[Bleeding] Added Conversations API. Addresses BUKKIT-864

By: rmichela <deltahat@gmail.com>

paper-api/src/main/java/org/bukkit/conversations/NumericPrompt.java

@@ -0,0 +1,75 @@
+package org.bukkit.conversations;
+
+import org.apache.commons.lang.math.NumberUtils;
+
+/**
+ * NumericPrompt is the base class for any prompt that requires a {@link Number} response from the user.
+ */
+public abstract class NumericPrompt extends ValidatingPrompt{
+    public NumericPrompt() {
+        super();
+    }
+
+    @Override
+    protected boolean isInputValid(ConversationContext context, String input) {
+        return NumberUtils.isNumber(input) && isNumberValid(context, NumberUtils.createNumber(input));
+    }
+
+    /**
+     * Override this method to do further validation on the numeric player input after the input has been determined
+     * to actually be a number.
+     * @param context Context information about the conversation.
+     * @param input The number the player provided.
+     * @return The validity of the player's input.
+     */
+    protected boolean isNumberValid(ConversationContext context, Number input) {
+        return true;
+    }
+
+    @Override
+    protected Prompt acceptValidatedInput(ConversationContext context, String input) {
+        try
+        {
+            return acceptValidatedInput(context, NumberUtils.createNumber(input));
+        } catch (NumberFormatException e) {
+            return acceptValidatedInput(context, NumberUtils.INTEGER_ZERO);
+        }
+    }
+
+    /**
+     * Override this method to perform some action with the user's integer response.
+     * @param context Context information about the conversation.
+     * @param input The user's response as a {@link Number}.
+     * @return The next {@link Prompt} in the prompt graph.
+     */
+    protected abstract Prompt acceptValidatedInput(ConversationContext context, Number input);
+
+    @Override
+    protected String getFailedValidationText(ConversationContext context, String invalidInput) {
+        if (NumberUtils.isNumber(invalidInput)) {
+            return getFailedValidationText(context, NumberUtils.createNumber(invalidInput));
+        } else {
+            return getInputNotNumericText(context, invalidInput);
+        }
+    }
+
+    /**
+     * Optionally override this method to display an additional message if the user enters an invalid number.
+     * @param context Context information about the conversation.
+     * @param invalidInput The invalid input provided by the user.
+     * @return A message explaining how to correct the input.
+     */
+    protected String getInputNotNumericText(ConversationContext context, String invalidInput) {
+        return null;
+    }
+
+    /**
+     * Optionally override this method to display an additional message if the user enters an invalid numeric input.
+     * @param context Context information about the conversation.
+     * @param invalidInput The invalid input provided by the user.
+     * @return A message explaining how to correct the input.
+     */
+    protected String getFailedValidationText(ConversationContext context, Number invalidInput) {
+        return null;
+    }
+}