");
+        res.append(PADDING).append(DIVIDER).append(NEWLINE);
         return res.toString();
     }
 }