import Combine
import Foundation

final class ArchivedMessagesMiddleware {
    static let shared = ArchivedMessagesMiddleware()

    func middleware(state: AppState, action: AppAction) -> AnyPublisher<AppAction, Never> {
        switch action {
        case .conversationAction(.messagesUpdated(let messages)):
            if state.conversationsState.archivedMessagesRequested {
                return Empty().eraseToAnyPublisher()
            } else {
                guard let chat = state.conversationsState.currentChat else {
                    return Empty().eraseToAnyPublisher()
                }
                return Deferred {
                    Future<AppAction, Never> { promise in
                        if let currentClient = state.accountsState.accounts.first(where: { $0.bareJid == chat.account }) {
                            let features = state.accountsState.discoFeatures[currentClient.bareJid] ?? []
                            if features.map({ $0.xep }).contains("XEP-0313") {
                                let roster = chat.participant
                                if let lastMessage = state.conversationsState.currentMessages.first {
                                    promise(.success(.xmppAction(.xmppLoadArchivedMessages(jid: currentClient.bareJid, to: roster?.bareJid, fromDate: lastMessage.date))))
                                } else {
                                    let date = Date()
                                    let archivesRequestDate = Calendar.current.date(byAdding: .day, value: -Const.mamRequestLength, to: date) ?? date
                                    promise(.success(.xmppAction(.xmppLoadArchivedMessages(jid: currentClient.bareJid, to: roster?.bareJid, fromDate: archivesRequestDate))))
                                }
                                // let oldestMessageDate = state.conversationsState.currentMessages.first?.date ?? Date()
                                // let archivesRequestDate = Calendar.current.date(byAdding: .day, value: -Const.mamRequestLength, to: oldestMessageDate) ?? Date()
                                // promise(.success(.xmppAction(.xmppLoadArchivedMessages(jid: currentClient.bareJid, to: roster?.bareJid, fromDate: archivesRequestDate))))
                            } else {
                                promise(.success(.info("MessageMiddleware: XEP-0313 not supported for client \(currentClient.bareJid)")))
                            }
                        } else {
                            promise(.success(.info("MessageMiddleware: No client found for account \(chat.account), probably some error here")))
                        }
                    }
                }
                .eraseToAnyPublisher()
            }

        default:
            return Empty().eraseToAnyPublisher()
        }
    }
}