Add support for round room paint calculations

durimkryeziu · durimkryeziu · commit 5a0989401d16 · 2026-05-24T03:57:32.000+02:00
Refactored RoomDimensions from a concrete record to a sealed interface
to support multiple room shapes. Created RectangularRoom and RoundRoom
implementations, with RoundRoom calculating area as πr². Added shape
selection menu to PaintCalculator to prompt for room type before
collecting dimensions.
diff --git a/paint-calculator/src/main/java/dev/delivercraft/paint/PaintCalculator.java b/paint-calculator/src/main/java/dev/delivercraft/paint/PaintCalculator.java
@@ -7,6 +7,14 @@
 
 final class PaintCalculator {
 
+    private static final String SHAPE_MENU = "Select room shape: 1) Rectangular  2) Round";
+
+    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 final LineReader lineReader;
 
     private final LineWriter lineWriter;
@@ -17,13 +25,30 @@ final class PaintCalculator {
     }
 
     void calculatePaint() {
-        RoomDimension length = readDimension("What is the length of the room in feet? ");
-        RoomDimension width = readDimension("What is the width of the room in feet? ");
+        this.lineWriter.writeLine(SHAPE_MENU);
+        String shapeChoice = this.lineReader.readLine();
+
+        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");
+        };
 
-        PaintEstimate estimate = PaintEstimator.estimate(new RoomDimensions(length, width));
+        PaintEstimate estimate = PaintEstimator.estimate(dimensions);
+
+        this.lineWriter.writeLine("You will need to purchase %s %s of paint to cover %s square feet.".formatted(
+                estimate.gallons(), estimate.gallonWord(), estimate.area()));
+    }
+
+    private RectangularRoom readRectangularDimensions() {
+        RoomDimension length = readDimension(LENGTH_PROMPT);
+        RoomDimension width = readDimension(WIDTH_PROMPT);
+        return new RectangularRoom(length, width);
+    }
 
-        this.lineWriter.writeLine("You will need to purchase %s %s of paint to cover %s square feet."
-                .formatted(estimate.gallons(), estimate.gallonWord(), estimate.area()));
+    private RoundRoom readRoundDimensions() {
+        RoomDimension radius = readDimension(RADIUS_PROMPT);
+        return new RoundRoom(radius);
     }
 
     private RoomDimension readDimension(String prompt) {
diff --git a/paint-calculator/src/main/java/dev/delivercraft/paint/RectangularRoom.java b/paint-calculator/src/main/java/dev/delivercraft/paint/RectangularRoom.java
@@ -0,0 +1,17 @@
+package dev.delivercraft.paint;
+
+import java.math.BigDecimal;
+import java.util.Objects;
+
+public record RectangularRoom(RoomDimension length, RoomDimension width) implements RoomDimensions {
+
+    public RectangularRoom(RoomDimension length, RoomDimension width) {
+        this.length = Objects.requireNonNull(length, "length must not be null");
+        this.width = Objects.requireNonNull(width, "width must not be null");
+    }
+
+    @Override
+    public BigDecimal area() {
+        return this.length.value().multiply(this.width.value());
+    }
+}
diff --git a/paint-calculator/src/main/java/dev/delivercraft/paint/RoomDimensions.java b/paint-calculator/src/main/java/dev/delivercraft/paint/RoomDimensions.java
@@ -1,16 +1,8 @@
 package dev.delivercraft.paint;
 
 import java.math.BigDecimal;
-import java.util.Objects;
 
-record RoomDimensions(RoomDimension length, RoomDimension width) {
+sealed interface RoomDimensions permits RectangularRoom, RoundRoom {
 
-    RoomDimensions {
-        Objects.requireNonNull(length, "length must not be null");
-        Objects.requireNonNull(width, "width must not be null");
-    }
-
-    BigDecimal area() {
-        return this.length.value().multiply(this.width.value());
-    }
+    BigDecimal area();
 }
diff --git a/paint-calculator/src/main/java/dev/delivercraft/paint/RoundRoom.java b/paint-calculator/src/main/java/dev/delivercraft/paint/RoundRoom.java
@@ -0,0 +1,20 @@
+package dev.delivercraft.paint;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.Objects;
+
+public record RoundRoom(RoomDimension radius) implements RoomDimensions {
+
+    public RoundRoom(RoomDimension radius) {
+        this.radius = Objects.requireNonNull(radius, "radius must not be null");
+    }
+
+    @Override
+    public BigDecimal area() {
+        return this.radius.value()
+                .multiply(this.radius.value())
+                .multiply(BigDecimal.valueOf(Math.PI))
+                .setScale(2, RoundingMode.HALF_UP);
+    }
+}
diff --git a/paint-calculator/src/test/java/dev/delivercraft/paint/MainTest.java b/paint-calculator/src/test/java/dev/delivercraft/paint/MainTest.java
@@ -22,7 +22,7 @@ class MainTest {
     void main_GivenValidInput_ShouldPrintPaintEstimate() throws IOException {
         InputStream originalInput = System.in;
         PrintStream originalOutput = System.out;
-        String inputText = "18%n20%n".formatted();
+        String inputText = "1%n18%n20%n".formatted();
         ByteArrayInputStream input = new ByteArrayInputStream(inputText.getBytes(StandardCharsets.UTF_8));
         ByteArrayOutputStream output = new ByteArrayOutputStream();
 
diff --git a/paint-calculator/src/test/java/dev/delivercraft/paint/PaintCalculatorTest.java b/paint-calculator/src/test/java/dev/delivercraft/paint/PaintCalculatorTest.java
@@ -1,10 +1,5 @@
 package dev.delivercraft.paint;
 
-import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
-
-import java.util.stream.Stream;
-
 import dev.delivercraft.io.CapturingLineWriter;
 import dev.delivercraft.io.LineWriter;
 import dev.delivercraft.io.StubLineReader;
@@ -14,6 +9,11 @@
 import org.junit.jupiter.params.provider.MethodSource;
 import org.junit.jupiter.params.provider.ValueSource;
 
+import java.util.stream.Stream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
 class PaintCalculatorTest {
 
     private static final String VALID_LENGTH = "18";
@@ -36,59 +36,82 @@ 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 RADIUS_PROMPT = "What is the radius of the room in feet? ";
+
+    private static final String RECTANGULAR_SHAPE = "1";
+
+    private static final String TEN_FEET = "10";
+
+    private static final String INVALID_LENGTH_OUTPUT =
+            SHAPE_MENU + System.lineSeparator() + LENGTH_PROMPT;
+
+    private static final String INVALID_WIDTH_OUTPUT =
+            SHAPE_MENU + System.lineSeparator() + LENGTH_PROMPT + WIDTH_PROMPT;
+
     @Test
     void calculatePaint_GivenExampleDimensions_ShouldDisplayGallonsAndArea() {
         LineWriter lineWriter = new CapturingLineWriter();
-        PaintCalculator calculator = new PaintCalculator(new StubLineReader(VALID_LENGTH, VALID_WIDTH), lineWriter);
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(RECTANGULAR_SHAPE, VALID_LENGTH, VALID_WIDTH), lineWriter);
 
         calculator.calculatePaint();
 
-        assertThat(lineWriter).hasToString(LENGTH_PROMPT + WIDTH_PROMPT
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator()
+                + LENGTH_PROMPT + WIDTH_PROMPT
                 + "You will need to purchase 2 gallons of paint to cover 360 square feet."
                 + System.lineSeparator());
     }
 
     @Test
     void calculatePaint_GivenSmallCeiling_ShouldUseSingularGallon() {
         LineWriter lineWriter = new CapturingLineWriter();
-        PaintCalculator calculator = new PaintCalculator(new StubLineReader("10", "10"), lineWriter);
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(RECTANGULAR_SHAPE, TEN_FEET, TEN_FEET), lineWriter);
 
         calculator.calculatePaint();
 
-        assertThat(lineWriter).hasToString(LENGTH_PROMPT + WIDTH_PROMPT
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator()
+                + LENGTH_PROMPT + WIDTH_PROMPT
                 + "You will need to purchase 1 gallon of paint to cover 100 square feet."
                 + System.lineSeparator());
     }
 
     @Test
     void calculatePaint_GivenFractionalDimensions_ShouldDisplayExactDecimalArea() {
         LineWriter lineWriter = new CapturingLineWriter();
-        PaintCalculator calculator = new PaintCalculator(new StubLineReader("10.5", "10.1"), lineWriter);
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(RECTANGULAR_SHAPE, "10.5", "10.1"), lineWriter);
 
         calculator.calculatePaint();
 
-        assertThat(lineWriter).hasToString(LENGTH_PROMPT + WIDTH_PROMPT
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator()
+                + LENGTH_PROMPT + WIDTH_PROMPT
                 + "You will need to purchase 1 gallon of paint to cover 106.05 square feet."
                 + System.lineSeparator());
     }
 
     @Test
     void calculatePaint_GivenAreaJustOverOneGallon_ShouldRoundGallonsUp() {
         LineWriter lineWriter = new CapturingLineWriter();
-        PaintCalculator calculator = new PaintCalculator(new StubLineReader("35.1", "10"), lineWriter);
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(RECTANGULAR_SHAPE, "35.1", "10"), lineWriter);
 
         calculator.calculatePaint();
 
-        assertThat(lineWriter).hasToString(LENGTH_PROMPT + WIDTH_PROMPT
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator()
+                + LENGTH_PROMPT + WIDTH_PROMPT
                 + "You will need to purchase 2 gallons of paint to cover 351 square feet."
                 + System.lineSeparator());
     }
 
     @ParameterizedTest
     @MethodSource("invalidInputFlows")
-    void calculatePaint_GivenInvalidInput_ShouldFailFast(String length, String width, String expectedOutput) {
+    void calculatePaint_GivenInvalidInput_ShouldFailFast(String shape, String length, String width,
+                                                         String expectedOutput) {
         LineWriter lineWriter = new CapturingLineWriter();
-        PaintCalculator calculator = new PaintCalculator(new StubLineReader(length, width), lineWriter);
+        PaintCalculator calculator = new PaintCalculator(new StubLineReader(shape, length, width), lineWriter);
 
         assertThatIllegalArgumentException()
                 .isThrownBy(calculator::calculatePaint);
@@ -98,30 +121,67 @@ void calculatePaint_GivenInvalidInput_ShouldFailFast(String length, String width
 
     private static Stream<Arguments> invalidInputFlows() {
         return Stream.of(
-                Arguments.of(EMPTY_INPUT, VALID_WIDTH, LENGTH_PROMPT),
-                Arguments.of(null, VALID_WIDTH, LENGTH_PROMPT),
-                Arguments.of(NON_NUMERIC_INPUT, VALID_WIDTH, LENGTH_PROMPT),
-                Arguments.of(ZERO_INPUT, VALID_WIDTH, LENGTH_PROMPT),
-                Arguments.of(NEGATIVE_INPUT, VALID_WIDTH, LENGTH_PROMPT),
-                Arguments.of(SCIENTIFIC_INPUT, VALID_WIDTH, LENGTH_PROMPT),
-                Arguments.of(SHORT_DECIMAL, VALID_WIDTH, LENGTH_PROMPT),
-                Arguments.of(VALID_LENGTH, EMPTY_INPUT, LENGTH_PROMPT + WIDTH_PROMPT),
-                Arguments.of(VALID_LENGTH, null, LENGTH_PROMPT + WIDTH_PROMPT),
-                Arguments.of(VALID_LENGTH, NON_NUMERIC_INPUT, LENGTH_PROMPT + WIDTH_PROMPT),
-                Arguments.of(VALID_LENGTH, ZERO_INPUT, LENGTH_PROMPT + WIDTH_PROMPT),
-                Arguments.of(VALID_LENGTH, NEGATIVE_INPUT, LENGTH_PROMPT + WIDTH_PROMPT),
-                Arguments.of(VALID_LENGTH, SCIENTIFIC_INPUT, LENGTH_PROMPT + WIDTH_PROMPT),
-                Arguments.of(VALID_LENGTH, SHORT_DECIMAL, LENGTH_PROMPT + WIDTH_PROMPT));
+                Arguments.of(RECTANGULAR_SHAPE, EMPTY_INPUT, VALID_WIDTH, INVALID_LENGTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, null, VALID_WIDTH, INVALID_LENGTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, NON_NUMERIC_INPUT, VALID_WIDTH, INVALID_LENGTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, ZERO_INPUT, VALID_WIDTH, INVALID_LENGTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, NEGATIVE_INPUT, VALID_WIDTH, INVALID_LENGTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, SCIENTIFIC_INPUT, VALID_WIDTH, INVALID_LENGTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, SHORT_DECIMAL, VALID_WIDTH, INVALID_LENGTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, VALID_LENGTH, EMPTY_INPUT, INVALID_WIDTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, VALID_LENGTH, null, INVALID_WIDTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, VALID_LENGTH, NON_NUMERIC_INPUT, INVALID_WIDTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, VALID_LENGTH, ZERO_INPUT, INVALID_WIDTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, VALID_LENGTH, NEGATIVE_INPUT, INVALID_WIDTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, VALID_LENGTH, SCIENTIFIC_INPUT, INVALID_WIDTH_OUTPUT),
+                Arguments.of(RECTANGULAR_SHAPE, VALID_LENGTH, SHORT_DECIMAL, INVALID_WIDTH_OUTPUT));
     }
 
     @ParameterizedTest
     @ValueSource(strings = {"18", " 18 ", "18.0", "0.5"})
     void calculatePaint_GivenPlainDecimalInput_ShouldAcceptInput(String input) {
         LineWriter lineWriter = new CapturingLineWriter();
-        PaintCalculator calculator = new PaintCalculator(new StubLineReader(input, "20"), lineWriter);
+        PaintCalculator calculator = new PaintCalculator(
+                new StubLineReader(RECTANGULAR_SHAPE, input, "20"), lineWriter);
 
         calculator.calculatePaint();
 
         assertThat(lineWriter.toString()).contains("You will need to purchase");
     }
+
+    @Test
+    void calculatePaint_GivenRoundRoomSelection_ShouldCalculateCorrectArea() {
+        LineWriter lineWriter = new CapturingLineWriter();
+        PaintCalculator calculator = new PaintCalculator(new StubLineReader("2", "10"), lineWriter);
+
+        calculator.calculatePaint();
+
+        assertThat(lineWriter).hasToString(SHAPE_MENU + System.lineSeparator()
+                + RADIUS_PROMPT
+                + "You will need to purchase 1 gallon of paint to cover 314.16 square feet."
+                + System.lineSeparator());
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"3", "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");
+        assertThat(lineWriter.toString()).isEqualTo(SHAPE_MENU + System.lineSeparator());
+    }
+
+    @Test
+    void calculatePaint_GivenNullShapeInput_ShouldThrowIllegalArgumentException() {
+        LineWriter lineWriter = new CapturingLineWriter();
+        PaintCalculator calculator = new PaintCalculator(() -> null, lineWriter);
+
+        assertThatIllegalArgumentException()
+                .isThrownBy(calculator::calculatePaint)
+                .withMessage("Please enter 1 or 2");
+        assertThat(lineWriter.toString()).isEqualTo(SHAPE_MENU + System.lineSeparator());
+    }
 }
diff --git a/paint-calculator/src/test/java/dev/delivercraft/paint/PaintEstimatorTest.java b/paint-calculator/src/test/java/dev/delivercraft/paint/PaintEstimatorTest.java
@@ -10,7 +10,7 @@ class PaintEstimatorTest {
 
     @Test
     void estimate_GivenExampleDimensions_ShouldCalculateAreaAndGallons() {
-        RoomDimensions dimensions = new RoomDimensions(
+        RoomDimensions dimensions = new RectangularRoom(
                 RoomDimension.of("18"),
                 RoomDimension.of("20"));
 
@@ -22,7 +22,7 @@ void estimate_GivenExampleDimensions_ShouldCalculateAreaAndGallons() {
 
     @Test
     void estimate_GivenAreaJustOverOneGallon_ShouldRoundGallonsUp() {
-        RoomDimensions dimensions = new RoomDimensions(
+        RoomDimensions dimensions = new RectangularRoom(
                 RoomDimension.of("35.1"),
                 RoomDimension.of("10"));
 
diff --git a/paint-calculator/src/test/java/dev/delivercraft/paint/RoundRoomTest.java b/paint-calculator/src/test/java/dev/delivercraft/paint/RoundRoomTest.java
