//
//  MPPositive_PlayerLoadViewModel.swift
//  MusicPlayer
//
//  Created by Mr.Zhou on 2024/5/9.
//

import UIKit
///播放器管理ViewModel
class MPPositive_PlayerLoadViewModel: NSObject {
    /// 单曲常规列表
    var songVideos:[MPPositive_SongItemModel]!
    ///随机播放列表
    var randomVideos:[MPPositive_SongItemModel]!
    ///当前播放音乐ViewModel
    var currentVideo:MPPositive_SongViewModel!{
        willSet{
            DispatchQueue.main.asyncAfter(deadline: .now()) {
                [weak self] in
                guard let self = self else {return}
                if newValue != nil {
                    MP_AnalyticsManager.shared.player_b_pvAction(newValue.song.videoId, videoname: newValue.title ?? "", artistname: newValue.song.shortBylineText ?? "")
                    if currentVideo != nil {
                        //当值变化时通知播放器页面，更新UI
                        NotificationCenter.notificationKey.post(notificationName: .positive_player_reload, object: currentVideo)
                    }else {
                        //当值变化时通知播放器页面，更新UI
                        NotificationCenter.notificationKey.post(notificationName: .positive_player_reload)
                    }
                }
            }
        }
    }

    ///单曲播放队列ViewModel
    var listViewVideos:[MPPositive_SongViewModel]!
    ///异步请求组
    var group:DispatchGroup?
    ///palyer管理model初始化方法
    /// - Parameters:
    ///   - songs: 全部歌曲列表
    ///   - firstVideoId: 需要播放的第一首歌
    init(_ songs:[MPPositive_SongItemModel], currentVideoId: String) {
        super.init()
        self.songVideos = songs
        //根据列表生成一份随机播放列表
        self.randomVideos = self.songVideos.shuffled()
        self.listViewVideos = []
    }
 
    ///将选中Video的上1位，下两位项包括本身总计4项Video进行补全转为ViewModel,并播放这首音乐
    func improveData(_ targetVideoId:String, isRandom:Bool = false) {
        //对于选中Video的集合
        var array:[MPPositive_SongItemModel] = []
        if isRandom  {
            //获取targetVideoId的索引
            guard let targetIndex = self.randomVideos.firstIndex(where: {$0.videoId == targetVideoId}) else {
                return
            }
            array.append(self.randomVideos[targetIndex])
            //获取上一位
            let previousIndex = targetIndex-1
            if previousIndex >= 0 {
                array.append(self.randomVideos[previousIndex])
            }
            let nextIndex = targetIndex+1
            let lastIndex = targetIndex+2
            if nextIndex < randomVideos.count {
                array.append(self.randomVideos[nextIndex])
            }
            if lastIndex < randomVideos.count  {
                array.append(self.randomVideos[lastIndex])
            }
        }else {
            //获取targetVideoId的索引
            guard let targetIndex = self.songVideos.firstIndex(where: {$0.videoId == targetVideoId}) else {
                return
            }
            array.append(self.songVideos[targetIndex])
            //获取上一位
            let previousIndex = targetIndex-1
            if previousIndex >= 0 {
                array.append(self.songVideos[previousIndex])
            }
            let nextIndex = targetIndex+1
            let lastIndex = targetIndex+2
            if nextIndex < songVideos.count {
                array.append(self.songVideos[nextIndex])
            }
            if lastIndex < songVideos.count  {
                array.append(self.songVideos[lastIndex])
            }
        }
        //获取完成，优先检索ViewModel，看看是否已存在补完video
        let videoIDs = Set(listViewVideos.map({$0.song.videoId}))
        //比较videoID,去掉已经补完的内容
        array = array.filter({!videoIDs.contains($0.videoId)})
        
        group = DispatchGroup()
        
        //去重完毕,对剩下内容补完
        for item in array {
            group?.enter()
            //补全歌词id和相关内容id
            if item.lyricsID == nil || item.relatedID == nil {
                improveDataforLycirsAndRelated(item) {[weak self] (result)  in
                    item.lyricsID = result.0
                    item.relatedID = result.1
                    self?.group?.leave()
                }
            }else {
                self.group?.leave()
            }
            group?.enter()
            //判断当前videoID是否进行过下载
            if let resource = getDocumentsFileURL(item.videoId) {
                //下载过，resource直接填入
                item.resourceUrls = [resource]
                //补全完成,转化为ViewModel，并添加进listViewVideos
                listViewVideos.append(.init(item))
                self.group?.leave()
            }else {
                //没有下载过
                //补全资源路径组和封面路径组
                improveDataforResouceAndCover(item) {[weak self] resourceUrls, coverUrls in
                    if let resourceUrls = resourceUrls {
                        item.resourceUrls = resourceUrls.0
                        item.itags = resourceUrls.1
                        item.mimeTypes = resourceUrls.2
                    }
                    item.coverUrls = coverUrls
                    //补全完成,转化为ViewModel，并添加进listViewVideos
                    self?.listViewVideos.append(.init(item))
                    self?.group?.leave()
                }
            }
        }
        group?.notify(queue: .main, execute: {
            [weak self] in
            //确定播放音乐
            self?.currentVideo = self?.listViewVideos.first(where: {$0.song.videoId == targetVideoId})
            //只保留最后四首
            self?.listViewVideos = self?.listViewVideos.suffix(4)
            self?.group = nil
        })
    }
    ///重新获取指定歌曲资源
    func remakeImproveData(_ completion:@escaping (() -> Void)) {
        //当前歌曲不能播放，需要重新配置资源
        improveDataforResouceAndCover(currentVideo.song) {[weak self] resourceUrls, coverUrls in
            guard let self = self else {return}
            if let resourceUrls = resourceUrls {
                currentVideo.song.resourceUrls = resourceUrls.0
                currentVideo.song.itags = resourceUrls.1
                currentVideo.song.mimeTypes = resourceUrls.2
            }
            //成功更新资源，将重新补完的歌曲，放进listViewVideos中
            listViewVideos.forEach({ item in
                if item.song.videoId == self.currentVideo.song.videoId {
                    item.song.resourceUrls = self.currentVideo.song.resourceUrls
                    item.song.itags = self.currentVideo.song.itags
                    item.song.mimeTypes = self.currentVideo.song.mimeTypes
                }
            })
//            currentVideo.resourceAsset = .init(url: .init(string: currentVideo.song.resourceUrls!.first!)!)
//            currentVideo.resourcePlayerItem = .init(asset: currentVideo.resourceAsset!)
//            currentVideo.resourcePlayerItem = .init(url: .init(string: (currentVideo.song.resourceUrls?.first ?? ""))!, bitrate: Int64(currentVideo.song.bitrates?.first ?? 0), title: currentVideo.title, videoId: currentVideo.song.videoId)
            currentVideo.configure()
            //当值变化时通知播放器页面，更新UI
            NotificationCenter.notificationKey.post(notificationName: .positive_player_reload)
            completion()
        }
    }
    
    ///移除选中的song，并更新listViewVideos，移除相同index的值
    func removeData(_ targetVideoId:String) {
        let targetIndex = songVideos.firstIndex(where: {$0.videoId == targetVideoId}) ?? 0
        //将选中的音乐移除，同时更新listView
        songVideos = songVideos.filter({$0.videoId != targetVideoId})
        randomVideos = randomVideos.filter({$0.videoId != targetVideoId})
        listViewVideos = listViewVideos.filter({$0.song.videoId != targetVideoId})
        if currentVideo != nil {
            //判断是否当前音乐
            if currentVideo.song.videoId == targetVideoId {
                //判断targetIndex是否大于最大音乐值
                if targetIndex < songVideos.count {
                    let videoId = songVideos[targetIndex].videoId ?? ""
                    improveData(videoId)
                }else {
                    //移除的是原来最后一首音乐，播放新的最后一首音乐
                    let videoId = songVideos.last?.videoId ?? ""
                    improveData(videoId)
                }
            }
        }
    }
    //判断当前videoId是不是下载过
    private func findVideoIdForDocument(_ videoId:String) -> Bool {
        return MPPositive_DownloadItemModel.fetch(.init(format: "videoId == %@", videoId)).count != 0
    }
}