[ios] Introduce API Client

Addresses https://github.com/mapbox/mapbox-gl-native/issues/3704

This introduces a new utility class that wraps networking via
NSURLSession. All related code that used to live inside the telemetry
MGLMapboxEvents class has been pulled into the new MGLAPIClient.
An API client instance is used as a service by telemetry and can be
reused in the future when and if our networking needs grow or become
more complex.

1 files changed, 33 insertions, 165 deletions

diff --git a/platform/ios/src/MGLMapboxEvents.m b/platform/ios/src/MGLMapboxEvents.m
index bec86fd399..7f4b632e8f 100644
--- a/platform/ios/src/MGLMapboxEvents.m
+++ b/platform/ios/src/MGLMapboxEvents.m
@@ -5,13 +5,12 @@
 #import "NSProcessInfo+MGLAdditions.h"
 #import "NSBundle+MGLAdditions.h"
 #import "NSException+MGLAdditions.h"
+#import "MGLAPIClient.h"
 
 #include <mbgl/platform/darwin/reachability.h>
 #include <sys/sysctl.h>
 
 static const NSUInteger version = 1;
-static NSString *const MGLMapboxEventsUserAgent = @"MapboxEventsiOS/1.1";
-static NSString *MGLMapboxEventsAPIBase = @"https://api.tiles.mapbox.com";
 
 NSString *const MGLEventTypeAppUserTurnstile = @"appUserTurnstile";
 NSString *const MGLEventTypeMapLoad = @"map.load";
@@ -94,16 +93,13 @@ const NSTimeInterval MGLFlushInterval = 60;
 
 @property (nonatomic) MGLMapboxEventsData *data;
 @property (nonatomic, copy) NSString *appBundleId;
-@property (nonatomic, copy) NSString *appName;
-@property (nonatomic, copy) NSString *appVersion;
-@property (nonatomic, copy) NSString *appBuildNumber;
 @property (nonatomic, copy) NSString *instanceID;
 @property (nonatomic, copy) NSString *dateForDebugLogFile;
 @property (nonatomic, copy) NSData *digicertCert;
 @property (nonatomic, copy) NSData *geoTrustCert;
 @property (nonatomic, copy) NSData *testServerCert;
 @property (nonatomic) NSDateFormatter *rfc3339DateFormatter;
-@property (nonatomic) NSURLSession *session;
+@property (nonatomic) MGLAPIClient *apiClient;
 @property (nonatomic) BOOL usesTestServer;
 @property (nonatomic) BOOL canEnableDebugLogging;
 @property (nonatomic, getter=isPaused) BOOL paused;
@@ -145,47 +141,16 @@ const NSTimeInterval MGLFlushInterval = 60;
     self = [super init];
     if (self) {
         _appBundleId = [[NSBundle mainBundle] bundleIdentifier];
-        _appName = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleName"];
-        _appVersion = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"];
-        _appBuildNumber = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"];
         _instanceID = [[NSUUID UUID] UUIDString];
+        _apiClient = [[MGLAPIClient alloc] init];
 
         NSString *uniqueID = [[NSProcessInfo processInfo] globallyUniqueString];
         _serialQueue = dispatch_queue_create([[NSString stringWithFormat:@"%@.%@.events.serial", _appBundleId, uniqueID] UTF8String], DISPATCH_QUEUE_SERIAL);
 
-        // Configure Events Infrastructure
-        // ===============================
-
-        // Check for TEST Metrics URL
-        NSString *testURL = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"MGLMetricsTestServerURL"];
-        if (testURL != nil) {
-            MGLMapboxEventsAPIBase = testURL;
-            _usesTestServer = YES;
-        } else {
-            // Explicitly Set For Clarity
-            _usesTestServer = NO;
-        }
-
         _paused = YES;
         [self resumeMetricsCollection];
         NSBundle *resourceBundle = [NSBundle mgl_frameworkBundle];
 
-        // Load Local Copy of Server's Public Key
-        NSString *cerPath = nil;
-        cerPath = [resourceBundle pathForResource:@"api_mapbox_com-geotrust" ofType:@"der"];
-        if (cerPath != nil) {
-            _geoTrustCert = [NSData dataWithContentsOfFile:cerPath];
-        }
-
-        cerPath = [resourceBundle pathForResource:@"api_mapbox_com-digicert" ofType:@"der"];
-        if (cerPath != nil) {
-            _digicertCert = [NSData dataWithContentsOfFile:cerPath];
-        }
-        cerPath = [resourceBundle pathForResource:@"star_tilestream_net" ofType:@"der"];
-        if (cerPath != nil) {
-            _testServerCert = [NSData dataWithContentsOfFile:cerPath];
-        }
-
         // Events Control
         _eventQueue = [[NSMutableArray alloc] init];
         
@@ -313,8 +278,6 @@ const NSTimeInterval MGLFlushInterval = 60;
     self.timer = nil;
     [self.eventQueue removeAllObjects];
     self.data = nil;
-    [self.session invalidateAndCancel];
-    self.session = nil;
     
     [self validateUpdatingLocation];
 }
@@ -341,7 +304,6 @@ const NSTimeInterval MGLFlushInterval = 60;
     
     self.paused = NO;
     self.data = [[MGLMapboxEventsData alloc] init];
-    self.session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:nil];
     
     [self validateUpdatingLocation];
 }
@@ -429,16 +391,24 @@ const NSTimeInterval MGLFlushInterval = 60;
             return;
         }
         
-        NSDictionary *vevt = @{@"event" : MGLEventTypeAppUserTurnstile,
-                               @"created" : [strongSelf.rfc3339DateFormatter stringFromDate:[NSDate date]],
-                               @"appBundleId" : strongSelf.appBundleId,
-                               @"vendorId": vendorID,
-                               @"version": @(version),
-                               @"instance": strongSelf.instanceID};
-        
-        [strongSelf.eventQueue addObject:vevt];
-        [strongSelf flush];
-        [strongSelf writeEventToLocalDebugLog:vevt];
+        NSDictionary *turnstileEventAttributes = @{@"event" : MGLEventTypeAppUserTurnstile,
+                                                   @"created" : [strongSelf.rfc3339DateFormatter stringFromDate:[NSDate date]],
+                                                   @"appBundleId" : strongSelf.appBundleId,
+                                                   @"vendorId": vendorID,
+                                                   @"version": @(version),
+                                                   @"instance": strongSelf.instanceID};
+      
+        if ([MGLAccountManager accessToken] == nil) {
+            return;
+        }
+        [strongSelf.apiClient postEvent:turnstileEventAttributes completionHandler:^(NSError * _Nullable error) {
+            if (error) {
+                [MGLMapboxEvents pushDebugEvent:MGLEventTypeLocalDebug withAttributes:@{MGLEventKeyLocalDebugDescription: @"Network error",
+                                                                                        @"error": error}];
+                return;
+            }
+            [strongSelf writeEventToLocalDebugLog:turnstileEventAttributes];
+        }];
     });
 }
 
@@ -471,42 +441,22 @@ const NSTimeInterval MGLFlushInterval = 60;
 // Called implicitly from public use of +flush.
 //
 - (void)postEvents:(NS_ARRAY_OF(MGLMapboxEventAttributes *) *)events {
-    __weak MGLMapboxEvents *weakSelf = self;
-
+    if ([self isPaused]) {
+        return;
+    }
+    
+    __weak __typeof__(self) weakSelf = self;
     dispatch_async(self.serialQueue, ^{
-        MGLMapboxEvents *strongSelf = weakSelf;
-        
-        if (!strongSelf) {
-            return;
-        }
-
-        NSString *url = [NSString stringWithFormat:@"%@/events/v1?access_token=%@", MGLMapboxEventsAPIBase, [MGLAccountManager accessToken]];
-        NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:url]];
-        [request setValue:strongSelf.userAgent forHTTPHeaderField:@"User-Agent"];
-        [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
-        [request setHTTPMethod:@"POST"];
-        
-        if ([NSJSONSerialization isValidJSONObject:events]) {
-            NSData *jsonData = [NSJSONSerialization dataWithJSONObject:events options:NSJSONWritingPrettyPrinted error:nil];
-            [request setHTTPBody:jsonData];
-
-            if (!strongSelf.paused) {
-                [[strongSelf.session dataTaskWithRequest:request] resume];
-            } else {
-                for (MGLMapboxEventAttributes *event in events) {
-                    if ([event[@"event"] isEqualToString:MGLEventTypeAppUserTurnstile]) {
-                        NSURLSession *temporarySession = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]
-                                                                                       delegate:strongSelf
-                                                                                  delegateQueue:nil];
-                        [[temporarySession dataTaskWithRequest:request] resume];
-                        [temporarySession finishTasksAndInvalidate];
-                    }
-                }
+        __strong __typeof__(weakSelf) strongSelf = weakSelf;
+        [self.apiClient postEvents:events completionHandler:^(NSError * _Nullable error) {
+            if (error) {
+                [MGLMapboxEvents pushDebugEvent:MGLEventTypeLocalDebug withAttributes:@{MGLEventKeyLocalDebugDescription: @"Network error",
+                                                                                        @"error": error}];
+                return;
             }
-
             [MGLMapboxEvents pushDebugEvent:MGLEventTypeLocalDebug withAttributes:@{MGLEventKeyLocalDebugDescription: @"post",
                                                                                     @"debug.eventsCount": @(events.count)}];
-        }
+        }];
     });
 }
 
@@ -519,10 +469,6 @@ const NSTimeInterval MGLFlushInterval = 60;
                                                  repeats:YES];
 }
 
-- (NSString *)userAgent {
-    return [NSString stringWithFormat:@"%@/%@/%@ %@", self.appName, self.appVersion, self.appBuildNumber, MGLMapboxEventsUserAgent];
-}
-
 - (NSInteger)batteryLevel {
     return [[NSNumber numberWithFloat:100 * [UIDevice currentDevice].batteryLevel] integerValue];
 }
@@ -694,84 +640,6 @@ const NSTimeInterval MGLFlushInterval = 60;
     [self validateUpdatingLocation];
 }
 
-#pragma mark NSURLSessionDelegate
-
-- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^) (NSURLSessionAuthChallengeDisposition disposition, NSURLCredential *credential))completionHandler {
-
-    if([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
-
-        SecTrustRef serverTrust = [[challenge protectionSpace] serverTrust];
-        SecTrustResultType trustResult;
-
-        // Validate the certificate chain with the device's trust store anyway
-        // This *might* give use revocation checking
-        SecTrustEvaluate(serverTrust, &trustResult);
-        if (trustResult == kSecTrustResultUnspecified)
-        {
-            // Look for a pinned certificate in the server's certificate chain
-            long numKeys = SecTrustGetCertificateCount(serverTrust);
-
-            BOOL found = NO;
-            // Try GeoTrust Cert First
-            for (int lc = 0; lc < numKeys; lc++) {
-                SecCertificateRef certificate = SecTrustGetCertificateAtIndex(serverTrust, lc);
-                NSData *remoteCertificateData = CFBridgingRelease(SecCertificateCopyData(certificate));
-
-                // Compare Remote Key With Local Version
-                if ([remoteCertificateData isEqualToData:_geoTrustCert]) {
-                    // Found the certificate; continue connecting
-                    completionHandler(NSURLSessionAuthChallengeUseCredential, [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust]);
-                    found = YES;
-                    break;
-                }
-            }
-
-            if (!found) {
-                // Fallback to Digicert Cert
-                for (int lc = 0; lc < numKeys; lc++) {
-                    SecCertificateRef certificate = SecTrustGetCertificateAtIndex(serverTrust, lc);
-                    NSData *remoteCertificateData = CFBridgingRelease(SecCertificateCopyData(certificate));
-
-                    // Compare Remote Key With Local Version
-                    if ([remoteCertificateData isEqualToData:_digicertCert]) {
-                        // Found the certificate; continue connecting
-                        completionHandler(NSURLSessionAuthChallengeUseCredential, [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust]);
-                        found = YES;
-                        break;
-                    }
-                }
-
-                if (!found && _usesTestServer) {
-                    // See if this is test server
-                    for (int lc = 0; lc < numKeys; lc++) {
-                        SecCertificateRef certificate = SecTrustGetCertificateAtIndex(serverTrust, lc);
-                        NSData *remoteCertificateData = CFBridgingRelease(SecCertificateCopyData(certificate));
-
-                        // Compare Remote Key With Local Version
-                        if ([remoteCertificateData isEqualToData:_testServerCert]) {
-                            // Found the certificate; continue connecting
-                            completionHandler(NSURLSessionAuthChallengeUseCredential, [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust]);
-                            found = YES;
-                            break;
-                        }
-                    }
-                }
-
-                if (!found) {
-                    // The certificate wasn't found in GeoTrust nor Digicert. Cancel the connection.
-                    completionHandler(NSURLSessionAuthChallengeCancelAuthenticationChallenge, [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust]);
-                }
-            }
-        }
-        else
-        {
-            // Certificate chain validation failed; cancel the connection
-            completionHandler(NSURLSessionAuthChallengeCancelAuthenticationChallenge, [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust]);
-        }
-    }
-
-}
-
 #pragma mark MGLMapboxEvents Debug
 
 + (void)pushDebugEvent:(NSString *)event withAttributes:(MGLMapboxEventAttributes *)attributeDictionary {