import Testing
import Foundation
@testable import Music

@MainActor
struct PlaylistViewModelTests {

    // Verifies createPlaylistAndAddTrack does the full job in one call:
    //   1. Seed a track into an in-memory DB and build a PlaylistViewModel over it.
    //   2. Call createPlaylistAndAddTrack with a name and the seeded track.
    //   3. The returned playlist has the given name and a real (non-nil) id.
    //   4. The DB shows that playlist now contains exactly the seeded track.
    //   5. The new playlist is recorded as the last-used playlist.
    @Test func createPlaylistAndAddTrackCreatesPlaylistAndAddsTrack() throws {
        // 1. Seed a track and build the view model.
        let db = try DatabaseService(inMemory: true)
        var track = Track.fixture(fileURL: "/song.mp3", title: "Song A")
        try db.insert(&track)
        let vm = PlaylistViewModel(db: db)

        // 2. Create a new playlist and add the track in one step.
        let created = try vm.createPlaylistAndAddTrack(name: "Road Trip", track: track)

        // 3. The returned playlist is well-formed (a real id was assigned, name matches).
        let createdId = try #require(created.id)
        #expect(created.name == "Road Trip")

        // 4. The playlist contains exactly the seeded track.
        let tracks = try db.fetchPlaylistTracks(playlistId: createdId)
        #expect(tracks.count == 1)
        #expect(tracks[0].id == track.id)

        // 5. The new playlist became the last-used playlist.
        #expect(vm.lastUsedPlaylistId == createdId)
    }
}