import XCTest
@testable import MixBoard

/// UI-level verification tests for the MixBoard UI Revamp.
/// Tests sidebar selection model, player bar layout invariants, and edge cases.
final class UIRevampTests: XCTestCase {

    // MARK: - SidebarSection Selection Model

    func testSidebarSectionEquality_LibraryDestinations() {
        let browse1 = SidebarSection.library(.browse)
        let browse2 = SidebarSection.library(.browse)
        let albums = SidebarSection.library(.albums)

        XCTAssertEqual(browse1, browse2)
        XCTAssertNotEqual(browse1, albums)
    }

    func testSidebarSectionEquality_QueueIsSingleton() {
        let queue1 = SidebarSection.queue
        let queue2 = SidebarSection.queue
        XCTAssertEqual(queue1, queue2)
    }

    func testSidebarSectionEquality_QueueNotEqualToLibrary() {
        let queue = SidebarSection.queue
        let library = SidebarSection.library(.browse)
        XCTAssertNotEqual(queue, library)
    }

    func testLibraryDestination_AllCases() {
        let allCases = LibraryDestination.allCases
        XCTAssertEqual(allCases.count, 6)
        XCTAssertTrue(allCases.contains(.browse))
        XCTAssertTrue(allCases.contains(.albums))
        XCTAssertTrue(allCases.contains(.artists))
        XCTAssertTrue(allCases.contains(.genres))
        XCTAssertTrue(allCases.contains(.years))
        XCTAssertTrue(allCases.contains(.search))
    }

    func testLibraryDestination_InitialNavStack() {
        XCTAssertTrue(LibraryDestination.browse.initialNavStack.isEmpty)
        XCTAssertEqual(LibraryDestination.albums.initialNavStack, [.category(.album)])
        XCTAssertEqual(LibraryDestination.artists.initialNavStack, [.category(.artist)])
        XCTAssertEqual(LibraryDestination.genres.initialNavStack, [.category(.genre)])
        XCTAssertEqual(LibraryDestination.years.initialNavStack, [.category(.year)])
        XCTAssertEqual(LibraryDestination.search.initialNavStack, [.search(query: "")])
    }

    func testLibraryDestination_DisplayNames() {
        XCTAssertEqual(LibraryDestination.browse.displayName, "Browse")
        XCTAssertEqual(LibraryDestination.albums.displayName, "Albums")
        XCTAssertEqual(LibraryDestination.artists.displayName, "Artists")
        XCTAssertEqual(LibraryDestination.genres.displayName, "Genres")
        XCTAssertEqual(LibraryDestination.years.displayName, "Years")
        XCTAssertEqual(LibraryDestination.search.displayName, "Search")
    }

    func testLibraryDestination_Icons() {
        for dest in LibraryDestination.allCases {
            XCTAssertFalse(dest.icon.isEmpty, "\(dest) should have an icon")
        }
    }

    // MARK: - Sidebar Selection Toggle Logic (⌘B)

    func testCommandBToggle_FromNil_NavigatesToLibrary() {
        var selection: SidebarSection? = nil

        // Simulate ⌘B press
        if case .library = selection {
            selection = nil
        } else {
            selection = .library(.browse)
        }

        XCTAssertEqual(selection, .library(.browse))
    }

    func testCommandBToggle_FromLibrary_NavigatesToNil() {
        var selection: SidebarSection? = SidebarSection.library(.browse)

        // Simulate ⌘B press
        if case .library = selection {
            selection = nil
        } else {
            selection = .library(.browse)
        }

        XCTAssertNil(selection)
    }

    func testCommandBToggle_FromQueue_NavigatesToLibrary() {
        var selection: SidebarSection? = SidebarSection.queue

        // Simulate ⌘B press
        if case .library = selection {
            selection = nil
        } else {
            selection = .library(.browse)
        }

        XCTAssertEqual(selection, .library(.browse))
    }

    func testCommandBToggle_FromAlbumsLibrary_NavigatesToNil() {
        var selection: SidebarSection? = SidebarSection.library(.albums)

        // Simulate ⌘B press — any .library case should toggle off
        if case .library = selection {
            selection = nil
        } else {
            selection = .library(.browse)
        }

        XCTAssertNil(selection)
    }

    // MARK: - Sidebar Selection: Mutual Exclusivity

    func testSidebarSelection_LibraryReplacesPlaylist() {
        // Selecting a library item should replace any playlist selection
        // (single selection model ensures this automatically)
        var selection: SidebarSection? = nil

        // Select a library destination
        selection = .library(.albums)
        if case .library = selection {
            // OK
        } else {
            XCTFail("Should be library selection")
        }

        // Now select queue
        selection = .queue
        XCTAssertEqual(selection, .queue)
        if case .library = selection {
            XCTFail("Should no longer be library")
        }
    }

    // MARK: - Player ViewModel State (Player Bar Support)

    @MainActor
    func testPlayerVMDefaultState_NoTrackLoaded() {
        let playerVM = PlayerViewModel()

        // When no track is loaded, currentTrack should be nil
        XCTAssertNil(playerVM.currentTrack, "currentTrack should be nil when nothing is loaded")
        XCTAssertFalse(playerVM.isPlaying)
    }

    @MainActor
    func testPlayerVMShuffleToggle() {
        let playerVM = PlayerViewModel()

        let initial = playerVM.shuffleEnabled
        playerVM.shuffleEnabled.toggle()
        XCTAssertNotEqual(playerVM.shuffleEnabled, initial)
        playerVM.shuffleEnabled.toggle()
        XCTAssertEqual(playerVM.shuffleEnabled, initial)
    }

    @MainActor
    func testPlayerVMRepeatModeCycles() {
        let playerVM = PlayerViewModel()

        // Test repeat mode cycling: off → all → one → off
        XCTAssertEqual(playerVM.repeatMode, .off)

        playerVM.repeatMode = .all
        XCTAssertEqual(playerVM.repeatMode, .all)

        playerVM.repeatMode = .one
        XCTAssertEqual(playerVM.repeatMode, .one)

        playerVM.repeatMode = .off
        XCTAssertEqual(playerVM.repeatMode, .off)
    }

    @MainActor
    func testPlayerVMVolumeRange() {
        let playerVM = PlayerViewModel()

        // Volume should accept full range
        playerVM.volume = 0.0
        XCTAssertEqual(playerVM.volume, 0.0, accuracy: 0.001)

        playerVM.volume = 0.5
        XCTAssertEqual(playerVM.volume, 0.5, accuracy: 0.001)

        playerVM.volume = 1.0
        XCTAssertEqual(playerVM.volume, 1.0, accuracy: 0.001)
    }

    // MARK: - Player Bar: Track Info Presence

    @MainActor
    func testPlayerBar_NoTrack_ShowsNotPlaying() {
        let playerVM = PlayerViewModel()
        XCTAssertNil(playerVM.currentTrack, "No track loaded — center zone should show 'Not Playing'")
        XCTAssertFalse(playerVM.isPlaying)
    }

    @MainActor
    func testPlayerBar_WithTrack_CenterZonePopulated() async throws {
        let url = try TestHelpers.createTestAudioFile(name: "ui_test", duration: 1.0)
        let track = Track(title: "Test Track", artist: "Test Artist", filePath: url.path, duration: 1.0, fileFormat: "WAV")

        let playerVM = PlayerViewModel()
        playerVM.loadAndPlay(track)
        playerVM.syncForTest()

        XCTAssertNotNil(playerVM.currentTrack)
        XCTAssertEqual(playerVM.currentTrack?.title, "Test Track")
        XCTAssertEqual(playerVM.currentTrack?.artist, "Test Artist")

        playerVM.stop()
    }

    // MARK: - Player Bar: Volume Icon Mapping

    @MainActor
    func testVolumeIconMapping() {
        let testCases: [(volume: Double, expectedIcon: String)] = [
            (0.0, "speaker.slash.fill"),
            (0.1, "speaker.wave.1.fill"),
            (0.15, "speaker.wave.1.fill"),
            (0.32, "speaker.wave.1.fill"),
            (0.33, "speaker.wave.2.fill"),
            (0.5, "speaker.wave.2.fill"),
            (0.65, "speaker.wave.2.fill"),
            (0.66, "speaker.wave.3.fill"),
            (0.85, "speaker.wave.3.fill"),
            (0.9, "speaker.wave.3.fill"),
            (1.0, "speaker.wave.3.fill"),
        ]

        for testCase in testCases {
            let icon = volumeIcon(for: testCase.volume)
            XCTAssertEqual(icon, testCase.expectedIcon,
                           "Volume \(testCase.volume) should show \(testCase.expectedIcon)")
        }
    }

    /// Mirror of PlayerView.volumeIcon computed property.
    private func volumeIcon(for volume: Double) -> String {
        if volume == 0 { return "speaker.slash.fill" }
        if volume < 0.33 { return "speaker.wave.1.fill" }
        if volume < 0.66 { return "speaker.wave.2.fill" }
        return "speaker.wave.3.fill"
    }
}