import Foundation

// TODO: add versioning (XEP-0237) if needed
final class RosterModule: XmppModule {
    let id = "Roseter module"

    private weak var storage: (any XMPPStorage)?

    init(_ storage: any XMPPStorage) {
        self.storage = storage
    }

    func reduce(oldState: ClientState, with _: Event) -> ClientState {
        oldState
    }

    func process(state: ClientState, with event: Event) async -> Event? {
        switch event {
        case .streamReady:
            return .requestRoster

        case .requestRoster:
            let req = Stanza.iqGet(
                from: state.jid.full,
                payload: XMLElement(name: "query", xmlns: "jabber:iq:roster", attributes: [:], content: nil, nodes: [])
            )
            if let req {
                return .stanzaOutbound(req)
            } else {
                return nil
            }

        case .stanzaInbound(let stanza):
            if stanza.type == .iq(.result) {
                if let query = stanza.wrapped.nodes.first(where: { $0.name == "query" }), query.xmlns == "jabber:iq:roster" {
                    return await processRoster(state: state, xml: query)
                }
            }
            return nil

        default:
            return nil
        }
    }
}

private extension RosterModule {
    func processRoster(state: ClientState, xml: XMLElement) async -> Event? {
        // get exists roster items
        var existItems: [Roster] = []
        if let data = await storage?.getRoster(jid: state.jid), let decoded = try? JSONDecoder().decode([XMLElement].self, from: data) {
            existItems = decoded.compactMap { Roster(wrap: $0, owner: state.jid) }
        }

        // extract items from incoming xml
        var newItems = xml.nodes
            .compactMap { Roster(wrap: $0, owner: state.jid) }

        // manage it ?????
        var roster: [XMLElement] = newItems.map { $0.wrapped }

        // save updated roster
        if let data = try? JSONEncoder().encode(roster) {
            await storage?.setRoster(jid: state.jid, roster: data)
        }

        return nil
    }
}

// <iq to='testmon3@test.anal.company/TwtWkVOZ3liz' type='result' id='7l899q9r'>
//     <query ver='27' xmlns='jabber:iq:roster'>
//         <item jid='fmodf@conversations.im' subscription='both' xmlns='jabber:iq:roster'/>
//         <item subscription='to' jid='testmon4@test.anal.company' xmlns='jabber:iq:roster'/>
//     </query>
// </iq>