//
//  OperatingAreaViewController.swift
//  suixinkan_ios
//

import SnapKit
import UIKit

/// 运营区域页：汇总信息、围栏地图与区域列表。
final class OperatingAreaViewController: UIViewController {
    private let viewModel = OperatingAreaViewModel()
    private let mapView = OperatingAreaMapView()
    private let tableView = UITableView(frame: .zero, style: .insetGrouped)
    private let summaryLabel = UILabel()
    private lazy var blockReasonView = AppContentUnavailableView(title: "无法展示地图", systemImage: "mappin.slash")

    private var dataSource: UITableViewDiffableDataSource<Int, String>!
    private var services: AppServices { AppServices.shared }

    /// 视图加载完成后的 UI 初始化与数据绑定。
    override func viewDidLoad() {
        super.viewDidLoad()
        title = "运营区域"
        view.backgroundColor = UIColor(hex: 0xF5F7FA)
        setupLayout()
        wireViewModel()
        Task { await reload(showLoading: true) }
    }

    private func setupLayout() {
        summaryLabel.font = .systemFont(ofSize: AppMetrics.FontSize.subheadline)
        summaryLabel.textColor = AppDesign.textSecondary
        summaryLabel.numberOfLines = 0

        mapView.snp.makeConstraints { make in
            make.height.equalTo(320)
        }

        blockReasonView.isHidden = true

        tableView.register(TitleSubtitleTableViewCell.self, forCellReuseIdentifier: TitleSubtitleTableViewCell.reuseIdentifier)
        tableView.refreshControl = UIRefreshControl()
        tableView.refreshControl?.addTarget(self, action: #selector(onPullRefresh), for: .valueChanged)

        dataSource = UITableViewDiffableDataSource<Int, String>(tableView: tableView) { [weak self] tableView, indexPath, itemID in
            guard let self else { return UITableViewCell() }
            let cell = tableView.dequeueReusableCell(
                withIdentifier: TitleSubtitleTableViewCell.reuseIdentifier,
                for: indexPath
            ) as! TitleSubtitleTableViewCell
            guard let item = self.viewModel.items.first(where: { String($0.id) == itemID }) else {
                return cell
            }
            let ringCount = self.viewModel.fenceRings.filter { $0.itemId == item.id }.count
            cell.configure(
                title: item.name.isEmpty ? "未命名区域" : item.name,
                subtitle: [item.typeText, item.statusText].filter { !$0.isEmpty }.joined(separator: " · "),
                detail: "围栏 \(ringCount) 个"
            )
            return cell
        }

        let headerStack = UIStackView(arrangedSubviews: [summaryLabel, blockReasonView, mapView])
        headerStack.axis = .vertical
        headerStack.spacing = AppMetrics.Spacing.medium

        let headerContainer = UIView()
        headerContainer.addSubview(headerStack)
        headerStack.snp.makeConstraints { make in
            make.edges.equalToSuperview().inset(AppMetrics.Spacing.pageHorizontal)
        }
        headerContainer.layoutIfNeeded()
        let height = headerStack.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize).height
        headerContainer.frame = CGRect(x: 0, y: 0, width: view.bounds.width, height: height + 24)
        tableView.tableHeaderView = headerContainer

        view.addSubview(tableView)
        tableView.snp.makeConstraints { make in
            make.edges.equalToSuperview()
        }
    }

    private func wireViewModel() {
        viewModel.onChange = { [weak self] in
            self?.render()
        }
    }

    private func render() {
        summaryLabel.text = "\(viewModel.title) · \(scopeText()) · 区域 \(viewModel.summary.areaCount) · 围栏 \(viewModel.summary.fenceCount)"

        if let reason = viewModel.blockReason {
            blockReasonView.isHidden = false
            blockReasonView.update(title: reason.message, systemImage: "mappin.slash")
            mapView.isHidden = true
        } else {
            blockReasonView.isHidden = true
            mapView.isHidden = false
            mapView.rings = viewModel.fenceRings
        }
        applyTableSnapshot()
    }

    /// 通过 Diffable snapshot 刷新区域列表。
    private func applyTableSnapshot(animated: Bool = true) {
        var snapshot = NSDiffableDataSourceSnapshot<Int, String>()
        snapshot.appendSections([0])
        snapshot.appendItems(viewModel.items.map { String($0.id) }, toSection: 0)
        dataSource.apply(snapshot, animatingDifferences: animated)
    }

    private func scopeText() -> String {
        switch viewModel.mode {
        case .storeAdmin:
            return services.accountContext.currentStore?.name ?? "当前店铺"
        case .scenicAdmin:
            return services.accountContext.currentScenic?.name ?? "当前景区"
        case nil:
            return services.accountContext.currentScenic?.name
                ?? services.accountContext.currentStore?.name
                ?? "未选择业务范围"
        }
    }

    @objc private func onPullRefresh() {
        Task {
            await reload(showLoading: false)
            tableView.refreshControl?.endRefreshing()
        }
    }

    private func reload(showLoading: Bool) async {
        if showLoading { services.globalLoading.show() }
        defer { if showLoading { services.globalLoading.hide() } }

        await viewModel.reload(
            api: services.operatingAreaAPI,
            accountContext: services.accountContext,
            permissionContext: services.permissionContext
        )
        if let message = viewModel.errorMessage {
            services.toastCenter.show(message)
        }
    }
}

extension OperatingAreaViewModel: ViewModelBindable {}