// Copyright 2018 Google
//
// 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 "FIRStorageGetDownloadURLTask.h"

#import "FIRStorageTask_Private.h"

@implementation FIRStorageGetDownloadURLTask {
 @private
  FIRStorageVoidURLError _completion;
}

@synthesize fetcher = _fetcher;
@synthesize fetcherCompletion = _fetcherCompletion;

- (instancetype)initWithReference:(FIRStorageReference *)reference
                   fetcherService:(GTMSessionFetcherService *)service
                       completion:(FIRStorageVoidURLError)completion {
  self = [super initWithReference:reference fetcherService:service];
  if (self) {
    _completion = [completion copy];
  }
  return self;
}

- (void)dealloc {
  [_fetcher stopFetching];
}

+ (NSURL *)downloadURLFromMetadataDictionary:(NSDictionary *)dictionary {
  NSString *downloadTokens = dictionary[kFIRStorageMetadataDownloadTokens];

  if (downloadTokens && downloadTokens.length > 0) {
    NSArray<NSString *> *downloadTokenArray = [downloadTokens componentsSeparatedByString:@","];
    NSString *bucket = dictionary[kFIRStorageMetadataBucket];
    NSString *path = dictionary[kFIRStorageMetadataName];
    NSString *fullPath = [NSString stringWithFormat:kFIRStorageFullPathFormat, bucket,
                                                    [FIRStorageUtils GCSEscapedString:path]];

    NSURLComponents *components = [[NSURLComponents alloc] init];
    components.scheme = kFIRStorageScheme;
    components.host = kFIRStorageHost;
    components.percentEncodedPath = fullPath;

    // The backend can return an arbitrary number of download tokens, but we only expose the first
    // token via the download URL.
    NSURLQueryItem *altItem = [[NSURLQueryItem alloc] initWithName:@"alt" value:@"media"];
    NSURLQueryItem *tokenItem =
        [[NSURLQueryItem alloc] initWithName:@"token" value:downloadTokenArray[0]];
    components.queryItems = @[ altItem, tokenItem ];

    return [components URL];
  }

  return nil;
}

- (void)enqueue {
  NSMutableURLRequest *request = [self.baseRequest mutableCopy];
  request.HTTPMethod = @"GET";
  request.timeoutInterval = self.reference.storage.maxOperationRetryTime;

  FIRStorageVoidURLError callback = _completion;
  _completion = nil;

  GTMSessionFetcher *fetcher = [self.fetcherService fetcherWithRequest:request];
  _fetcher = fetcher;
  fetcher.comment = @"GetDownloadURLTask";

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-retain-cycles"
  _fetcherCompletion = ^(NSData *data, NSError *error) {
    NSURL *downloadURL;
    if (error) {
      if (!self.error) {
        self.error = [FIRStorageErrors errorWithServerError:error reference:self.reference];
      }
    } else {
      NSDictionary *responseDictionary = [NSDictionary frs_dictionaryFromJSONData:data];
      if (responseDictionary != nil) {
        downloadURL =
            [FIRStorageGetDownloadURLTask downloadURLFromMetadataDictionary:responseDictionary];
        if (!downloadURL) {
          self.error =
              [FIRStorageErrors errorWithCustomMessage:@"Failed to retrieve a download URL."];
        }
      } else {
        self.error = [FIRStorageErrors errorWithInvalidRequest:data];
      }
    }

    if (callback) {
      callback(downloadURL, self.error);
    }

    self->_fetcherCompletion = nil;
  };
#pragma clang diagnostic pop

  __weak FIRStorageGetDownloadURLTask *weakSelf = self;
  [fetcher beginFetchWithCompletionHandler:^(NSData *data, NSError *error) {
    weakSelf.fetcherCompletion(data, error);
  }];
}

@end