Add L-shaped room support to paint calculator

paint-calculator/src/main/java/dev/delivercraft/paint/LShapedRoom.java

@@ -0,0 +1,27 @@
+package dev.delivercraft.paint;
+
+import java.math.BigDecimal;
+import java.util.Objects;
+
+public record LShapedRoom(RectangularRoom outer, RectangularRoom cutout) implements RoomDimensions {
+
+    public LShapedRoom(RectangularRoom outer, RectangularRoom cutout) {
+        this.outer = Objects.requireNonNull(outer, "outer must not be null");
+        this.cutout = Objects.requireNonNull(cutout, "cutout must not be null");
+
+        BigDecimal outerLength = outer.length().value();
+        BigDecimal outerWidth = outer.width().value();
+        BigDecimal cutoutLength = cutout.length().value();
+        BigDecimal cutoutWidth = cutout.width().value();
+
+        if (cutoutLength.compareTo(outerLength) >= 0 || cutoutWidth.compareTo(outerWidth) >= 0) {
+            throw new IllegalArgumentException(
+                    "Cut-out must be smaller than the outer rectangle on both length and width.");
+        }
+    }
+
+    @Override
+    public BigDecimal area() {
+        return this.outer.area().subtract(this.cutout.area());
+    }
+}

paint-calculator/src/main/java/dev/delivercraft/paint/PaintCalculator.java

@@ -7,14 +7,22 @@
 
 final class PaintCalculator {
 
-    private static final String SHAPE_MENU = "Select room shape: 1) Rectangular  2) Round";
+    private static final String SHAPE_MENU = "Select room shape: 1) Rectangular  2) Round  3) L-shaped";
 
     private static final String LENGTH_PROMPT = "What is the length of the room in feet? ";
 
     private static final String WIDTH_PROMPT = "What is the width of the room in feet? ";
 
     private static final String RADIUS_PROMPT = "What is the radius of the room in feet? ";
 
+    private static final String OUTER_LENGTH_PROMPT = "What is the length of the outer rectangle in feet? ";
+
+    private static final String OUTER_WIDTH_PROMPT = "What is the width of the outer rectangle in feet? ";
+
+    private static final String CUTOUT_LENGTH_PROMPT = "What is the length of the cut-out in feet? ";
+
+    private static final String CUTOUT_WIDTH_PROMPT = "What is the width of the cut-out in feet? ";
+
     private final LineReader lineReader;
 
     private final LineWriter lineWriter;
@@ -31,7 +39,8 @@ void calculatePaint() {
         RoomDimensions dimensions = switch (shapeChoice != null ? shapeChoice.trim() : null) {
             case "1" -> readRectangularDimensions();
             case "2" -> readRoundDimensions();
-            case null, default -> throw new IllegalArgumentException("Please enter 1 or 2");
+            case "3" -> readLShapedDimensions();
+            case null, default -> throw new IllegalArgumentException("Please enter 1, 2 or 3");
         };
 
         PaintEstimate estimate = PaintEstimator.estimate(dimensions);
@@ -51,6 +60,16 @@ private RoundRoom readRoundDimensions() {
         return new RoundRoom(radius);
     }
 
+    private LShapedRoom readLShapedDimensions() {
+        RoomDimension outerLength = readDimension(OUTER_LENGTH_PROMPT);
+        RoomDimension outerWidth = readDimension(OUTER_WIDTH_PROMPT);
+        RoomDimension cutoutLength = readDimension(CUTOUT_LENGTH_PROMPT);
+        RoomDimension cutoutWidth = readDimension(CUTOUT_WIDTH_PROMPT);
+        return new LShapedRoom(
+                new RectangularRoom(outerLength, outerWidth),
+                new RectangularRoom(cutoutLength, cutoutWidth));
+    }
+
     private RoomDimension readDimension(String prompt) {
         this.lineWriter.write(prompt);
         return RoomDimension.of(this.lineReader.readLine());

paint-calculator/src/main/java/dev/delivercraft/paint/RoomDimensions.java

@@ -2,7 +2,7 @@
 
 import java.math.BigDecimal;
 
-sealed interface RoomDimensions permits RectangularRoom, RoundRoom {
+sealed interface RoomDimensions permits RectangularRoom, RoundRoom, LShapedRoom {
 
     BigDecimal area();
 }

paint-calculator/src/test/java/dev/delivercraft/paint/LShapedRoomTest.java

@@ -0,0 +1,120 @@
+package dev.delivercraft.paint;
+
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+class LShapedRoomTest {
+
+    private static final RectangularRoom ANY_OUTER =
+            new RectangularRoom(RoomDimension.of("20"), RoomDimension.of("15"));
+
+    private static final RectangularRoom ANY_CUTOUT =
+            new RectangularRoom(RoomDimension.of("5"), RoomDimension.of("4"));
+
+    private static final String CUTOUT_TOO_BIG_MSG =
+            "Cut-out must be smaller than the outer rectangle on both length and width.";
+
+    @Test
+    void construction_GivenNullOuter_ShouldThrowNullPointerException() {
+        assertThatThrownBy(() -> new LShapedRoom(null, ANY_CUTOUT))
+                .isInstanceOf(NullPointerException.class)
+                .hasMessage("outer must not be null");
+    }
+
+    @Test
+    void construction_GivenNullCutout_ShouldThrowNullPointerException() {
+        assertThatThrownBy(() -> new LShapedRoom(ANY_OUTER, null))
+                .isInstanceOf(NullPointerException.class)
+                .hasMessage("cutout must not be null");
+    }
+
+    @Test
+    void area_GivenOuter20x15AndCutout5x4_ShouldReturn280() {
+        LShapedRoom room = new LShapedRoom(ANY_OUTER, ANY_CUTOUT);
+
+        assertThat(room.area()).isEqualByComparingTo(new BigDecimal("280"));
+    }
+
+    @Test
+    void area_GivenFractionalDimensions_ShouldComputeExactly() {
+        LShapedRoom room = new LShapedRoom(
+                new RectangularRoom(RoomDimension.of("10.5"), RoomDimension.of("10.1")),
+                new RectangularRoom(RoomDimension.of("2.5"), RoomDimension.of("2")));
+
+        // 10.5 * 10.1 = 106.05 ; 2.5 * 2 = 5.0 ; diff = 101.05
+        assertThat(room.area()).isEqualByComparingTo(new BigDecimal("101.05"));
+    }
+
+    @Test
+    void construction_GivenCutoutEqualOnLength_ShouldThrow() {
+        RectangularRoom cutout = new RectangularRoom(RoomDimension.of("20"), RoomDimension.of("4"));
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(() -> new LShapedRoom(ANY_OUTER, cutout))
+                .withMessage(CUTOUT_TOO_BIG_MSG);
+    }
+
+    @Test
+    void construction_GivenCutoutEqualOnWidth_ShouldThrow() {
+        RectangularRoom cutout = new RectangularRoom(RoomDimension.of("5"), RoomDimension.of("15"));
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(() -> new LShapedRoom(ANY_OUTER, cutout))
+                .withMessage(CUTOUT_TOO_BIG_MSG);
+    }
+
+    @Test
+    void construction_GivenCutoutEqualOnBothAxes_ShouldThrow() {
+        RectangularRoom cutout = new RectangularRoom(RoomDimension.of("20"), RoomDimension.of("15"));
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(() -> new LShapedRoom(ANY_OUTER, cutout))
+                .withMessage(CUTOUT_TOO_BIG_MSG);
+    }
+
+    @Test
+    void construction_GivenCutoutLargerOnLength_ShouldThrow() {
+        RectangularRoom cutout = new RectangularRoom(RoomDimension.of("21"), RoomDimension.of("4"));
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(() -> new LShapedRoom(ANY_OUTER, cutout))
+                .withMessage(CUTOUT_TOO_BIG_MSG);
+    }
+
+    @Test
+    void construction_GivenCutoutLargerOnWidth_ShouldThrow() {
+        RectangularRoom cutout = new RectangularRoom(RoomDimension.of("5"), RoomDimension.of("16"));
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(() -> new LShapedRoom(ANY_OUTER, cutout))
+                .withMessage(CUTOUT_TOO_BIG_MSG);
+    }
+
+    @Test
+    void estimate_GivenLShapedRoom_ShouldRoundGallonsUp() {
+        // outer 20*15 = 300 ; cutout 5*4 = 20 ; area = 280 ; 280/350 -> ceil 1
+        PaintEstimate estimate = PaintEstimator.estimate(new LShapedRoom(ANY_OUTER, ANY_CUTOUT));
+
+        assertThat(estimate.area()).isEqualTo("280");
+        assertThat(estimate.gallons()).isEqualTo(BigInteger.ONE);
+    }
+
+    @Test
+    void estimate_GivenLargeLShapedRoom_ShouldRequireMultipleGallons() {
+        // outer 50*30 = 1500 ; cutout 10*10 = 100 ; area = 1400 ; 1400/350 = 4 exact
+        RoomDimensions room = new LShapedRoom(
+                new RectangularRoom(RoomDimension.of("50"), RoomDimension.of("30")),
+                new RectangularRoom(RoomDimension.of("10"), RoomDimension.of("10")));
+
+        PaintEstimate estimate = PaintEstimator.estimate(room);
+
+        assertThat(estimate.area()).isEqualTo("1400");
+        assertThat(estimate.gallons()).isEqualTo(BigInteger.valueOf(4));
+    }
+}

paint-calculator/src/test/java/dev/delivercraft/paint/PaintCalculatorTest.java

@@ -36,10 +36,20 @@ class PaintCalculatorTest {
 
     private static final String WIDTH_PROMPT = "What is the width of the room in feet? ";
 
-    private static final String SHAPE_MENU = "Select room shape: 1) Rectangular  2) Round";
+    private static final String SHAPE_MENU = "Select room shape: 1) Rectangular  2) Round  3) L-shaped";
 
     private static final String RADIUS_PROMPT = "What is the radius of the room in feet? ";
 
+    private static final String OUTER_LENGTH_PROMPT = "What is the length of the outer rectangle in feet? ";
+
+    private static final String OUTER_WIDTH_PROMPT = "What is the width of the outer rectangle in feet? ";
+
+    private static final String CUTOUT_LENGTH_PROMPT = "What is the length of the cut-out in feet? ";
+
+    private static final String CUTOUT_WIDTH_PROMPT = "What is the width of the cut-out in feet? ";
+
+    private static final String L_SHAPED_SHAPE = "3";
+
     private static final String RECTANGULAR_SHAPE = "1";
 
     private static final String TEN_FEET = "10";
@@ -142,7 +152,7 @@ private static Stream<Arguments> invalidInputFlows() {
     void calculatePaint_GivenPlainDecimalInput_ShouldAcceptInput(String input) {
         LineWriter lineWriter = new CapturingLineWriter();
         PaintCalculator calculator = new PaintCalculator(
-                new StubLineReader(RECTANGULAR_SHAPE, input, "20"), lineWriter);
+                new StubLineReader(RECTANGULAR_SHAPE, input, VALID_WIDTH), lineWriter);
 
         calculator.calculatePaint();
 
@@ -162,15 +172,72 @@ void calculatePaint_GivenRoundRoomSelection_ShouldCalculateCorrectArea() {
                 + System.lineSeparator());
     }
 
+    @Test
+    void calculatePaint_GivenLShapedRoomSelection_ShouldCalculateCorrectArea() {
+        // outer 20*15 = 300 ; cutout 5*4 = 20 ; area = 280 ; 280/350 -> ceil 1
+        LineWriter lineWriter = new CapturingLineWriter();
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(L_SHAPED_SHAPE, VALID_WIDTH, "15", "5", "4"), lineWriter);
+
+        calculator.calculatePaint();
+
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator()
+                + OUTER_LENGTH_PROMPT + OUTER_WIDTH_PROMPT
+                + CUTOUT_LENGTH_PROMPT + CUTOUT_WIDTH_PROMPT
+                + "You will need to purchase 1 gallon of paint to cover 280 square feet."
+                + System.lineSeparator());
+    }
+
+    @Test
+    void calculatePaint_GivenLShapedRoomWithInvalidOuterLength_ShouldFailFastBeforePromptingWidth() {
+        LineWriter lineWriter = new CapturingLineWriter();
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(L_SHAPED_SHAPE, NON_NUMERIC_INPUT), lineWriter);
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(calculator::calculatePaint);
+
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator() + OUTER_LENGTH_PROMPT);
+    }
+
+    @Test
+    void calculatePaint_GivenLShapedRoomWithInvalidCutoutWidth_ShouldFailFastAfterAllPriorPrompts() {
+        LineWriter lineWriter = new CapturingLineWriter();
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(L_SHAPED_SHAPE, VALID_WIDTH, "15", "5", NEGATIVE_INPUT), lineWriter);
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(calculator::calculatePaint);
+
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator()
+                + OUTER_LENGTH_PROMPT + OUTER_WIDTH_PROMPT
+                + CUTOUT_LENGTH_PROMPT + CUTOUT_WIDTH_PROMPT);
+    }
+
+    @Test
+    void calculatePaint_GivenCutoutNotSmallerThanOuter_ShouldThrowWithDescriptiveMessage() {
+        LineWriter lineWriter = new CapturingLineWriter();
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(L_SHAPED_SHAPE, VALID_WIDTH, "15", VALID_WIDTH, "4"), lineWriter);
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(calculator::calculatePaint)
+                .withMessage("Cut-out must be smaller than the outer rectangle on both length and width.");
+
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator()
+                + OUTER_LENGTH_PROMPT + OUTER_WIDTH_PROMPT
+                + CUTOUT_LENGTH_PROMPT + CUTOUT_WIDTH_PROMPT);
+    }
+
     @ParameterizedTest
-    @ValueSource(strings = {"3", "0", "abc", "", "  "})
+    @ValueSource(strings = {"4", "0", "abc", "", "  "})
     void calculatePaint_GivenInvalidShapeInput_ShouldThrowIllegalArgumentException(String invalidInput) {
         LineWriter lineWriter = new CapturingLineWriter();
         PaintCalculator calculator = new PaintCalculator(new StubLineReader(invalidInput), lineWriter);
 
         assertThatIllegalArgumentException()
                 .isThrownBy(calculator::calculatePaint)
-                .withMessage("Please enter 1 or 2");
+                .withMessage("Please enter 1, 2 or 3");
         assertThat(lineWriter.toString()).isEqualTo(SHAPE_MENU + System.lineSeparator());
     }
 
@@ -181,7 +248,7 @@ void calculatePaint_GivenNullShapeInput_ShouldThrowIllegalArgumentException() {
 
         assertThatIllegalArgumentException()
                 .isThrownBy(calculator::calculatePaint)
-                .withMessage("Please enter 1 or 2");
+                .withMessage("Please enter 1, 2 or 3");
         assertThat(lineWriter.toString()).isEqualTo(SHAPE_MENU + System.lineSeparator());
     }
 }