vOOice/VoiceInk/Services/CloudTranscription/OpenAICompatibleTranscriptionService.swift

import Foundation
import os

class OpenAICompatibleTranscriptionService {
    private let logger = Logger(subsystem: "com.prakashjoshipax.voiceink", category: "OpenAICompatibleService")
    
    func transcribe(audioURL: URL, model: CustomCloudModel) async throws -> String {
        guard let url = URL(string: model.apiEndpoint) else {
            throw NSError(domain: "OpenAICompatibleTranscriptionService", code: -1, userInfo: [NSLocalizedDescriptionKey: "Invalid API endpoint URL"])
        }
        
        let config = APIConfig(
            url: url,
            apiKey: model.apiKey,
            modelName: model.modelName
        )
        
        let boundary = "Boundary-\(UUID().uuidString)"
        var request = URLRequest(url: config.url)
        request.httpMethod = "POST"
        request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")
        request.setValue("Bearer \(config.apiKey)", forHTTPHeaderField: "Authorization")
        
        let body = try createOpenAICompatibleRequestBody(audioURL: audioURL, modelName: config.modelName, boundary: boundary)
        
        let (data, response) = try await URLSession.shared.upload(for: request, from: body)
        guard let httpResponse = response as? HTTPURLResponse else {
            throw CloudTranscriptionError.networkError(URLError(.badServerResponse))
        }
        
        if !(200...299).contains(httpResponse.statusCode) {
            let errorMessage = String(data: data, encoding: .utf8) ?? "No error message"
            logger.error("OpenAI-compatible API request failed with status \(httpResponse.statusCode): \(errorMessage, privacy: .public)")
            throw CloudTranscriptionError.apiRequestFailed(statusCode: httpResponse.statusCode, message: errorMessage)
        }
        
        do {
            let transcriptionResponse = try JSONDecoder().decode(TranscriptionResponse.self, from: data)
            return transcriptionResponse.text
        } catch {
            logger.error("Failed to decode OpenAI-compatible API response: \(error.localizedDescription)")
            throw CloudTranscriptionError.noTranscriptionReturned
        }
    }
    
    private func createOpenAICompatibleRequestBody(audioURL: URL, modelName: String, boundary: String) throws -> Data {
        var body = Data()
        let crlf = "\r\n"
        
        guard let audioData = try? Data(contentsOf: audioURL) else {
            throw CloudTranscriptionError.audioFileNotFound
        }
        
        let selectedLanguage = UserDefaults.standard.string(forKey: "SelectedLanguage") ?? "auto"
        let prompt = UserDefaults.standard.string(forKey: "TranscriptionPrompt") ?? ""
        
        body.append("--\(boundary)\(crlf)".data(using: .utf8)!)
        body.append("Content-Disposition: form-data; name=\"file\"; filename=\"\(audioURL.lastPathComponent)\"\(crlf)".data(using: .utf8)!)
        body.append("Content-Type: audio/wav\(crlf)\(crlf)".data(using: .utf8)!)
        body.append(audioData)
        body.append(crlf.data(using: .utf8)!)
        
        body.append("--\(boundary)\(crlf)".data(using: .utf8)!)
        body.append("Content-Disposition: form-data; name=\"model\"\(crlf)\(crlf)".data(using: .utf8)!)
        body.append(modelName.data(using: .utf8)!)
        body.append(crlf.data(using: .utf8)!)
        
        if selectedLanguage != "auto", !selectedLanguage.isEmpty {
            body.append("--\(boundary)\(crlf)".data(using: .utf8)!)
            body.append("Content-Disposition: form-data; name=\"language\"\(crlf)\(crlf)".data(using: .utf8)!)
            body.append(selectedLanguage.data(using: .utf8)!)
            body.append(crlf.data(using: .utf8)!)
        }
        
        // Include prompt for OpenAI-compatible APIs
        if !prompt.isEmpty {
            body.append("--\(boundary)\(crlf)".data(using: .utf8)!)
            body.append("Content-Disposition: form-data; name=\"prompt\"\(crlf)\(crlf)".data(using: .utf8)!)
            body.append(prompt.data(using: .utf8)!)
            body.append(crlf.data(using: .utf8)!)
        }
        
        body.append("--\(boundary)\(crlf)".data(using: .utf8)!)
        body.append("Content-Disposition: form-data; name=\"response_format\"\(crlf)\(crlf)".data(using: .utf8)!)
        body.append("json".data(using: .utf8)!)
        body.append(crlf.data(using: .utf8)!)
        
        body.append("--\(boundary)\(crlf)".data(using: .utf8)!)
        body.append("Content-Disposition: form-data; name=\"temperature\"\(crlf)\(crlf)".data(using: .utf8)!)
        body.append("0".data(using: .utf8)!)
        body.append(crlf.data(using: .utf8)!)
        body.append("--\(boundary)--\(crlf)".data(using: .utf8)!)
        
        return body
    }
    
    private struct APIConfig {
        let url: URL
        let apiKey: String
        let modelName: String
    }
    
    private struct TranscriptionResponse: Decodable {
        let text: String
        let language: String?
        let duration: Double?
    }
}