//
//  CooperationOrderListViewModel.swift
//  suixinkan
//

import Foundation

/// 合作订单列表 ViewModel，对齐 Android `CooperationOrderListViewModel`。
final class CooperationOrderListViewModel {

    private(set) var selectedTab = 0
    private(set) var searchText = ""
    private(set) var leads: [ReferralLeadEntity] = []
    private(set) var orders: [AcquisitionOrderEntity] = []
    private(set) var isRefreshing = false
    private(set) var isLoadingMore = false
    private(set) var canLoadMore = false

    var onStateChange: (() -> Void)?
    var onShowMessage: ((String) -> Void)?

    private let pageSize = 10
    private var leadsPage = 1
    private var ordersPage = 1
    private var leadsTotal = 0
    private var ordersTotal = 0

    func onTabSelected(_ index: Int) {
        guard selectedTab != index else { return }
        selectedTab = index
        notifyStateChange()
    }

    func onSearchTextChange(_ text: String) {
        searchText = text
        notifyStateChange()
    }

    func refreshCurrentTab(api: OrderAPI) async {
        if selectedTab == 0 {
            await refreshLeads(api: api)
        } else {
            await refreshAcquisitionOrders(api: api)
        }
    }

    func refreshLeads(api: OrderAPI) async {
        leadsPage = 1
        isRefreshing = true
        isLoadingMore = false
        notifyStateChange()
        await loadLeads(api: api)
    }

    func refreshAcquisitionOrders(api: OrderAPI) async {
        ordersPage = 1
        isRefreshing = true
        isLoadingMore = false
        notifyStateChange()
        await loadAcquisitionOrders(api: api)
    }

    func loadMore(api: OrderAPI) async {
        guard !isRefreshing, !isLoadingMore, canLoadMore else { return }
        isLoadingMore = true
        notifyStateChange()
        if selectedTab == 0 {
            leadsPage += 1
            await loadLeads(api: api)
        } else {
            ordersPage += 1
            await loadAcquisitionOrders(api: api)
        }
    }

    func shouldLoadMore(at index: Int) -> Bool {
        guard canLoadMore, !isRefreshing, !isLoadingMore else { return false }
        let count = selectedTab == 0 ? leads.count : orders.count
        return index >= max(0, count - 3)
    }

    private func loadLeads(api: OrderAPI) async {
        do {
            let response = try await api.referralLeads(
                page: String(leadsPage),
                pageSize: String(pageSize)
            )
            leadsTotal = response.total
            if leadsPage == 1 {
                leads = response.list
            } else {
                leads.append(contentsOf: response.list)
            }
            canLoadMore = leads.count < leadsTotal
        } catch {
            onShowMessage?(error.localizedDescription)
        }
        isRefreshing = false
        isLoadingMore = false
        notifyStateChange()
    }

    private func loadAcquisitionOrders(api: OrderAPI) async {
        let keyword = searchText.trimmingCharacters(in: .whitespacesAndNewlines)
        do {
            let response = try await api.acquisitionOrders(
                keyword: keyword.isEmpty ? nil : keyword,
                page: String(ordersPage),
                pageSize: String(pageSize)
            )
            ordersTotal = response.total
            if ordersPage == 1 {
                orders = response.list
            } else {
                orders.append(contentsOf: response.list)
            }
            canLoadMore = orders.count < ordersTotal
        } catch {
            onShowMessage?(error.localizedDescription)
        }
        isRefreshing = false
        isLoadingMore = false
        notifyStateChange()
    }

    private func notifyStateChange() {
        onStateChange?()
    }
}