import Testing
import Foundation
import MusicShared
import Network
@testable import Music

@MainActor
struct RemoteLibraryDisplayTests {

    // Reproduces the reported remote-mode bug: "connect + DB download seem fine,
    // but no tracks show up". This exercises the exact step enterRemoteMode performs
    // after the download — pointing a LibraryViewModel at the downloaded DB — and
    // asserts the view model's `tracks` array actually populates.
    @Test(.timeLimit(.minutes(1)))
    func remoteLibraryViewModelPopulatesTracksAfterDownload() async throws {
        // 1. Create a host database and insert three tracks (the "host library").
        let tempDir = FileManager.default.temporaryDirectory.appendingPathComponent(UUID().uuidString)
        try FileManager.default.createDirectory(at: tempDir, withIntermediateDirectories: true)
        defer { try? FileManager.default.removeItem(at: tempDir) }
        let hostDBPath = tempDir.appendingPathComponent("host.sqlite").path
        let hostDB = try DatabaseService(path: hostDBPath)
        for i in 1...3 {
            var t = Track.fixture(fileURL: "/song\(i).mp3", title: "Song \(i)")
            try hostDB.insert(&t)
        }

        // 2. Start the HostServer configured with the DB so GET /db serves a backup copy.
        let server = HostServer(dbPath: hostDBPath)
        server.configure(player: nil, db: hostDB)
        try server.start()
        try await Task.sleep(for: .milliseconds(200))
        let port = server.actualPort!
        defer { server.stop() }

        // 3. Download the DB over HTTP and write the body to disk, exactly as
        //    RemoteClient.handleDBData does when a remote connects to a host.
        let body = try await httpGet(host: "127.0.0.1", port: port, path: "/db")
        let downloadedPath = tempDir.appendingPathComponent("remote_db.sqlite").path
        try body.write(to: URL(fileURLWithPath: downloadedPath))

        // 4. Point a LibraryViewModel at the downloaded DB — this is precisely what
        //    MusicApp.enterRemoteMode() does after a successful connect.
        let remoteDB = try DatabaseService(path: downloadedPath)
        let library = LibraryViewModel(db: remoteDB)

        // 5. The LibraryViewModel loads via an async GRDB ValueObservation, so poll
        //    briefly for the observation to deliver its initial value.
        try await waitUntil { library.tracks.count == 3 }

        // 6. The remote library MUST display all three downloaded tracks. If this
        //    fails with 0 tracks, it reproduces the "no tracks after connect" bug.
        #expect(library.tracks.count == 3)
    }

    // MARK: - Helpers

    /// Polls `condition` on the main actor until it becomes true or the timeout elapses.
    private func waitUntil(
        timeout: Duration = .seconds(3),
        _ condition: @MainActor () -> Bool
    ) async throws {
        let deadline = ContinuousClock.now + timeout
        while ContinuousClock.now < deadline {
            if condition() { return }
            try await Task.sleep(for: .milliseconds(50))
        }
    }

    /// Performs a simple HTTP GET using NWConnection and returns the response body.
    private func httpGet(host: String, port: UInt16, path: String) async throws -> Data {
        try await withCheckedThrowingContinuation { continuation in
            let connection = NWConnection(
                host: NWEndpoint.Host(host),
                port: NWEndpoint.Port(rawValue: port)!,
                using: .tcp
            )
            connection.stateUpdateHandler = { state in
                if case .ready = state {
                    let request = "GET \(path) HTTP/1.1\r\nHost: \(host)\r\nConnection: close\r\n\r\n"
                    connection.send(content: Data(request.utf8), completion: .contentProcessed { _ in })
                    connection.receiveMessage { data, _, _, error in
                        if let error {
                            continuation.resume(throwing: error)
                        } else if let data, let range = data.range(of: Data("\r\n\r\n".utf8)) {
                            continuation.resume(returning: Data(data[range.upperBound...]))
                        } else {
                            continuation.resume(returning: data ?? Data())
                        }
                        connection.cancel()
                    }
                } else if case .failed(let error) = state {
                    continuation.resume(throwing: error)
                }
            }
            connection.start(queue: .main)
        }
    }
}