import CoreDomain
import CoreModel
import Observation

@MainActor
@Observable
public final class ProfileViewModel {
    public private(set) var uiState: ProfileUiState = .loading

    private let profileUseCase: ProfileUseCase
    private let sessionUseCase: SessionUseCase
    private var loadTask: Task<Void, Never>?
    private var dataTask: Task<Void, Never>?

    public init(profileUseCase: ProfileUseCase, sessionUseCase: SessionUseCase) {
        self.profileUseCase = profileUseCase
        self.sessionUseCase = sessionUseCase
    }

    public func load() {
        loadTask?.cancel()
        loadTask = Task { [weak self] in
            guard let self else { return }
            do {
                for try await isLoggedIn in self.sessionUseCase.observeIsLoggedIn() {
                    self.handleLoginState(isLoggedIn)
                }
            } catch is CancellationError {
            } catch {
                self.uiState = .error(error.localizedDescription)
            }
        }
    }

    public func logout() {
        Task { [weak self] in
            try? await self?.sessionUseCase.logout()
        }
    }

    private func handleLoginState(_ isLoggedIn: Bool) {
        dataTask?.cancel()
        guard isLoggedIn else {
            uiState = .loggedOut
            return
        }
        uiState = .loading
        dataTask = Task { [weak self] in
            guard let self else { return }
            do {
                for try await profile in self.profileUseCase.observeProfile() {
                    self.uiState = .success(profile)
                }
            } catch is CancellationError {
            } catch {
                self.uiState = .error(error.localizedDescription)
            }
        }
    }
}