import Foundation

public enum AppLifecycleState: Equatable, Sendable {
    case foreground
    case background
}

public struct ScopedSessionEvent: Equatable, Sendable {
    public var accountId: String
    public var generation: Int
    public var event: SessionEvent

    public init(accountId: String, generation: Int, event: SessionEvent) {
        self.accountId = accountId
        self.generation = generation
        self.event = event
    }
}

@MainActor
public final class SessionLifecycleCoordinator: ObservableObject {
    @Published public private(set) var lifecycleState: AppLifecycleState = .foreground
    @Published public private(set) var activeAccountId: String
    @Published public private(set) var generation = 0

    public init(activeAccountId: String) {
        self.activeAccountId = activeAccountId
    }

    public var shouldPollEvents: Bool {
        lifecycleState == .foreground
    }

    public func enterBackground() {
        lifecycleState = .background
    }

    public func enterForeground() {
        lifecycleState = .foreground
    }

    public func switchAccount(to accountId: String) {
        guard accountId != activeAccountId else {
            return
        }
        activeAccountId = accountId
        generation += 1
    }

    public func accepts(_ event: ScopedSessionEvent) -> Bool {
        event.accountId == activeAccountId && event.generation == generation
    }
}