#if os(iOS)
import Foundation
import AVFoundation
import UIKit

/// iOS HLS 录制器 — 下载 HLS 流片段并合并为 MP4
@MainActor
final class HLSRecorder: ObservableObject {
    @Published var isRecording = false
    @Published var durationText = "00:00"
    
    var onRecordingSaved: ((URL) -> Void)?
    var onError: ((String) -> Void)?
    
    private var recordTask: Task<Void, Never>?
    private var startTime: Date?
    private var timer: Timer?
    
    func startRecording(url: URL) {
        guard !isRecording else { return }
        isRecording = true
        startTime = Date()
        
        timer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { [weak self] _ in
            Task { @MainActor in
                guard let self, let start = self.startTime else { return }
                let elapsed = Int(Date().timeIntervalSince(start))
                self.durationText = String(format: "%02d:%02d:%02d", elapsed/3600, (elapsed%3600)/60, elapsed%60)
            }
        }
        
        recordTask = Task {
            do {
                let outputURL = try await downloadAndMergeHLS(url: url)
                await MainActor.run {
                    self.isRecording = false
                    self.timer?.invalidate()
                    self.onRecordingSaved?(outputURL)
                }
            } catch {
                await MainActor.run {
                    self.isRecording = false
                    self.timer?.invalidate()
                    self.onError?(error.localizedDescription)
                }
            }
        }
    }
    
    func stopRecording() {
        recordTask?.cancel()
        recordTask = nil
        isRecording = false
        timer?.invalidate()
    }
    
    private func downloadAndMergeHLS(url: URL) async throws -> URL {
        // 1. Download m3u8
        let (data, _) = try await URLSession.shared.data(from: url)
        guard let playlist = String(data: data, encoding: .utf8) else {
            throw RecorderError.invalidPlaylist
        }
        
        // 2. Check if master playlist - if so, pick first variant
        let lines = playlist.components(separatedBy: .newlines)
        var isMaster = false
        var variantURL: URL?
        for line in lines {
            let trimmed = line.trimmingCharacters(in: .whitespaces)
            if trimmed.hasPrefix("#EXT-X-STREAM-INF") { isMaster = true }
            if isMaster && !trimmed.hasPrefix("#") && !trimmed.isEmpty {
                variantURL = resolveURL(trimmed, baseURL: url)
                break
            }
        }
        
        // If master, re-download variant playlist
        let mediaPlaylist: String
        let baseURL: URL
        if let vURL = variantURL {
            let (vData, _) = try await URLSession.shared.data(from: vURL)
            guard let vStr = String(data: vData, encoding: .utf8) else { throw RecorderError.invalidPlaylist }
            mediaPlaylist = vStr
            baseURL = vURL.deletingLastPathComponent()
        } else {
            mediaPlaylist = playlist
            baseURL = url.deletingLastPathComponent()
        }
        
        // 3. Parse segment URLs
        let mLines = mediaPlaylist.components(separatedBy: .newlines)
        var segmentURLs: [URL] = []
        for line in mLines {
            let trimmed = line.trimmingCharacters(in: .whitespaces)
            if !trimmed.hasPrefix("#") && !trimmed.isEmpty {
                segmentURLs.append(resolveURL(trimmed, baseURL: baseURL))
            }
        }
        
        guard !segmentURLs.isEmpty else { throw RecorderError.noSegments }
        
        // 4. Download all segments to temp dir
        let tempDir = FileManager.default.temporaryDirectory
            .appendingPathComponent("MiniPlayer_rec_\(UUID().uuidString)")
        try FileManager.default.createDirectory(at: tempDir, withIntermediateDirectories: true)
        
        var segmentFiles: [URL] = []
        for (i, segURL) in segmentURLs.enumerated() {
            let localFile = tempDir.appendingPathComponent("seg_\(String(format: "%04d", i)).ts")
            let (segData, _) = try await URLSession.shared.data(from: segURL)
            try segData.write(to: localFile)
            segmentFiles.append(localFile)
        }
        
        // 5. Merge segments into single MPEG-TS file
        let mergedTS = tempDir.appendingPathComponent("merged.ts")
        let output = try FileHandle(forWritingTo: mergedTS)
        for segFile in segmentFiles {
            let segData = try Data(contentsOf: segFile)
            output.write(segData)
        }
        output.closeFile()
        
        // 6. Remux TS → MP4 using AVAssetExportSession
        let outputMP4 = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
            .appendingPathComponent("MiniPlayer_Recording_\(Int(Date().timeIntervalSince1970)).mp4")
        
        let asset = AVURLAsset(url: mergedTS)
        if let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetPassthrough) {
            exportSession.outputURL = outputMP4
            exportSession.outputFileType = .mp4
            await exportSession.export()
            if exportSession.status != .completed {
                throw RecorderError.exportFailed(exportSession.error?.localizedDescription ?? "Unknown")
            }
        } else {
            try FileManager.default.moveItem(at: mergedTS, to: outputMP4.deletingPathExtension().appendingPathExtension("ts"))
            try? FileManager.default.removeItem(at: tempDir)
            return outputMP4.deletingPathExtension().appendingPathExtension("ts")
        }
        
        // 7. Clean up temp
        try? FileManager.default.removeItem(at: tempDir)
        
        return outputMP4
    }
    
    private func resolveURL(_ urlString: String, baseURL: URL) -> URL {
        if urlString.hasPrefix("http://") || urlString.hasPrefix("https://") {
            return URL(string: urlString)!
        }
        return baseURL.appendingPathComponent(urlString)
    }
    
    enum RecorderError: LocalizedError {
        case invalidPlaylist
        case noSegments
        case exportFailed(String)
        var errorDescription: String? {
            switch self {
            case .invalidPlaylist: return "Cannot parse HLS playlist"
            case .noSegments: return "No segments found in playlist"
            case .exportFailed(let msg): return "Export failed: \(msg)"
            }
        }
    }
}
#endif