import CoreDomain
import CoreModel
import Observation

@MainActor
@Observable
public final class CheckinViewModel {
    public private(set) var uiState: CheckinUiState = .loading
    public var selectedStatus: CheckinStatus = .normal
    public var submitting = false

    private let checkinUseCase: CheckinUseCase
    private let sessionUseCase: SessionUseCase
    private var loadTask: Task<Void, Never>?
    private var dataTask: Task<Void, Never>?

    public init(checkinUseCase: CheckinUseCase, sessionUseCase: SessionUseCase) {
        self.checkinUseCase = checkinUseCase
        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)
            }
        }
    }

    /// 提交打卡（对齐 android：只即时高亮选中 pill，卡片/成员靠流重新发射刷新）。
    public func submit(_ status: CheckinStatus) {
        guard !submitting else { return }
        selectedStatus = status
        submitting = true
        Task { [weak self] in
            guard let self else { return }
            try? await self.checkinUseCase.submitCheckin(status: status)
            self.submitting = false
        }
    }

    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 record in self.checkinUseCase.observeCheckin() {
                    self.uiState = .success(record)
                }
            } catch is CancellationError {
            } catch {
                self.uiState = .error(error.localizedDescription)
            }
        }
    }
}