import Foundation
import VelodyDomain

public protocol RemoteLibraryStore: Actor {
    func loadRemoteTracks() async throws -> [RemoteTrack]
    func replaceRemoteTracks(_ tracks: [RemoteTrack]) async throws
}

public actor FileRemoteLibraryStore: RemoteLibraryStore {
    private let fileURL: URL
    private let fileManager: FileManager
    private let encoder = JSONEncoder()
    private let decoder = JSONDecoder()

    public init(
        fileURL: URL? = nil,
        fileManager: FileManager = .default
    ) throws {
        self.fileManager = fileManager
        if let fileURL {
            self.fileURL = fileURL
        } else {
            self.fileURL = try Self.defaultFileURL(fileManager: fileManager)
        }
    }

    public func loadRemoteTracks() async throws -> [RemoteTrack] {
        guard fileManager.fileExists(atPath: fileURL.path) else {
            return []
        }

        let data = try Data(contentsOf: fileURL)
        return try decoder.decode([RemoteTrack].self, from: data)
    }

    public func replaceRemoteTracks(_ tracks: [RemoteTrack]) async throws {
        try fileManager.createDirectory(
            at: fileURL.deletingLastPathComponent(),
            withIntermediateDirectories: true
        )

        let data = try encoder.encode(tracks)
        try data.write(to: fileURL, options: .atomic)
    }

    private static func defaultFileURL(fileManager: FileManager) throws -> URL {
        guard let applicationSupportURL = fileManager.urls(
            for: .applicationSupportDirectory,
            in: .userDomainMask
        ).first else {
            throw CocoaError(.fileNoSuchFile)
        }

        return applicationSupportURL
            .appendingPathComponent("Velody", isDirectory: true)
            .appendingPathComponent("remote-library.json")
    }
}

public actor InMemoryRemoteLibraryStore: RemoteLibraryStore {
    private var tracks: [RemoteTrack]

    public init(tracks: [RemoteTrack] = []) {
        self.tracks = tracks
    }

    public func loadRemoteTracks() async throws -> [RemoteTrack] {
        tracks
    }

    public func replaceRemoteTracks(_ tracks: [RemoteTrack]) async throws {
        self.tracks = tracks
    }
}