// Copyright 2020 Google LLC
//
// 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.

#import "FirebasePerformance/Sources/Instrumentation/FPRProxyObjectHelper.h"

#import <objc/runtime.h>
#import <string.h>

FOUNDATION_STATIC_INLINE NSArray<id> *FPRIvarObjectsForProxy(id proxy) {
  NSMutableArray<id> *array = [NSMutableArray array];
  // NSProxy subclasses can forward -class to a wrapped object, so use the runtime class.
  Class currentClass = object_getClass(proxy);
  while (currentClass && currentClass != [NSProxy class]) {
    unsigned int count = 0;
    Ivar *ivars = class_copyIvarList(currentClass, &count);
    if (ivars) {
      for (NSUInteger i = 0; i < count; i++) {
        const char *typeEncoding = ivar_getTypeEncoding(ivars[i]);
        if (typeEncoding && strncmp(typeEncoding, "@", 1) == 0) {
          id ivarObject = object_getIvar(proxy, ivars[i]);
          if (ivarObject) {
            [array addObject:ivarObject];
          }
        }
      }
      free(ivars);
    }
    currentClass = class_getSuperclass(currentClass);
  }
  return array;
}

@implementation FPRProxyObjectHelper

+ (void)registerProxyObject:(id)proxy
              forSuperclass:(Class)superclass
            varFoundHandler:(void (^)(id ivar))varFoundHandler {
  NSArray<id> *ivars = FPRIvarObjectsForProxy(proxy);
  for (id ivar in ivars) {
    if ([ivar isKindOfClass:superclass]) {
      varFoundHandler(ivar);
    }
  }
}

+ (void)registerProxyObject:(id)proxy
                forProtocol:(Protocol *)protocol
            varFoundHandler:(void (^)(id ivar))varFoundHandler {
  NSArray *ivars = FPRIvarObjectsForProxy(proxy);
  for (id ivar in ivars) {
    if ([ivar conformsToProtocol:protocol]) {
      varFoundHandler(ivar);
    }
  }
}

@end