HTTP Paginated Response

Source/ARTConstants.h

@@ -0,0 +1,12 @@
+//
+//  ARTConstants.h
+//  Ably
+//
+//  Created by Ricardo Pereira on 23/08/2018.
+//  Copyright © 2018 Ably. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+extern NSString *const ARTHttpHeaderFieldErrorCodeKey;
+extern NSString *const ARTHttpHeaderFieldErrorMessageKey;

Source/ARTConstants.m

@@ -0,0 +1,13 @@
+//
+//  ARTConstants.m
+//  Ably
+//
+//  Created by Ricardo Pereira on 23/08/2018.
+//  Copyright © 2018 Ably. All rights reserved.
+//
+
+#import "ARTConstants.h"
+
+NSString *const ARTHttpHeaderFieldErrorCodeKey = @"X-Ably-Errorcode";
+NSString *const ARTHttpHeaderFieldErrorMessageKey = @"X-Ably-Errormessage";
+

Source/ARTHTTPPaginatedResponse+Private.h

@@ -0,0 +1,23 @@
+//
+//  ARTHTTPPaginatedResponse+Private.h
+//  Ably
+//
+//  Created by Yavor Georgiev on 28.08.15.
+//  Copyright (c) 2015 г. Ably. All rights reserved.
+//
+
+#import <Ably/ARTHTTPPaginatedResponse.h>
+
+@class ARTRest;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface ARTHTTPPaginatedResponse ()
+
++ (void)executePaginated:(ARTRest *)rest withRequest:(NSMutableURLRequest *)request andResponseProcessor:(ARTPaginatedResultResponseProcessor)responseProcessor callback:(void (^)(ARTPaginatedResult * _Nullable, ARTErrorInfo * _Nullable))callback UNAVAILABLE_ATTRIBUTE;
+
++ (void)executePaginated:(ARTRest *)rest withRequest:(NSMutableURLRequest *)request callback:(void (^)(ARTHTTPPaginatedResponse *_Nullable result, ARTErrorInfo *_Nullable error))callback;
+
+@end
+
+NS_ASSUME_NONNULL_END

Source/ARTHTTPPaginatedResponse.h

@@ -0,0 +1,37 @@
+//
+//  ARTHTTPPaginatedResponse.h
+//  Ably
+//
+//  Created by Ricardo Pereira on 17/08/2018.
+//  Copyright © 2018 Ably. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+#import <Ably/ARTPaginatedResult.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface ARTHTTPPaginatedResponse : ARTPaginatedResult<NSDictionary *>
+
+/// Return the HTTP status code of the response
+@property (nonatomic, readonly) NSInteger statusCode;
+
+/// Returns true when the HTTP status code indicates success i.e. 200 <= statusCode < 300
+@property (nonatomic, readonly) BOOL success;
+
+/// Returns the error code if the X-Ably-Errorcode HTTP header is sent in the response
+@property (nonatomic, readonly) NSInteger errorCode;
+
+/// Returns error message if the X-Ably-Errormessage HTTP header is sent in the response
+@property (nullable, nonatomic, readonly) NSString *errorMessage;
+
+/// Returns a dictionary containing all the HTTP header fields of the response header.
+@property (nonatomic, readonly) NSDictionary<NSString *, NSString *> *headers;
+
+- (void)first:(void (^)(ARTHTTPPaginatedResponse * _Nullable, ARTErrorInfo * _Nullable))callback;
+- (void)next:(void (^)(ARTHTTPPaginatedResponse * _Nullable, ARTErrorInfo * _Nullable))callback;
+
+@end
+
+NS_ASSUME_NONNULL_END

Source/ARTHTTPPaginatedResponse.m

@@ -0,0 +1,139 @@
+//
+//  ARTHTTPPaginatedResponse.m
+//  Ably
+//
+//  Created by Ricardo Pereira on 17/08/2018.
+//  Copyright © 2018 Ably. All rights reserved.
+//
+
+#import "ARTHTTPPaginatedResponse.h"
+
+#import "ARTHttp.h"
+#import "ARTAuth.h"
+#import "ARTRest+Private.h"
+#import "ARTPaginatedResult+Private.h"
+#import "ARTNSMutableURLRequest+ARTPaginated.h"
+#import "ARTNSHTTPURLResponse+ARTPaginated.h"
+#import "ARTEncoder.h"
+#import "ARTConstants.h"
+
+@implementation ARTHTTPPaginatedResponse {
+    NSHTTPURLResponse *_response;
+}
+
+- (instancetype)initWithResponse:(NSHTTPURLResponse *)response
+                           items:(NSArray *)items
+                            rest:(ARTRest *)rest
+                        relFirst:(NSMutableURLRequest *)relFirst
+                      relCurrent:(NSMutableURLRequest *)relCurrent
+                         relNext:(NSMutableURLRequest *)relNext
+               responseProcessor:(ARTPaginatedResultResponseProcessor)responseProcessor {
+    self = [super initWithItems:items rest:rest relFirst:relFirst relCurrent:relCurrent relNext:relNext responseProcessor:responseProcessor];
+    if (self) {
+        _response = response;
+    }
+    return self;
+}
+
+- (NSInteger)statusCode {
+    return _response.statusCode;
+}
+
+- (BOOL)success {
+    return _response.statusCode >= 200 && _response.statusCode < 300;
+}
+
+- (NSInteger)errorCode {
+    NSString *code = [_response.allHeaderFields valueForKey:ARTHttpHeaderFieldErrorCodeKey];
+    return [code integerValue];
+}
+
+- (NSString *)errorMessage {
+    NSString *message = [_response.allHeaderFields valueForKey:ARTHttpHeaderFieldErrorMessageKey];
+    return message;
+}
+
+- (NSDictionary<NSString *,NSString *> *)headers {
+    return _response.allHeaderFields;
+}
+
+- (void)first:(void (^)(ARTHTTPPaginatedResponse *_Nullable result, ARTErrorInfo *_Nullable error))callback {
+ART_TRY_OR_REPORT_CRASH_START(self.rest) {
+    if (callback) {
+        void (^userCallback)(ARTHTTPPaginatedResponse *_Nullable result, ARTErrorInfo *_Nullable error) = callback;
+        callback = ^(ARTHTTPPaginatedResponse *_Nullable result, ARTErrorInfo *_Nullable error) {
+            ART_EXITING_ABLY_CODE(self.rest);
+            dispatch_async(self.userQueue, ^{
+                userCallback(result, error);
+            });
+        };
+    }
+
+    [self.class executePaginated:self.rest withRequest:self.relFirst callback:callback];
+} ART_TRY_OR_REPORT_CRASH_END
+}
+
+- (void)next:(void (^)(ARTHTTPPaginatedResponse *_Nullable result, ARTErrorInfo *_Nullable error))callback {
+ART_TRY_OR_REPORT_CRASH_START(self.rest) {
+    if (callback) {
+        void (^userCallback)(ARTHTTPPaginatedResponse *_Nullable result, ARTErrorInfo *_Nullable error) = callback;
+        callback = ^(ARTHTTPPaginatedResponse *_Nullable result, ARTErrorInfo *_Nullable error) {
+            ART_EXITING_ABLY_CODE(self.rest);
+            dispatch_async(self.userQueue, ^{
+                userCallback(result, error);
+            });
+        };
+    }
+
+    if (!self.relNext) {
+        // If there is no next page, we can't make a request, so we answer the callback
+        // with a nil PaginatedResult. That's why the callback has the result as nullable
+        // anyway. (That, and that it can fail.)
+        callback(nil, nil);
+        return;
+    }
+
+    [self.class executePaginated:self.rest withRequest:self.relNext callback:callback];
+} ART_TRY_OR_REPORT_CRASH_END
+}
+
++ (void)executePaginated:(ARTRest *)rest withRequest:(NSMutableURLRequest *)request callback:(void (^)(ARTHTTPPaginatedResponse *_Nullable result, ARTErrorInfo *_Nullable error))callback {
+ART_TRY_OR_REPORT_CRASH_START(rest) {
+    [rest.logger debug:__FILE__ line:__LINE__ message:@"HTTP Paginated request: %@", request];
+
+    [rest executeRequest:request withAuthOption:ARTAuthenticationOn completion:^(NSHTTPURLResponse *response, NSData *data, NSError *error) {
+        if (error && ![error.domain isEqualToString:ARTAblyErrorDomain]) {
+            callback(nil, [ARTErrorInfo createFromNSError:error]);
+            return;
+        }
+
+        [[rest logger] debug:__FILE__ line:__LINE__ message:@"HTTP Paginated response: %@", response];
+        [[rest logger] debug:__FILE__ line:__LINE__ message:@"HTTP Paginated response data: %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]];
+
+        NSError *decodeError = nil;
+
+        ARTPaginatedResultResponseProcessor responseProcessor = ^(NSHTTPURLResponse *response, NSData *data, NSError **errorPtr) {
+            id<ARTEncoder> encoder = [rest.encoders objectForKey:response.MIMEType];
+            return [encoder decodeToArray:data error:errorPtr];
+        };
+        NSArray *items = error ? nil : responseProcessor(response, data, &decodeError);
+
+        if (decodeError) {
+            callback(nil, [ARTErrorInfo createFromNSError:decodeError]);
+            return;
+        }
+
+        NSDictionary *links = [response extractLinks];
+
+        NSMutableURLRequest *firstRel = [NSMutableURLRequest requestWithPath:links[@"first"] relativeTo:request];
+        NSMutableURLRequest *currentRel = [NSMutableURLRequest requestWithPath:links[@"current"] relativeTo:request];
+        NSMutableURLRequest *nextRel = [NSMutableURLRequest requestWithPath:links[@"next"] relativeTo:request];
+
+        ARTHTTPPaginatedResponse *result = [[ARTHTTPPaginatedResponse alloc] initWithResponse:response items:items rest:rest relFirst:firstRel relCurrent:currentRel relNext:nextRel responseProcessor:responseProcessor];
+
+        callback(result, nil);
+    }];
+} ART_TRY_OR_REPORT_CRASH_END
+}
+
+@end

Source/ARTHttp.m

@@ -8,6 +8,7 @@
 
 #import "ARTHttp.h"
 #import "ARTURLSessionServerTrust.h"
+#import "ARTConstants.h"
 
 @interface ARTHttp ()
 
@@ -51,7 +52,7 @@ - (void)executeRequest:(NSMutableURLRequest *)request completion:(void (^)(NSHTT
         } else {
             [self.logger debug:@"%@ %@: statusCode %ld", request.HTTPMethod, request.URL.absoluteString, (long)httpResponse.statusCode];
             [self.logger verbose:@"Headers %@", httpResponse.allHeaderFields];
-            NSString *headerErrorMessage = httpResponse.allHeaderFields[@"X-Ably-ErrorMessage"];
+            NSString *headerErrorMessage = httpResponse.allHeaderFields[ARTHttpHeaderFieldErrorMessageKey];
             if (headerErrorMessage && ![headerErrorMessage isEqualToString:@""]) {
                 [self.logger warn:@"%@", headerErrorMessage];
             }

Source/ARTNSHTTPURLResponse+ARTPaginated.h

@@ -0,0 +1,19 @@
+//
+//  ARTNSHTTPURLResponse+ARTPaginated.h
+//  Ably
+//
+//  Created by Ricardo Pereira on 23/08/2018.
+//  Copyright © 2018 Ably. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface NSHTTPURLResponse (ARTPaginated)
+
+- (nullable NSDictionary *)extractLinks;
+
+@end
+
+NS_ASSUME_NONNULL_END

Source/ARTNSHTTPURLResponse+ARTPaginated.m

@@ -0,0 +1,44 @@
+//
+//  ARTNSHTTPURLResponse+ARTPaginated.m
+//  Ably
+//
+//  Created by Ricardo Pereira on 23/08/2018.
+//  Copyright © 2018 Ably. All rights reserved.
+//
+
+#import "ARTNSHTTPURLResponse+ARTPaginated.h"
+
+@implementation NSHTTPURLResponse (ARTPaginated)
+
+- (NSDictionary *)extractLinks {
+    NSString *linkHeader = self.allHeaderFields[@"Link"];
+    if (!linkHeader) {
+        return nil;
+    }
+
+    static NSRegularExpression *linkRegex;
+    static dispatch_once_t onceToken;
+
+    dispatch_once(&onceToken, ^{
+        linkRegex = [NSRegularExpression regularExpressionWithPattern:@"\\s*<([^>]*)>;\\s*rel=\"([^\"]*)\"" options:0 error:nil];
+    });
+
+    NSMutableDictionary *links = [NSMutableDictionary dictionary];
+
+    NSArray *matches = [linkRegex matchesInString:linkHeader options:0 range:NSMakeRange(0, linkHeader.length)];
+    for (NSTextCheckingResult *match in matches) {
+        NSRange linkUrlRange = [match rangeAtIndex:1];
+        NSRange linkRelRange = [match rangeAtIndex:2];
+
+        NSString *linkUrl = [linkHeader substringWithRange:linkUrlRange];
+        NSString *linkRels = [linkHeader substringWithRange:linkRelRange];
+
+        for (NSString *linkRel in [linkRels componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]) {
+            [links setObject:linkUrl forKey:linkRel];
+        }
+    }
+
+    return links;
+}
+
+@end

Source/ARTNSMutableURLRequest+ARTPaginated.h

@@ -0,0 +1,19 @@
+//
+//  ARTNSMutableURLRequest+ARTPaginated.h
+//  Ably
+//
+//  Created by Ricardo Pereira on 23/08/2018.
+//  Copyright © 2018 Ably. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface NSMutableURLRequest (ARTPaginated)
+
++ (nullable NSMutableURLRequest *)requestWithPath:(NSString *)path relativeTo:(NSURLRequest *)request;
+
+@end
+
+NS_ASSUME_NONNULL_END

Source/ARTNSMutableURLRequest+ARTPaginated.m

@@ -0,0 +1,21 @@
+//
+//  ARTNSMutableURLRequest+ARTPaginated.m
+//  Ably
+//
+//  Created by Ricardo Pereira on 23/08/2018.
+//  Copyright © 2018 Ably. All rights reserved.
+//
+
+#import "ARTNSMutableURLRequest+ARTPaginated.h"
+
+@implementation NSMutableURLRequest (ARTPaginated)
+
++ (NSMutableURLRequest *)requestWithPath:(NSString *)path relativeTo:(NSURLRequest *)request {
+    if (!path) {
+        return nil;
+    }
+    NSURL *url = [NSURL URLWithString:path relativeToURL:request.URL];
+    return [NSMutableURLRequest requestWithURL:url];
+}
+
+@end

Source/ARTPaginatedResult+Private.h

@@ -16,11 +16,26 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface ARTPaginatedResult<ItemType> ()
 
+@property (nonatomic, readonly) ARTRest *rest;
+@property (nonatomic, readonly) dispatch_queue_t userQueue;
+@property (nonatomic, readonly) dispatch_queue_t queue;
+@property (nonatomic, readonly) NSMutableURLRequest *relFirst;
+@property (nonatomic, readonly) NSMutableURLRequest *relCurrent;
+@property (nonatomic, readonly) NSMutableURLRequest *relNext;
+
 typedef NSArray<ItemType> *_Nullable(^ARTPaginatedResultResponseProcessor)(NSHTTPURLResponse *_Nullable, NSData *_Nullable, NSError *_Nullable *_Nullable);
 
-+ (void)executePaginated:(ARTRest *)rest withRequest:(NSMutableURLRequest *)request
-              andResponseProcessor:(ARTPaginatedResultResponseProcessor)responseProcessor
-                       callback:(void (^)(ARTPaginatedResult<ItemType> *_Nullable result, ARTErrorInfo *_Nullable error))callback;
+- (instancetype)initWithItems:(NSArray *)items
+                         rest:(ARTRest *)rest
+                     relFirst:(NSMutableURLRequest *)relFirst
+                   relCurrent:(NSMutableURLRequest *)relCurrent
+                      relNext:(NSMutableURLRequest *)relNext
+            responseProcessor:(ARTPaginatedResultResponseProcessor)responseProcessor;
+
++ (void)executePaginated:(ARTRest *)rest
+             withRequest:(NSMutableURLRequest *)request
+    andResponseProcessor:(ARTPaginatedResultResponseProcessor)responseProcessor
+                callback:(void (^)(ARTPaginatedResult<ItemType> *_Nullable result, ARTErrorInfo *_Nullable error))callback;
 
 @end