//
//  LoginViewController.swift
//  suixinkan
//

import SnapKit
import UIKit

/// 登录页，UI 严格对齐 Android `LoginScreen`。
final class LoginViewController: BaseViewController {

    private let viewModel = LoginViewModel()

    private let backgroundImageView = UIImageView()
    private let welcomeLabel = UILabel()
    private let formCardView = UIView()
    private let topFormStack = UIStackView()
    private let accountField = LoginTextField(placeholder: "请输入账号")
    private let passwordField = PasswordInputField()
    private let agreementRow = AgreementRowView()
    private let loginButton = AppButton(title: "登录", style: .primary)
    private let loginByCodeButton = AppButton(title: "验证码登录", style: .secondary)
    private let registerContainer = UIStackView()
    private let registerPrefixLabel = UILabel()
    private let registerButton = UIButton(type: .system)

    private var hasPlayedEntranceAnimation = false

    override var preferredStatusBarStyle: UIStatusBarStyle {
        .lightContent
    }

    override func setupNavigationBar() {
        navigationController?.setNavigationBarHidden(true, animated: false)
    }

    override func setupUI() {
        view.backgroundColor = .black

        backgroundImageView.image = UIImage(named: "img_login_bg")
        backgroundImageView.contentMode = .scaleAspectFill
        backgroundImageView.clipsToBounds = true

        welcomeLabel.text = "欢迎使用\n随心瞰商家版"
        welcomeLabel.numberOfLines = 2
        welcomeLabel.font = .systemFont(ofSize: 28, weight: .semibold)
        welcomeLabel.textColor = .white

        formCardView.backgroundColor = .white
        formCardView.layer.cornerRadius = 16
        formCardView.clipsToBounds = true

        topFormStack.axis = .vertical
        topFormStack.spacing = 0
        topFormStack.alignment = .fill

        loginButton.addTarget(self, action: #selector(loginButtonTapped), for: .touchUpInside)
        loginByCodeButton.addTarget(self, action: #selector(loginByCodeButtonTapped), for: .touchUpInside)

        registerContainer.axis = .horizontal
        registerContainer.alignment = .center
        registerContainer.spacing = 0

        registerPrefixLabel.text = "没有账号？"
        registerPrefixLabel.font = .systemFont(ofSize: 14, weight: .medium)
        registerPrefixLabel.textColor = AppColor.text333

        registerButton.setTitle("去注册", for: .normal)
        registerButton.titleLabel?.font = .systemFont(ofSize: 14, weight: .medium)
        registerButton.setTitleColor(AppColor.primary, for: .normal)
        registerButton.addTarget(self, action: #selector(registerButtonTapped), for: .touchUpInside)

        registerContainer.addArrangedSubview(registerPrefixLabel)
        registerContainer.addArrangedSubview(registerButton)

        view.addSubview(backgroundImageView)
        view.addSubview(welcomeLabel)
        view.addSubview(formCardView)
        formCardView.addSubview(topFormStack)
        formCardView.addSubview(registerContainer)

        topFormStack.addArrangedSubview(accountField)
        topFormStack.setCustomSpacing(8, after: accountField)
        topFormStack.addArrangedSubview(passwordField)
        topFormStack.setCustomSpacing(24, after: passwordField)
        topFormStack.addArrangedSubview(agreementRow)
        topFormStack.setCustomSpacing(16, after: agreementRow)
        topFormStack.addArrangedSubview(loginButton)
        topFormStack.setCustomSpacing(8, after: loginButton)
        topFormStack.addArrangedSubview(loginByCodeButton)

        bindViewModel()
        updateUI()
    }

    override func setupConstraints() {
        backgroundImageView.snp.makeConstraints { make in
            make.edges.equalToSuperview()
        }

        welcomeLabel.snp.makeConstraints { make in
            make.top.equalTo(view.safeAreaLayoutGuide).offset(48)
            make.leading.trailing.equalToSuperview().inset(24)
        }

        formCardView.snp.makeConstraints { make in
            make.top.equalTo(welcomeLabel.snp.bottom).offset(48)
            make.leading.trailing.equalToSuperview().inset(24)
            make.bottom.equalTo(view.safeAreaLayoutGuide).offset(-24)
        }

        topFormStack.snp.makeConstraints { make in
            make.top.leading.trailing.equalToSuperview().inset(16)
            make.bottom.equalToSuperview().inset(16)
        }

        registerContainer.snp.makeConstraints { make in
            make.centerX.equalToSuperview()
            make.bottom.equalToSuperview().inset(16)
        }
    }

    override func bindActions() {
        accountField.onTextChange = { [weak self] text in
            self?.viewModel.updateAccount(text)
        }
        accountField.onReturnKey = { [weak self] in
            self?.passwordField.becomeFirstResponder()
        }

        passwordField.onTextChange = { [weak self] text in
            self?.viewModel.updatePassword(text)
        }
        passwordField.onReturnKey = { [weak self] in
            self?.view.endEditing(true)
            self?.viewModel.login()
        }

        agreementRow.onCheckedChange = { [weak self] in
            self?.viewModel.togglePrivacyChecked()
        }
        agreementRow.onUserAgreementTap = { [weak self] in
            self?.viewModel.onUserAgreement?()
        }
        agreementRow.onPrivacyPolicyTap = { [weak self] in
            self?.viewModel.onPrivacyPolicy?()
        }
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        playEntranceAnimationIfNeeded()
    }

    private func bindViewModel() {
        viewModel.onStateChange = { [weak self] in
            self?.updateUI()
        }
        viewModel.onShowMessage = { [weak self] message in
            self?.showToast(message)
        }
        viewModel.onLogin = { [weak self] in
            self?.showToast("登录功能待接入")
        }
        viewModel.onLoginByCode = { [weak self] in
            self?.showToast("验证码登录待接入")
        }
        viewModel.onRegister = { [weak self] in
            self?.showToast("注册待接入")
        }
        viewModel.onUserAgreement = { [weak self] in
            self?.showToast("用户协议待接入")
        }
        viewModel.onPrivacyPolicy = { [weak self] in
            self?.showToast("隐私政策待接入")
        }
    }

    private func updateUI() {
        agreementRow.isChecked = viewModel.isPrivacyChecked
        loginButton.isEnabled = viewModel.isLoginEnabled

        let showRegisterSection = viewModel.enableRegister
        loginByCodeButton.isHidden = !showRegisterSection
        registerContainer.isHidden = !showRegisterSection

        topFormStack.snp.remakeConstraints { make in
            make.top.leading.trailing.equalToSuperview().inset(16)
            if showRegisterSection {
                make.bottom.lessThanOrEqualTo(registerContainer.snp.top).offset(-16)
            } else {
                make.bottom.equalToSuperview().inset(16)
            }
        }
    }

    private func playEntranceAnimationIfNeeded() {
        guard !hasPlayedEntranceAnimation else { return }
        hasPlayedEntranceAnimation = true

        formCardView.transform = CGAffineTransform(translationX: 0, y: view.bounds.height)
        welcomeLabel.alpha = 0

        UIView.animate(withDuration: 0.4, delay: 0, options: .curveEaseOut) {
            self.formCardView.transform = .identity
            self.welcomeLabel.alpha = 1
        }
    }

    @objc private func loginButtonTapped() {
        view.endEditing(true)
        viewModel.login()
    }

    @objc private func loginByCodeButtonTapped() {
        view.endEditing(true)
        viewModel.onLoginByCode?()
    }

    @objc private func registerButtonTapped() {
        view.endEditing(true)
        viewModel.onRegister?()
    }
}