Connect4/Persistance/Sources/Persistance/Storage.swift

import Foundation
import Model

@available(macOS 13.0, *)
public struct Storage {
    private static let gameDirectory = try! URL(for: .applicationDirectory, in: .userDomainMask).appending(path: "Connect4")
    private static let unfinishedGame = gameDirectory.appending(path: "unfinished.json")
    private static let finishedGameDirectory = gameDirectory.appending(path: "finished")
    
    /* func hasUnfinishedGame() -> Bool {
     return FileManager.default.fileExists(atPath: unfinishedGameDirectory.path)
     } */
    
    public static func loadUnfinishedGame(callbackFactory: @escaping (_ name: String, _ type: PieceType) -> MoveCallback) async throws -> Game? {
        // Will read the file asynchronously
        let content = await Task {
            if FileManager.default.fileExists(atPath: unfinishedGame.path) {
                return FileManager.default.contents(atPath: unfinishedGame.path)
            } else {
                return nil
            }
        }.value
        guard let content = content else { return nil }
        
        let decoder = JSONDecoder()
        decoder.userInfo[.gameDecodingContext] = CodableContext(creatingCallbacks: callbackFactory)
        
        return (try decoder.decode(CodableGameWrapper.self, from: content)).game
    }
    
    public static func save(game: Game, finished: Bool) async throws {
        let (directory, file) = if finished {
            (
                finishedGameDirectory.path,
                finishedGameDirectory
                    .appending(path: "\(Date())")
                    .appendingPathExtension(".json")
            )
        } else {
            (gameDirectory.path, unfinishedGame)
        }
        
        let encoder = JSONEncoder()
        encoder.outputFormatting = .prettyPrinted
        encoder.userInfo[.gameDecodingContext] = CodableContext()
        
        let data = try encoder.encode(CodableGameWrapper(of: game))
        
        // Does Swift have true async IO natively???
        try await Task {
            try FileManager.default.createDirectory(atPath: directory, withIntermediateDirectories: true)
            try data.write(to: file)
        }.value
    }
    
    public static func clearUnfinished() async throws {
        try await Task {
            try FileManager.default.removeItem(at: unfinishedGame)
        }.value
    }
}