/*
 * Copyright 2008 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 com.google.gwt.dev.jjs.ast;

import com.google.gwt.dev.javac.JsInteropUtil;
import com.google.gwt.dev.jjs.SourceInfo;
import com.google.gwt.dev.jjs.SourceOrigin;
import com.google.gwt.dev.util.StringInterner;

import java.io.Serializable;

/**
 * Java field definition.
 */
public class JField extends JVariable implements JMember {

  /**
   * Determines whether the variable is final, volatile, or neither.
   */
  public enum Disposition {
    COMPILE_TIME_CONSTANT, FINAL, NONE, THIS_REF, VOLATILE;

    public boolean isFinal() {
      return this == COMPILE_TIME_CONSTANT || this == FINAL || this == THIS_REF;
    }

    public boolean isThisRef() {
      return this == THIS_REF;
    }

    private boolean isCompileTimeConstant() {
      return this == COMPILE_TIME_CONSTANT;
    }

    private boolean isVolatile() {
      return this == VOLATILE;
    }
  }

  private static class ExternalSerializedForm implements Serializable {

    private final JDeclaredType enclosingType;
    private final String signature;

    public ExternalSerializedForm(JField field) {
      enclosingType = field.getEnclosingType();
      signature = field.getSignature();
    }

    private Object readResolve() {
      String name = StringInterner.get().intern(signature.substring(0, signature.indexOf(':')));
      JField result =
          new JField(SourceOrigin.UNKNOWN, name, enclosingType, JReferenceType.NULL_TYPE, false,
              Disposition.NONE);
      result.signature = signature;
      return result;
    }
  }

  private static class ExternalSerializedNullField implements Serializable {
    public static final ExternalSerializedNullField INSTANCE = new ExternalSerializedNullField();

    private Object readResolve() {
      return NULL_FIELD;
    }
  }

  public static final JField NULL_FIELD = new JField(SourceOrigin.UNKNOWN, "nullField",
      JClassType.NULL_CLASS, JReferenceType.NULL_TYPE, false, Disposition.FINAL);

  private JsMemberType jsMembertype = JsMemberType.NONE;
  private String jsName;
  private String jsNamespace;
  private boolean exported;
  private boolean isJsOverlay = false;
  private final JDeclaredType enclosingType;
  private final boolean isCompileTimeConstant;
  private final boolean isStatic;
  private final boolean isThisRef;
  private boolean isVolatile;
  private transient String signature;

  /**
   * The access modifier; stored as an int to reduce memory / serialization footprint.
   */
  private final int access;

  public JField(SourceInfo info, String name, JDeclaredType enclosingType, JType type,
      boolean isStatic, Disposition disposition, AccessModifier access) {
    super(info, name, type, disposition.isFinal());
    this.enclosingType = enclosingType;
    this.isStatic = isStatic;
    this.isCompileTimeConstant = disposition.isCompileTimeConstant();
    this.isVolatile = disposition.isVolatile();
    this.isThisRef = disposition.isThisRef();
    this.access = access.ordinal();
    // Disposition is not cached because we can be set final later.
  }

  public JField(SourceInfo info, String name, JDeclaredType enclosingType, JType type,
      boolean isStatic, Disposition disposition) {
    this(info, name, enclosingType, type, isStatic, disposition, AccessModifier.DEFAULT);
  }

  @Override
  public String getQualifiedName() {
    return getEnclosingType().getName() + "." + getName();
  }

  @Override
  public JDeclaredType getEnclosingType() {
    return enclosingType;
  }

  public JValueLiteral getLiteralInitializer() {
    JExpression initializer = getInitializer();
    if (initializer instanceof JValueLiteral) {
      return (JValueLiteral) initializer;
    }
    return null;
  }


  @Override
  public JFieldRef makeRef(SourceInfo info) {
    throw new UnsupportedOperationException();
  }

  @Override
  public void setJsMemberInfo(
      JsMemberType jsMembertype, String namespace, String name, boolean exported) {
    this.jsMembertype = jsMembertype;
    this.jsName = name != null ? name : jsMembertype.computeName(this);
    this.jsNamespace = namespace;
    this.exported = exported;
  }

  @Override
  public void setJsOverlay() {
    isJsOverlay = true;
  }

  @Override
  public JsMemberType getJsMemberType() {
    return jsMembertype;
  }

  @Override
  public boolean isJsInteropEntryPoint() {
    return exported && isStatic() && !isJsNative() && !isJsOverlay();
  }

  @Override
  public boolean canBeReferencedExternally() {
    return exported && !isJsNative();
  }

  @Override
  public boolean canBeImplementedExternally() {
    return isJsNative();
  }

  @Override
  public String getJsNamespace() {
    return jsNamespace == null ? enclosingType.getQualifiedJsName() : jsNamespace;
  }

  @Override
  public String getQualifiedJsName() {
    String namespace = getJsNamespace();
    return JsInteropUtil.isGlobal(namespace) ? jsName : namespace + "." + jsName;
  }

  @Override
  public boolean isAbstract() {
    return false;
  }

  @Override
  public boolean isJsNative() {
    return !isJsOverlay() && enclosingType.isJsNative();
  }

  @Override
  public boolean isJsOverlay() {
    return isJsOverlay;
  }

  @Override
  public boolean isJsMethodVarargs() {
    return false;
  }

  @Override
  public String getJsName() {
    return jsName;
  }

  public String getSignature() {
    if (signature == null) {
      StringBuilder sb = new StringBuilder();
      sb.append(getName());
      sb.append(':');
      sb.append(getType().getJsniSignatureName());
      signature = sb.toString();
    }
    return signature;
  }

  public boolean isCompileTimeConstant() {
    return isCompileTimeConstant;
  }

  @Override
  public boolean isExternal() {
    return getEnclosingType().isExternal();
  }

  @Override
  public boolean isPublic() {
    return access == AccessModifier.PUBLIC.ordinal();
  }

  @Override
  public boolean isPrivate() {
    return access == AccessModifier.PRIVATE.ordinal();
  }

  @Override
  public boolean needsDynamicDispatch() {
    return !isStatic;
  }

  @Override
  public boolean isStatic() {
    return isStatic;
  }

  @Override
  public boolean isSynthetic() {
    return false;
  }

  public boolean isThisRef() {
    return isThisRef;
  }

  public boolean isVolatile() {
    return isVolatile;
  }

  @Override
  public void setFinal() {
    if (isVolatile()) {
      throw new IllegalStateException("Volatile fields cannot be set final");
    }
    super.setFinal();
  }

  @Override
  public void setInitializer(JDeclarationStatement declStmt) {
    this.declStmt = declStmt;
  }

  @Override
  public void traverse(JVisitor visitor, Context ctx) {
    if (visitor.visit(this, ctx)) {
      // Do not visit declStmt, it gets visited within its own code block.
    }
    visitor.endVisit(this, ctx);
  }

  protected Object writeReplace() {
    if (isExternal()) {
      return new ExternalSerializedForm(this);
    } else if (this == NULL_FIELD) {
      return ExternalSerializedNullField.INSTANCE;
    } else {
      return this;
    }
  }

  boolean replaces(JField originalField) {
    if (this == originalField) {
      return true;
    }
    return originalField.isExternal() && originalField.getSignature().equals(this.getSignature())
        && this.getEnclosingType().replaces(originalField.getEnclosingType());
  }
}