/*
 * Copyright 2015, The Querydsl Team (http://www.querydsl.com/team)
 *
 * Licensed 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 com.querydsl.core.types.dsl;

import java.lang.reflect.AnnotatedElement;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.annotation.Nullable;

import com.querydsl.core.types.*;

/**
 * {@code ListPath} represents list paths
 *
 * @author tiwe
 *
 * @param <E> component type
 * @param <Q> result type for {@code get(int)} and {@code any()} results
 */
public class ListPath<E, Q extends SimpleExpression<? super E>> extends CollectionPathBase<List<E>, E, Q> implements ListExpression<E, Q> {

    private static final long serialVersionUID = 3302301599074388860L;

    private final Map<Integer,Q> cache = new HashMap<Integer,Q>();

    private final Class<E> elementType;

    private final PathImpl<List<E>> pathMixin;

    private final Class<Q> queryType;

    @Nullable
    private transient Q any;

    protected ListPath(Class<? super E> elementType, Class<Q> queryType, String variable) {
        this(elementType, queryType, PathMetadataFactory.forVariable(variable));
    }

    protected ListPath(Class<? super E> elementType, Class<Q> queryType, Path<?> parent, String property) {
        this(elementType, queryType, PathMetadataFactory.forProperty(parent, property));
    }

    protected ListPath(Class<? super E> elementType, Class<Q> queryType, PathMetadata metadata) {
        this(elementType, queryType, metadata, PathInits.DIRECT);
    }

    @SuppressWarnings("unchecked")
    protected ListPath(Class<? super E> elementType, Class<Q> queryType, PathMetadata metadata, PathInits inits) {
        super(new ParameterizedPathImpl<List<E>>((Class) List.class, metadata, elementType), inits);
        this.elementType = (Class<E>) elementType;
        this.queryType = queryType;
        this.pathMixin = (PathImpl<List<E>>) mixin;
    }

    @Override
    public final <R,C> R accept(Visitor<R,C> v, C context) {
        return v.visit(pathMixin, context);
    }

    @Override
    public Q any() {
        if (any == null) {
            any = newInstance(queryType, PathMetadataFactory.forCollectionAny(this));
        }
        return any;
    }

    protected PathMetadata forListAccess(int index) {
        return PathMetadataFactory.forListAccess(this, index);
    }

    protected PathMetadata forListAccess(Expression<Integer> index) {
        return PathMetadataFactory.forListAccess(this, index);
    }

    private Q create(int index) {
        PathMetadata md = forListAccess(index);
        return newInstance(queryType, md);
    }

    @Override
    public Q get(Expression<Integer> index) {
        PathMetadata md = forListAccess(index);
        return newInstance(queryType, md);
    }


    @Override
    public Q get(int index) {
        if (cache.containsKey(index)) {
            return cache.get(index);
        } else {
            Q rv = create(index);
            cache.put(index, rv);
            return rv;
        }
    }

    @Override
    public Class<E> getElementType() {
        return elementType;
    }

    @Override
    public PathMetadata getMetadata() {
        return pathMixin.getMetadata();
    }

    @Override
    public Path<?> getRoot() {
        return pathMixin.getRoot();
    }

    @Override
    public AnnotatedElement getAnnotatedElement() {
        return pathMixin.getAnnotatedElement();
    }

    @Override
    public Class<?> getParameter(int index) {
        if (index == 0) {
            return elementType;
        } else {
            throw new IndexOutOfBoundsException(String.valueOf(index));
        }
    }

}