//
//  MP_DownloadManager.swift
//  MusicPlayer
//
//  Created by 忆海16 on 2024/5/14.
//

import Foundation
import Foundation
import Alamofire

class DownloadManager: NSObject, URLSessionDownloadDelegate {
    static let shared = DownloadManager()

    var session: URLSession!
    var progressHandlers: [URL: (CGFloat) -> Void] = [:]
    var completionHandlers: [URL: (Result<URL, Error>) -> Void] = [:]
    var downloadTasks: [URL: URLSessionDownloadTask] = [:]
    var progressStorage: [URL: CGFloat] = [:] // 新增进度存储

    private override init() {
        super.init()
        let configuration = URLSessionConfiguration.background(withIdentifier: "com.yourApp.backgroundDownload")
        session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
    }

    func downloadVideo(from url: URL, videoId: String, progressHandler: @escaping (CGFloat) -> Void, completion: @escaping (Result<URL, Error>) -> Void) {
        let downloadTask = session.downloadTask(with: url)
        progressHandlers[url] = progressHandler
        completionHandlers[url] = completion
        downloadTasks[url] = downloadTask
        downloadTask.resume()
    }

    func getProgress(for url: URL) -> CGFloat? {
        return progressStorage[url]
    }

    // URLSessionDownloadDelegate methods
    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
        guard let originalURL = downloadTask.originalRequest?.url else { return }
        let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
        let downloadsURL = documentsURL.appendingPathComponent("Downloads")

        if !FileManager.default.fileExists(atPath: downloadsURL.path) {
            do {
                try FileManager.default.createDirectory(at: downloadsURL, withIntermediateDirectories: true, attributes: nil)
            } catch {
                completionHandlers[originalURL]?(.failure(error))
                return
            }
        }

        let fileURL = downloadsURL.appendingPathComponent("\(MP_PlayerManager.shared.loadPlayer.currentVideo.song.videoId ?? "").mp4")
        do {
            try FileManager.default.moveItem(at: location, to: fileURL)
            completionHandlers[originalURL]?(.success(fileURL))
            progressStorage[originalURL] = nil // 清除已完成任务的进度记录
        } catch {
            completionHandlers[originalURL]?(.failure(error))
        }
    }

    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
        guard let originalURL = downloadTask.originalRequest?.url else { return }
        let progress = CGFloat(totalBytesWritten) / CGFloat(totalBytesExpectedToWrite)
        progressHandlers[originalURL]?(progress)
        progressStorage[originalURL] = progress // 存储当前进度
        
    }

    func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
        guard let originalURL = task.originalRequest?.url else { return }
        if let error = error {
            completionHandlers[originalURL]?(.failure(error))
        }
    }
}



//class DownloadManager {
//    
//    static let shared = DownloadManager()
//    
//    private init() {}
//    
//    func downloadVideo(from url: URL, videoId: String, progressView: CircularProgressView, completion: @escaping (Result<URL, Error>) -> Void) {
//        let destination: DownloadRequest.Destination = { _, _ in
//            let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
//            let downloadsURL = documentsURL.appendingPathComponent("Downloads")
//            
//            // 检查并创建 Downloads 文件夹
//            if !FileManager.default.fileExists(atPath: downloadsURL.path) {
//                do {
//                    try FileManager.default.createDirectory(at: downloadsURL, withIntermediateDirectories: true, attributes: nil)
//                } catch {
//                    completion(.failure(error))
//                    return (downloadsURL, [.removePreviousFile, .createIntermediateDirectories])
//                }
//            }
//            
//            let fileURL = downloadsURL.appendingPathComponent("\(videoId).mp4")
//            return (fileURL, [.removePreviousFile, .createIntermediateDirectories])
//        }
//
//        AF.download(url, to: destination).downloadProgress { progress in
//            progressView.setProgress(to: CGFloat(progress.fractionCompleted))
//        }.response { response in
//            if let error = response.error {
//                completion(.failure(error))
//            } else if let filePath = response.fileURL {
//                completion(.success(filePath))
//            }
//        }
//    }
//}