MyApp/LocalRepository.swift

1import Foundation2import AVFoundation3 4@MainActor5final class LocalRepository {6    let directory: URL7    init(directory: URL? = nil) throws {8        var url = try directory ?? FileManager.default.url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true)9            .appendingPathComponent("SimonSaysParty", isDirectory: true)10        try FileManager.default.createDirectory(at: url, withIntermediateDirectories: true)11        var values = URLResourceValues()12        values.isExcludedFromBackup = true13        try url.setResourceValues(values)14        self.directory = url15    }16    func loadGame() throws -> SavedGame? {17        let file = url("game.json")18        guard FileManager.default.fileExists(atPath: file.path) else { return nil }19        return try JSONDecoder().decode(SavedGame.self, from: Data(contentsOf: file))20    }21    func saveGame(_ game: SavedGame) throws {22        try JSONEncoder().encode(game).write(to: url("game.json"), options: [.atomic, .completeFileProtection])23    }24    func removeGame() throws {25        let file = url("game.json")26        if FileManager.default.fileExists(atPath: file.path) { try FileManager.default.removeItem(at: file) }27    }28    func url(_ name: String) -> URL { directory.appendingPathComponent(name) }29    func load() throws -> [Attempt] {30        let metadata = url("attempts.json")31        guard FileManager.default.fileExists(atPath: metadata.path) else { return [] }32        return try JSONDecoder().decode([Attempt].self, from: Data(contentsOf: metadata))33    }34    func save(_ attempts: [Attempt]) throws {35        try JSONEncoder().encode(attempts).write(to: url("attempts.json"), options: [.atomic, .completeFileProtection])36    }37    func deleteFiles(_ attempt: Attempt) throws {38        for name in [attempt.rawFile, attempt.narrationFile, attempt.exportFile].compactMap({ $0 }) {39            let file = url(name)40            if FileManager.default.fileExists(atPath: file.path) { try FileManager.default.removeItem(at: file) }41        }42    }43    func cleanup(_ attempts: inout [Attempt]) throws {44        let cutoff = Date().addingTimeInterval(-7 * 86400)45        for index in attempts.indices where attempts[index].snapshot.created < cutoff {46            try deleteFiles(attempts[index])47            attempts[index].rawFile = nil48            attempts[index].narrationFile = nil49            attempts[index].exportFile = nil50        }51        let referenced = Set(attempts.flatMap { [$0.rawFile, $0.narrationFile, $0.exportFile].compactMap { $0 } })52        for file in try FileManager.default.contentsOfDirectory(at: directory, includingPropertiesForKeys: nil) {53            // Only this application's UUID-named media are eligible for orphan cleanup.54            if ["mov", "caf", "mp4"].contains(file.pathExtension),55               UUID(uuidString: String(file.deletingPathExtension().lastPathComponent.prefix(36))) != nil,56               !referenced.contains(file.lastPathComponent) {57                try FileManager.default.removeItem(at: file)58            }59        }60        try save(attempts)61    }62}63 64enum ClipExportService {65    static func export(raw: URL, narration: URL, offset: Double, to destination: URL) async throws {66        let source = AVURLAsset(url: raw)67        let voice = AVURLAsset(url: narration)68        let composition = AVMutableComposition()69        let duration = try await source.load(.duration)70        guard let sourceVideo = try await source.loadTracks(withMediaType: .video).first,71              let video = composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid),72              let sourceAudio = try await source.loadTracks(withMediaType: .audio).first,73              let room = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid),74              let voiceAudio = try await voice.loadTracks(withMediaType: .audio).first,75              let clean = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid) else {76            throw PartyError.message("Clip is missing video, microphone audio or narration.")77        }78        let full = CMTimeRange(start: .zero, duration: duration)79        try video.insertTimeRange(full, of: sourceVideo, at: .zero)80        video.preferredTransform = try await sourceVideo.load(.preferredTransform)81        try room.insertTimeRange(full, of: sourceAudio, at: .zero)82        let start = CMTime(seconds: offset, preferredTimescale: 600)83        let voiceDuration = try await voice.load(.duration)84        try clean.insertTimeRange(CMTimeRange(start: .zero, duration: min(voiceDuration, duration - start)), of: voiceAudio, at: start)85        let mix = AVMutableAudioMix()86        let roomParameters = AVMutableAudioMixInputParameters(track: room)87        let fade = CMTime(seconds: 0.08, preferredTimescale: 600)88        // Reduce microphone echo during narration; the unmodified original remains available.89        roomParameters.setVolume(1, at: .zero)90        roomParameters.setVolumeRamp(fromStartVolume: 1, toEndVolume: 0.12,91                                     timeRange: CMTimeRange(start: max(.zero, start - fade), duration: fade))92        roomParameters.setVolume(0.12, at: start)93        roomParameters.setVolumeRamp(fromStartVolume: 0.12, toEndVolume: 1,94                                     timeRange: CMTimeRange(start: start + voiceDuration, duration: fade))95        mix.inputParameters = [roomParameters]96        guard let exporter = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetHighestQuality) else {97            throw PartyError.message("MP4 export unavailable.")98        }99        exporter.audioMix = mix100        try await exporter.export(to: destination, as: .mp4)101    }102}