#import "BITChannel.h"

#if HOCKEYSDK_FEATURE_TELEMETRY

#import "BITHockeyHelper.h"
#import "HockeySDK.h"
#import "BITTelemetryContext.h"
#import "BITTelemetryData.h"
#import "HockeySDKPrivate.h"
#import "BITOrderedDictionary.h"
#import "BITEnvelope.h"
#import "BITData.h"
#import "BITDevice.h"
#import "BITPersistencePrivate.h"

static char *const BITDataItemsOperationsQueue = "net.hockeyapp.senderQueue";
char *BITSafeJsonEventsString;

NSInteger const defaultMaxBatchCount  = 1;
static NSInteger const schemaVersion  = 2;

@implementation BITChannel

@synthesize persistence = _persistence;

#pragma mark - Initialisation

- (instancetype)init {
  if(self = [super init]) {
    bit_resetSafeJsonStream(&BITSafeJsonEventsString);
    _dataItemCount = 0;
    dispatch_queue_t serialQueue = dispatch_queue_create(BITDataItemsOperationsQueue, DISPATCH_QUEUE_SERIAL);
    _dataItemsOperations = serialQueue;
  }
  return self;
}

- (instancetype)initWithTelemetryContext:(BITTelemetryContext *)telemetryContext persistence:(BITPersistence *) persistence {
  if(self = [self init]) {
    _telemetryContext = telemetryContext;
    _persistence = persistence;
  }
  return self;
}

#pragma mark - Queue management

- (BOOL)isQueueBusy{
  
  [self.persistence isFreeSpaceAvailable];
  return true;
}

- (void)persistDataItemQueue {
  if(!BITSafeJsonEventsString || strlen(BITSafeJsonEventsString) == 0) {
    return;
  }
  
  NSData *bundle = [NSData dataWithBytes:BITSafeJsonEventsString length:strlen(BITSafeJsonEventsString)];
  [self.persistence persistBundle:bundle];
  
  // Reset both, the async-signal-safe and item counter.
  [self resetQueue];
}

- (void)resetQueue {
  bit_resetSafeJsonStream(&BITSafeJsonEventsString);
  _dataItemCount = 0;
}

#pragma mark - Adding to queue

- (void)enqueueTelemetryItem:(BITTelemetryData *)item {
  if(item) {
    BITOrderedDictionary *dict = [self dictionaryForTelemetryData:item];
    __weak typeof(self) weakSelf = self;
    
    dispatch_async(self.dataItemsOperations, ^{
      typeof(self) strongSelf = weakSelf;
      
      // Enqueue item
      [strongSelf appendDictionaryToJsonStream:dict];
      
      if(strongSelf->_dataItemCount >= self.maxBatchCount) {
        // Max batch count has been reached, so write queue to disk and delete all items.
        [strongSelf persistDataItemQueue];
        
      }
    });
  }
}

#pragma mark - Envelope telemerty items

- (BITOrderedDictionary *)dictionaryForTelemetryData:(BITTelemetryData *) telemetryData {
  
  BITEnvelope *envelope = [self envelopeForTelemetryData:telemetryData];
  BITOrderedDictionary *dict = [envelope serializeToDictionary];
  return dict;
}

- (BITEnvelope *)envelopeForTelemetryData:(BITTelemetryData *)telemetryData {
  telemetryData.version = @(schemaVersion);
  
  BITData *data = [BITData new];
  data.baseData = telemetryData;
  data.baseType = telemetryData.dataTypeName;
  
  BITEnvelope *envelope = [BITEnvelope new];
  envelope.appId = bit_mainBundleIdentifier();
  envelope.appVer = _telemetryContext.application.version;
  envelope.time = bit_utcDateString([NSDate date]);
  envelope.iKey = _telemetryContext.appIdentifier;
  
  BITDevice *deviceContext = _telemetryContext.device;
  if (deviceContext.deviceId) {
    envelope.deviceId = deviceContext.deviceId;
  }
  if (deviceContext.os) {
    envelope.os = deviceContext.os;
  }
  if (deviceContext.osVersion) {
    envelope.osVer = deviceContext.osVersion;
  }
  
  envelope.tags = _telemetryContext.contextDictionary;
  envelope.data = data;
  envelope.name = telemetryData.envelopeTypeName;
  
  return envelope;
}

#pragma mark - Serialization Helper

- (NSString *)serializeDictionaryToJSONString:(BITOrderedDictionary *)dictionary {
  NSError *error;
  NSData *data = [NSJSONSerialization dataWithJSONObject:dictionary options:(NSJSONWritingOptions)0 error:&error];
  if (!data) {
    BITHockeyLog(@"ERROR: JSONSerialization error: %@", error.localizedDescription);
    return @"{}";
  } else {
    return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
  }
}

#pragma mark JSON Stream

- (void)appendDictionaryToJsonStream:(BITOrderedDictionary *)dictionary {
  if(dictionary) {
    NSString *string = [self serializeDictionaryToJSONString:dictionary];
    
    // Since we can't persist every event right away, we write it to a simple C string.
    // This can then be written to disk by a signal handler in case of a crash.
    bit_appendStringToSafeJsonStream(string, &(BITSafeJsonEventsString));
    _dataItemCount += 1;
  }
}

void bit_appendStringToSafeJsonStream(NSString *string, char **jsonString) {
  if (jsonString == NULL) { return; }
  
  if (!string) { return; }
  
  if (*jsonString == NULL || strlen(*jsonString) == 0) {
    bit_resetSafeJsonStream(jsonString);
  }
  
  if (string.length == 0) { return; }
  
  char *new_string = NULL;
  // Concatenate old string with new JSON string and add a comma.
  asprintf(&new_string, "%s%.*s\n", *jsonString, (int)MIN(string.length, (NSUInteger)INT_MAX), string.UTF8String);
  free(*jsonString);
  *jsonString = new_string;
}

void bit_resetSafeJsonStream(char **string) {
  if (!string) { return; }
  free(*string);
  *string = strdup("");
}

#pragma mark - Batching

- (NSInteger)maxBatchCount {
  if(_maxBatchCount <= 0){
    return defaultMaxBatchCount;
  }
  return _maxBatchCount;
}

@end

#endif /* HOCKEYSDK_FEATURE_TELEMETRY */