NetNewsWire/Frameworks/Account/GoogleReaderCompatible/GoogleReaderCompatibleAPICaller.swift

//
//  GoogleReaderCompatibleAPICaller.swift
//  Account
//
//  Created by Maurice Parker on 5/2/19.
//  Copyright © 2019 Ranchero Software, LLC. All rights reserved.
//

// GoogleReaderCompatible currently has a maximum of 250 requests per second.  If you begin to receive
// HTTP Response Codes of 403, you have exceeded this limit.  Wait 5 minutes and your
// IP address will become unblocked and you can use the service again.

import Foundation
import RSWeb

enum CreateGoogleReaderSubscriptionResult {
	case created(GoogleReaderCompatibleSubscription)
	//case multipleChoice([GoogleReaderCompatibleSubscriptionChoice])
	case alreadySubscribed
	case notFound
}

final class GoogleReaderCompatibleAPICaller: NSObject {
	
	struct ConditionalGetKeys {
		static let subscriptions = "subscriptions"
		static let tags = "tags"
		static let taggings = "taggings"
		static let icons = "icons"
		static let unreadEntries = "unreadEntries"
		static let starredEntries = "starredEntries"
	}
	
	enum GoogleReaderState: String {
		case read = "user/-/state/com.google/read"
		case starred = "user/-/state/com.google/starred"
	}
	
	enum GoogleReaderEndpoints: String {
		case login = "/accounts/ClientLogin"
		case token = "/reader/api/0/token"
		case tagList = "/reader/api/0/tag/list"
		case subscriptionList = "/reader/api/0/subscription/list"
		case subscriptionEdit = "/reader/api/0/subscription/edit"
		case subscriptionAdd = "/reader/api/0/subscription/quickadd"
		case contents = "/reader/api/0/stream/items/contents"
		case itemIds = "/reader/api/0/stream/items/ids"
		case editTag = "/reader/api/0/edit-tag"
	}
	
	// private let GoogleReaderCompatibleBaseURL = URL(string: "https://api.GoogleReaderCompatible.com/v2/")!
	private var transport: Transport!
	
	var credentials: Credentials?
	weak var accountMetadata: AccountMetadata?

	var server: String? {
		get {
			return APIBaseURL?.host
		}
	}
	
	private var APIBaseURL: URL? {
		get {
			guard let accountMetadata = accountMetadata else {
				return nil
			}
	
			return accountMetadata.endpointURL
		}
	}
	
	
	init(transport: Transport) {
		super.init()
		self.transport = transport
	}
	
	func validateCredentials(endpoint: URL, completion: @escaping (Result<Credentials?, Error>) -> Void) {
		guard let credentials = credentials else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		guard case .googleBasicLogin(let username, _) = credentials else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		let request = URLRequest(url: endpoint.appendingPathComponent(GoogleReaderEndpoints.login.rawValue), credentials: credentials)

		transport.send(request: request) { result in
			switch result {
			case .success(let (_, data)):
				guard let resultData = data else {
					completion(.failure(TransportError.noData))
					break
				}
				
				// Convert the return data to UTF8 and then parse out the Auth token
				guard let rawData = String(data: resultData, encoding: .utf8) else {
					completion(.failure(TransportError.noData))
					break
				}
				
				var authData: [String: String] = [:]
				rawData.split(separator: "\n").forEach({ (line: Substring) in
					let items = line.split(separator: "=").map{String($0)}
					authData[items[0]] = items[1]
				})
				
				guard let authString = authData["Auth"] else {
					completion(.failure(CredentialsError.incompleteCredentials))
					break
				}
				
				// Save Auth Token for later use
				self.credentials = .googleAuthLogin(username: username, apiKey: authString)
				
				completion(.success(self.credentials))
			case .failure(let error):
				completion(.failure(error))
			}
		}
		
	}
	
	func requestAuthorizationToken(endpoint: URL, completion: @escaping (Result<String, Error>) -> Void) {
		guard let credentials = credentials else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		let request = URLRequest(url: endpoint.appendingPathComponent(GoogleReaderEndpoints.token.rawValue), credentials: credentials)
		
		transport.send(request: request) { result in
			switch result {
			case .success(let (_, data)):
				guard let resultData = data else {
					completion(.failure(TransportError.noData))
					break
				}
				
				// Convert the return data to UTF8 and then parse out the Auth token
				guard let rawData = String(data: resultData, encoding: .utf8) else {
					completion(.failure(TransportError.noData))
					break
				}
				
				
				completion(.success(rawData))
			case .failure(let error):
				completion(.failure(error))
			}
		}
	}
	
	func importOPML(opmlData: Data, completion: @escaping (Result<GoogleReaderCompatibleImportResult, Error>) -> Void) {
		
//		let callURL = GoogleReaderCompatibleBaseURL.appendingPathComponent("imports.json")
//		var request = URLRequest(url: callURL, credentials: credentials)
//		request.addValue("text/xml; charset=utf-8", forHTTPHeaderField: HTTPRequestHeader.contentType)
//
//		transport.send(request: request, method: HTTPMethod.post, payload: opmlData) { result in
//
//			switch result {
//			case .success(let (_, data)):
//
//				guard let resultData = data else {
//					completion(.failure(TransportError.noData))
//					break
//				}
//
//				do {
//					let result = try JSONDecoder().decode(GoogleReaderCompatibleImportResult.self, from: resultData)
//					completion(.success(result))
//				} catch {
//					completion(.failure(error))
//				}
//
//			case .failure(let error):
//				completion(.failure(error))
//			}
//
//		}
		
	}
	
	func retrieveOPMLImportResult(importID: Int, completion: @escaping (Result<GoogleReaderCompatibleImportResult?, Error>) -> Void) {
		
//		let callURL = GoogleReaderCompatibleBaseURL.appendingPathComponent("imports/\(importID).json")
//		let request = URLRequest(url: callURL, credentials: credentials)
//		
//		transport.send(request: request, resultType: GoogleReaderCompatibleImportResult.self) { result in
//			
//			switch result {
//			case .success(let (_, importResult)):
//				completion(.success(importResult))
//			case .failure(let error):
//				completion(.failure(error))
//			}
//			
//		}
		
	}
	
	func retrieveTags(completion: @escaping (Result<[GoogleReaderCompatibleTag]?, Error>) -> Void) {
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		// Add query string for getting JSON (probably should break this out as I will be doing it a lot)
		guard var components = URLComponents(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.tagList.rawValue), resolvingAgainstBaseURL: false) else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		components.queryItems = [
			URLQueryItem(name: "output", value: "json")
		]

		guard let callURL = components.url else {
			completion(.failure(TransportError.noURL))
			return
		}

		let conditionalGet = accountMetadata?.conditionalGetInfo[ConditionalGetKeys.tags]
		let request = URLRequest(url: callURL, credentials: credentials, conditionalGet: conditionalGet)
		
		transport.send(request: request, resultType: GoogleReaderCompatibleTagContainer.self) { result in
			
			switch result {
			case .success(let (response, wrapper)):
				self.storeConditionalGet(key: ConditionalGetKeys.tags, headers: response.allHeaderFields)
				completion(.success(wrapper?.tags))
			case .failure(let error):
				completion(.failure(error))
			}
			
		}
		
	}

	func renameTag(oldName: String, newName: String, completion: @escaping (Result<Void, Error>) -> Void) {
//		let callURL = GoogleReaderCompatibleBaseURL.appendingPathComponent("tags.json")
//		let request = URLRequest(url: callURL, credentials: credentials)
//		let payload = GoogleReaderCompatibleRenameTag(oldName: oldName, newName: newName)
//		transport.send(request: request, method: HTTPMethod.post, payload: payload, completion: completion)
	}
	
	func deleteTag(name: String, completion: @escaping (Result<[GoogleReaderCompatibleTagging]?, Error>) -> Void) {
		
//		let callURL = GoogleReaderCompatibleBaseURL.appendingPathComponent("tags.json")
//		let request = URLRequest(url: callURL, credentials: credentials)
//		let payload = GoogleReaderCompatibleDeleteTag(name: name)
//
//		transport.send(request: request, method: HTTPMethod.delete, payload: payload, resultType: [GoogleReaderCompatibleTagging].self) { result in
//
//			switch result {
//			case .success(let (_, taggings)):
//				completion(.success(taggings))
//			case .failure(let error):
//				completion(.failure(error))
//			}
//
//		}
		
	}
	
	func retrieveSubscriptions(completion: @escaping (Result<[GoogleReaderCompatibleSubscription]?, Error>) -> Void) {
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		// Add query string for getting JSON (probably should break this out as I will be doing it a lot)
		guard var components = URLComponents(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.subscriptionList.rawValue), resolvingAgainstBaseURL: false) else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		components.queryItems = [
			URLQueryItem(name: "output", value: "json")
		]
		
		guard let callURL = components.url else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		let conditionalGet = accountMetadata?.conditionalGetInfo[ConditionalGetKeys.subscriptions]
		let request = URLRequest(url: callURL, credentials: credentials, conditionalGet: conditionalGet)
		
		transport.send(request: request, resultType: GoogleReaderCompatibleSubscriptionContainer.self) { result in
			
			switch result {
			case .success(let (response, container)):
				self.storeConditionalGet(key: ConditionalGetKeys.subscriptions, headers: response.allHeaderFields)
				completion(.success(container?.subscriptions))
			case .failure(let error):
				completion(.failure(error))
			}
			
		}
		
	}
	
	func createSubscription(url: String, completion: @escaping (Result<CreateGoogleReaderSubscriptionResult, Error>) -> Void) {
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		self.requestAuthorizationToken(endpoint: baseURL) { (result) in
			switch result {
			case .success(let token):
				guard var components = URLComponents(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.subscriptionAdd.rawValue), resolvingAgainstBaseURL: false) else {
					completion(.failure(TransportError.noURL))
					return
				}
				
				components.queryItems = [
					URLQueryItem(name: "quickadd", value: url)
				]
				
				guard let callURL = components.url else {
					completion(.failure(TransportError.noURL))
					return
				}
				
				var request = URLRequest(url: callURL, credentials: self.credentials)
				request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
				request.httpMethod = "POST"
				
				let postData = "T=\(token)".data(using: String.Encoding.utf8)
				
				self.transport.send(request: request, method: HTTPMethod.post, data: postData!, resultType: GoogleReaderCompatibleQuickAddResult.self, completion: { (result) in
					switch result {
					case .success(let (_, subResult)):
						
						switch subResult?.numResults {
						case 0:
							completion(.success(.alreadySubscribed))
						default:
							// We have a feed ID but need to get feed information
							guard let streamId = subResult?.streamId else {
								completion(.failure(AccountError.createErrorNotFound))
								return
							}
							
							// There is no call to get a single subscription entry, so we get them all,
							// look up the one we just subscribed to and return that
							self.retrieveSubscriptions(completion: { (result) in
								switch result {
								case .success(let subscriptions):
									guard let subscriptions = subscriptions else {
										completion(.failure(AccountError.createErrorNotFound))
										return
									}
									
									let newStreamId = "feed/\(streamId)"
									
									guard let subscription = subscriptions.first(where: { (sub) -> Bool in
										sub.feedID == newStreamId
									}) else {
										completion(.failure(AccountError.createErrorNotFound))
										return
									}
									
									completion(.success(.created(subscription)))
									
								case .failure(let error):
									completion(.failure(error))
								}
							})
							}
					case .failure(let error):
						completion(.failure(error))
					}
				})
				
				
			case .failure(let error):
				completion(.failure(error))
			}
		}
	}
	
	func renameSubscription(subscriptionID: String, newName: String, completion: @escaping (Result<Void, Error>) -> Void) {
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		self.requestAuthorizationToken(endpoint: baseURL) { (result) in
			switch result {
			case .success(let token):
				var request = URLRequest(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.subscriptionEdit.rawValue), credentials: self.credentials)
				
				
				request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
				request.httpMethod = "POST"
				
				let postData = "T=\(token)&s=\(subscriptionID)&ac=edit&t=\(newName)".data(using: String.Encoding.utf8)
				
				self.transport.send(request: request, method: HTTPMethod.post, payload: postData!, completion: { (result) in
					switch result {
					case .success:
						completion(.success(()))
						break
					case .failure(let error):
						completion(.failure(error))
						break
					}
				})
				
				
			case .failure(let error):
				completion(.failure(error))
			}
		}
	}
	
	func deleteSubscription(subscriptionID: String, completion: @escaping (Result<Void, Error>) -> Void) {
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		self.requestAuthorizationToken(endpoint: baseURL) { (result) in
			switch result {
			case .success(let token):
				var request = URLRequest(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.subscriptionEdit.rawValue), credentials: self.credentials)

				
				request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
				request.httpMethod = "POST"
				
				let postData = "T=\(token)&s=\(subscriptionID)&ac=unsubscribe".data(using: String.Encoding.utf8)
				
				self.transport.send(request: request, method: HTTPMethod.post, payload: postData!, completion: { (result) in
					switch result {
					case .success:
						completion(.success(()))
						break
					case .failure(let error):
						completion(.failure(error))
						break
					}
				})
				
				
			case .failure(let error):
				completion(.failure(error))
			}
		}
	}
	
	func createTagging(feedID: Int, name: String, completion: @escaping (Result<Int, Error>) -> Void) {
		
//		let callURL = GoogleReaderCompatibleBaseURL.appendingPathComponent("taggings.json")
//		var request = URLRequest(url: callURL, credentials: credentials)
//		request.addValue("application/json; charset=utf-8", forHTTPHeaderField: HTTPRequestHeader.contentType)
//
//		let payload: Data
//		do {
//			payload = try JSONEncoder().encode(GoogleReaderCompatibleCreateTagging(feedID: feedID, name: name))
//		} catch {
//			completion(.failure(error))
//			return
//		}
//
//		transport.send(request: request, method: HTTPMethod.post, payload:payload) { result in
//
//			switch result {
//			case .success(let (response, _)):
//				if let taggingLocation = response.valueForHTTPHeaderField(HTTPResponseHeader.location),
//					let lowerBound = taggingLocation.range(of: "v2/taggings/")?.upperBound,
//					let upperBound = taggingLocation.range(of: ".json")?.lowerBound,
//					let taggingID = Int(taggingLocation[lowerBound..<upperBound]) {
//						completion(.success(taggingID))
//				} else {
//					completion(.failure(TransportError.noData))
//				}
//			case .failure(let error):
//				completion(.failure(error))
//			}
//
//		}
		
	}

	func deleteTagging(taggingID: String, completion: @escaping (Result<Void, Error>) -> Void) {
//		let callURL = GoogleReaderCompatibleBaseURL.appendingPathComponent("taggings/\(taggingID).json")
//		var request = URLRequest(url: callURL, credentials: credentials)
//		request.addValue("application/json; charset=utf-8", forHTTPHeaderField: HTTPRequestHeader.contentType)
//		transport.send(request: request, method: HTTPMethod.delete, completion: completion)
	}
	
	func retrieveIcons(completion: @escaping (Result<[GoogleReaderCompatibleIcon]?, Error>) -> Void) {
		
//		let callURL = GoogleReaderCompatibleBaseURL.appendingPathComponent("icons.json")
//		let conditionalGet = accountMetadata?.conditionalGetInfo[ConditionalGetKeys.icons]
//		let request = URLRequest(url: callURL, credentials: credentials, conditionalGet: conditionalGet)
//
//		transport.send(request: request, resultType: [GoogleReaderCompatibleIcon].self) { result in
//
//			switch result {
//			case .success(let (response, icons)):
//				self.storeConditionalGet(key: ConditionalGetKeys.icons, headers: response.allHeaderFields)
//				completion(.success(icons))
//			case .failure(let error):
//				completion(.failure(error))
//			}
//
//		}
//
	}
	
	func retrieveEntries(articleIDs: [String], completion: @escaping (Result<([GoogleReaderCompatibleEntry]?), Error>) -> Void) {
		
		guard !articleIDs.isEmpty else {
			completion(.success(([GoogleReaderCompatibleEntry]())))
			return
		}
		
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		self.requestAuthorizationToken(endpoint: baseURL) { (result) in
			switch result {
			case .success(let token):
				// Do POST asking for data about all the new articles
				var request = URLRequest(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.contents.rawValue), credentials: self.credentials)
				request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
				request.httpMethod = "POST"
				
				// Get ids from above into hex representation of value
				let idsToFetch = articleIDs.map({ (reference) -> String in
					return "i=\(reference)"
				}).joined(separator:"&")
				
				let postData = "T=\(token)&output=json&\(idsToFetch)".data(using: String.Encoding.utf8)
				//let postData = "T=\(token)&output=json&i=1349530380539369".data(using: String.Encoding.utf8)
				
				self.transport.send(request: request, method: HTTPMethod.post, data: postData!, resultType: GoogleReaderCompatibleEntryWrapper.self, completion: { (result) in
					switch result {
					case .success(let (_, entryWrapper)):
						guard let entryWrapper = entryWrapper else {
							completion(.failure(GoogleReaderCompatibleAccountDelegateError.invalidResponse))
							return
						}
						
						completion(.success((entryWrapper.entries)))
					case .failure(let error):
						completion(.failure(error))
					}
				})
				
				
			case .failure(let error):
				completion(.failure(error))
			}
		}

	}

	func retrieveEntries(feedID: String, completion: @escaping (Result<([GoogleReaderCompatibleEntry]?, String?), Error>) -> Void) {
		
		let since = Calendar.current.date(byAdding: .month, value: -3, to: Date()) ?? Date()
		
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		// Add query string for getting JSON (probably should break this out as I will be doing it a lot)
		guard var components = URLComponents(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.itemIds.rawValue), resolvingAgainstBaseURL: false) else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		components.queryItems = [
			URLQueryItem(name: "s", value: feedID),
			URLQueryItem(name: "ot", value: String(since.timeIntervalSince1970)),
			URLQueryItem(name: "output", value: "json")
		]
		
		guard let callURL = components.url else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		let request = URLRequest(url: callURL, credentials: credentials, conditionalGet: nil)
		
		transport.send(request: request, resultType: GoogleReaderCompatibleReferenceWrapper.self) { result in
			
			switch result {
			case .success(let (_, unreadEntries)):
				
				guard let itemRefs = unreadEntries?.itemRefs else {
					completion(.success(([], nil)))
					return
				}
				
				let itemIds = itemRefs.map { (reference) -> String in
					// Convert the IDs to the (stupid) Google Hex Format
					let idValue = Int(reference.itemId)!
					return String(idValue, radix: 16, uppercase: false)
				}
				
				self.retrieveEntries(articleIDs: itemIds) { (results) in
					switch results {
					case .success(let entries):
						completion(.success((entries,nil)))
					case .failure(let error):
						completion(.failure(error))
					}
				}
				
			case .failure(let error):
				completion(.failure(error))
			}
			
		}
		
	}

	func retrieveEntries(completion: @escaping (Result<([GoogleReaderCompatibleEntry]?, String?, Int?), Error>) -> Void) {
		
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		let since: Date = {
			if let lastArticleFetch = self.accountMetadata?.lastArticleFetch {
				return lastArticleFetch
			} else {
				return Calendar.current.date(byAdding: .month, value: -3, to: Date()) ?? Date()
			}
		}()
		
		let sinceString = since.timeIntervalSince1970
		
		// Add query string for getting JSON (probably should break this out as I will be doing it a lot)
		guard var components = URLComponents(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.itemIds.rawValue), resolvingAgainstBaseURL: false) else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		components.queryItems = [
			URLQueryItem(name: "o", value: String(sinceString)),
			URLQueryItem(name: "n", value: "10000"),
			URLQueryItem(name: "output", value: "json"),
			URLQueryItem(name: "xt", value: "user/-/state/com.google/read"),
			URLQueryItem(name: "s", value: "user/-/state/com.google/reading-list")
		]
		
		guard let callURL = components.url else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		let conditionalGet = accountMetadata?.conditionalGetInfo[ConditionalGetKeys.unreadEntries]
		let request = URLRequest(url: callURL, credentials: credentials, conditionalGet: conditionalGet)
		
		self.transport.send(request: request, resultType: GoogleReaderCompatibleReferenceWrapper.self) { result in
			
			switch result {
			case .success(let (_, entries)):
				
				guard let entries = entries else {
					completion(.failure(GoogleReaderCompatibleAccountDelegateError.invalidResponse))
					return
				}
				
				self.requestAuthorizationToken(endpoint: baseURL) { (result) in
					switch result {
					case .success(let token):
						// Do POST asking for data about all the new articles
						var request = URLRequest(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.contents.rawValue), credentials: self.credentials)
						request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
						request.httpMethod = "POST"
						
						// Get ids from above into hex representation of value
						let idsToFetch = entries.itemRefs.map({ (reference) -> String in
							let idValue = Int(reference.itemId)!
							let idHexString = String(idValue, radix: 16, uppercase: false)
							return "i=\(idHexString)"
						}).joined(separator:"&")
						
						let postData = "T=\(token)&output=json&\(idsToFetch)".data(using: String.Encoding.utf8)

						self.transport.send(request: request, method: HTTPMethod.post, data: postData!, resultType: GoogleReaderCompatibleEntryWrapper.self, completion: { (result) in
							switch result {
							case .success(let (response, entryWrapper)):
								guard let entryWrapper = entryWrapper else {
									completion(.failure(GoogleReaderCompatibleAccountDelegateError.invalidResponse))
									return
								}
								
								let dateInfo = HTTPDateInfo(urlResponse: response)
								self.accountMetadata?.lastArticleFetch = dateInfo?.date
								
								
								completion(.success((entryWrapper.entries, nil, nil)))
							case .failure(let error):
								completion(.failure(error))
							}
						})
						
						
					case .failure(let error):
						completion(.failure(error))
					}
				}
				
			case .failure(let error):
				self.accountMetadata?.lastArticleFetch = nil
				completion(.failure(error))
			}
			
		}
	}
	
	func retrieveEntries(page: String, completion: @escaping (Result<([GoogleReaderCompatibleEntry]?, String?), Error>) -> Void) {
		
		guard let url = URL(string: page), var callComponents = URLComponents(url: url, resolvingAgainstBaseURL: false) else {
			completion(.success((nil, nil)))
			return
		}
		
		callComponents.queryItems?.append(URLQueryItem(name: "mode", value: "extended"))
		let request = URLRequest(url: callComponents.url!, credentials: credentials)

		transport.send(request: request, resultType: [GoogleReaderCompatibleEntry].self) { result in
			
			switch result {
			case .success(let (response, entries)):
				
				let pagingInfo = HTTPLinkPagingInfo(urlResponse: response)
				completion(.success((entries, pagingInfo.nextPage)))

			case .failure(let error):
				self.accountMetadata?.lastArticleFetch = nil
				completion(.failure(error))
			}
			
		}
		
	}

	func retrieveUnreadEntries(completion: @escaping (Result<[Int]?, Error>) -> Void) {
		
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		// Add query string for getting JSON (probably should break this out as I will be doing it a lot)
		guard var components = URLComponents(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.itemIds.rawValue), resolvingAgainstBaseURL: false) else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		components.queryItems = [
			URLQueryItem(name: "s", value: "user/-/state/com.google/reading-list"),
			URLQueryItem(name: "n", value: "10000"),
			URLQueryItem(name: "xt", value: "user/-/state/com.google/read"),
			URLQueryItem(name: "output", value: "json")
		]
		
		guard let callURL = components.url else {
			completion(.failure(TransportError.noURL))
			return
		}

		let conditionalGet = accountMetadata?.conditionalGetInfo[ConditionalGetKeys.unreadEntries]
		let request = URLRequest(url: callURL, credentials: credentials, conditionalGet: conditionalGet)
		
		transport.send(request: request, resultType: GoogleReaderCompatibleReferenceWrapper.self) { result in
			
			switch result {
			case .success(let (response, unreadEntries)):
				
				guard let itemRefs = unreadEntries?.itemRefs else {
					completion(.success([]))
					return
				}
				
				let itemIds = itemRefs.map{ Int($0.itemId)! }
				
				self.storeConditionalGet(key: ConditionalGetKeys.unreadEntries, headers: response.allHeaderFields)
				completion(.success(itemIds))
			case .failure(let error):
				completion(.failure(error))
			}
			
		}
		
	}
	
	func updateStateToEntries(entries: [Int], state: GoogleReaderState, add: Bool, completion: @escaping (Result<Void, Error>) -> Void) {
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		self.requestAuthorizationToken(endpoint: baseURL) { (result) in
			switch result {
			case .success(let token):
				// Do POST asking for data about all the new articles
				var request = URLRequest(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.editTag.rawValue), credentials: self.credentials)
				request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
				request.httpMethod = "POST"
				
				// Get ids from above into hex representation of value
				let idsToFetch = entries.map({ (idValue) -> String in
					let idHexString = String(format: "%.16llx", idValue)
					return "i=\(idHexString)"
				}).joined(separator:"&")
				
				let actionIndicator = add ? "a" : "r"
				
				let postData = "T=\(token)&\(idsToFetch)&\(actionIndicator)=\(state.rawValue)".data(using: String.Encoding.utf8)
				
				self.transport.send(request: request, method: HTTPMethod.post, payload: postData!, completion: { (result) in
					switch result {
					case .success:
						completion(.success(()))
					case .failure(let error):
						completion(.failure(error))
					}
				})
				
				
			case .failure(let error):
				completion(.failure(error))
			}
		}
	}
	
	func createUnreadEntries(entries: [Int], completion: @escaping (Result<Void, Error>) -> Void) {
		updateStateToEntries(entries: entries, state: .read, add: false, completion: completion)
	}
	
	func deleteUnreadEntries(entries: [Int], completion: @escaping (Result<Void, Error>) -> Void) {
		updateStateToEntries(entries: entries, state: .read, add: true, completion: completion)

	}
	
	func createStarredEntries(entries: [Int], completion: @escaping (Result<Void, Error>) -> Void) {
		updateStateToEntries(entries: entries, state: .starred, add: true, completion: completion)
		
	}
	
	func deleteStarredEntries(entries: [Int], completion: @escaping (Result<Void, Error>) -> Void) {
		updateStateToEntries(entries: entries, state: .starred, add: false, completion: completion)
	}
	
	func retrieveStarredEntries(completion: @escaping (Result<[Int]?, Error>) -> Void) {
		guard let baseURL = APIBaseURL else {
			completion(.failure(CredentialsError.incompleteCredentials))
			return
		}
		
		guard var components = URLComponents(url: baseURL.appendingPathComponent(GoogleReaderEndpoints.itemIds.rawValue), resolvingAgainstBaseURL: false) else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		components.queryItems = [
			URLQueryItem(name: "s", value: "user/-/state/com.google/starred"),
			URLQueryItem(name: "n", value: "10000"),
			URLQueryItem(name: "output", value: "json")
		]
		
		guard let callURL = components.url else {
			completion(.failure(TransportError.noURL))
			return
		}
		
		let conditionalGet = accountMetadata?.conditionalGetInfo[ConditionalGetKeys.starredEntries]
		let request = URLRequest(url: callURL, credentials: credentials, conditionalGet: conditionalGet)
		
		transport.send(request: request, resultType: GoogleReaderCompatibleReferenceWrapper.self) { result in
			
			switch result {
			case .success(let (response, unreadEntries)):
				
				guard let itemRefs = unreadEntries?.itemRefs else {
					completion(.success([]))
					return
				}
				
				let itemIds = itemRefs.map{ Int($0.itemId)! }
				
				self.storeConditionalGet(key: ConditionalGetKeys.starredEntries, headers: response.allHeaderFields)
				completion(.success(itemIds))
			case .failure(let error):
				completion(.failure(error))
			}
			
		}
		
	}
	

	
}

// MARK: Private

extension GoogleReaderCompatibleAPICaller {
	
	func storeConditionalGet(key: String, headers: [AnyHashable : Any]) {
		if var conditionalGet = accountMetadata?.conditionalGetInfo {
			conditionalGet[key] = HTTPConditionalGetInfo(headers: headers)
			accountMetadata?.conditionalGetInfo = conditionalGet
		}
	}
	
	func extractPageNumber(link: String?) -> Int? {
		
		guard let link = link else {
			return nil
		}
		
		if let lowerBound = link.range(of: "page=")?.upperBound {
			if let upperBound = link.range(of: "&")?.lowerBound {
				return Int(link[lowerBound..<upperBound])
			}
			if let upperBound = link.range(of: ">")?.lowerBound {
				return Int(link[lowerBound..<upperBound])
			}
		}
		
		return nil
		
	}
	
}