import Foundation
import Testing
@testable import Music

// Reproduces the playlist-bar duplication bug.
//
// Regular playlists and smart playlists live in two separate SQLite tables, each
// with its own `autoIncrementedPrimaryKey("id")`. The two id sequences are
// independent, so a regular playlist and a smart playlist routinely share the
// same `id` value (both start at 1, 2, 3, ...). PlaylistViewModel.allPlaylists
// merges the two kinds into one [any PlaylistRepresentable] collection, and
// PlaylistBarView's `ForEach(playlists, id: \.id)` keyed off the bare `id`.
//
// When two items share an id, SwiftUI collapses them into a single identity:
// it renders one row twice and ties both buttons to the same view, so selecting
// or updating one leaks to the other (the reported "shown twice / name changes
// on both buttons" symptom). The fix is a type-disambiguated `listIdentity` that
// stays unique across the merged collection.
struct PlaylistBarIdentityTests {

    // Step 1: build a regular playlist and a smart playlist that share id == 1,
    //         exactly as the two independent autoincrement tables would produce.
    // Step 2: collect the identities the playlist bar uses to key its ForEach.
    // Step 3: assert the two identities are distinct, so SwiftUI keeps two rows.
    @Test func regularAndSmartPlaylistWithSameIdHaveDistinctListIdentity() {
        let regular = Playlist.fixture(id: 1, name: "Rock")
        let smart = SmartPlaylist.fixture(id: 1, name: "Recently Added")

        let items: [any PlaylistRepresentable] = [regular, smart]
        let identities = items.map(\.listIdentity)

        #expect(Set(identities).count == items.count)
    }

    // Step 1: build the merged collection the way allPlaylists does, with regular
    //         and smart playlists whose ids overlap across the two tables.
    // Step 2: map every item to its list identity.
    // Step 3: assert all identities are unique across the whole collection — the
    //         invariant SwiftUI ForEach needs to avoid duplicate/leaking rows.
    @Test func mergedPlaylistsHaveUniqueListIdentities() {
        let regulars: [any PlaylistRepresentable] = [
            Playlist.fixture(id: 1, name: "Rock"),
            Playlist.fixture(id: 2, name: "Jazz"),
        ]
        let smarts: [any PlaylistRepresentable] = [
            SmartPlaylist.fixture(id: 1, name: "Recently Added"),
            SmartPlaylist.fixture(id: 2, name: "Top Rated"),
        ]
        let all = regulars + smarts
        let identities = all.map(\.listIdentity)

        #expect(Set(identities).count == all.count)
    }
}