stub/src/main/java/org/apache/commons/proxy2/stub/StubConfigurer.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.proxy2.stub;

import org.apache.commons.lang3.reflect.TypeUtils;
import org.apache.commons.proxy2.ObjectProvider;
import org.apache.commons.proxy2.provider.ConstantProvider;

/**
 * Configuration mechanism for a stub.  Implements {@link StubConfiguration} for maximum fluency.
 * A {@link StubConfigurer} needs to know the type of stub object to which it applies.
 * Any useful runtime subclass should have the type variable non-generically
 * declared (else its {@link #configure(Object)} implementation wouldn't be worth much),
 * so usually the no-arg constructor can be used.  Example:
 * <code><pre>
 * new StubConfigurer&lt;java.util.Iterable&lt;String&gt;&gt;() {
 *     protected void configure(Iterable&lt;String&gt; stub) {
 *         when(stub.iterator()).thenReturn(Arrays.asList("foo", "bar", "baz").iterator());
 *     }
 * }
 * </pre></code>
 *
 * @param <T>
 * @author Matt Benson
 */
//TODO add argument matcher capturing
public abstract class StubConfigurer<T> implements StubConfiguration {
    private Class<T> stubType;

    /** Stateful reference to the StubInterceptor currently being configured */
    private StubInterceptor stubInterceptor;

    /**
     * Create a new StubConfigurer instance.  This constructor should only be called
     * by classes that explicitly assign the T type parameter in the class definition.
     * This should include basically any runtime-usable subclass.
     */
    protected StubConfigurer() {
        this(null);
    }

    /**
     * Create a new StubConfigurer instance.
     * @param stubType
     */
    protected StubConfigurer(Class<T> stubType) {
        super();
        if (stubType != null) {
            this.stubType = stubType;
            return;
        }
        @SuppressWarnings("unchecked")
        final Class<T> resolvedVariable = (Class<T>) TypeUtils.getRawType(
                StubConfigurer.class.getTypeParameters()[0], getClass());
        if (resolvedVariable == null) {
            throw new IllegalArgumentException(
                    "stubType was not specified and could not be calculated for "
                            + getClass());
        }
        this.stubType = resolvedVariable;
    }

    /**
     * Get the stubType.
     * @return Class<T>
     */
    public Class<? extends T> getStubType() {
        return stubType;
    }

    /**
     * {@inheritDoc}
     */
    public <RT> org.apache.commons.proxy2.stub.StubConfiguration.When<RT> when(
            RT call) {
        return new When<RT>() {

            public StubConfiguration thenReturn(RT result) {
                requireStubInterceptor().addAnswer(result);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<? extends RT> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenBooleanArray when(
            boolean[] call) {
        return new WhenBooleanArray() {

            public StubConfiguration thenReturn(boolean... b) {
                requireStubInterceptor().addAnswer(b);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<boolean[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenByteArray when(
            byte[] call) {
        return new WhenByteArray() {

            public StubConfiguration thenReturn(byte... b) {
                requireStubInterceptor().addAnswer(b);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<byte[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenShortArray when(
            short[] call) {
        return new WhenShortArray() {

            public StubConfiguration thenReturn(short... s) {
                requireStubInterceptor().addAnswer(s);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<short[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenIntArray when(
            int[] call) {
        return new WhenIntArray() {

            public StubConfiguration thenReturn(int... i) {
                requireStubInterceptor().addAnswer(i);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<int[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenCharArray when(
            char[] call) {
        return new WhenCharArray() {

            public StubConfiguration thenReturn(char... c) {
                requireStubInterceptor().addAnswer(c);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<char[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenLongArray when(
            long[] call) {
        return new WhenLongArray() {

            public StubConfiguration thenReturn(long... l) {
                requireStubInterceptor().addAnswer(l);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<long[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenFloatArray when(
            float[] call) {
        return new WhenFloatArray() {

            public StubConfiguration thenReturn(float... f) {
                requireStubInterceptor().addAnswer(f);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<float[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenDoubleArray when(
            double[] call) {
        return new WhenDoubleArray() {

            public StubConfiguration thenReturn(double... d) {
                requireStubInterceptor().addAnswer(d);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<double[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public <C> org.apache.commons.proxy2.stub.StubConfiguration.WhenObjectArray<C> when(
            C[] call) {
        return new WhenObjectArray<C>() {

            public StubConfiguration thenReturn(C... c) {
                requireStubInterceptor().addAnswer(c);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<C[]> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public org.apache.commons.proxy2.stub.StubConfiguration.WhenClass when(
            Class<?> call) {
        return new WhenClass() {

            public StubConfiguration thenReturn(Class<?> c) {
                requireStubInterceptor().addAnswer(c);
                return StubConfigurer.this;
            }

            public StubConfiguration thenAnswer(
                    ObjectProvider<Class<?>> objectProvider) {
                requireStubInterceptor().addAnswer(objectProvider);
                return StubConfigurer.this;
            }

            public StubConfiguration thenThrow(Throwable t) {
                return thenThrow(new ConstantProvider<Throwable>(t));
            }

            public StubConfiguration thenThrow(
                    ObjectProvider<? extends Throwable> throwableProvider) {
                requireStubInterceptor().addThrow(throwableProvider);
                return StubConfigurer.this;
            }
        };
    }

    /**
     * Apply thyself against the specified stub interceptor.
     * @param stubInterceptor
     */
    final void configure(StubInterceptor stubInterceptor, T stub) {
        if (stubInterceptor == null) {
            throw new IllegalArgumentException(
                    "Cannot configure null StubInterceptor");
        }
        synchronized (this) {
            this.stubInterceptor = stubInterceptor;
            try {
                configure(stub);
            } finally {
                this.stubInterceptor = null;
            }
        }
    }

    /**
     * Specify the behavior of <code>stub</code> via the {@link StubConfiguration} interface.
     * @param stub
     */
    protected abstract void configure(T stub);

    synchronized StubInterceptor requireStubInterceptor() {
        if (stubInterceptor == null) {
            throw new IllegalStateException(
                    "no StubInterceptor currently in use");
        }
        return stubInterceptor;
    }

}