Added support for captions extraction.

Author: b5i

Sources/YouTubeKit/BaseProtocols/Continuation/ResponseContinuation.swift

@@ -15,5 +15,5 @@ public protocol ResponseContinuation: YouTubeResponse {
     var continuationToken: String? { get set }
 
     /// Results of the continuation search.
-    var results: [ResultsType] { get set }    
+    var results: [ResultsType] { get set }
 }

Sources/YouTubeKit/BaseProtocols/Video/YouTubeVideo+getCaptions.swift

@@ -0,0 +1,41 @@
+//
+//  YouTubeVideo+getCaptions.swift
+//  
+//
+//  Created by Antoine Bollengier on 27.06.2024.
+//  Copyright © 2024 Antoine Bollengier (github.com/b5i). All rights reserved.
+//  
+
+public extension YouTubeVideo {
+    /// Get the captions for the current video.
+    static func getCaptions(youtubeModel: YouTubeModel, captionType: YTCaption, result: @escaping @Sendable (Result<VideoCaptionsResponse, Error>) -> Void) {
+        VideoCaptionsResponse.sendNonThrowingRequest(youtubeModel: youtubeModel, data: [.customURL: captionType.url.absoluteString], result: { response in
+            switch response {
+            case .success(let data):
+                result(.success(data))
+            case .failure(let error):
+                result(.failure(error))
+            }
+        })
+    }
+    
+    /// Get the captions for the current video.
+    @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+    static func getCaptionsThrowing(youtubeModel: YouTubeModel, captionType: YTCaption) async throws -> VideoCaptionsResponse {
+        return try await withCheckedThrowingContinuation({ (continuation: CheckedContinuation<VideoCaptionsResponse, Error>) in
+            self.getCaptions(youtubeModel: youtubeModel, captionType: captionType, result: { result in
+                continuation.resume(with: result)
+            })
+        })
+    }
+    
+    /// Get the captions for the current video.
+    @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+    static func getCaptions(youtubeModel: YouTubeModel, captionType: YTCaption) async -> Result<VideoCaptionsResponse, Error> {
+        return await withCheckedContinuation({ (continuation: CheckedContinuation<Result<VideoCaptionsResponse, Error>, Never>) in
+            self.getCaptions(youtubeModel: youtubeModel, captionType: captionType, result: { result in
+                continuation.resume(returning: result)
+            })
+        })
+    }
+}

Sources/YouTubeKit/BaseProtocols/Video/YouTubeVideo.swift

@@ -189,4 +189,15 @@ public protocol YouTubeVideo {
     ///
     /// Requires a ``YouTubeModel`` where ``YouTubeModel/cookies`` is defined.
     func removeLikeFromVideo(youtubeModel: YouTubeModel) async -> Error?
+    
+    /// Get the captions for the current video.
+    static func getCaptions(youtubeModel: YouTubeModel, captionType: YTCaption, result: @escaping @Sendable (Result<VideoCaptionsResponse, Error>) -> Void)
+    
+    /// Get the captions for the current video.
+    @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+    static func getCaptionsThrowing(youtubeModel: YouTubeModel, captionType: YTCaption) async throws -> VideoCaptionsResponse
+    
+    /// Get the captions for the current video.
+    @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+    static func getCaptions(youtubeModel: YouTubeModel, captionType: YTCaption) async -> Result<VideoCaptionsResponse, Error>
 }

Sources/YouTubeKit/BaseStructs/YTCaption.swift

@@ -0,0 +1,26 @@
+//
+//  YTCaption.swift
+//
+//
+//  Created by Antoine Bollengier on 27.06.2024.
+//  Copyright © 2024 Antoine Bollengier (github.com/b5i). All rights reserved.
+//
+
+import Foundation
+
+public struct YTCaption: Sendable {
+    public var languageCode: String
+    
+    public var languageName: String
+    
+    public var url: URL
+    
+    public var isTranslated: Bool
+    
+    public init(languageCode: String, languageName: String, url: URL, isTranslated: Bool) {
+        self.languageCode = languageCode
+        self.languageName = languageName
+        self.url = url
+        self.isTranslated = isTranslated
+    }
+}

Sources/YouTubeKit/ErrorHandling/ParameterValidator+commonValidators.swift

@@ -76,4 +76,16 @@ public extension ParameterValidator {
             return .success(privacy)
         }
     })
+    
+    static let urlValidator = ParameterValidator(needExistence: true, validator: { url in
+        let validatorName = "URL validator"
+        
+        guard let url = url else { return .failure(.init(reason: "Nil value.", validatorFailedNameDescriptor: validatorName)) } // should never be called because of the needExistence
+        
+        if URL(string: url) != nil {            
+            return .success(url)
+        } else {
+            return .failure(.init(reason: "Given url is not a valid URL.", validatorFailedNameDescriptor: validatorName))
+        }
+    })
 }

Sources/YouTubeKit/HeaderTypes+RawRepresentable.swift

@@ -77,6 +77,8 @@ extension HeaderTypes: RawRepresentable {
             return "subscribeToChannelHeaders"
         case .unsubscribeFromChannelHeaders:
             return "unsubscribeFromChannelHeaders"
+        case .videoCaptionsHeaders:
+            return "videoCaptionsHeaders"
         case .customHeaders(let stringIdentifier):
             return stringIdentifier
         }

Sources/YouTubeKit/HeaderTypes.swift

@@ -147,6 +147,8 @@ public enum HeaderTypes: Codable, Sendable {
     /// - Parameter browseId: The channel's id should be taken from ``YTChannel/channelId`` or ``YTLittleChannelInfos/channelId``.
     case unsubscribeFromChannelHeaders
 
+    case videoCaptionsHeaders
+    
     /// For custom headers
     case customHeaders(String)
 }

Sources/YouTubeKit/HeadersList.swift

@@ -156,10 +156,13 @@ public struct HeadersList: Codable {
             case params
             case visitorData
 
-            ///Those are used during the modification of a playlist
+            /// Those are used during the modification of a playlist
             case movingVideoId
             case videoBeforeId
             case playlistEditToken
+            
+            /// Used to completly replace the URL of the request, including the parameters that could potentially 
+            case customURL
         }
     }
 
@@ -170,9 +173,9 @@ public struct HeadersList: Codable {
     /// - Returns: An `URLRequest`built with the provided parameters and headers.
     public static func setHeadersAgentFor(
         content: HeadersList,
-        data: [AddQueryInfo.ContentTypes : String]
+        data: YouTubeResponse.RequestData
     ) -> URLRequest {
-        var url = content.url
+        var url = URL(string: data[.customURL] ?? "") ?? content.url
         if content.parameters != nil {
             var parametersToAppend: [URLQueryItem] = []
             for parameter in content.parameters! {

Sources/YouTubeKit/URL+AppendQueryItems.swift

@@ -8,7 +8,7 @@
 import Foundation
 
 public extension URL {
-    ///adapted from https://stackoverflow.com/questions/34060754/how-can-i-build-a-url-with-query-parameters-containing-multiple-values-for-the-s
+    /// adapted from https://stackoverflow.com/questions/34060754/how-can-i-build-a-url-with-query-parameters-containing-multiple-values-for-the-s
     /// If `queryItems` contains mulitple times headers with the same name, only the first will be kept.
     mutating func append(queryItems queryItemsToAdd: [URLQueryItem]) {
         guard var urlComponents = URLComponents(string: self.absoluteString) else { return }
@@ -30,4 +30,12 @@ public extension URL {
         /// Returns the url from new url components.
         self = urlComponents.url!
     }
+    
+    func appending(queryItems queryItemsToAdd: [URLQueryItem]) -> URL {
+        var secondSelf = self
+        
+        secondSelf.append(queryItems: queryItemsToAdd)
+        
+        return secondSelf
+    }
 }

Sources/YouTubeKit/YouTubeModel.swift

@@ -108,10 +108,9 @@ public class YouTubeModel {
 
         do {
             try ResponseType.validateRequest(data: &data)
-            
-            
+
             /// Create request
-            let request = HeadersList.setHeadersAgentFor(
+            let request: URLRequest = HeadersList.setHeadersAgentFor(
                 content: headers,
                 data: data
             )
@@ -258,6 +257,8 @@ public class YouTubeModel {
             return subscribeToChannelHeaders()
         case .unsubscribeFromChannelHeaders:
             return unsubscribeFromChannelHeaders()
+        case .videoCaptionsHeaders:
+            return videoCaptionsHeaders()
         case .customHeaders(let stringIdentifier):
             if let headersGenerator = customHeadersFunctions[stringIdentifier] {
                 return headersGenerator()
@@ -1299,6 +1300,29 @@ public class YouTubeModel {
             )
         }
     }
+    
+    func videoCaptionsHeaders() -> HeadersList {
+        if let headers = self.customHeaders[.videoCaptionsHeaders] {
+            return headers
+        } else {
+            return HeadersList(
+                url: URL(string: "https://www.youtube.com/")!, // will be overriden by the customURL option
+                method: .GET,
+                headers: [
+                    .init(name: "Accept", content: "*/*"),
+                    .init(name: "Accept-Encoding", content: "gzip, deflate, br"),
+                    .init(name: "Host", content: "www.youtube.com"),
+                    .init(name: "User-Agent", content: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.1 Safari/605.1.15"),
+                    .init(name: "Accept-Language", content: "\(self.selectedLocale);q=0.9"),
+                    .init(name: "Origin", content: "https://www.youtube.com/"),
+                    .init(name: "Referer", content: "https://www.youtube.com/"),
+                    .init(name: "Content-Type", content: "application/xml"),
+                    .init(name: "X-Origin", content: "https://www.youtube.com")
+                ],
+                parameters: []
+            )
+        }
+    }
 }
 
 #if swift(>=5.10)

Sources/YouTubeKit/YouTubeResponseTypes/VideoInfos/VideoCaptionsResponse.swift

@@ -0,0 +1,115 @@
+//
+//  VideoCaptionsResponse.swift
+//
+//
+//  Created by Antoine Bollengier on 27.06.2024.
+//  Copyright © 2024 Antoine Bollengier (github.com/b5i). All rights reserved.
+//  
+
+import Foundation
+
+/// Struct representing a response containing the captions of a video.
+public struct VideoCaptionsResponse: YouTubeResponse {
+    public static let headersType: HeaderTypes = .videoCaptionsHeaders
+    
+    public static let parametersValidationList: ValidationList = [.customURL: .urlValidator]
+        
+    public var captionParts: [CaptionPart]
+    
+    public init(captionParts: [CaptionPart]) {
+        self.captionParts = captionParts
+    }
+    
+    public static func decodeData(data: Data) throws -> VideoCaptionsResponse {
+        var toReturn = VideoCaptionsResponse(captionParts: [])
+        
+        #if os(iOS) || os(tvOS) || os(watchOS) || os(macOS) || os(visionOS)
+        let dataText = CFXMLCreateStringByUnescapingEntities(nil, CFXMLCreateStringByUnescapingEntities(nil, String(decoding: data, as: UTF8.self) as CFString, nil), nil) as String
+        #else
+        let dataText = String(decoding: data, as: UTF8.self)
+        #endif
+        
+        let regexResults = dataText.ytkRegexMatches(for: #"(?:<text start=\"([0-9\.]*)\" dur=\"([0-9\.]*)">([\w\W]*?)<\/text>)"#)
+        
+        var currentEndTime: Double = Double.infinity
+        
+        for result in regexResults.reversed() {
+            guard result.count == 4 else { continue }
+            
+            let startTime = Double(result[1]) ?? 0
+            let duration = min(Double(result[2]) ?? 0, currentEndTime - startTime)
+            
+            let text = result[3]
+                        
+            toReturn.captionParts.append(
+                CaptionPart(
+                    text: text,
+                    startTime: startTime,
+                    duration: duration
+                )
+            )
+            
+            currentEndTime = startTime
+        }
+        
+        toReturn.captionParts.reverse()
+
+        return toReturn
+    }
+    
+    /// Decode json to give an instance of ``VideoInfosResponse``.
+    /// - Parameter json: the json to be decoded.
+    /// - Returns: an instance of ``VideoInfosResponse``.
+    public static func decodeJSON(json: JSON) throws -> VideoCaptionsResponse {
+        throw ResponseExtractionError(reponseType: Self.self, stepDescription: "Can't decode a VideoCaptionsResponse from some raw JSON.")
+    }
+    
+    public func getFormattedString(withFormat format: CaptionFormats) -> String {
+        func getTimeString(_ time: Double) -> String {
+            let hours: String = String(format: "%02d", Int(time / 3600))
+            let minutes: String = String(format: "%02d", Int(time - (time / 3600).rounded(.down) * 3600) / 60)
+            let seconds: String = String(format: "%02d", Int(time.truncatingRemainder(dividingBy: 60)))
+            let milliseconds: String = String(format: "%03d", Int(time.truncatingRemainder(dividingBy: 1) * 1000))
+                        
+            return "\(hours):\(minutes):\(seconds)\(format == .vtt ? "." : ",")\(milliseconds)"
+        }
+        
+        return """
+                \(format == .vtt ? "WEBVTT\n\n" : "")\(
+                self.captionParts.enumerated()
+                    .map { offset, captionPart in
+                        return """
+                               \(offset + 1)
+                               \(getTimeString(captionPart.startTime)) --> \(getTimeString(captionPart.startTime + captionPart.duration))
+                               \(captionPart.text)
+                               """
+                    }
+                    .joined(separator: "\n\n")
+                )
+                """
+    }
+    
+    public enum CaptionFormats {
+        case vtt
+        case srt
+    }
+    
+    public struct CaptionPart: Sendable, Codable {
+        /// Text of the caption.
+        ///
+        /// - Warning: The text might contain HTML entities (if `CFXMLCreateStringByUnescapingEntities` is not present), to remove them, call a function like `CFXMLCreateStringByUnescapingEntities()` two times on the text.
+        public var text: String
+        
+        /// Start time of the caption, in seconds.
+        public var startTime: Double
+        
+        /// Duration of the caption, in seconds.
+        public var duration: Double
+        
+        public init(text: String, startTime: Double, duration: Double) {
+            self.text = text
+            self.startTime = startTime
+            self.duration = duration
+        }
+    }
+}