Base setup for Items upgrade/degrade Quality

Java/src/main/java/com/gildedrose/enums/AttributeType.java

@@ -0,0 +1,8 @@
+package com.gildedrose.enums;
+
+public enum AttributeType {
+	
+	SELL,
+	QUALITY;
+
+}

Java/src/main/java/com/gildedrose/enums/CountType.java

@@ -0,0 +1,9 @@
+package com.gildedrose.enums;
+
+public enum CountType {
+	
+	PLUS,
+	MINUS,
+	NONE;
+
+}

Java/src/main/java/com/gildedrose/generic/EventHandler.java

@@ -0,0 +1,32 @@
+package com.gildedrose.generic;
+
+import com.gildedrose.Item;
+
+/***
+ * EventHandler helps to upgrade/degrade the items
+ * @author VIJAY G
+ *
+ */
+public interface EventHandler {
+
+	default void increaseQualityByValue(Item item, Integer value) {
+		item.quality += value;
+	}
+
+	default void decreaseQualityByValue(Item item, Integer value) {
+		item.quality -= value;
+	}
+
+	default void increaseSellInByValue(Item item, Integer value) {
+		item.sellIn += value;
+	}
+
+	default void decreaseSellInByValue(Item item, Integer value) {
+		item.sellIn -= value;
+	}
+	
+	default void neutralizeQuality(Item item) {
+		item.quality = 0;
+	}
+
+}

Java/src/main/java/com/gildedrose/generic/IItemType.java

@@ -0,0 +1,49 @@
+package com.gildedrose.generic;
+
+import com.gildedrose.Item;
+import com.gildedrose.enums.CountType;
+import com.gildedrose.enums.AttributeType;
+
+/***
+ * IItemType helps to update the quality of the item
+ * on daily basis and type of item invokes
+ * @author VIJAY G
+ *
+ * @param <T> - Type of item
+ */
+public interface IItemType<T> extends EventHandler {
+	
+	int MIN = 0;
+	int MAX = 50;
+	int INCREMENTOR = 1;
+	
+	default void updateQuality(Item item) {
+		if(isValid(item, AttributeType.QUALITY) && CountType.PLUS.equals(getT().getQualityType())) {
+			increaseQualityByValue(item, getIncrementor(item));
+		} else if(isValid(item, AttributeType.QUALITY) && CountType.MINUS.equals(getT().getQualityType())) {
+			decreaseQualityByValue(item, getIncrementor(item));
+		}
+		if(isValid(item, AttributeType.SELL) && CountType.PLUS.equals(getT().getSellType())) {
+			increaseSellInByValue(item, getIncrementor(item));
+		} else if(isValid(item, AttributeType.SELL) && CountType.MINUS.equals(getT().getSellType())) {
+			decreaseSellInByValue(item, getIncrementor(item));
+		}
+		
+		if(isNeutralized(item)) {
+			neutralizeQuality(item);
+		}
+	}
+	
+	default int getIncrementor(Item item) {
+		return INCREMENTOR;
+	}
+	
+	default boolean isNeutralized(Item item) {
+		return false;
+	}
+	
+	boolean isValid(Item item, AttributeType dayType);
+	
+	ItemType<T> getT();
+
+}

Java/src/main/java/com/gildedrose/generic/ItemType.java

@@ -0,0 +1,60 @@
+package com.gildedrose.generic;
+
+import com.gildedrose.Item;
+import com.gildedrose.enums.CountType;
+import com.gildedrose.enums.AttributeType;
+
+/***
+ * ItemType provides as a template for all types of items, 
+ * which can be appendable/detachable to the system at any time.
+ * @author VIJAY G
+ *
+ * @param <T>
+ */
+public abstract class ItemType<T> implements IItemType<T> {
+	
+	private boolean validationRequired;
+	private CountType sellType;
+	private CountType qualityType;
+	
+	protected ItemType(boolean validationRequired, CountType sellType, CountType qualityType) {
+		this.validationRequired = validationRequired;
+		this.sellType = sellType;
+		this.qualityType = qualityType;
+	}
+	
+	public boolean isValid(Item item, AttributeType dayType) {
+		boolean validationRequired = getT().isValidationRequired();
+		if(!validationRequired) {
+			return true;
+		}
+		if(dayType.equals(AttributeType.QUALITY) && CountType.PLUS.equals(getT().getQualityType())) {
+			return item.quality < MAX;
+		} else if(dayType.equals(AttributeType.QUALITY) && CountType.MINUS.equals(getT().getQualityType())) {
+			return item.quality > MIN;
+		}
+		if(dayType.equals(AttributeType.SELL) && CountType.PLUS.equals(getT().getQualityType())) {
+			return item.sellIn < MAX;
+		} else if(dayType.equals(AttributeType.SELL) && CountType.MINUS.equals(getT().getQualityType())) {
+			return item.sellIn > MIN;
+		}
+		return false;
+	}
+
+	public ItemType<T> getT() {
+		return this;
+	}
+
+	public CountType getSellType() {
+		return sellType;
+	}
+
+	public CountType getQualityType() {
+		return qualityType;
+	}
+
+	public boolean isValidationRequired() {
+		return validationRequired;
+	}
+
+}