/*
 * Copyright (C) 2014 Google, Inc.
 *
 * 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.writer;

import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import java.io.IOException;
import java.util.List;
import java.util.Set;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.TypeElement;

import static com.google.common.base.Preconditions.checkState;
import static javax.lang.model.element.Modifier.PRIVATE;
import static javax.lang.model.element.Modifier.PROTECTED;
import static javax.lang.model.element.Modifier.PUBLIC;

public final class ClassWriter extends TypeWriter {
  private Optional<TypeName> superclass;
  private final List<ConstructorWriter> constructorWriters;
  private final List<TypeVariableName> typeParameters;

  ClassWriter(ClassName className) {
    super(className);
    this.superclass = Optional.absent();
    this.constructorWriters = Lists.newArrayList();
    this.typeParameters = Lists.newArrayList();
  }

  public void setSuperclass(TypeName typeReference) {
    checkState(!superclass.isPresent());
    superclass = Optional.of(typeReference);
  }

  /**
   * If {@code supertype} is a class, makes this class extend it; if it is an interface, makes this
   * class implement it.
   */
  public void setSupertype(TypeElement supertype) {
    switch (supertype.getKind()) {
      case CLASS:
        setSuperclass(ClassName.fromTypeElement(supertype));
        break;
      case INTERFACE:
        addImplementedType(supertype);
        break;
      default:
        throw new IllegalArgumentException(supertype + " must be a class or interface");
    }
  }

  public ConstructorWriter addConstructor() {
    ConstructorWriter constructorWriter = new ConstructorWriter(name.simpleName());
    constructorWriters.add(constructorWriter);
    return constructorWriter;
  }

  public void addTypeParameter(TypeVariableName typeVariableName) {
    this.typeParameters.add(typeVariableName);
  }

  public void addTypeParameters(Iterable<TypeVariableName> typeVariableNames) {
    Iterables.addAll(typeParameters, typeVariableNames);
  }

  public List<TypeVariableName> typeParameters() {
    return ImmutableList.copyOf(typeParameters);
  }

  @Override
  public Appendable write(Appendable appendable, Context context) throws IOException {
    context = context.createSubcontext(FluentIterable.from(nestedTypeWriters)
        .transform(new Function<TypeWriter, ClassName>() {
          @Override public ClassName apply(TypeWriter input) {
            return input.name;
          }
        })
        .toSet());
    writeAnnotations(appendable, context);
    writeModifiers(appendable).append("class ").append(name.simpleName());
    Writables.join(", ", typeParameters, "<", ">", appendable, context);
    if (superclass.isPresent()) {
      appendable.append(" extends ");
      superclass.get().write(appendable, context);
    }
    Writables.join(", ", implementedTypes, " implements ", "", appendable, context);
    appendable.append(" {");
    if (!fieldWriters.isEmpty()) {
      appendable.append('\n');
    }
    for (VariableWriter fieldWriter : fieldWriters.values()) {
      fieldWriter.write(new IndentingAppendable(appendable), context).append("\n");
    }
    for (ConstructorWriter constructorWriter : constructorWriters) {
      appendable.append('\n');
      if (!isDefaultConstructor(constructorWriter)) {
        constructorWriter.write(new IndentingAppendable(appendable), context);
      }
    }
    for (MethodWriter methodWriter : methodWriters) {
      appendable.append('\n');
      methodWriter.write(new IndentingAppendable(appendable), context);
    }
    for (TypeWriter nestedTypeWriter : nestedTypeWriters) {
      appendable.append('\n');
      nestedTypeWriter.write(new IndentingAppendable(appendable), context);
    }
    appendable.append("}\n");
    return appendable;
  }

  private static final Set<Modifier> VISIBILIY_MODIFIERS =
      Sets.immutableEnumSet(PUBLIC, PROTECTED, PRIVATE);

  private boolean isDefaultConstructor(ConstructorWriter constructorWriter) {
    return Sets.intersection(VISIBILIY_MODIFIERS, modifiers)
        .equals(Sets.intersection(VISIBILIY_MODIFIERS, constructorWriter.modifiers))
        && constructorWriter.body().isEmpty();
  }

  @Override
  public Set<ClassName> referencedClasses() {
    return FluentIterable.from(ImmutableList.<HasClassReferences>of())
        .append(nestedTypeWriters)
        .append(fieldWriters.values())
        .append(constructorWriters)
        .append(methodWriters)
        .append(implementedTypes)
        .append(superclass.asSet())
        .append(annotations)
        .append(typeParameters)
        .transformAndConcat(HasClassReferences.COMBINER)
        .toSet();
  }
}