music-assistant/Tests/MusicAssistantCoreTests/ExistingLyricsRevisionDirectorTests.swift

import MusicAssistantCore
import XCTest

final class ExistingLyricsRevisionDirectorTests: XCTestCase {
    func testReviseExistingLyricsBuildsRevisionRequestAndUpdatesProjectLyrics() async throws {
        let revisedAt = Date(timeIntervalSince1970: 500)
        let project = SongProject(
            id: "lyric-project",
            title: "Lyric Project",
            idea: "Make the hook stronger",
            lyrics: Lyrics(text: "Original lines"),
            createdAt: Date(timeIntervalSince1970: 100),
            updatedAt: Date(timeIntervalSince1970: 200)
        )
        let aiService = RecordingLyricsAIService(
            revisionResult: LyricsRevisionResult(
                lyrics: Lyrics(text: "Revised lines"),
                notes: ["Improved hook phrasing."]
            )
        )
        let director = ExistingLyricsRevisionDirector(aiService: aiService)
        let conversation = [
            AIConversationMessage(role: .user, content: "Keep it direct.")
        ]

        let result = try await director.reviseExistingLyrics(
            in: project,
            instruction: "  Improve the chorus.  ",
            mode: .improve,
            conversation: conversation,
            localeIdentifier: "en_US",
            revisedAt: revisedAt
        )
        let recordedRequest = await aiService.recordedRevisionRequests.first

        XCTAssertEqual(recordedRequest?.context.userInstruction, "Improve the chorus.")
        XCTAssertEqual(recordedRequest?.context.conversation, conversation)
        XCTAssertEqual(recordedRequest?.context.localeIdentifier, "en_US")
        XCTAssertEqual(recordedRequest?.project, project)
        XCTAssertEqual(recordedRequest?.sourceLyrics, Lyrics(text: "Original lines"))
        XCTAssertEqual(recordedRequest?.mode, .improve)
        XCTAssertEqual(result.project.id, project.id)
        XCTAssertEqual(result.project.createdAt, project.createdAt)
        XCTAssertEqual(result.project.lyrics, Lyrics(text: "Revised lines"))
        XCTAssertEqual(result.project.updatedAt, revisedAt)
        XCTAssertEqual(result.changedScopes, [.lyrics])
        XCTAssertEqual(result.notes, ["Improved hook phrasing."])
    }

    func testReviseExistingLyricsCanUseExplicitSourceLyricsWithoutMutatingOtherProjectFields() async throws {
        let project = SongProject(
            title: "Existing Project",
            idea: "Complete second verse",
            genres: [GenreStyle(id: "pop", name: "Pop")],
            lyrics: Lyrics(text: "Stored project lyrics")
        )
        let sourceLyrics = Lyrics(text: "External draft lyrics")
        let aiService = RecordingLyricsAIService(
            revisionResult: LyricsRevisionResult(
                lyrics: Lyrics(text: "Completed external draft")
            )
        )
        let director = ExistingLyricsRevisionDirector(aiService: aiService)

        let result = try await director.reviseExistingLyrics(
            in: project,
            sourceLyrics: sourceLyrics,
            instruction: "Complete this draft.",
            mode: .complete,
            revisedAt: Date(timeIntervalSince1970: 900)
        )
        let recordedRequest = await aiService.recordedRevisionRequests.first

        XCTAssertEqual(recordedRequest?.sourceLyrics, sourceLyrics)
        XCTAssertEqual(result.project.title, project.title)
        XCTAssertEqual(result.project.idea, project.idea)
        XCTAssertEqual(result.project.genres, project.genres)
        XCTAssertEqual(result.project.lyrics.text, "Completed external draft")
    }

    func testReviseExistingLyricsRejectsBlankSourceBeforeCallingAI() async {
        let aiService = RecordingLyricsAIService(
            revisionResult: LyricsRevisionResult(lyrics: Lyrics(text: "Unused"))
        )
        let director = ExistingLyricsRevisionDirector(aiService: aiService)

        do {
            _ = try await director.reviseExistingLyrics(
                in: SongProject(title: "Blank", idea: "Blank", lyrics: Lyrics(text: " \n ")),
                instruction: "Improve.",
                mode: .improve
            )
            XCTFail("Expected blank source lyrics to throw.")
        } catch let error as ExistingLyricsRevisionDirectorError {
            XCTAssertEqual(error, .emptySourceLyrics)
        } catch {
            XCTFail("Expected ExistingLyricsRevisionDirectorError.")
        }

        let requestCount = await aiService.recordedRevisionRequests.count
        XCTAssertEqual(requestCount, 0)
    }

    func testReviseExistingLyricsRejectsBlankInstructionAndWriteFromIdeaMode() async {
        let aiService = RecordingLyricsAIService(
            revisionResult: LyricsRevisionResult(lyrics: Lyrics(text: "Unused"))
        )
        let director = ExistingLyricsRevisionDirector(aiService: aiService)
        let project = SongProject(title: "Song", idea: "Idea", lyrics: Lyrics(text: "Draft"))

        do {
            _ = try await director.reviseExistingLyrics(
                in: project,
                instruction: " ",
                mode: .correct
            )
            XCTFail("Expected blank instruction to throw.")
        } catch let error as ExistingLyricsRevisionDirectorError {
            XCTAssertEqual(error, .emptyInstruction)
        } catch {
            XCTFail("Expected ExistingLyricsRevisionDirectorError.")
        }

        do {
            _ = try await director.reviseExistingLyrics(
                in: project,
                instruction: "Write from idea.",
                mode: .writeFromIdea
            )
            XCTFail("Expected unsupported mode to throw.")
        } catch let error as ExistingLyricsRevisionDirectorError {
            XCTAssertEqual(error, .unsupportedMode(.writeFromIdea))
        } catch {
            XCTFail("Expected ExistingLyricsRevisionDirectorError.")
        }

        let requestCount = await aiService.recordedRevisionRequests.count
        XCTAssertEqual(requestCount, 0)
    }
}

private actor RecordingLyricsAIService: AIService {
    private(set) var recordedRevisionRequests: [LyricsRevisionRequest] = []
    private let revisionResult: LyricsRevisionResult

    init(revisionResult: LyricsRevisionResult) {
        self.revisionResult = revisionResult
    }

    func generateSongProject(from request: SongProjectGenerationRequest) async throws -> SongProjectGenerationResult {
        SongProjectGenerationResult(project: request.seedProject ?? SongProject(title: "Unused", idea: "Unused"))
    }

    func reviseLyrics(from request: LyricsRevisionRequest) async throws -> LyricsRevisionResult {
        recordedRevisionRequests.append(request)
        return revisionResult
    }

    func proposeProjectUpdate(from request: SongProjectUpdateRequest) async throws -> SongProjectUpdateResult {
        SongProjectUpdateResult(project: request.project)
    }
}