//
//  ProfileViewController.swift
//  suixinkan
//

import PhotosUI
import SnapKit
import UIKit

// MARK: - Diffable 标识

private typealias ProfileTableSection = Int
private typealias ProfileTableRow = String

/// 个人信息页 section 索引。
private enum ProfileSectionID {
    static let info = 0
    static let logout = 1
}

/// 个人信息页行标识。
private enum ProfileRowID {
    static let name = "profile:name"
    static let account = "profile:account"
    static let phone = "profile:phone"
    static let realName = "profile:realName"
    static let settings = "profile:settings"
    static let logout = "profile:logout"
}

/// 个人信息页 value1 样式 Cell，供 Diffable reconfigure 正确复用。
private final class ProfileValueTableViewCell: UITableViewCell {
    /// 初始化 value1 样式 Cell。
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: .value1, reuseIdentifier: reuseIdentifier)
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

private enum ProfileCellReuseID {
    static let value = "profile.value"
    static let logout = "profile.logout"
}

/// 个人信息页，展示用户资料、账号状态和设置入口。
final class ProfileViewController: UIViewController, UITableViewDelegate {

    private let viewModel = ProfileViewModel()

    private let avatarImageView = UIImageView()
    private let nicknameLabel = UILabel()
    private let uidLabel = UILabel()
    private let editButton = UIButton(type: .system)

    private lazy var tableView: UITableView = {
        let table = UITableView(frame: .zero, style: .insetGrouped)
        table.delegate = self
        return table
    }()

    private lazy var refreshControl = UIRefreshControl()

    /// Diffable 数据源，驱动个人信息列表刷新。
    private var tableDataSource: UITableViewDiffableDataSource<ProfileTableSection, ProfileTableRow>!

    /// 视图加载完成后的 UI 初始化与数据绑定。
    override func viewDidLoad() {
        super.viewDidLoad()
        title = "个人信息"
        view.backgroundColor = UIColor(hex: 0xF7FAFF)
        setupHeader()
        configureTableDataSource()
        view.addSubview(tableView)
        tableView.snp.makeConstraints { make in
            make.top.equalTo(view.safeAreaLayoutGuide).offset(150)
            make.leading.trailing.bottom.equalToSuperview()
        }
        refreshControl.addTarget(self, action: #selector(refreshPulled), for: .valueChanged)
        tableView.refreshControl = refreshControl

        viewModel.onChange = { [weak self] in self?.applyViewModel() }
        editButton.addTarget(self, action: #selector(editTapped), for: .touchUpInside)

        let avatarTap = UITapGestureRecognizer(target: self, action: #selector(pickAvatar))
        avatarImageView.isUserInteractionEnabled = true
        avatarImageView.addGestureRecognizer(avatarTap)

        Task { await reloadProfile(showToast: false) }
    }

    /// 配置 Diffable 数据源。
    private func configureTableDataSource() {
        tableView.register(ProfileValueTableViewCell.self, forCellReuseIdentifier: ProfileCellReuseID.value)
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: ProfileCellReuseID.logout)

        tableDataSource = UITableViewDiffableDataSource<ProfileTableSection, ProfileTableRow>(
            tableView: tableView
        ) { [weak self] (tableView: UITableView, indexPath: IndexPath, row: ProfileTableRow) -> UITableViewCell? in
            guard let self else { return UITableViewCell() }
            switch row {
            case ProfileRowID.logout:
                let cell = tableView.dequeueReusableCell(withIdentifier: ProfileCellReuseID.logout, for: indexPath)
                cell.textLabel?.text = "退出登录"
                cell.textLabel?.textColor = UIColor(hex: 0xEF4444)
                cell.textLabel?.textAlignment = .center
                cell.selectionStyle = .default
                cell.accessoryType = .none
                return cell
            default:
                let cell = tableView.dequeueReusableCell(
                    withIdentifier: ProfileCellReuseID.value,
                    for: indexPath
                )
                cell.textLabel?.textAlignment = .natural
                cell.textLabel?.textColor = .label
                cell.accessoryType = .none
                cell.selectionStyle = .none
                switch row {
                case ProfileRowID.name:
                    cell.textLabel?.text = "姓名"
                    cell.detailTextLabel?.text = self.viewModel.displayRealName
                case ProfileRowID.account:
                    cell.textLabel?.text = "当前账号"
                    cell.detailTextLabel?.text = self.appServices.accountContext.profile?.displayName ?? "--"
                    cell.accessoryType = .disclosureIndicator
                    cell.selectionStyle = .default
                case ProfileRowID.phone:
                    cell.textLabel?.text = "手机号"
                    cell.detailTextLabel?.text = self.viewModel.displayPhone
                case ProfileRowID.realName:
                    cell.textLabel?.text = "实名认证"
                    cell.detailTextLabel?.text = self.viewModel.realNameStatusText
                    cell.accessoryType = .disclosureIndicator
                    cell.selectionStyle = .default
                case ProfileRowID.settings:
                    cell.textLabel?.text = "设置"
                    cell.accessoryType = .disclosureIndicator
                    cell.selectionStyle = .default
                default:
                    break
                }
                return cell
            }
        }
        applyTableSnapshot(animated: false)
    }

    /// 构建 Diffable snapshot。
    private func buildTableSnapshot() -> NSDiffableDataSourceSnapshot<ProfileTableSection, ProfileTableRow> {
        var snapshot = NSDiffableDataSourceSnapshot<ProfileTableSection, ProfileTableRow>()
        snapshot.appendSections([ProfileSectionID.info, ProfileSectionID.logout])
        snapshot.appendItems([
            ProfileRowID.name,
            ProfileRowID.account,
            ProfileRowID.phone,
            ProfileRowID.realName,
            ProfileRowID.settings
        ], toSection: ProfileSectionID.info)
        snapshot.appendItems([ProfileRowID.logout], toSection: ProfileSectionID.logout)
        return snapshot
    }

    /// 应用 snapshot 刷新列表，必要时重配 Cell 内容。
    private func applyTableSnapshot(animated: Bool = true, reconfigure: Bool = false) {
        var snapshot = buildTableSnapshot()
        if reconfigure {
            snapshot.reconfigureItems(snapshot.itemIdentifiers)
        }
        tableDataSource.apply(snapshot, animatingDifferences: animated)
    }

    /// 初始化Header相关 UI 或状态。
    private func setupHeader() {
        let header = UIView()
        header.backgroundColor = .white
        header.layer.cornerRadius = 17
        view.addSubview(header)

        avatarImageView.layer.cornerRadius = 43
        avatarImageView.clipsToBounds = true
        avatarImageView.contentMode = .scaleAspectFill
        avatarImageView.backgroundColor = AppDesignUIKit.primarySoft

        nicknameLabel.font = .systemFont(ofSize: 24, weight: .semibold)
        nicknameLabel.textColor = UIColor(hex: 0x252525)
        uidLabel.font = .systemFont(ofSize: 18, weight: .semibold)
        uidLabel.textColor = UIColor(hex: 0x606A7A)

        editButton.setImage(UIImage(systemName: "pencil"), for: .normal)
        editButton.tintColor = .white
        editButton.backgroundColor = AppDesignUIKit.primary
        editButton.layer.cornerRadius = 22

        header.addSubview(avatarImageView)
        header.addSubview(nicknameLabel)
        header.addSubview(uidLabel)
        header.addSubview(editButton)

        header.snp.makeConstraints { make in
            make.top.equalTo(view.safeAreaLayoutGuide).offset(16)
            make.leading.trailing.equalToSuperview().inset(19)
            make.height.equalTo(132)
        }
        avatarImageView.snp.makeConstraints { make in
            make.leading.equalToSuperview().offset(18)
            make.centerY.equalToSuperview()
            make.width.height.equalTo(86)
        }
        nicknameLabel.snp.makeConstraints { make in
            make.leading.equalTo(avatarImageView.snp.trailing).offset(14)
            make.trailing.lessThanOrEqualTo(editButton.snp.leading).offset(-8)
            make.top.equalTo(avatarImageView).offset(8)
        }
        uidLabel.snp.makeConstraints { make in
            make.leading.equalTo(nicknameLabel)
            make.top.equalTo(nicknameLabel.snp.bottom).offset(8)
        }
        editButton.snp.makeConstraints { make in
            make.trailing.equalToSuperview().inset(18)
            make.centerY.equalToSuperview()
            make.width.height.equalTo(44)
        }
    }

    /// apply视图模型相关逻辑。
    private func applyViewModel() {
        nicknameLabel.text = viewModel.displayNickname
        uidLabel.text = "UID:  \(appServices.accountContext.profile?.userId ?? "--")"
        if let data = viewModel.pendingAvatarData, let image = UIImage(data: data) {
            avatarImageView.image = image
        } else {
            avatarImageView.loadRemoteAvatar(urlString: viewModel.displayAvatarURL)
        }
        editButton.setImage(UIImage(systemName: viewModel.isEditingProfile ? "checkmark" : "pencil"), for: .normal)
        editButton.isEnabled = !viewModel.isSaving
        applyTableSnapshot(animated: false, reconfigure: true)
    }

    /// 刷新Pulled展示。
    @objc private func refreshPulled() {
        Task {
            await reloadProfile(showToast: true)
            refreshControl.endRefreshing()
        }
    }

    /// 刷新Profile。
    private func reloadProfile(showToast: Bool) async {
        do {
            try await appServices.globalLoading.withOptionalLoading(!showToast && viewModel.userInfo == nil, message: "加载资料...") {
                try await self.viewModel.reload(api: self.appServices.profileAPI)
            }
        } catch {
            if showToast { self.showToast(error.localizedDescription) }
        }
    }

    /// 点击edit的处理逻辑。
    @objc private func editTapped() {
        if viewModel.isEditingProfile {
            Task { await saveProfileEdits() }
        } else {
            viewModel.beginEditing()
            presentNicknameEditor()
        }
    }

    /// 弹出NicknameEditor页面。
    private func presentNicknameEditor() {
        let alert = UIAlertController(title: "编辑昵称", message: nil, preferredStyle: .alert)
        alert.addTextField { [weak self] field in
            field.text = self?.viewModel.editingNickname
            field.placeholder = "请输入昵称"
        }
        alert.addAction(UIAlertAction(title: "取消", style: .cancel) { [weak self] _ in
            self?.viewModel.cancelEditing()
        })
        alert.addAction(UIAlertAction(title: "保存", style: .default) { [weak self] _ in
            guard let self else { return }
            self.viewModel.editingNickname = alert.textFields?.first?.text ?? ""
            Task { await self.saveProfileEdits() }
        })
        present(alert, animated: true)
    }

    /// save个人中心Edits相关逻辑。
    private func saveProfileEdits() async {
        guard let scenicId = appServices.accountContext.currentScenic?.id else {
            showToast("请先选择景区")
            return
        }
        do {
            try await appServices.globalLoading.withLoading(message: "保存中...") {
                try await self.viewModel.saveProfile(
                    api: self.appServices.profileAPI,
                    uploader: self.appServices.ossUploadService,
                    scenicId: scenicId
                )
            }
            showToast("资料已更新")
        } catch {
            showToast(error.localizedDescription)
        }
    }

    /// pick头像相关逻辑。
    @objc private func pickAvatar() {
        var config = PHPickerConfiguration()
        config.filter = .images
        config.selectionLimit = 1
        let picker = PHPickerViewController(configuration: config)
        picker.delegate = self
        present(picker, animated: true)
    }

    /// 点击logout的处理逻辑。
    @objc private func logoutTapped() {
        let alert = UIAlertController(title: "确认退出当前账号？", message: nil, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "取消", style: .cancel))
        alert.addAction(UIAlertAction(title: "退出登录", style: .destructive) { [weak self] _ in
            guard let self else { return }
            self.appServices.authSessionCoordinator.logout(
                appSession: self.appServices.appSession,
                accountContext: self.appServices.accountContext,
                permissionContext: self.appServices.permissionContext,
                scenicSpotContext: self.appServices.scenicSpotContext,
                appNavigator: self.appServices.appNavigator,
                toastCenter: self.appServices.toastCenter
            )
        })
        present(alert, animated: true)
    }

    /// UITableView 代理：处理行选中。
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
        guard let row = tableDataSource.itemIdentifier(for: indexPath) else { return }
        switch row {
        case ProfileRowID.logout:
            logoutTapped()
        case ProfileRowID.account:
            appServices.appNavigator.push(.profile(.accountSwitch), from: self)
        case ProfileRowID.realName:
            appServices.appNavigator.push(.profile(.realNameAuth), from: self)
        case ProfileRowID.settings:
            appServices.appNavigator.push(.profile(.settings), from: self)
        default:
            break
        }
    }
}

extension ProfileViewController: PHPickerViewControllerDelegate {
    /// picker 业务逻辑。
    func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
        picker.dismiss(animated: true)
        guard let provider = results.first?.itemProvider, provider.canLoadObject(ofClass: UIImage.self) else { return }
        provider.loadObject(ofClass: UIImage.self) { [weak self] object, _ in
            guard let self, let image = object as? UIImage, let data = image.jpegData(compressionQuality: 0.9) else { return }
            DispatchQueue.main.async {
                do {
                    try self.viewModel.prepareAvatarImage(data: data)
                } catch {
                    self.showToast(error.localizedDescription)
                }
            }
        }
    }
}