//
//  KeyboardAvoidingDialogView.swift
//  suixinkan
//

import SnapKit
import UIKit

/// 自定义居中弹窗的键盘避让基类，负责在键盘弹出时同步移动内容卡片。
class KeyboardAvoidingDialogView: UIView {

    /// 需要避让键盘的弹窗内容视图，通常是白色卡片容器。
    var keyboardAvoidingContentView: UIView?

    /// 内容视图相对父视图的 centerY 约束，用于随键盘动画更新偏移。
    var keyboardAvoidingCenterYConstraint: Constraint?

    /// 内容视图与屏幕顶部、键盘顶部之间保留的最小距离。
    var keyboardAvoidingMinimumSpacing: CGFloat = AppSpacing.md

    private var keyboardObservers: [NSObjectProtocol] = []

    override init(frame: CGRect) {
        super.init(frame: frame)
    }

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

    deinit {
        unregisterKeyboardObservers()
    }

    override func didMoveToSuperview() {
        super.didMoveToSuperview()
        if superview == nil {
            unregisterKeyboardObservers()
        } else {
            registerKeyboardObservers()
        }
    }

    private func registerKeyboardObservers() {
        unregisterKeyboardObservers()
        let center = NotificationCenter.default
        keyboardObservers = [
            center.addObserver(
                forName: UIResponder.keyboardWillChangeFrameNotification,
                object: nil,
                queue: .main
            ) { [weak self] notification in
                self?.handleKeyboardNotification(notification)
            },
            center.addObserver(
                forName: UIResponder.keyboardWillHideNotification,
                object: nil,
                queue: .main
            ) { [weak self] notification in
                self?.handleKeyboardNotification(notification)
            }
        ]
    }

    private func unregisterKeyboardObservers() {
        keyboardObservers.forEach(NotificationCenter.default.removeObserver)
        keyboardObservers.removeAll()
    }

    private func handleKeyboardNotification(_ notification: Notification) {
        layoutIfNeeded()
        guard let userInfo = notification.userInfo else { return }

        let duration = (userInfo[UIResponder.keyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue ?? 0.25
        let curveRaw = (userInfo[UIResponder.keyboardAnimationCurveUserInfoKey] as? NSNumber)?.uintValue
            ?? UInt(UIView.AnimationCurve.easeInOut.rawValue)
        let options = UIView.AnimationOptions(rawValue: curveRaw << 16)

        keyboardAvoidingCenterYConstraint?.update(offset: keyboardAvoidanceOffset(from: userInfo))
        UIView.animate(withDuration: duration, delay: 0, options: options) {
            self.layoutIfNeeded()
        }
    }

    private func keyboardAvoidanceOffset(from userInfo: [AnyHashable: Any]) -> CGFloat {
        guard
            let contentView = keyboardAvoidingContentView,
            let keyboardFrameValue = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue
        else {
            return 0
        }

        let keyboardFrame = convert(keyboardFrameValue.cgRectValue, from: nil)
        guard keyboardFrame.minY < bounds.height else { return 0 }

        let contentHeight = contentView.bounds.height
        let baseMinY = bounds.midY - contentHeight / 2
        let baseMaxY = bounds.midY + contentHeight / 2
        let desiredBottom = keyboardFrame.minY - keyboardAvoidingMinimumSpacing
        let neededShift = max(0, baseMaxY - desiredBottom)
        let maxShift = max(0, baseMinY - keyboardAvoidingMinimumSpacing)
        return -min(neededShift, maxShift)
    }
}