/*
    * 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.addthis.codec.reflection;
  
  import javax.annotation.Nonnull;
  import javax.annotation.Nullable;
  
  import java.lang.reflect.Field;
  import java.lang.reflect.Modifier;
  
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.SortedMap;
  import java.util.TreeMap;
  
  import com.addthis.codec.annotations.FieldConfig;
  import com.addthis.codec.annotations.Pluggable;
  import com.addthis.codec.plugins.PluginMap;
  import com.addthis.codec.plugins.PluginRegistry;
  
  import com.google.common.annotations.Beta;
  import com.google.common.collect.ImmutableSortedMap;
  
  import com.typesafe.config.Config;
  import com.typesafe.config.ConfigFactory;
  import com.typesafe.config.ConfigObject;
  import com.typesafe.config.ConfigValue;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  @Beta
  public class CodableClassInfo {
      private static final Logger log = LoggerFactory.getLogger(CodableClassInfo.class);
  
      @Nonnull private final Class<?>     baseClass;
      @Nonnull private final PluginMap    pluginMap;
      @Nonnull private final Config       fieldDefaults;
      @Nonnull private final ImmutableSortedMap<String, CodableFieldInfo> classData;
  
      public CodableClassInfo(@Nonnull Class<?> clazz) {
          this(clazz, ConfigFactory.load(), PluginRegistry.defaultRegistry());
      }
  
      public CodableClassInfo(@Nonnull Class<?> clazz,
                              @Nonnull Config globalDefaults,
                              @Nonnull PluginRegistry pluginRegistry) {
  
          // skip native classes
          if (Fields.isNative(clazz) || clazz.isArray()) {
              classData = ImmutableSortedMap.of();
              baseClass = clazz;
              pluginMap = PluginMap.EMPTY;
              fieldDefaults = ConfigFactory.empty();
              return;
          }
  
          // find any parent class (or itself) with a Pluggable annotation
          Class<?> findBaseClass = clazz;
          PluginMap findPluginMap = PluginMap.EMPTY;
  
          Class<?> ptr = clazz;
          while (ptr != null) {
              if (pluginRegistry.byClass().containsKey(ptr)) {
                  findPluginMap = pluginRegistry.byClass().get(ptr);
                  findBaseClass = ptr;
                  break;
              }
              Pluggable pluggable = ptr.getAnnotation(Pluggable.class);
              if (pluggable != null) {
                  String category = pluggable.value();
                  findPluginMap = pluginRegistry.asMap().get(category);
                  findBaseClass = ptr;
                  if (findPluginMap == null) {
                      log.warn("missing plugin map for {}, reached from {}", ptr, clazz);
                      findPluginMap = PluginMap.EMPTY;
                  }
                  break;
              }
              ptr = ptr.getSuperclass();
          }
          pluginMap = findPluginMap;
          baseClass = findBaseClass;
  
          // find all fields in the class and its parent classes, and aggregate any defaults
          Map<String, Field> fields = new HashMap<>();
          // slower than using unwrapped, mutable conversions but this preserves origins
         ConfigObject buildDefaults = ConfigFactory.empty().root();
 
         Class<?> ptrForFields = clazz;
         while (ptrForFields != null) {
             String canonicalClassName = ptrForFields.getCanonicalName();
             ConfigObject classDefaults;
             if ((canonicalClassName != null) && globalDefaults.hasPath(canonicalClassName)) {
                 classDefaults = globalDefaults.getObject(canonicalClassName);
             } else {
                 classDefaults = ConfigFactory.empty().root();
             }
             for (Field field : ptrForFields.getDeclaredFields()) {
                 if (fields.get(field.getName()) == null) {
                     fields.put(field.getName(), field);
                 } else {
                     classDefaults = classDefaults.withoutKey(field.getName());
                     log.debug("({}) ignoring field in parent class ({}) with duplicate name ({})",
                               clazz, ptrForFields, field.getName());
                 }
             }
             for (Map.Entry<String, ConfigValue> pair : classDefaults.entrySet()) {
                 if (!buildDefaults.containsKey(pair.getKey())) {
                     buildDefaults = buildDefaults.withValue(pair.getKey(), pair.getValue());
                 }
             }
             ptrForFields = ptrForFields.getSuperclass();
         }
         fieldDefaults = buildDefaults.toConfig();
 
         // turn all the found fields into CodableFieldInfo objects
         Map<String, CodableFieldInfo> buildClassData = buildFieldInfoMap(fields.values());
         classData = ImmutableSortedMap.<String, CodableFieldInfo>naturalOrder()
                                       .putAll(buildClassData).build();
     }
 
     @Nonnull public PluginMap getPluginMap() {
         return pluginMap;
     }
 
     @Nonnull public Config getFieldDefaults() {
         return fieldDefaults;
     }
 
     @Nonnull public Class<?> getBaseClass() {
         return baseClass;
     }
 
     @Nonnull public String getClassField() {
         return pluginMap.classField();
     }
 
     @Nullable public Class<?> getArraySugar() {
         return pluginMap.arraySugar();
     }
 
     @Nullable public Class<?> getDefaultSugar() {
         return pluginMap.defaultSugar();
     }
 
     @Nullable public String getClassName(Object val) {
         if (val.getClass() != baseClass) {
             return pluginMap.getClassName(val.getClass());
         } else {
             return null;
         }
     }
 
     @Nonnull public Class<?> getClass(String name) throws ClassNotFoundException {
         return pluginMap.getClass(name);
     }
 
     public int size() {
         return classData.size();
     }
 
     @Nonnull public Collection<CodableFieldInfo> values() {
         return classData.values();
     }
 
     /** Immutable view of codable fields as a map of field names to {@link CodableFieldInfo}s. */
     @Nonnull public Map<String, CodableFieldInfo> fields() {
         return classData;
     }
 
     /**
      * Decide whether it is okay to read/ write a field. If configured via an annotation on the field, use that.
      * Otherwise return true only if the field is both public and non-final.
      */
     private static boolean isCodable(Field field) {
         FieldConfig fieldConfigPolicy = field.getAnnotation(FieldConfig.class);
         if (fieldConfigPolicy != null) {
             return fieldConfigPolicy.codable();
         }
         int modifierBitSet = field.getModifiers();
         return !Modifier.isFinal(modifierBitSet) && Modifier.isPublic(modifierBitSet);
     }
 
     @Nonnull private static Map<String, CodableFieldInfo> buildFieldInfoMap(Iterable<Field> fields) {
         SortedMap<String, CodableFieldInfo> buildClassData = new TreeMap<>();
         for (Field field : fields) {
             if (isCodable(field)) {
                 CodableFieldInfo info = new CodableFieldInfo(field);
                 buildClassData.put(field.getName(), info);
             }
         }
         return buildClassData;
     }
 
 }