//
//  ReferralOrderSelectView.swift
//  suixinkan
//
//  Created by Codex on 2026/6/29.
//

import SwiftUI
import Combine

/// 带客单全页选择 ViewModel，分步选择获客员与带客单并确认绑定。
@MainActor
final class ReferralOrderSelectViewModel: ObservableObject {
    enum Step {
        case selectAcquirer
        case selectReferralOrder
    }

    @Published var step: Step = .selectAcquirer
    @Published var acquirers: [CooperativeSaler] = []
    @Published var selectedAcquirer: CooperativeSaler?
    @Published var referralOrders: [ReferralOrder] = []
    @Published var selectedReferralOrder: ReferralOrder?
    @Published var isLoadingMore = false
    @Published var canLoadMore = false
    @Published private(set) var hasLoadedAcquirersOnce = false
    @Published private(set) var hasLoadedReferralOrdersOnce = false

    private var orderNumber = ""
    private var currentPage = 1
    private var totalCount = 0
    private var isReloadingReferralOrders = false
    private let pageSize = 10

    /// 初始化订单号并加载获客员列表。
    func initOrder(orderNumber: String, api: CooperationOrderServing, storeId: Int?) async {
        if self.orderNumber == orderNumber && !acquirers.isEmpty { return }
        self.orderNumber = orderNumber
        await loadAcquirers(api: api, storeId: storeId)
    }

    private func loadAcquirers(api: CooperationOrderServing, storeId: Int?) async {
        do {
            let storeParam = storeId.flatMap { $0 > 0 ? $0 : nil }
            let data = try await api.cooperativeSalers(storeId: storeParam, page: 1, pageSize: 50)
            acquirers = data.list
            if data.list.count == 1 {
                await selectAcquirer(data.list[0], api: api)
            } else {
                step = .selectAcquirer
            }
        } catch {
            if !hasLoadedAcquirersOnce {
                acquirers = []
            }
        }
        hasLoadedAcquirersOnce = true
    }

    /// 选择获客员并加载其带客单列表。
    func selectAcquirer(_ acquirer: CooperativeSaler, api: CooperationOrderServing) async {
        selectedAcquirer = acquirer
        selectedReferralOrder = nil
        hasLoadedReferralOrdersOnce = false
        step = .selectReferralOrder
        await refreshReferralOrders(api: api)
    }

    /// 返回获客员选择步骤。
    func backToAcquirerStep() {
        if acquirers.count <= 1 { return }
        step = .selectAcquirer
        selectedReferralOrder = nil
        referralOrders = []
    }

    /// 选中带客单。
    func selectReferralOrder(_ order: ReferralOrder) {
        selectedReferralOrder = order
    }

    /// 刷新带客单列表。
    func refreshReferralOrders(api: CooperationOrderServing) async {
        guard let acquirer = selectedAcquirer else { return }
        guard !isReloadingReferralOrders else { return }
        isReloadingReferralOrders = true
        defer { isReloadingReferralOrders = false }
        currentPage = 1
        isLoadingMore = false
        await loadReferralOrders(api: api, saleUserId: acquirer.displayId)
    }

    /// 加载更多带客单。
    func loadMoreReferralOrders(api: CooperationOrderServing) async {
        guard !isReloadingReferralOrders, !isLoadingMore, canLoadMore,
              let acquirer = selectedAcquirer else { return }
        isLoadingMore = true
        currentPage += 1
        await loadReferralOrders(api: api, saleUserId: acquirer.displayId)
    }

    private func loadReferralOrders(api: CooperationOrderServing, saleUserId: Int) async {
        do {
            let data = try await api.saleUserReferralOrders(
                saleUserId: saleUserId,
                page: currentPage,
                pageSize: pageSize
            )
            totalCount = data.total
            if currentPage == 1 {
                referralOrders = data.list
            } else {
                referralOrders.append(contentsOf: data.list)
            }
            canLoadMore = referralOrders.count < totalCount
        } catch {
            if currentPage == 1, !hasLoadedReferralOrdersOnce {
                referralOrders = []
            }
            if currentPage > 1 {
                currentPage = max(currentPage - 1, 1)
            }
        }
        if currentPage == 1 {
            hasLoadedReferralOrdersOnce = true
        }
        isLoadingMore = false
    }

    /// 确认绑定选中的带客单。
    func confirmBind(api: CooperationOrderServing) async throws {
        guard let referralOrder = selectedReferralOrder else {
            throw NSError(domain: "ReferralOrder", code: 1, userInfo: [NSLocalizedDescriptionKey: "请选择带客单"])
        }
        guard !orderNumber.isEmpty else {
            throw NSError(domain: "ReferralOrder", code: 2, userInfo: [NSLocalizedDescriptionKey: "订单号无效"])
        }
        try await api.saleUserBindReferralOrder(
            orderNumber: orderNumber,
            referralOrderNo: referralOrder.displayReferralOrderNo
        )
    }
}

/// 带客单全页选择视图，用于订单管理绑定订单来源。
struct ReferralOrderSelectView: View {
    @EnvironmentObject private var accountContext: AccountContext
    @EnvironmentObject private var toastCenter: ToastCenter
    @Environment(\.cooperationOrderAPI) private var cooperationOrderAPI
    @Environment(\.globalLoading) private var globalLoading
    @Environment(\.dismiss) private var dismiss
    @StateObject private var viewModel = ReferralOrderSelectViewModel()
    let orderNumber: String
    let onBound: () -> Void

    @State private var binding = false

    var body: some View {
        Group {
            if viewModel.step == .selectAcquirer {
                acquirerList
            } else {
                referralOrderList
            }
        }
        .navigationTitle(viewModel.step == .selectAcquirer ? "选择获客员" : "选择带客单")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItem(placement: .cancellationAction) {
                Button {
                    if viewModel.step == .selectReferralOrder && viewModel.acquirers.count > 1 {
                        viewModel.backToAcquirerStep()
                    } else {
                        dismiss()
                    }
                } label: {
                    Image(systemName: "chevron.backward")
                }
            }
        }
        .safeAreaInset(edge: .bottom) {
            if viewModel.step == .selectReferralOrder {
                Button {
                    Task { await confirmBind() }
                } label: {
                    Text(binding ? "提交中..." : "确认绑定")
                        .font(.system(size: 16))
                        .foregroundStyle(.white)
                        .frame(maxWidth: .infinity)
                        .frame(height: 48)
                        .background(
                            viewModel.selectedReferralOrder != nil
                                ? OrderSourceColors.primary
                                : OrderSourceColors.primary.opacity(0.4),
                            in: RoundedRectangle(cornerRadius: 8)
                        )
                }
                .buttonStyle(.plain)
                .disabled(viewModel.selectedReferralOrder == nil || binding)
                .padding(.horizontal, 16)
                .padding(.vertical, 10)
                .background(.white)
            }
        }
        .background(OrderSourceColors.pageBg.ignoresSafeArea())
        .task {
            await globalLoading.withLoading {
                await viewModel.initOrder(
                    orderNumber: orderNumber,
                    api: cooperationOrderAPI,
                    storeId: accountContext.currentStore?.id
                )
            }
            if viewModel.acquirers.isEmpty {
                toastCenter.show("暂无合作获客员，请先绑定获客员")
                dismiss()
            }
        }
    }

    private func selectAcquirer(_ acquirer: CooperativeSaler) async {
        await globalLoading.withLoading {
            await viewModel.selectAcquirer(acquirer, api: cooperationOrderAPI)
        }
    }

    private var acquirerList: some View {
        ScrollView {
            LazyVStack(spacing: 12) {
                ForEach(viewModel.acquirers, id: \.displayId) { acquirer in
                    AcquirerSelectCard(
                        name: acquirer.displayName,
                        phone: acquirer.displayPhone
                    ) {
                        Task { await selectAcquirer(acquirer) }
                    }
                }
            }
            .padding(.horizontal, 14)
            .padding(.vertical, 12)
        }
    }

    private var referralOrderList: some View {
        ScrollView {
            LazyVStack(spacing: 12) {
                if let acquirer = viewModel.selectedAcquirer, !acquirer.displayName.isEmpty {
                    Text("获客员：\(acquirer.displayName)")
                        .font(.system(size: 13))
                        .foregroundStyle(OrderSourceColors.text666)
                        .frame(maxWidth: .infinity, alignment: .leading)
                        .padding(.bottom, 4)
                }

                if viewModel.hasLoadedReferralOrdersOnce && viewModel.referralOrders.isEmpty {
                    Text("暂无可绑定带客单")
                        .font(.system(size: 14))
                        .foregroundStyle(OrderSourceColors.text999)
                        .frame(maxWidth: .infinity)
                        .padding(.vertical, 32)
                } else {
                    ForEach(Array(viewModel.referralOrders.enumerated()), id: \.element.id) { index, order in
                        let selected = viewModel.selectedReferralOrder?.id == order.id
                        ReferralOrderSelectCard(
                            order: order,
                            selected: selected
                        ) {
                            viewModel.selectReferralOrder(order)
                        }
                        .onAppear {
                            guard index >= viewModel.referralOrders.count - 3 else { return }
                            guard viewModel.canLoadMore, !viewModel.isLoadingMore else { return }
                            Task { await viewModel.loadMoreReferralOrders(api: cooperationOrderAPI) }
                        }
                    }

                    if viewModel.isLoadingMore {
                        ProgressView()
                            .tint(OrderSourceColors.primary)
                            .frame(maxWidth: .infinity)
                            .padding(.vertical, 16)
                    }
                }
            }
            .padding(.horizontal, 14)
            .padding(.vertical, 12)
        }
        .refreshable {
            await globalLoading.withOptionalLoading(false) {
                await viewModel.refreshReferralOrders(api: cooperationOrderAPI)
            }
        }
    }

    private func confirmBind() async {
        binding = true
        defer { binding = false }
        do {
            try await viewModel.confirmBind(api: cooperationOrderAPI)
            onBound()
            dismiss()
        } catch {
            toastCenter.show(error.localizedDescription)
        }
    }
}

/// 订单号 Sheet 标识，用于导航到带客单选择页。
struct OrderNumberSheetItem: Identifiable {
    let orderNumber: String
    var id: String { orderNumber }
}