/*
 * Copyright (C) 2017 The Dagger Authors.
 *
 * 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 dagger.internal.codegen.writing;

import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.CodeBlock;
import dagger.internal.codegen.binding.ComponentDescriptor.ComponentMethodDescriptor;
import dagger.internal.codegen.javapoet.Expression;

/** A factory of code expressions used to access a single request for a binding in a component. */
// TODO(bcorso): Rename this to RequestExpression?
abstract class BindingExpression {

  /**
   * Returns an expression that evaluates to the value of a request based on the given requesting
   * class.
   *
   * @param requestingClass the class that will contain the expression
   */
  abstract Expression getDependencyExpression(ClassName requestingClass);

  /**
   * Equivalent to {@link #getDependencyExpression} that is used only when the request is for an
   * implementation of a component method. By default, just delegates to {@link
   * #getDependencyExpression}.
   */
  Expression getDependencyExpressionForComponentMethod(
      ComponentMethodDescriptor componentMethod, ComponentImplementation component) {
    return getDependencyExpression(component.name());
  }

  /** Returns {@code true} if this binding expression should be encapsulated in a method. */
  boolean requiresMethodEncapsulation() {
    return false;
  }

  /**
   * Returns an expression for the implementation of a component method with the given request.
   *
   * @param component the component that will contain the implemented method
   */
  CodeBlock getComponentMethodImplementation(
      ComponentMethodDescriptor componentMethod, ComponentImplementation component) {
    // By default, just delegate to #getDependencyExpression().
    return CodeBlock.of(
        "return $L;",
        getDependencyExpressionForComponentMethod(componentMethod, component).codeBlock());
  }
}