//  LocalyticsUploader.m
//  Copyright (C) 2013 Char Software Inc., DBA Localytics
//
//  This code is provided under the Localytics Modified BSD License.
//  A copy of this license has been distributed in a file called LICENSE
//  with this source code.
//
// Please visit www.localytics.com for more information.

#import "LocalyticsUploader.h"
#import "LocalyticsSession.h"
#import "LocalyticsSession+Private.h"
#import "LocalyticsDatabase.h"
#import "WebserviceConstants.h"
#import <zlib.h>

#ifndef LOCALYTICS_URL
#define LOCALYTICS_URL           @"http://analytics.localytics.com/api/v2/applications/%@/uploads"
#endif

#ifndef LOCALYTICS_URL_SECURED
#define LOCALYTICS_URL_SECURED   @"https://analytics.localytics.com/api/v2/applications/%@/uploads"
#endif

NSString * const kLocalyticsKeyResponseBody = @"localytics.key.responseBody";

@interface LocalyticsUploader ()
- (void)finishUpload;
- (NSData *)gzipDeflatedDataWithData:(NSData *)data;

@property (readwrite) BOOL isUploading;

@end

@implementation LocalyticsUploader
@synthesize isUploading = _isUploading;

#pragma mark - Class Methods

- (void)uploaderWithApplicationKey:(NSString *)localyticsApplicationKey useHTTPS:(BOOL)useHTTPS installId:(NSString *)installId libraryVersion:(NSString *)libraryVersion
{
	[self uploaderWithApplicationKey:localyticsApplicationKey useHTTPS:useHTTPS installId:installId libraryVersion:libraryVersion resultTarget:nil callback:NULL];
}


- (void)uploaderWithApplicationKey:(NSString *)localyticsApplicationKey useHTTPS:(BOOL)useHTTPS installId:(NSString *)installId libraryVersion:(NSString *)libraryVersion resultTarget:(id)target callback:(SEL)callbackMethod
{
	
	// Do nothing if already uploading.
	if (self.isUploading == true)
	{
		LocalyticsLog("Upload already in progress.  Aborting.");
		return;
	}
	
	LocalyticsLog("Beginning upload process");
	self.isUploading = true;
	
	// Prepare the data for upload.  The upload could take a long time, so some effort has to be made to be sure that events
	// which get written while the upload is taking place don't get lost or duplicated.  To achieve this, the logic is:
	// 1) Append every header row blob string and and those of its associated events to the upload string.
	// 2) Deflate and upload the data.
	// 3) On success, delete all blob headers and staged events. Events added while an upload is in process are not
	//    deleted because they are not associated a header (and cannot be until the upload completes).
	
	// Step 1
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	
	LocalyticsDatabase *db = [[LocalyticsSession shared] db];
	NSString *blobString = [db uploadBlobString];
	
	if ([blobString length] == 0) {
		// There is nothing outstanding to upload.
		LocalyticsLog("Abandoning upload. There are no new events.");
		[pool drain];
		[self finishUpload];
		
		return;
	}
	
	NSData *requestData = [blobString dataUsingEncoding:NSUTF8StringEncoding];
	if(LOCALYTICS_LOGGING_ENABLED) {
		NSString *logString = [[[NSString alloc] initWithData:requestData
													 encoding:NSUTF8StringEncoding] autorelease];
		NSUInteger stringLength = [logString length];
		
		logString = [logString stringByReplacingOccurrencesOfString:@"{"
														 withString:@"\n\t{"];
		logString = [logString stringByReplacingOccurrencesOfString:@",\""
														 withString:@",\n\t\""];
		
		LocalyticsLog("Uploading data (length: %u)\n%@",
					  stringLength,
					  logString);
	}
	
	// Step 2
	NSData *deflatedRequestData = [[self gzipDeflatedDataWithData:requestData] retain];
	
	[pool drain];
	
	NSString *urlStringFormat;
	if (useHTTPS) {
		urlStringFormat = LOCALYTICS_URL_SECURED;
	} else {
		urlStringFormat = LOCALYTICS_URL;
	}
	NSURL *apiUrl = [NSURL URLWithString:[NSString stringWithFormat:urlStringFormat,[localyticsApplicationKey stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]];
	NSMutableURLRequest *submitRequest = [self createRequestWithURL:apiUrl
														  installId:installId
													 libraryVersion:libraryVersion
														requestData:deflatedRequestData];
	
	[deflatedRequestData release];
	
	// Perform synchronous upload in an async dispatch. This is necessary because the calling block will not persist to
	// receive the response data.
	dispatch_group_async([[LocalyticsSession shared] criticalGroup], [[LocalyticsSession shared] queue], ^{
		@try  {
			NSURLResponse *response = nil;
			NSError *responseError = nil;
			NSData  *responseData = [NSURLConnection sendSynchronousRequest:submitRequest returningResponse:&response error:&responseError];
			NSInteger responseStatusCode = [(NSHTTPURLResponse *)response statusCode];
			
			if (responseError) {
				// On error, simply print the error and close the uploader.  We have to assume the data was not transmited
				// so it is not deleted.  In the event that we accidently store data which was succesfully uploaded, the
				// duplicate data will be ignored by the server when it is next uploaded.
				LocalyticsLog("Error Uploading.  Code: %d,  Description: %@",
							  [responseError code],
							  [responseError localizedDescription]);
			} else {
				// Step 3
				// While response status codes in the 5xx range leave upload rows intact, the default case is to delete.
				if (responseStatusCode >= 500 && responseStatusCode < 600) {
					LocalyticsLog("Upload failed with response status code %d", responseStatusCode);
				} else {
					// Because only one instance of the uploader can be running at a time it should not be possible for
					// new upload rows to appear so there is no fear of deleting data which has not yet been uploaded.
					LocalyticsLog("Upload completed successfully. Response code %d", responseStatusCode);
					[[[LocalyticsSession shared] db] deleteUploadedData];
				}
			}
			
			if ([responseData length] > 0) {
				if (LOCALYTICS_LOGGING_ENABLED) {
					NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
					LocalyticsLog("Response body: %@", responseString);
					[responseString release];
				}
				NSDictionary *userInfo = [NSDictionary dictionaryWithObject:responseData forKey:kLocalyticsKeyResponseBody];
				if (target) {
					[target performSelector:callbackMethod withObject:userInfo];
				}
			}
			
			[self finishUpload];
		}
		@catch (NSException * e) {}
	});
}

- (NSMutableURLRequest *)createRequestWithURL:(NSURL *)URL installId:(NSString *)installId libraryVersion:(NSString *)libraryVersion requestData:(NSData *)requestData
{
	
	NSMutableURLRequest *submitRequest = [NSMutableURLRequest requestWithURL:URL
																 cachePolicy:NSURLRequestReloadIgnoringCacheData
															 timeoutInterval:60.0];
	[submitRequest setHTTPMethod:@"POST"];
	[submitRequest setValue:[self uploadTimeStamp] forHTTPHeaderField:HEADER_CLIENT_TIME];
	[submitRequest setValue:installId forHTTPHeaderField:HEADER_INSTALL_ID];
	[submitRequest setValue:libraryVersion forHTTPHeaderField:HEADER_CLIENT_VERSION];
	[submitRequest setValue:@"application/x-gzip" forHTTPHeaderField:@"Content-Type"];
	[submitRequest setValue:@"gzip" forHTTPHeaderField:@"Content-Encoding"];
	[submitRequest setValue:[NSString stringWithFormat:@"%d", requestData.length] forHTTPHeaderField:@"Content-Length"];
	
	[submitRequest setHTTPBody:requestData];
	
	return submitRequest;
}

- (void)finishUpload
{
	self.isUploading = false;
	
	// Upload data has been deleted. Recover the disk space if necessary.
	[[[LocalyticsSession shared] db] vacuumIfRequired];
}

/*!
 @method gzipDeflatedDataWithData
 @abstract Deflates the provided data using gzip at the default compression level (6).
 @return the deflated data
 */
- (NSData *)gzipDeflatedDataWithData:(NSData *)data
{
	if ([data length] == 0) return data;
	
	z_stream strm;
	
	strm.zalloc = Z_NULL;
	strm.zfree = Z_NULL;
	strm.opaque = Z_NULL;
	strm.total_out = 0;
	strm.next_in=(Bytef *)[data bytes];
	strm.avail_in = [data length];
	
	// Compresssion Levels:
	//   Z_NO_COMPRESSION
	//   Z_BEST_SPEED
	//   Z_BEST_COMPRESSION
	//   Z_DEFAULT_COMPRESSION
	
	if (deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (15+16), 8, Z_DEFAULT_STRATEGY) != Z_OK) return nil;
	
	NSMutableData *compressed = [NSMutableData dataWithLength:16384];  // 16K chunks for expansion
	
	do {
		
		if (strm.total_out >= [compressed length])
			[compressed increaseLengthBy: 16384];
		
		strm.next_out = [compressed mutableBytes] + strm.total_out;
		strm.avail_out = [compressed length] - strm.total_out;
		
		deflate(&strm, Z_FINISH);
		
	} while (strm.avail_out == 0);
	
	deflateEnd(&strm);
	
	[compressed setLength: strm.total_out];
	return [NSData dataWithData:compressed];
}

/*!
 @method uploadTimeStamp
 @abstract Gets the current time, along with local timezone, formatted as a DateTime for the webservice.
 @return a DateTime of the current local time and timezone.
 */
- (NSString *)uploadTimeStamp {
	return [ NSString stringWithFormat:@"%ld", (long)[[NSDate date] timeIntervalSince1970] ];
}

#pragma mark - System Functions

- (id)copyWithZone:(NSZone *)zone {
#pragma unused(zone)
	return self;
}

- (id)retain {
	return self;
}

- (unsigned)retainCount {
	// maximum value of an unsigned int - prevents additional retains for the class
	return UINT_MAX;
}

- (oneway void)release {
	// ignore release commands
}

- (id)autorelease {
	return self;
}

@end