//
//  MAURBackgroundSync.m
//
//  Created by Marian Hello on 07/07/16.
//  Copyright © 2016 mauron85. All rights reserved.
//

#import "UIKit/UIKit.h"
#import "MAURLogging.h"
#import "MAURBackgroundSync.h"
#import "MAURSQLiteLocationDAO.h"

@interface MAURBackgroundSync ()  <NSURLSessionDelegate, NSURLSessionTaskDelegate>
{
    NSURLSession *urlSession;
    NSMutableArray *tasks;
}
@end

@implementation MAURBackgroundSync

- (instancetype) init
{
    if(!(self = [super init])) return nil;
    
    NSURLSessionConfiguration *conf = [NSURLSessionConfiguration backgroundSessionConfiguration:@"com.marianhello.session"];
    conf.allowsCellularAccess = YES;
    urlSession = [NSURLSession sessionWithConfiguration:conf delegate:self delegateQueue:[NSOperationQueue mainQueue]];
    
    return self;
}

- (void)start
{
    __block UIBackgroundTaskIdentifier bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
        [[UIApplication sharedApplication] endBackgroundTask:bgTask];
    }];    
    
    [urlSession getTasksWithCompletionHandler:^(NSArray *dataTasks, NSArray *uploadTasks, NSArray *downloadTasks) {
        for(NSURLSessionUploadTask *task in uploadTasks) {
            DDLogInfo(@"Restored upload task %zu for %@", (unsigned long)task.taskIdentifier, task.originalRequest.URL);
            [tasks addObject:task];
            [task resume];
        }
        
        [[UIApplication sharedApplication] endBackgroundTask:bgTask];
    }];
}

- (void)cancel
{
    for(NSURLSessionTask *task in tasks) {
        [task cancel];
    }
}

- (void) sync:(NSString * _Nonnull)url withTemplate:(id)locationTemplate withHttpHeaders:(NSMutableDictionary * _Nullable)httpHeaders
{
    MAURSQLiteLocationDAO* locationDAO = [MAURSQLiteLocationDAO sharedInstance];
    NSArray *locations = [locationDAO getLocationsForSync];
    
    NSMutableArray *jsonArray = [[NSMutableArray alloc] initWithCapacity:[locations count]];
    for (MAURLocation *location in locations) {
        [jsonArray addObject:[location toResultFromTemplate:locationTemplate]];
    }
    
    NSError *error = nil;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsonArray options:0 error:&error];
    
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    dateFormatter.locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"];
    dateFormatter.dateFormat = @"yyyyMMdd_HHmms";
    dateFormatter.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];
    NSString *fileName = [NSString stringWithFormat:@"locations_%@.json", [dateFormatter stringFromDate:[NSDate date]]];
    NSURL *jsonUrl = [NSURL fileURLWithPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0] stringByAppendingPathComponent:fileName]];
    [jsonData writeToFile:jsonUrl.path atomically:NO];
    uint64_t bytesTotalForThisFile = [[[NSFileManager defaultManager] attributesOfItemAtPath:jsonUrl.path error:nil] fileSize];
    
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:url]];
    [request setHTTPMethod:@"POST"];
    [request setValue:[NSString stringWithFormat:@"%llu", bytesTotalForThisFile] forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    
    if (httpHeaders != nil) {
        for(id key in httpHeaders) {
            id value = [httpHeaders objectForKey:key];
            [request addValue:value forHTTPHeaderField:key];
        }
    }
    NSURLSessionTask *task = [urlSession uploadTaskWithRequest:request fromFile:jsonUrl];
    task.taskDescription = fileName;
    [tasks addObject:task];
    DDLogInfo(@"Started upload for %@ as task %zu/%@/%@", jsonUrl.lastPathComponent, (unsigned long)task.taskIdentifier, task.taskDescription, task);
    [task resume];
    
}

// http://stackoverflow.com/a/572623/48125
NSString *stringFromFileSize(unsigned long long theSize)
{
    double floatSize = theSize;
    if (theSize<1023)
        return([NSString stringWithFormat:@"%lli bytes",theSize]);
    floatSize = floatSize / 1024;
    if (floatSize<1023)
        return([NSString stringWithFormat:@"%1.1f KB",floatSize]);
    floatSize = floatSize / 1024;
    if (floatSize<1023)
        return([NSString stringWithFormat:@"%1.1f MB",floatSize]);
    floatSize = floatSize / 1024;
    
    return([NSString stringWithFormat:@"%1.1f GB",floatSize]);
}

- (NSString*)status
{
    int64_t sent = 0, toSend = 0;
    for(NSURLSessionUploadTask *task in tasks) {
        sent += task.countOfBytesSent;
        toSend += task.countOfBytesExpectedToSend;
    }
    return [NSString stringWithFormat:@"%@ being uploaded (%@ of %@)\nFiles on disk: %@",
        [tasks valueForKeyPath:@"taskDescription"],
        stringFromFileSize(sent),
        stringFromFileSize(toSend),

        [[NSFileManager defaultManager]
         contentsOfDirectoryAtPath:NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0]
         error:NULL]
    ];
}


#pragma mark -
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(nullable NSError *)error
{
    NSInteger statusCode = [(NSHTTPURLResponse *)task.response statusCode];
    
    DDLogInfo(@"Finished uploading task %zu %@: %@ %@, HTTP %ld", (unsigned long)[task taskIdentifier], task.originalRequest.URL, error ?: @"Success", task.response, (long)statusCode);
    
    [tasks removeObject:task];
    NSURL *fullPath = [NSURL fileURLWithPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0] stringByAppendingPathComponent:task.taskDescription]];
    [[NSFileManager defaultManager] removeItemAtURL:fullPath error:NULL];
    
    if (statusCode == 285)
    {
        // Okay, but we don't need to continue sending these
        DDLogDebug(@"Locations were uploaded to the server, and received an \"HTTP 285 Updates Not Required\"");
        
        dispatch_async(dispatch_get_main_queue(), ^{
            if (_delegate && [_delegate respondsToSelector:@selector(backgroundSyncRequestedAbortUpdates:)])
            {
                [_delegate backgroundSyncRequestedAbortUpdates:self];
            }
        });
    }

    if (statusCode == 401)
    {   
        dispatch_async(dispatch_get_main_queue(), ^{
            if (_delegate && [_delegate respondsToSelector:@selector(backgroundSyncHttpAuthorizationUpdates:)])
            {
                [_delegate backgroundSyncHttpAuthorizationUpdates:self];
            }
        });
    }
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data
{
    DDLogInfo(@"Response:: %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
}

- (void)URLSession:(NSURLSession *)session didBecomeInvalidWithError:(nullable NSError *)error
{
    DDLogError(@"Autosync failed :( %@", error);
}

- (void)URLSessionDidFinishEventsForBackgroundURLSession:(NSURLSession *)session
{
    DDLogInfo(@"finished events for bg session");
}

@end