Merge pull request #136 from seetohjinwei/add-dateparser

Implement DateParser class

docs/UserGuide.md

@@ -181,6 +181,17 @@ If your changes to the data file makes its format invalid, AddressBook will disc
 
 _Details coming soon ..._
 
+## Miscellaneous Information
+
+### Accepted Date Formats
+
+The following date formats are accepted:
+
+* yyyy-MM-dd (2022-10-31)
+* MMM dd yyyy (Oct 31 2022)
+* MM dd yyyy (10 31 2022)
+* dd MMM yyyy (31 Oct 2022)
+
 --------------------------------------------------------------------------------------------------------------------
 
 ## FAQ

src/main/java/taskbook/commons/core/Messages.java

@@ -11,5 +11,6 @@ public class Messages {
     public static final String MESSAGE_INVALID_PERSON_DISPLAYED_INDEX = "The person index provided is invalid";
     public static final String MESSAGE_INVALID_TASK_DISPLAYED_INDEX = "The task index provided is invalid";
     public static final String MESSAGE_PERSONS_LISTED_OVERVIEW = "%1$d persons listed!";
+    public static final String MESSAGE_INVALID_DATE_FORMAT = "Invalid date format!";
 
 }

src/main/java/taskbook/logic/parser/DateParser.java

@@ -0,0 +1,37 @@
+package taskbook.logic.parser;
+
+import static taskbook.commons.core.Messages.MESSAGE_INVALID_DATE_FORMAT;
+
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeFormatterBuilder;
+import java.time.format.DateTimeParseException;
+
+import taskbook.logic.parser.exceptions.ParseException;
+
+/**
+ * Parses user input's date into internal Date object.
+ * Accepts multiple Date formats.
+ */
+public class DateParser {
+
+    private static final DateTimeFormatter PARSER_OPTIONAL_FORMATS = new DateTimeFormatterBuilder()
+        .appendOptional(DateTimeFormatter.ISO_LOCAL_DATE)
+        .appendOptional(DateTimeFormatter.ofPattern("yyyy-MM-dd"))
+        .appendOptional(DateTimeFormatter.ofPattern("MMM dd yyyy"))
+        .appendOptional(DateTimeFormatter.ofPattern("MM dd yyyy"))
+        .appendOptional(DateTimeFormatter.ofPattern("dd MMM yyyy"))
+        .toFormatter();
+
+    /**
+     * Parses {@code userInput} into a Date object and returns it.
+     * @throws ParseException if {@code userInput} does not conform the expected formats.
+     */
+    public static LocalDate parse(String userInput) throws ParseException {
+        try {
+            return LocalDate.parse(userInput, PARSER_OPTIONAL_FORMATS);
+        } catch (DateTimeParseException e) {
+            throw new ParseException(MESSAGE_INVALID_DATE_FORMAT);
+        }
+    }
+}

src/test/java/taskbook/logic/parser/DateParserTest.java

@@ -0,0 +1,62 @@
+package taskbook.logic.parser;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.time.LocalDate;
+
+import org.junit.jupiter.api.Test;
+
+import taskbook.logic.parser.exceptions.ParseException;
+
+public class DateParserTest {
+
+    private final LocalDate expectedOutput = LocalDate.parse("2022-10-31");
+
+    @Test
+    public void parse_validArgument1_returnsCorrectOutput() throws ParseException {
+        LocalDate actual = DateParser.parse("2022-10-31");
+        assertEquals(actual, expectedOutput);
+    }
+
+    @Test
+    public void parse_validArgument2_returnsCorrectOutput() throws ParseException {
+        LocalDate actual = DateParser.parse("Oct 31 2022");
+        assertEquals(actual, expectedOutput);
+    }
+
+    @Test
+    public void parse_validArgument3_returnsCorrectOutput() throws ParseException {
+        LocalDate actual = DateParser.parse("10 31 2022");
+        assertEquals(actual, expectedOutput);
+    }
+
+    @Test
+    public void parse_validArgument4_returnsCorrectOutput() throws ParseException {
+        LocalDate actual = DateParser.parse("31 Oct 2022");
+        assertEquals(actual, expectedOutput);
+    }
+
+    @Test
+    public void parse_emptyArgument_throwsException() {
+        assertThrowsException("");
+    }
+
+    @Test
+    public void parse_invalidInput_throwsException() {
+        assertThrowsException("Halloween");
+    }
+
+    @Test
+    public void parse_invalidFormat_throwsException() {
+        assertThrowsException("31st October 2022");
+    }
+
+    public void assertThrowsException(String userInput) {
+        try {
+            DateParser.parse(userInput);
+            throw new AssertionError("The expected ParseException is not thrown.");
+        } catch (ParseException e) {
+            // intentionally empty catch block
+        }
+    }
+}