/*
    * 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.maven.di.impl;
  
  import java.lang.reflect.*;
  import java.util.*;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.function.Function;
  
  import org.apache.maven.api.annotations.Nullable;
  
  import static java.util.stream.Collectors.joining;
  
  /**
   * Various helper methods for type processing
   */
  public class Types {
      public static final Type[] NO_TYPES = new Type[0];
      public static final WildcardType WILDCARD_TYPE_ANY = new WildcardTypeImpl(new Type[] {Object.class}, new Type[0]);
      private static final Map<Type, Map<TypeVariable<?>, Type>> TYPE_BINDINGS_CACHE = new ConcurrentHashMap<>();
  
      /**
       * Returns a raw {@link Class} for a given {@link Type}.
       * <p>
       * A type can be any of {@link Class}, {@link ParameterizedType}, {@link WildcardType},
       * {@link GenericArrayType} or {@link TypeVariable}
       */
      public static Class<?> getRawType(Type type) {
          if (type instanceof Class) {
              return (Class<?>) type;
          } else if (type instanceof ParameterizedType) {
              return (Class<?>) ((ParameterizedType) type).getRawType();
          } else if (type instanceof WildcardType) {
              Type[] upperBounds = ((WildcardType) type).getUpperBounds();
              return getRawType(getUppermostType(upperBounds));
          } else if (type instanceof GenericArrayType) {
              Class<?> rawComponentType = getRawType(((GenericArrayType) type).getGenericComponentType());
              try {
                  return Class.forName("[L" + rawComponentType.getName() + ";");
              } catch (ClassNotFoundException e) {
                  throw new RuntimeException(e);
              }
          } else if (type instanceof TypeVariable) {
              return getRawType(getUppermostType(((TypeVariable<?>) type).getBounds()));
          } else {
              throw new IllegalArgumentException("Unsupported type: " + type);
          }
      }
  
      /**
       * Returns the most common type among given types
       */
      public static Type getUppermostType(Type[] types) {
          Type result = types[0];
          for (int i = 1; i < types.length; i++) {
              Type type = types[i];
              if (isAssignable(type, result)) {
                  result = type;
                  continue;
              } else if (isAssignable(result, type)) {
                  continue;
              }
              throw new IllegalArgumentException("Unrelated types: " + result + " , " + type);
          }
          return result;
      }
  
      /**
       * Returns an array of actual type arguments for a given {@link Type}
       *
       * @param type type whose actual type arguments should be retrieved
       * @return an array of actual type arguments for a given {@link Type}
       */
      public static Type[] getActualTypeArguments(Type type) {
          if (type instanceof Class) {
              return ((Class<?>) type).isArray() ? new Type[] {((Class<?>) type).getComponentType()} : NO_TYPES;
          } else if (type instanceof ParameterizedType) {
              return ((ParameterizedType) type).getActualTypeArguments();
          } else if (type instanceof GenericArrayType) {
              return new Type[] {((GenericArrayType) type).getGenericComponentType()};
          }
          throw new IllegalArgumentException("Unsupported type: " + type);
      }
 
     /**
      * Returns a map of type bindings for a given {@link Type}
      */
     public static Map<TypeVariable<?>, Type> getTypeBindings(Type type) {
         Type[] typeArguments = getActualTypeArguments(type);
         if (typeArguments.length == 0) {
             return Collections.emptyMap();
         }
         TypeVariable<?>[] typeVariables = getRawType(type).getTypeParameters();
         Map<TypeVariable<?>, Type> map = new HashMap<>();
         for (int i = 0; i < typeVariables.length; i++) {
             map.put(typeVariables[i], typeArguments[i]);
         }
         return map;
     }
 
     /**
      * Returns a map of all type bindings for a given {@link Type}.
      * Includes type bindings from a whole class hierarchy
      */
     public static Map<TypeVariable<?>, Type> getAllTypeBindings(Type type) {
         return TYPE_BINDINGS_CACHE.computeIfAbsent(type, t -> {
             Map<TypeVariable<?>, Type> mapping = new HashMap<>();
             getAllTypeBindingsImpl(t, mapping);
             return mapping;
         });
     }
 
     private static void getAllTypeBindingsImpl(Type type, Map<TypeVariable<?>, Type> mapping) {
         Class<?> cls = getRawType(type);
 
         if (type instanceof ParameterizedType) {
             Type[] typeArguments = ((ParameterizedType) type).getActualTypeArguments();
             if (typeArguments.length != 0) {
                 TypeVariable<? extends Class<?>>[] typeVariables = cls.getTypeParameters();
                 for (int i = 0; i < typeArguments.length; i++) {
                     Type typeArgument = typeArguments[i];
                     mapping.put(
                             typeVariables[i],
                             typeArgument instanceof TypeVariable
                                     ? Objects.requireNonNull(mapping.get(typeArgument))
                                     : typeArgument);
                 }
             }
         }
 
         Type superclass = cls.getGenericSuperclass();
         if (superclass != null) {
             getAllTypeBindingsImpl(superclass, mapping);
         }
 
         for (Type anInterface : cls.getGenericInterfaces()) {
             getAllTypeBindingsImpl(anInterface, mapping);
         }
     }
 
     /**
      * Binds a given type with actual type arguments
      *
      * @param type     a type to be bound
      * @param bindings a map of actual types
      */
     public static Type bind(Type type, Map<TypeVariable<?>, Type> bindings) {
         return bind(type, bindings::get);
     }
 
     /**
      * Binds a given type with actual type arguments
      *
      * @param type     a type to be bound
      * @param bindings a lookup function for actual types
      */
     public static Type bind(Type type, Function<TypeVariable<?>, Type> bindings) {
         if (type instanceof Class) {
             return type;
         }
         if (type instanceof TypeVariable<?>) {
             TypeVariable<?> typeVariable = (TypeVariable<?>) type;
             Type actualType = bindings.apply(typeVariable);
             if (actualType == null) {
                 throw new IllegalArgumentException("Type variable not found: " + typeVariable + " ( "
                         + typeVariable.getGenericDeclaration() + " ) ");
             }
             return actualType;
         }
         if (type instanceof ParameterizedType) {
             ParameterizedType parameterizedType = (ParameterizedType) type;
             Type[] typeArguments = parameterizedType.getActualTypeArguments();
             Type[] typeArguments2 = new Type[typeArguments.length];
             for (int i = 0; i < typeArguments.length; i++) {
                 typeArguments2[i] = bind(typeArguments[i], bindings);
             }
             return new ParameterizedTypeImpl(
                     parameterizedType.getOwnerType(), parameterizedType.getRawType(), typeArguments2);
         }
         if (type instanceof GenericArrayType) {
             Type componentType = ((GenericArrayType) type).getGenericComponentType();
             return new GenericArrayTypeImpl(bind(componentType, bindings));
         }
         if (type instanceof WildcardType) {
             WildcardType wildcardType = (WildcardType) type;
             Type[] upperBounds = wildcardType.getUpperBounds();
             Type[] upperBounds2 = new Type[upperBounds.length];
             for (int i = 0; i < upperBounds.length; i++) {
                 upperBounds2[i] = bind(upperBounds[i], bindings);
             }
             Type[] lowerBounds = wildcardType.getLowerBounds();
             Type[] lowerBounds2 = new Type[lowerBounds.length];
             for (int i = 0; i < lowerBounds.length; i++) {
                 lowerBounds2[i] = bind(lowerBounds[i], bindings);
             }
             return new WildcardTypeImpl(upperBounds2, lowerBounds2);
         }
         throw new IllegalArgumentException("Unsupported type: " + type);
     }
 
     /**
      * Creates an instance of {@link ParameterizedType}
      *
      * @param ownerType  an owner type
      * @param rawType    a type to be parameterized
      * @param parameters parameter types
      * @return an instance of {@link ParameterizedType}
      */
     public static ParameterizedType parameterizedType(@Nullable Type ownerType, Type rawType, Type[] parameters) {
         return new ParameterizedTypeImpl(ownerType, rawType, parameters);
     }
 
     /**
      * Creates an instance of {@link ParameterizedType}
      *
      * @see #parameterizedType(Type, Type, Type[])
      */
     public static ParameterizedType parameterizedType(Class<?> rawType, Type... parameters) {
         return new ParameterizedTypeImpl(null, rawType, parameters);
     }
 
     /**
      * Get all super classes and interface implemented by the given type.
      */
     public static Set<Type> getAllSuperTypes(Type original) {
         Deque<Type> todo = new ArrayDeque<>();
         todo.add(original);
         Set<Type> done = new HashSet<>();
         while (!todo.isEmpty()) {
             Type type = todo.remove();
             if (done.add(type)) {
                 Class<?> cls = getRawType(type);
                 Function<TypeVariable<?>, Type> bindings;
                 if (type instanceof ParameterizedType) {
                     Type[] typeArguments = ((ParameterizedType) type).getActualTypeArguments();
                     TypeVariable<? extends Class<?>>[] typeVariables = cls.getTypeParameters();
                     bindings = v -> {
                         for (int i = 0; i < typeArguments.length; i++) {
                             Type typeArgument = typeArguments[i];
                             if (v.equals(typeVariables[i])) {
                                 return typeArgument;
                             }
                         }
                         return null;
                     };
                 } else {
                     bindings = v -> null;
                 }
                 Type[] interfaces = cls.getGenericInterfaces();
                 for (Type itf : interfaces) {
                     todo.add(bind(itf, bindings));
                 }
                 Type supercls = cls.getGenericSuperclass();
                 if (supercls != null) {
                     todo.add(bind(supercls, bindings));
                 }
             }
         }
         return done;
     }
 
     public static Type simplifyType(Type original) {
         if (original instanceof Class) {
             return original;
         }
 
         if (original instanceof GenericArrayType) {
             Type componentType = ((GenericArrayType) original).getGenericComponentType();
             Type repackedComponentType = simplifyType(componentType);
             if (componentType != repackedComponentType) {
                 return genericArrayType(repackedComponentType);
             }
             return original;
         }
 
         if (original instanceof ParameterizedType) {
             ParameterizedType parameterizedType = (ParameterizedType) original;
             Type[] typeArguments = parameterizedType.getActualTypeArguments();
             Type[] repackedTypeArguments = simplifyTypes(typeArguments);
 
             if (isAllObjects(repackedTypeArguments)) {
                 return parameterizedType.getRawType();
             }
 
             if (typeArguments != repackedTypeArguments) {
                 return parameterizedType(
                         parameterizedType.getOwnerType(), parameterizedType.getRawType(), repackedTypeArguments);
             }
             return original;
         }
 
         if (original instanceof TypeVariable) {
             throw new IllegalArgumentException("Key should not contain a type variable: " + original);
         }
 
         if (original instanceof WildcardType) {
             WildcardType wildcardType = (WildcardType) original;
             Type[] upperBounds = wildcardType.getUpperBounds();
             if (upperBounds.length == 1) {
                 Type upperBound = upperBounds[0];
                 if (upperBound != Object.class) {
                     return simplifyType(upperBound);
                 }
             } else if (upperBounds.length > 1) {
                 throw new IllegalArgumentException("Multiple upper bounds not supported: " + original);
             }
 
             Type[] lowerBounds = wildcardType.getLowerBounds();
             if (lowerBounds.length == 1) {
                 return simplifyType(lowerBounds[0]);
             } else if (lowerBounds.length > 1) {
                 throw new IllegalArgumentException("Multiple lower bounds not supported: " + original);
             }
             return Object.class;
         }
 
         return original;
     }
 
     private static Type[] simplifyTypes(Type[] original) {
         int length = original.length;
         for (int i = 0; i < length; i++) {
             Type typeArgument = original[i];
             Type repackTypeArgument = simplifyType(typeArgument);
             if (repackTypeArgument != typeArgument) {
                 Type[] repackedTypeArguments = new Type[length];
                 System.arraycopy(original, 0, repackedTypeArguments, 0, i);
                 repackedTypeArguments[i++] = repackTypeArgument;
                 for (; i < length; i++) {
                     repackedTypeArguments[i] = simplifyType(original[i]);
                 }
                 return repackedTypeArguments;
             }
         }
         return original;
     }
 
     private static boolean isAllObjects(Type[] types) {
         for (Type type : types) {
             if (type != Object.class) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Tests whether a {@code from} type is assignable to {@code to} type
      *
      * @param to   a 'to' type that should be checked for possible assignment
      * @param from a 'from' type that should be checked for possible assignment
      * @return whether an object of type {@code from} is assignable to an object of type {@code to}
      */
     public static boolean isAssignable(Type to, Type from) {
         // shortcut
         if (to instanceof Class && from instanceof Class) {
             return ((Class<?>) to).isAssignableFrom((Class<?>) from);
         }
         return isAssignable(to, from, false);
     }
 
     private static boolean isAssignable(Type to, Type from, boolean strict) {
         if (to instanceof WildcardType || from instanceof WildcardType) {
             Type[] toUppers, toLowers;
             if (to instanceof WildcardType) {
                 WildcardType wildcardTo = (WildcardType) to;
                 toUppers = wildcardTo.getUpperBounds();
                 toLowers = wildcardTo.getLowerBounds();
             } else {
                 toUppers = new Type[] {to};
                 toLowers = strict ? toUppers : NO_TYPES;
             }
 
             Type[] fromUppers, fromLowers;
             if (from instanceof WildcardType) {
                 WildcardType wildcardTo = (WildcardType) to;
                 fromUppers = wildcardTo.getUpperBounds();
                 fromLowers = wildcardTo.getLowerBounds();
             } else {
                 fromUppers = new Type[] {from};
                 fromLowers = strict ? fromUppers : NO_TYPES;
             }
 
             for (Type toUpper : toUppers) {
                 for (Type fromUpper : fromUppers) {
                     if (!isAssignable(toUpper, fromUpper, false)) {
                         return false;
                     }
                 }
             }
             if (toLowers.length == 0) {
                 return true;
             }
             if (fromLowers.length == 0) {
                 return false;
             }
             for (Type toLower : toLowers) {
                 for (Type fromLower : fromLowers) {
                     if (!isAssignable(fromLower, toLower, false)) {
                         return false;
                     }
                 }
             }
             return true;
         }
         if (to instanceof GenericArrayType) {
             to = getRawType(to);
         }
         if (from instanceof GenericArrayType) {
             from = getRawType(from);
         }
         if (!strict && to instanceof Class) {
             return ((Class<?>) to).isAssignableFrom(getRawType(from));
         }
         Class<?> toRawClazz = getRawType(to);
         Type[] toTypeArguments = getActualTypeArguments(to);
         return isAssignable(toRawClazz, toTypeArguments, from, strict);
     }
 
     private static boolean isAssignable(Class<?> toRawClazz, Type[] toTypeArguments, Type from, boolean strict) {
         Class<?> fromRawClazz = getRawType(from);
         if (strict && !toRawClazz.equals(fromRawClazz)) {
             return false;
         }
         if (!strict && !toRawClazz.isAssignableFrom(fromRawClazz)) {
             return false;
         }
         if (toRawClazz.isArray()) {
             return true;
         }
         Type[] fromTypeArguments = getActualTypeArguments(from);
         if (toRawClazz == fromRawClazz) {
             if (toTypeArguments.length > fromTypeArguments.length) {
                 return false;
             }
             for (int i = 0; i < toTypeArguments.length; i++) {
                 if (!isAssignable(toTypeArguments[i], fromTypeArguments[i], true)) {
                     return false;
                 }
             }
             return true;
         }
         Map<TypeVariable<?>, Type> typeBindings = getTypeBindings(from);
         for (Type anInterface : fromRawClazz.getGenericInterfaces()) {
             if (isAssignable(
                     toRawClazz,
                     toTypeArguments,
                     bind(anInterface, key -> typeBindings.getOrDefault(key, wildcardTypeAny())),
                     false)) {
                 return true;
             }
         }
         Type superclass = fromRawClazz.getGenericSuperclass();
         return superclass != null && isAssignable(toRawClazz, toTypeArguments, bind(superclass, typeBindings), false);
     }
 
     public static final class ParameterizedTypeImpl implements ParameterizedType {
         private final @Nullable Type ownerType;
         private final Type rawType;
         private final Type[] actualTypeArguments;
 
         ParameterizedTypeImpl(@Nullable Type ownerType, Type rawType, Type[] actualTypeArguments) {
             this.ownerType = ownerType;
             this.rawType = rawType;
             this.actualTypeArguments = actualTypeArguments;
         }
 
         @Override
         public Type getRawType() {
             return rawType;
         }
 
         @Override
         public Type[] getActualTypeArguments() {
             return actualTypeArguments;
         }
 
         @Override
         public @Nullable Type getOwnerType() {
             return ownerType;
         }
 
         @Override
         public int hashCode() {
             return Objects.hashCode(ownerType) ^ Arrays.hashCode(actualTypeArguments) ^ rawType.hashCode();
         }
 
         @Override
         public boolean equals(Object other) {
             if (!(other instanceof ParameterizedType)) {
                 return false;
             }
             ParameterizedType that = (ParameterizedType) other;
             return this.getRawType().equals(that.getRawType())
                     && Objects.equals(this.getOwnerType(), that.getOwnerType())
                     && Arrays.equals(this.getActualTypeArguments(), that.getActualTypeArguments());
         }
 
         @Override
         public String toString() {
             return rawType.getTypeName()
                     + Arrays.stream(actualTypeArguments).map(Types::toString).collect(joining(", ", "<", ">"));
         }
     }
 
     /**
      * Creates an instance of {@link WildcardType} bound by upper and lower bounds
      *
      * @param upperBounds a wildcard upper bound types
      * @param lowerBounds a wildcard lower bound types
      * @return an instance of {@link WildcardType}
      */
     public static WildcardType wildcardType(Type[] upperBounds, Type[] lowerBounds) {
         return new WildcardTypeImpl(upperBounds, lowerBounds);
     }
 
     /**
      * Returns an instance of {@link WildcardType} that matches any type
      * <p>
      * E.g. {@code <?>}
      *
      * @see #wildcardType(Type[], Type[])
      */
     public static WildcardType wildcardTypeAny() {
         return WILDCARD_TYPE_ANY;
     }
 
     /**
      * Creates an instance of {@link WildcardType} bound by a single upper bound
      * <p>
      * E.g. {@code <? extends UpperBound>}
      *
      * @param upperBound a wildcard upper bound type
      * @return an instance of {@link WildcardType}
      * @see #wildcardType(Type[], Type[])
      */
     public static WildcardType wildcardTypeExtends(Type upperBound) {
         return new WildcardTypeImpl(new Type[] {upperBound}, NO_TYPES);
     }
 
     /**
      * Creates an instance of {@link WildcardType} bound by a single lower bound
      * <p>
      * E.g. {@code <? super LowerBound>}
      *
      * @param lowerBound a wildcard lower bound type
      * @return an instance of {@link WildcardType}
      * @see #wildcardType(Type[], Type[])
      */
     public static WildcardType wildcardTypeSuper(Type lowerBound) {
         return new WildcardTypeImpl(NO_TYPES, new Type[] {lowerBound});
     }
 
     public static class WildcardTypeImpl implements WildcardType {
         private final Type[] upperBounds;
         private final Type[] lowerBounds;
 
         WildcardTypeImpl(Type[] upperBounds, Type[] lowerBounds) {
             this.upperBounds = upperBounds;
             this.lowerBounds = lowerBounds;
         }
 
         @Override
         public Type[] getUpperBounds() {
             return upperBounds;
         }
 
         @Override
         public Type[] getLowerBounds() {
             return lowerBounds;
         }
 
         @Override
         public int hashCode() {
             return Arrays.hashCode(upperBounds) ^ Arrays.hashCode(lowerBounds);
         }
 
         @Override
         public boolean equals(Object other) {
             if (!(other instanceof WildcardType)) {
                 return false;
             }
             WildcardType that = (WildcardType) other;
             return Arrays.equals(this.getUpperBounds(), that.getUpperBounds())
                     && Arrays.equals(this.getLowerBounds(), that.getLowerBounds());
         }
 
         @Override
         public String toString() {
             return "?"
                     + (upperBounds.length == 0
                             ? ""
                             : " extends "
                                     + Arrays.stream(upperBounds)
                                             .map(Types::toString)
                                             .collect(joining(" & ")))
                     + (lowerBounds.length == 0
                             ? ""
                             : " super "
                                     + Arrays.stream(lowerBounds)
                                             .map(Types::toString)
                                             .collect(joining(" & ")));
         }
     }
 
     /**
      * Creates an instance of {@link GenericArrayType} with a given component type
      * <p>
      * Same as {@code T[]}
      *
      * @param componentType a component type of generic array
      * @return an instance of {@link GenericArrayType}
      * @see #wildcardType(Type[], Type[])
      */
     public static GenericArrayType genericArrayType(Type componentType) {
         return new GenericArrayTypeImpl(componentType);
     }
 
     public static final class GenericArrayTypeImpl implements GenericArrayType {
         private final Type componentType;
 
         GenericArrayTypeImpl(Type componentType) {
             this.componentType = componentType;
         }
 
         @Override
         public Type getGenericComponentType() {
             return componentType;
         }
 
         @Override
         public int hashCode() {
             return componentType.hashCode();
         }
 
         @Override
         public boolean equals(Object other) {
             if (!(other instanceof GenericArrayType)) {
                 return false;
             }
             GenericArrayType that = (GenericArrayType) other;
             return this.getGenericComponentType().equals(that.getGenericComponentType());
         }
 
         @Override
         public String toString() {
             return Types.toString(componentType) + "[]";
         }
     }
 
     private static String toString(Type type) {
         return type instanceof Class ? ((Class<?>) type).getName() : type.toString();
     }
 
     /**
      * Returns a simple name for a given {@link Type}
      *
      * @see Class#getSimpleName()
      */
     public static String getSimpleName(Type type) {
         if (type instanceof Class) {
             return ((Class<?>) type).getSimpleName();
         } else if (type instanceof ParameterizedType) {
             return Arrays.stream(((ParameterizedType) type).getActualTypeArguments())
                     .map(Types::getSimpleName)
                     .collect(joining(",", "<", ">"));
         } else if (type instanceof WildcardType) {
             WildcardType wildcardType = (WildcardType) type;
             Type[] upperBounds = wildcardType.getUpperBounds();
             Type[] lowerBounds = wildcardType.getLowerBounds();
             return "?"
                     + (upperBounds.length == 0
                             ? ""
                             : " extends "
                                     + Arrays.stream(upperBounds)
                                             .map(Types::getSimpleName)
                                             .collect(joining(" & ")))
                     + (lowerBounds.length == 0
                             ? ""
                             : " super "
                                     + Arrays.stream(lowerBounds)
                                             .map(Types::getSimpleName)
                                             .collect(joining(" & ")));
         } else if (type instanceof GenericArrayType) {
             return Types.getSimpleName(((GenericArrayType) type).getGenericComponentType()) + "[]";
         }
 
         return type.getTypeName();
     }
 }