/*
 * 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.juneau.reflect;

import static org.apache.juneau.internal.ConsumerUtils.*;

import java.lang.annotation.*;
import java.lang.reflect.*;
import java.util.*;
import java.util.function.*;

import org.apache.juneau.*;

/**
 * Lightweight utility class for introspecting information about a field.
 *
 * <h5 class='section'>See Also:</h5><ul>
 * </ul>
 */
public class FieldInfo implements Comparable<FieldInfo> {

   //-----------------------------------------------------------------------------------------------------------------
   // Static
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Convenience method for instantiating a {@link FieldInfo};
    *
    * @param declaringClass The class that declares this method.
    * @param f The field being wrapped.
    * @return A new {@link FieldInfo} object, or <jk>null</jk> if the field was null.
    */
   public static FieldInfo of(ClassInfo declaringClass, Field f) {
      if (f == null)
         return null;
      return ClassInfo.of(declaringClass).getFieldInfo(f);
   }

   /**
    * Convenience method for instantiating a {@link FieldInfo};
    *
    * @param f The field being wrapped.
    * @return A new {@link FieldInfo} object, or <jk>null</jk> if the field was null.
    */
   public static FieldInfo of(Field f) {
      if (f == null)
         return null;
      return ClassInfo.of(f.getDeclaringClass()).getFieldInfo(f);
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Instance
   //-----------------------------------------------------------------------------------------------------------------

   private final Field f;
   private final ClassInfo declaringClass;
   private volatile ClassInfo type;

   /**
    * Constructor.
    *
    * @param declaringClass The class that declares this method.
    * @param f The field being wrapped.
    */
   protected FieldInfo(ClassInfo declaringClass, Field f) {
      this.declaringClass = declaringClass;
      this.f = f;
   }

   /**
    * Returns the wrapped field.
    *
    * @return The wrapped field.
    */
   public Field inner() {
      return f;
   }

   /**
    * Returns metadata about the declaring class.
    *
    * @return Metadata about the declaring class.
    */
   public ClassInfo getDeclaringClass() {
      return declaringClass;
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Annotations
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Returns the specified annotation on this field.
    *
    * @param <A> The annotation type to look for.
    * @param type The annotation to look for.
    * @return The annotation, or <jk>null</jk> if not found.
    */
   public <A extends Annotation> A getAnnotation(Class<A> type) {
      return getAnnotation(AnnotationProvider.DEFAULT, type);
   }

   /**
    * Returns the specified annotation on this field.
    *
    * @param <A> The annotation type to look for.
    * @param annotationProvider The annotation provider.
    * @param type The annotation to look for.
    * @return The annotation, or <jk>null</jk> if not found.
    */
   public <A extends Annotation> A getAnnotation(AnnotationProvider annotationProvider, Class<A> type) {
      Value<A> t = Value.empty();
      annotationProvider.forEachAnnotation(type, f, x -> true, x -> t.set(x));
      return t.orElse(null);
   }

   /**
    * Returns <jk>true</jk> if the specified annotation is present.
    *
    * @param <A> The annotation type to look for.
    * @param type The annotation to look for.
    * @return <jk>true</jk> if the specified annotation is present.
    */
   public <A extends Annotation> boolean hasAnnotation(Class<A> type) {
      return f.isAnnotationPresent(type);
   }

   /**
    * Returns <jk>true</jk> if the specified annotation is not present on this field.
    *
    * @param <A> The annotation type to look for.
    * @param type The annotation to look for.
    * @return <jk>true</jk> if the specified annotation is not present on this field.
    */
   public <A extends Annotation> boolean hasNoAnnotation(Class<A> type) {
      return ! hasAnnotation(type);
   }

   /**
    * Returns <jk>true</jk> if the specified annotation is present.
    *
    * @param <A> The annotation type to look for.
    * @param annotationProvider The annotation provider.
    * @param type The annotation to look for.
    * @return <jk>true</jk> if the specified annotation is present.
    */
   public <A extends Annotation> boolean hasAnnotation(AnnotationProvider annotationProvider, Class<A> type) {
      return annotationProvider.firstAnnotation(type, f, x -> true) != null;
   }

   /**
    * Returns <jk>true</jk> if the specified annotation is not present.
    *
    * @param <A> The annotation type to look for.
    * @param annotationProvider The annotation provider.
    * @param type The annotation to look for.
    * @return <jk>true</jk> if the specified annotation is not present.
    */
   public <A extends Annotation> boolean hasNoAnnotation(AnnotationProvider annotationProvider, Class<A> type) {
      return ! hasAnnotation(annotationProvider, type);
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Characteristics
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Returns <jk>true</jk> if all specified flags are applicable to this field.
    *
    * @param flags The flags to test for.
    * @return <jk>true</jk> if all specified flags are applicable to this field.
    */
   public boolean isAll(ReflectFlags...flags) {
      for (ReflectFlags f : flags) {
         switch (f) {
            case DEPRECATED:
               if (isNotDeprecated())
                  return false;
               break;
            case NOT_DEPRECATED:
               if (isDeprecated())
                  return false;
               break;
            case PUBLIC:
               if (isNotPublic())
                  return false;
               break;
            case NOT_PUBLIC:
               if (isPublic())
                  return false;
               break;
            case STATIC:
               if (isNotStatic())
                  return false;
               break;
            case NOT_STATIC:
               if (isStatic())
                  return false;
               break;
            case TRANSIENT:
               if (isNotTransient())
                  return false;
               break;
            case NOT_TRANSIENT:
               if (isTransient())
                  return false;
               break;
            default:
               throw new BasicRuntimeException("Invalid flag for field: {0}", f);
         }
      }
      return true;
   }

   /**
    * Returns <jk>true</jk> if all specified flags are applicable to this field.
    *
    * @param flags The flags to test for.
    * @return <jk>true</jk> if all specified flags are applicable to this field.
    */
   public boolean isAny(ReflectFlags...flags) {
      for (ReflectFlags f : flags) {
         switch (f) {
            case DEPRECATED:
               if (isDeprecated())
                  return true;
               break;
            case NOT_DEPRECATED:
               if (isNotDeprecated())
                  return true;
               break;
            case PUBLIC:
               if (isPublic())
                  return true;
               break;
            case NOT_PUBLIC:
               if (isNotPublic())
                  return true;
               break;
            case STATIC:
               if (isStatic())
                  return true;
               break;
            case NOT_STATIC:
               if (isNotStatic())
                  return true;
               break;
            case TRANSIENT:
               if (isTransient())
                  return true;
               break;
            case NOT_TRANSIENT:
               if (isNotTransient())
                  return true;
               break;
            default:
               throw new BasicRuntimeException("Invalid flag for field: {0}", f);
         }
      }
      return false;
   }

   /**
    * Returns <jk>true</jk> if all specified flags are applicable to this field.
    *
    * @param flags The flags to test for.
    * @return <jk>true</jk> if all specified flags are applicable to this field.
    */
   public boolean is(ReflectFlags...flags) {
      return isAll(flags);
   }

   /**
    * Returns <jk>true</jk> if this field has the {@link Deprecated @Deprecated} annotation on it.
    *
    * @return <jk>true</jk> if this field has the {@link Deprecated @Deprecated} annotation on it.
    */
   public boolean isDeprecated() {
      return f.isAnnotationPresent(Deprecated.class);
   }

   /**
    * Returns <jk>true</jk> if this field doesn't have the {@link Deprecated @Deprecated} annotation on it.
    *
    * @return <jk>true</jk> if this field doesn't have the {@link Deprecated @Deprecated} annotation on it.
    */
   public boolean isNotDeprecated() {
      return ! f.isAnnotationPresent(Deprecated.class);
   }

   /**
    * Returns <jk>true</jk> if this field is public.
    *
    * @return <jk>true</jk> if this field is public.
    */
   public boolean isPublic() {
      return Modifier.isPublic(f.getModifiers());
   }

   /**
    * Returns <jk>true</jk> if this field is not public.
    *
    * @return <jk>true</jk> if this field is not public.
    */
   public boolean isNotPublic() {
      return ! Modifier.isPublic(f.getModifiers());
   }

   /**
    * Returns <jk>true</jk> if this field is static.
    *
    * @return <jk>true</jk> if this field is static.
    */
   public boolean isStatic() {
      return Modifier.isStatic(f.getModifiers());
   }

   /**
    * Returns <jk>true</jk> if this field is not static.
    *
    * @return <jk>true</jk> if this field is not static.
    */
   public boolean isNotStatic() {
      return ! Modifier.isStatic(f.getModifiers());
   }

   /**
    * Returns <jk>true</jk> if this field is transient.
    *
    * @return <jk>true</jk> if this field is transient.
    */
   public boolean isTransient() {
      return Modifier.isTransient(f.getModifiers());
   }

   /**
    * Returns <jk>true</jk> if this field is not transient.
    *
    * @return <jk>true</jk> if this field is not transient.
    */
   public boolean isNotTransient() {
      return ! Modifier.isTransient(f.getModifiers());
   }

   /**
    * Returns <jk>true</jk> if the field has the specified name.
    *
    * @param name The name to compare against.
    * @return <jk>true</jk> if the field has the specified name.
    */
   public boolean hasName(String name) {
      return f.getName().equals(name);
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Visibility
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Attempts to call <code>x.setAccessible(<jk>true</jk>)</code> and quietly ignores security exceptions.
    *
    * @return This object.
    */
   public FieldInfo accessible() {
      setAccessible();
      return this;
   }

   /**
    * Attempts to call <code>x.setAccessible(<jk>true</jk>)</code> and quietly ignores security exceptions.
    *
    * @return <jk>true</jk> if call was successful.
    */
   public boolean setAccessible() {
      try {
         if (f != null)
            f.setAccessible(true);
         return true;
      } catch (SecurityException e) {
         return false;
      }
   }

   /**
    * Identifies if the specified visibility matches this field.
    *
    * @param v The visibility to validate against.
    * @return <jk>true</jk> if this visibility matches the modifier attribute of this field.
    */
   public boolean isVisible(Visibility v) {
      return v.isVisible(f);
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Other methods
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Returns <jk>true</jk> if this object passes the specified predicate test.
    *
    * @param test The test to perform.
    * @return <jk>true</jk> if this object passes the specified predicate test.
    */
   public boolean matches(Predicate<FieldInfo> test) {
      return test(test, this);
   }

   /**
    * Performs an action on this object if the specified predicate test passes.
    *
    * @param test A test to apply to determine if action should be executed.  Can be <jk>null</jk>.
    * @param action An action to perform on this object.
    * @return This object.
    */
   public FieldInfo accept(Predicate<FieldInfo> test, Consumer<FieldInfo> action) {
      if (matches(test))
         action.accept(this);
      return this;
   }

   /**
    * Returns the type of this field.
    *
    * @return The type of this field.
    */
   public ClassInfo getType() {
      if (type == null) {
         synchronized(this) {
            type = ClassInfo.of(f.getType());
         }
      }
      return type;
   }

   @Override
   public String toString() {
      return f.getDeclaringClass().getName() + "." + f.getName();
   }

   @Override
   public int compareTo(FieldInfo o) {
      return getName().compareTo(o.getName());
   }

   /**
    * Returns the name of this field.
    *
    * @return The name of this field.
    */
   public String getName() {
      return f.getName();
   }

   /**
    * Returns the full name of this field.
    *
    * <h5 class='section'>Examples:</h5>
    * <ul>
    *    <li><js>"com.foo.MyClass.myField"</js> - Method.
    * </ul>
    *
    * @return The underlying executable name.
    */
   public String getFullName() {
      StringBuilder sb = new StringBuilder(128);
      ClassInfo dc = declaringClass;
      Package p = dc.getPackage();
      if (p != null)
         sb.append(p.getName()).append('.');
      dc.appendShortName(sb);
      sb.append(".").append(getName());
      return sb.toString();
   }

   /**
    * Returns the field value on the specified object.
    *
    * @param o The object containing the field.
    * @param <T> The object type to retrieve.
    * @return The field value.
    * @throws BeanRuntimeException Field was not accessible or field does not belong to object.
    */
   @SuppressWarnings("unchecked")
   public <T> T get(Object o) throws BeanRuntimeException {
      try {
         f.setAccessible(true);
         return (T)f.get(o);
      } catch (Exception e) {
         throw new BeanRuntimeException(e);
      }
   }

   /**
    * Same as {@link #get(Object)} but wraps the results in an {@link Optional}.
    *
    * @param o The object containing the field.
    * @param <T> The object type to retrieve.
    * @return The field value.
    * @throws BeanRuntimeException Field was not accessible or field does not belong to object.
    */
   public <T> Optional<T> getOptional(Object o) throws BeanRuntimeException {
      return Optional.ofNullable(get(o));
   }

   /**
    * Sets the field value on the specified object.
    *
    * @param o The object containing the field.
    * @param value The new field value.
    * @throws BeanRuntimeException Field was not accessible or field does not belong to object.
    */
   public void set(Object o, Object value) throws BeanRuntimeException {
      try {
         f.setAccessible(true);
         f.set(o, value);
      } catch (Exception e) {
         throw new BeanRuntimeException(e);
      }
   }

   /**
    * Sets the field value on the specified object if the value is <jk>null</jk>.
    *
    * @param o The object containing the field.
    * @param value The new field value.
    * @throws BeanRuntimeException Field was not accessible or field does not belong to object.
    */
   public void setIfNull(Object o, Object value) {
      Object v = get(o);
      if (v == null)
         set(o, value);
   }
}