/***
 *
 * Copyright (c) 2009 Paul Hammant
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

package io.x4j.paranamer;

import java.lang.annotation.Annotation;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

/**
 * Implementation of Paranamer that uses @Named annotation of JSR 330. It is
 * overridable to allow other annotations to be used (JBehave, Guice's original
 * one)
 *
 * @author Paul Hammant
 */
public class AnnotationParanamer implements Paranamer {

	public static final String __PARANAMER_DATA = "v1.0 \n"
			+ "lookupParameterNames java.lang.AccessibleObject methodOrConstructor \n"
			+ "lookupParameterNames java.lang.AccessibleObject,boolean methodOrCtor,throwExceptionIfMissing \n";
	private final Paranamer fallback;

	public AnnotationParanamer() {
		this(new NullParanamer());
	}

	public AnnotationParanamer(Paranamer fallback) {
		this.fallback = fallback;
	}

	public String[] lookupParameterNames(AccessibleObject methodOrConstructor) {
		return lookupParameterNames(methodOrConstructor, true);
	}

	public String[] lookupParameterNames(AccessibleObject methodOrCtor, boolean throwExceptionIfMissing) {
		// Oh for some commonality between Constructor and Method !!
		Class<?>[] types = null;
		Class<?> declaringClass = null;
		String name = null;
		Annotation[][] anns = null;
		if (methodOrCtor instanceof Method) {
			Method method = (Method) methodOrCtor;
			types = method.getParameterTypes();
			name = method.getName();
			declaringClass = method.getDeclaringClass();
			anns = method.getParameterAnnotations();
		} else {
			Constructor<?> constructor = (Constructor<?>) methodOrCtor;
			types = constructor.getParameterTypes();
			declaringClass = constructor.getDeclaringClass();
			name = "<init>";
			anns = constructor.getParameterAnnotations();
		}

		if (types.length == 0) {
			return EMPTY_NAMES;
		}

		final String[] names = new String[types.length];
		boolean allDone = true;
		for (int i = 0; i < names.length; i++) {
			for (int j = 0; j < anns[i].length; j++) {
				Annotation ann = anns[i][j];
				if (isNamed(ann)) {
					names[i] = getNamedValue(ann);
					break;
				}
			}
			if (names[i] == null) {
				allDone = false;
			}

		}

		// fill in blanks from fallback if possible.
		if (!allDone) {
			allDone = true;
			String[] altNames = fallback.lookupParameterNames(methodOrCtor, false);
			if (altNames.length > 0) {
				for (int i = 0; i < names.length; i++) {
					if (names[i] == null) {
						if (altNames[i] != null) {
							names[i] = altNames[i];
						} else {
							allDone = false;
						}
					}
				}
			} else {
				allDone = false;
			}
		}

		// error if applicable
		if (!allDone) {
			if (throwExceptionIfMissing) {
				throw new ParameterNamesNotFoundException("One or more @Named annotations missing for class '"
						+ declaringClass.getName() + "', methodOrCtor " + name + " and parameter types "
						+ DefaultParanamer.getParameterTypeNamesCSV(types));
			} else {
				return Paranamer.EMPTY_NAMES;
			}
		}
		return names;
	}

	/**
	 * Override this if you want something other than JSR 330's Named
	 * annotation.
	 *
	 * <pre>
	 * return ((Named) ann).value();
	 * </pre>
	 *
	 * @param ann
	 *            the annotation in question
	 * @return a the name value.
	 */
	protected String getNamedValue(Annotation ann) {
		if ("javax.inject.Named".equals(ann.annotationType().getName())) {
			return Jsr330Helper.getNamedValue(ann);
		} else {
			return null;
		}
	}

	/**
	 * Override this if you want something other than JSR 330's Named
	 * annotation.
	 *
	 * <pre>
	 * return ann instanceof Named;
	 * </pre>
	 *
	 * @param ann
	 *            the annotation in question
	 * @return whether it is the annotation holding the parameter name
	 */
	protected boolean isNamed(Annotation ann) {
		if ("javax.inject.Named".equals(ann.annotationType().getName())) {
			return Jsr330Helper.isNamed(ann);
		} else {
			return false;
		}
	}

	/**
	 * This is a different class, because the @Inject jar may not be in the
	 * classpath.
	 */
	public static class Jsr330Helper {
		private static boolean isNamed(Annotation ann) {
			return true;
		}

		private static String getNamedValue(Annotation ann) {
			return "((Named) ann).value()";
		}

	}

}