import Foundation

public protocol AIService: Sendable {
    func generateSongProject(from request: SongProjectGenerationRequest) async throws -> SongProjectGenerationResult
    func reviseLyrics(from request: LyricsRevisionRequest) async throws -> LyricsRevisionResult
    func proposeProjectUpdate(from request: SongProjectUpdateRequest) async throws -> SongProjectUpdateResult
}

public struct AIConversationMessage: Equatable, Identifiable, Sendable {
    public let id: String
    public var role: AIConversationRole
    public var content: String

    public init(
        id: String = UUID().uuidString,
        role: AIConversationRole,
        content: String
    ) {
        self.id = id
        self.role = role
        self.content = content
    }
}

public enum AIConversationRole: String, Equatable, Sendable {
    case user
    case assistant
    case system
}

public struct AIRequestContext: Equatable, Sendable {
    public var userInstruction: String
    public var conversation: [AIConversationMessage]
    public var localeIdentifier: String?
    internal var privateApplicationRules: PrivateApplicationRules?

    public init(
        userInstruction: String,
        conversation: [AIConversationMessage] = [],
        localeIdentifier: String? = nil
    ) {
        self.userInstruction = userInstruction
        self.conversation = conversation
        self.localeIdentifier = localeIdentifier
        self.privateApplicationRules = nil
    }

    internal mutating func injectPrivateApplicationRules(_ rules: PrivateApplicationRules?) {
        privateApplicationRules = rules
    }
}

public struct SongProjectGenerationRequest: Equatable, Sendable {
    public var context: AIRequestContext
    public var seedProject: SongProject?
    public var discussionMode: ConversationMode

    public init(
        context: AIRequestContext,
        seedProject: SongProject? = nil,
        discussionMode: ConversationMode = .auto
    ) {
        self.context = context
        self.seedProject = seedProject
        self.discussionMode = discussionMode
    }
}

public struct SongProjectGenerationResult: Equatable, Sendable {
    public var project: SongProject
    public var notes: [String]
    public var followUpQuestions: [String]

    public init(
        project: SongProject,
        notes: [String] = [],
        followUpQuestions: [String] = []
    ) {
        self.project = project
        self.notes = notes
        self.followUpQuestions = followUpQuestions
    }
}

public struct LyricsRevisionRequest: Equatable, Sendable {
    public var context: AIRequestContext
    public var project: SongProject
    public var sourceLyrics: Lyrics
    public var mode: LyricsRevisionMode

    public init(
        context: AIRequestContext,
        project: SongProject,
        sourceLyrics: Lyrics,
        mode: LyricsRevisionMode
    ) {
        self.context = context
        self.project = project
        self.sourceLyrics = sourceLyrics
        self.mode = mode
    }
}

public enum LyricsRevisionMode: String, Equatable, Sendable {
    case writeFromIdea
    case correct
    case improve
    case restructure
    case complete
}

public struct LyricsRevisionResult: Equatable, Sendable {
    public var lyrics: Lyrics
    public var notes: [String]

    public init(lyrics: Lyrics, notes: [String] = []) {
        self.lyrics = lyrics
        self.notes = notes
    }
}

public struct SongProjectUpdateRequest: Equatable, Sendable {
    public var context: AIRequestContext
    public var project: SongProject
    public var allowedScopes: [SongProjectUpdateScope]

    public init(
        context: AIRequestContext,
        project: SongProject,
        allowedScopes: [SongProjectUpdateScope]
    ) {
        self.context = context
        self.project = project
        self.allowedScopes = allowedScopes
    }
}

public enum SongProjectUpdateScope: String, Codable, Equatable, Sendable {
    case duration
    case genres
    case instruments
    case vocals
    case languages
    case lyrics
    case structure
    case arrangement
    case musicalParameters
    case emotionalArc
    case productionDirections
    case sunoOutput
}

public struct SongProjectUpdateResult: Equatable, Sendable {
    public var project: SongProject
    public var changedScopes: [SongProjectUpdateScope]
    public var notes: [String]
    public var followUpQuestions: [String]

    public init(
        project: SongProject,
        changedScopes: [SongProjectUpdateScope] = [],
        notes: [String] = [],
        followUpQuestions: [String] = []
    ) {
        self.project = project
        self.changedScopes = changedScopes
        self.notes = notes
        self.followUpQuestions = followUpQuestions
    }
}