import Foundation

public final class SongProjectDiscussionDirector: Sendable {
    private let aiService: any AIService

    public init(aiService: any AIService) {
        self.aiService = aiService
    }

    public func discuss(
        project: SongProject,
        userMessage: String,
        conversation: [AIConversationMessage] = [],
        localeIdentifier: String? = nil
    ) async throws -> SongProjectDiscussionResult {
        guard project.conversationMode == .discuss else {
            throw SongProjectDiscussionDirectorError.discussionModeNotEnabled
        }

        let trimmedMessage = userMessage.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !trimmedMessage.isEmpty else {
            throw SongProjectDiscussionDirectorError.emptyUserMessage
        }

        let result = try await aiService.discussSongProject(
            from: SongProjectDiscussionRequest(
                context: AIRequestContext(
                    userInstruction: trimmedMessage,
                    conversation: conversation,
                    localeIdentifier: localeIdentifier
                ),
                project: project
            )
        )

        return SongProjectDiscussionResult(
            questions: result.questions
                .map { $0.trimmingCharacters(in: .whitespacesAndNewlines) }
                .filter { !$0.isEmpty },
            notes: result.notes
        )
    }
}

public enum SongProjectDiscussionDirectorError: Error, Equatable, Sendable {
    case discussionModeNotEnabled
    case emptyUserMessage
}