Mulling over the generic comparator issue

7 files changed, 201 insertions, 90 deletions

diff --git a/src/eu/equalparts/cardbase/Cardbase.java b/src/eu/equalparts/cardbase/Cardbase.java
index 211f865..9245870 100644
--- a/src/eu/equalparts/cardbase/Cardbase.java
+++ b/src/eu/equalparts/cardbase/Cardbase.java
@@ -2,9 +2,11 @@ package eu.equalparts.cardbase;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.fasterxml.jackson.core.JsonGenerationException;
@@ -12,11 +14,12 @@ import com.fasterxml.jackson.core.JsonParseException;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.JsonMappingException;
 
+import eu.equalparts.cardbase.comparator.CardComparator;
 import eu.equalparts.cardbase.data.Card;
 import eu.equalparts.cardbase.utils.JSON;
 
 /**
- * Provides a variety of utility methods to interact with the loaded cardbase.
+ * Provides a variety of utility methods to interact with an optionally loaded cardbase.
  * 
  * @author Eduardo Pedroni
  */
@@ -32,7 +35,6 @@ public class Cardbase {
 	 * information to be printed to the console.
 	 */
 	public static final boolean DEBUG = System.getenv("CB_DEBUG") != null; 
-	
 	/**
 	 * Used in the hash generation.
 	 */
@@ -134,12 +136,22 @@ public class Cardbase {
 	}
 	
 	/**
+	 * @param field the name of the field by which to sort.
+	 * @return an unmodifiable collection representing the cardbase sorted in the required order.
+	 * @throws NoSuchFieldException if the field provided is invalid.
+	 */
+	public Collection<Card> sort(String field) throws NoSuchFieldException {
+		List<Card> sortedCards = new ArrayList<Card>(cards.values());
+		sortedCards.sort(new CardComparator(Card.class.getDeclaredField(field)));
+		return Collections.unmodifiableCollection(sortedCards);
+	}
+	
+	/**
 	 * Returns a card from the cardbase by set code and number.
 	 * If no such card is in the cardbase, returns null.
 	 * 
 	 * @param setCode the set to which the requested card belongs.
 	 * @param number the requested card's set number.
-	 * key
 	 * @return the requested {@code Card} or null if no card is found.
 	 */
 	public Card getCard(String setCode, String number) {
@@ -152,7 +164,6 @@ public class Cardbase {
 	 * If no such card is in the cardbase, returns null.
 	 * 
 	 * @param hash the Cardbase hash of the requested card.
-	 * 
 	 * @return the requested {@code Card} or null if no card is found.
 	 */
 	public Card getCardFromHash(String hash) {
diff --git a/src/eu/equalparts/cardbase/cli/CardbaseCLI.java b/src/eu/equalparts/cardbase/cli/CardbaseCLI.java
index 7a2e581..6a7f013 100644
--- a/src/eu/equalparts/cardbase/cli/CardbaseCLI.java
+++ b/src/eu/equalparts/cardbase/cli/CardbaseCLI.java
@@ -96,15 +96,15 @@ public class CardbaseCLI {
 	 * 
 	 * @param args a list of arguments. Only the first argument is used, as a cardbase JSON.
 	 */
-	private CardbaseCLI(String... args) {
+	public CardbaseCLI(String... args) {
 		System.out.println("Welcome to Cardbase CLI!");
 
 		// set debug flag if we are debugging
 		if (Cardbase.DEBUG) System.out.println("Debug mode is on.");
 
-		// make the CardbaseManager
-		if (args.length > 0) {
-			File cardbaseFile = new File(args[0]);
+		// make the Cardbase
+		if (args != null && args.length > 0) {
+			cardbaseFile = new File(args[0]);
 			if (cardbaseFile.exists() && cardbaseFile.isFile() && cardbaseFile.canRead()) {
 				System.out.println("Loading cardbase from \"" + args[0] + "\".");
 				try {
@@ -124,7 +124,7 @@ public class CardbaseCLI {
 					System.exit(1);
 				}
 			} else {
-				System.out.println(args[0] + " appears to be invalid.");
+				System.out.println(args[0] + " appears to be an invalid path.");
 				System.exit(0);
 			}
 		} else {
@@ -202,7 +202,7 @@ public class CardbaseCLI {
 	public void write(String[] args) {
 		File outputFile;
 		// user-provided file overrides everything else
-		if (args.length > 0) {
+		if (args != null && args.length > 0) {
 			outputFile = new File(sanitiseFileName(args[0]));
 		} else {
 			outputFile = cardbaseFile;
@@ -261,7 +261,7 @@ public class CardbaseCLI {
 	 * @param args the code of the chosen set.
 	 */
 	public void set(String[] args) {
-		if (args.length > 0) {
+		if (args != null && args.length > 0) {
 			try {
 				selectedSet = MTGUniverse.getFullCardSet(args[0]);
 				// if the set code is invalid, null is returned
@@ -306,7 +306,7 @@ public class CardbaseCLI {
 	 */
 	public void peruse(String[] args) {
 		// if a card is specified, peruse only that
-		if (args.length > 0) {
+		if (args != null && args.length > 0) {
 			if (selectedSet != null) {
 				Card card = cardbase.getCard(selectedSet.code, args[0]);
 				if (card != null) {
@@ -352,7 +352,7 @@ public class CardbaseCLI {
 	 */
 	public void remove(String[] args) {
 		if (selectedSet != null) {
-			if (args.length > 0) {
+			if (args != null && args.length > 0) {
 				Card cardToRemove = selectedSet.getCardByNumber(args[0]);
 				if (cardToRemove != null) {
 					Integer count = 1;
@@ -391,7 +391,7 @@ public class CardbaseCLI {
 				Card cardToAdd = selectedSet.getCardByNumber(number);
 				if (cardToAdd != null) {
 					Integer count = 1;
-					if (args.length > 0 && args[0].matches("[0-9]+")) {
+					if (args != null && args.length > 0 && args[0].matches("[0-9]+")) {
 						count = Integer.valueOf(args[0]);
 						if (count <= 0) {
 							System.out.println("Can't add " + count + " cards.");
diff --git a/src/eu/equalparts/cardbase/comparator/CardComparator.java b/src/eu/equalparts/cardbase/comparator/CardComparator.java
new file mode 100644
index 0000000..78200b8
--- /dev/null
+++ b/src/eu/equalparts/cardbase/comparator/CardComparator.java
@@ -0,0 +1,126 @@
+package eu.equalparts.cardbase.comparator;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.Comparator;
+import java.util.function.BiFunction;
+
+import eu.equalparts.cardbase.Cardbase;
+import eu.equalparts.cardbase.data.Card;
+
+/**
+ * I'm new to this reflection business, so bear with me.
+ * <br><br>
+ * The idea here is to avoid having to write one class
+ * for each comparable field in {@code Card}. The program
+ * can dynamically instantiate them as cards are compared 
+ * by different fields.
+ * <br><br>
+ * This class uses reflection to determine if the specified
+ * field is comparable with itself upon construction, and throws
+ * an {@code IllegalArgumentException} if that is not the case.
+ * 
+ * @author Eduardo Pedroni
+ *
+ */
+@SuppressWarnings({"rawtypes", "unchecked"})
+public class CardComparator implements Comparator<Card> {
+
+	public enum Order {
+		NATURAL, REVERSE;
+	}
+	
+	/**
+	 * The field being compared.
+	 */
+	private Field fieldToCompare;
+	
+	private BiFunction<Comparable, Comparable, Integer> comparisonDelegate = this::defaultComparison;
+
+	/**
+	 * Creates a new comparator for the specified field only. This class
+	 * will only be constructed successfully if the field comes from
+	 * {@code Card} and can be compared to itself (i.e. implements
+	 * {@code Comparable<T>} where T is its own type.
+	 * <br>
+	 * For reference, {@code String} and {@code Integer} are both self comparable.
+	 * 
+	 * @param fieldToCompare the field this comparator will use to compare cards, as declared in {@code Card}.
+	 */
+	public CardComparator(Field fieldToCompare) {
+		if (fieldToCompare.getDeclaringClass().equals(Card.class) &&
+				isSelfComparable(fieldToCompare.getType())) {
+
+			this.fieldToCompare = fieldToCompare;
+			
+			// if annotated with a special comparator, set the comparison delegate here
+			this.comparisonDelegate = ComparatorDelegates::compareManaCost;
+			
+		} else {
+			System.out.println(fieldToCompare.isAccessible());
+			System.out.println(fieldToCompare.getDeclaringClass().equals(Card.class));
+			System.out.println(isSelfComparable(fieldToCompare.getType()));
+			throw new IllegalArgumentException("The field provided is not valid.");
+		}
+	}
+
+	@Override
+	public int compare(Card o1, Card o2) {
+		/*
+		 * we've already checked that the field is self comparable,
+		 * so we are now free to cast to whatever type it is and compare.
+		 */
+		try {
+			Comparable field1 = (Comparable) fieldToCompare.get(o1);
+			Comparable field2 = (Comparable) fieldToCompare.get(o2);
+			
+			return comparisonDelegate.apply(field1, field2);
+		} catch (IllegalArgumentException e) {
+			System.out.println("Error: class Card does not define field" + fieldToCompare.getName() + ".");
+			if (Cardbase.DEBUG) e.printStackTrace();
+		} catch (IllegalAccessException e) {
+			System.out.println("Error: field " + fieldToCompare.getName() + " in Card is not visible.");
+			if (Cardbase.DEBUG) e.printStackTrace();
+		}
+		
+		// fallback, this shouldn't happen
+		return 0;
+	}
+	
+	/**
+	 * The standard comparison operation, which uses the field's own {@code compareTo()}
+	 * method.
+	 * 
+	 * @param field1 the first object to be compared.
+     * @param field2 the second object to be compared.
+     * @return a negative integer, zero, or a positive integer as the
+     *         first argument is less than, equal to, or greater than the
+     *         second.
+	 */
+	private int defaultComparison(Comparable field1, Comparable field2) {
+		return field1.compareTo(field2);
+	}
+
+	/**
+	 * Use reflection to determine if the specified class can be compared with itself.
+	 * 
+	 * @param type the type to analyse.
+	 * @return true if the type can be compared to itself using {@code compareTo()}, false otherwise.
+	 */
+	private boolean isSelfComparable(Class<?> type) {
+
+		// go through all interfaces implemented by this class
+		for (Type implementedInterface : type.getGenericInterfaces()) {
+			// check if any parameterised interface found is "Comparable"
+			if (implementedInterface instanceof ParameterizedType) {
+				ParameterizedType genericInterface = (ParameterizedType) implementedInterface;
+				if (genericInterface.getRawType().equals(Comparable.class)) {
+					// check that the type argument of comparable is the same as the field type itself
+					return genericInterface.getActualTypeArguments()[0].equals(type);
+				}
+			}
+		}
+		return false;
+	}
+}
diff --git a/src/eu/equalparts/cardbase/comparator/ComparatorDelegates.java b/src/eu/equalparts/cardbase/comparator/ComparatorDelegates.java
new file mode 100644
index 0000000..5736381
--- /dev/null
+++ b/src/eu/equalparts/cardbase/comparator/ComparatorDelegates.java
@@ -0,0 +1,39 @@
+package eu.equalparts.cardbase.comparator;
+
+
+abstract class ComparatorDelegates {
+
+	private ComparatorDelegates() {}
+	
+	public static Integer compareManaCost(Comparable<String> field1, Comparable<String> field2) {
+		// avoid casting syntax nightmare
+		String mc1 = (String) field1, mc2 = (String) field2;
+		
+		// first by number of colours
+		int mc1count = 0, mc2count = 0;
+		if (mc1.contains("W")) mc1count++;
+		if (mc1.contains("U")) mc1count++;
+		if (mc1.contains("B")) mc1count++;
+		if (mc1.contains("R")) mc1count++;
+		if (mc1.contains("G")) mc1count++;
+		
+		if (mc2.contains("W")) mc2count++;
+		if (mc2.contains("U")) mc2count++;
+		if (mc2.contains("B")) mc2count++;
+		if (mc2.contains("R")) mc2count++;
+		if (mc2.contains("G")) mc2count++;
+		
+		if (mc1count != mc2count)
+			return (mc1count < mc2count) ? -1 : ((mc1count == mc2count) ? 0 : 1);
+		
+		// next by colour wheel
+		
+		return 0;
+	}
+	
+}
+/*
+ * first by number of colours
+ * next by colour wheel: white > blue > black > red > green
+ * next by cmc
+ */
\ No newline at end of file
diff --git a/src/eu/equalparts/cardbase/comparator/SpecialFields.java b/src/eu/equalparts/cardbase/comparator/SpecialFields.java
new file mode 100644
index 0000000..8ecc82c
--- /dev/null
+++ b/src/eu/equalparts/cardbase/comparator/SpecialFields.java
@@ -0,0 +1,8 @@
+package eu.equalparts.cardbase.comparator;
+
+
+public class SpecialFields {
+
+	public @interface ManaCost {}
+	
+}
diff --git a/src/eu/equalparts/cardbase/comparators/CardComparators.java b/src/eu/equalparts/cardbase/comparators/CardComparators.java
deleted file mode 100644
index 99f7ded..0000000
--- a/src/eu/equalparts/cardbase/comparators/CardComparators.java
+++ /dev/null
@@ -1,76 +0,0 @@
-package eu.equalparts.cardbase.comparators;
-
-import java.util.Comparator;
-
-import eu.equalparts.cardbase.data.Card;
-
-public final class CardComparators {
-
-	private CardComparators() {}
-
-	public enum Order {
-		NATURAL, REVERSE;
-	}
-
-	public static class NameComparator implements Comparator<Card> {
-
-		private Order order = Order.NATURAL;
-
-		public NameComparator() {}
-
-		public NameComparator(Order order) {
-			this.order = order;
-		}
-
-		@Override
-		public int compare(Card o1, Card o2) {
-			if (order == Order.NATURAL) {
-				return o1.name.compareTo(o2.name);
-			} else {
-				return o2.name.compareTo(o1.name);
-			}
-
-		}
-	}
-
-	public static class LayoutComparator implements Comparator<Card> {
-
-		private Order order = Order.NATURAL;
-
-		public LayoutComparator() {}
-
-		public LayoutComparator(Order order) {
-			this.order = order;
-		}
-
-		@Override
-		public int compare(Card o1, Card o2) {
-			if (order == Order.NATURAL) {
-				return o1.layout.compareTo(o2.layout);
-			} else {
-				return o2.layout.compareTo(o1.layout);
-			}
-		}
-	}
-
-	public static class ManaCostComparator implements Comparator<Card> {
-
-		private Order order = Order.NATURAL;
-
-		public ManaCostComparator() {}
-
-		public ManaCostComparator(Order order) {
-			this.order = order;
-		}
-
-		@Override
-		public int compare(Card o1, Card o2) {
-			if (order == Order.NATURAL) {
-				return o1.manaCost.compareTo(o2.manaCost);
-			} else {
-				return o2.manaCost.compareTo(o1.manaCost);
-			}
-		}
-	}
-
-}
diff --git a/src/eu/equalparts/cardbase/data/Card.java b/src/eu/equalparts/cardbase/data/Card.java
index 2810564..7202660 100644
--- a/src/eu/equalparts/cardbase/data/Card.java
+++ b/src/eu/equalparts/cardbase/data/Card.java
@@ -1,9 +1,12 @@
 package eu.equalparts.cardbase.data;
 
+import eu.equalparts.cardbase.comparator.SpecialFields.ManaCost;
+
 public class Card {
 	
 	public String name;
 	public String layout;
+	@ManaCost
 	public String manaCost;
 	public Integer cmc;
 	public String type;