Add iOS client for WhisperLive (Audio-Transcription-iOS)

Audio-Transcription-iOS/RecordingViewModel.swift

@@ -0,0 +1,174 @@
+//
+//  RecordingViewModel.swift
+//  Lecture2Quiz
+//
+//  Created by ParkMazorika on 4/27/25.
+//
+
+import AVFoundation
+import Combine
+
+/// Represents a segment of transcribed audio with start/end timestamps and completion flag.
+struct TranscriptionSegment: Identifiable, Equatable {
+    var id = UUID()
+    var start: Double
+    var end: Double
+    var text: String
+    var completed: Bool
+}
+
+/// ViewModel responsible for managing audio recording and transcription logic.
+class AudioViewModel: ObservableObject {
+    @Published var isRecording = false            // Indicates if recording is active
+    @Published var isPaused = false               // Indicates if recording is currently paused
+    @Published var timeLabel = "00:00"            // Timer label formatted as mm:ss
+    @Published var transcriptionList: [String] = []  // Live transcription output
+    @Published var isLoading = false              // True while waiting for server response
+    @Published var finalScript: String = ""       // Final script from completed segments
+
+    private var timer: Timer?
+    private var elapsedTime: Int = 0
+
+    private var audioStreamer: AudioStreamer?     // Handles audio capture and streaming
+    private var audioWebSocket: AudioWebSocket?   // Manages WebSocket communication
+
+    private var segments: [TranscriptionSegment] = []  // Stores all transcription segments
+
+    init() {}
+
+    /// Starts audio recording and initializes WebSocket + AVAudioEngine.
+    func startRecording() {
+        let audioAPIUrl = "your server url"
+        audioWebSocket = AudioWebSocket(host: audioAPIUrl, port: 443)
+        audioStreamer = AudioStreamer(webSocket: audioWebSocket!)
+
+        isLoading = true
+
+        // Handle server transcription message
+        audioWebSocket?.onTranscriptionReceived = { [weak self] text in
+            self?.handleRawTranscriptionJSON(text)
+        }
+
+        // When server sends SERVER_READY
+        audioWebSocket?.onServerReady = { [weak self] in
+            guard let self = self else { return }
+            DispatchQueue.main.async {
+                self.isLoading = false
+                self.isRecording = true
+                self.isPaused = false
+                self.timeLabel = "00:00"
+                self.elapsedTime = 0
+                self.startTimer()
+                self.audioStreamer?.startStreaming()
+            }
+        }
+    }
+
+    /// Pauses the recording and stops the timer.
+    func pauseRecording() {
+        isPaused = true
+        audioStreamer?.pauseStreaming()
+        timer?.invalidate()
+    }
+
+    /// Resumes recording and restarts the timer.
+    func resumeRecording() {
+        isPaused = false
+        audioStreamer?.resumeStreaming()
+        startTimer()
+    }
+
+    /// Stops recording and finalizes connection to server.
+    func stopRecording() {
+        isRecording = false
+        isPaused = false
+        timer?.invalidate()
+
+        audioStreamer?.stopStreaming()
+        audioWebSocket?.sendEndOfAudio()
+        audioWebSocket?.onTranscriptionReceived = nil
+        audioWebSocket?.closeConnection()
+    }
+
+    /// Starts the recording timer (1-second interval).
+    private func startTimer() {
+        timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
+            self.elapsedTime += 1
+            let minutes = self.elapsedTime / 60
+            let seconds = self.elapsedTime % 60
+            self.timeLabel = String(format: "%02d:%02d", minutes, seconds)
+        }
+    }
+
+    /// Finalizes the transcription by joining all completed segments into one string.
+    func finalizeTranscription() {
+        isLoading = false
+        let completedText = segments
+            .filter { $0.completed }
+            .map { $0.text.trimmingCharacters(in: .whitespaces) }
+            .joined(separator: " ")
+        finalScript = completedText
+        print("Final transcript:\n\(finalScript)")
+    }
+
+    /// Handles incoming JSON from the server and updates UI state.
+    /// Supports both full JSON and raw string cases.
+    func handleRawTranscriptionJSON(_ jsonString: String) {
+        let trimmed = jsonString.trimmingCharacters(in: .whitespacesAndNewlines)
+        guard let data = trimmed.data(using: .utf8) else { return }
+
+        if trimmed.hasPrefix("{") {
+            // Parse JSON containing segment list
+            do {
+                if let dict = try JSONSerialization.jsonObject(with: data) as? [String: Any],
+                   let segmentDicts = dict["segments"] as? [[String: Any]] {
+
+                    for item in segmentDicts {
+                        guard let startStr = item["start"] as? String,
+                              let endStr = item["end"] as? String,
+                              let text = item["text"] as? String,
+                              let completed = item["completed"] as? Bool,
+                              let start = Double(startStr),
+                              let end = Double(endStr) else { continue }
+
+                        let newSegment = TranscriptionSegment(start: start, end: end, text: text, completed: completed)
+
+                        // Overwrite if already exists, else append
+                        if let index = self.segments.firstIndex(where: { $0.start == start }) {
+                            self.segments[index] = newSegment
+                        } else {
+                            self.segments.append(newSegment)
+                        }
+                    }
+
+                    // Update the UI
+                    DispatchQueue.main.async {
+                        let completedTexts = self.segments
+                            .filter { $0.completed }
+                            .sorted(by: { $0.start < $1.start })
+                            .map { $0.text.trimmingCharacters(in: .whitespaces) }
+
+                        let pendingText = self.segments
+                            .filter { !$0.completed }
+                            .sorted(by: { $0.start < $1.start })
+                            .map { $0.text.trimmingCharacters(in: .whitespaces) }
+                            .last ?? ""
+
+                        self.transcriptionList = completedTexts + (pendingText.isEmpty ? [] : [pendingText])
+                        self.finalScript = self.transcriptionList.joined(separator: " ")
+                    }
+                }
+            } catch {
+                print("JSON parsing error: \(error)")
+            }
+        } else {
+            // Handle raw text line
+            DispatchQueue.main.async {
+                if self.transcriptionList.last != trimmed {
+                    self.transcriptionList.append(trimmed)
+                    self.finalScript = self.transcriptionList.joined(separator: " ")
+                }
+            }
+        }
+    }
+}