OrderScheduling/Pods/DDUIGestureRecognizer/DDUIGestureRecognizer/Classes/DDUIPanGestureRecognizer/DDUIPanGestureRecognizer.swift

//
//   DDUIPanGestureRecognizer.swift
//   DDUIGestureRecognizer
//   Created by DDIsFriend on 2023/12/19.
    

import Foundation

open class DDUIPanGestureRecognizer : UIPanGestureRecognizer {
    public enum PanGestureFromType {
    case bottom,top
    }
    
    public enum ExpandLevel {
    case min,`default`,max
    }
    
    public struct PanGesValue {
        /// 从什么位置弹出
        public var from : PanGestureFromType = .bottom
        /// 最小显示的高度
        public var minDisplayHeight : CGFloat = 0
        /// 默认弹出的高度
        public var defaultDisplayHeight : CGFloat = 0
        /// 最大显示的高度
        public var maxDisplayHeight : CGFloat = 0
        /// 标记当前需要完全展开时的拖动比例（0,1]
        public var dragScale : CGFloat = 0.5
        /// 标记当前是否是展开的状态
        public var expandLevel : ExpandLevel = .min
        
        internal var translationY : CGFloat = 0
        internal var currentY : CGFloat = 0
    }
    
    public var panGesValue = PanGesValue.init()

    public var expandLevelChangedHandler : ((_ oldExpandLevel: ExpandLevel, _ newExpandLevel: ExpandLevel) -> Void)?
    
    /// 会执行默认方法
    /// - Parameter target: target
    public init() {
        super.init(target: nil, action: nil)
        self.addTarget(self, action: #selector(panGesAction(ges: )))
    }
    
    /// 需要自己添加target和action
    public override init(target: Any?, action: Selector?) {
        super.init(target: target, action: action)
    }
    
    @objc fileprivate func panGesAction(ges: DDUIPanGestureRecognizer) {
        baseAction(duration: 0.1) { viewFrame, minY, defaultY, maxY, currentY in
            switch ges.state {
            case .began:
                currentY = viewFrame.origin.y
                break
            case .changed:
                /// 拖动时的移动距离是当前changed与上一次changed的差值，即deltaY
                let translationPoint = ges.translation(in: ges.view)
                let deltaY = translationPoint.y - ges.panGesValue.translationY
                ges.panGesValue.translationY = translationPoint.y
                
                currentY = (viewFrame.origin.y) + deltaY
                break
            case .ended:
                /// 当currentY在maxY和defaultY之间时的临界值
                let criticalYBetweenOfMaxYAndDefaultY = maxY - (maxY - defaultY) * ges.panGesValue.dragScale
                if ges.panGesValue.currentY <= maxY && ges.panGesValue.currentY > criticalYBetweenOfMaxYAndDefaultY {
                    currentY = maxY
                }else if ges.panGesValue.currentY > defaultY && ges.panGesValue.currentY <= criticalYBetweenOfMaxYAndDefaultY {
                    currentY = defaultY
                }
                
                /// 当currentY在minY和defaultY之间时
                let criticalYBetweenOfMinYAndDefaultY = defaultY - (defaultY - minY) * ges.panGesValue.dragScale
                if ges.panGesValue.currentY <= defaultY && ges.panGesValue.currentY > criticalYBetweenOfMinYAndDefaultY {
                    currentY = defaultY
                }else if ges.panGesValue.currentY > minY && ges.panGesValue.currentY <= criticalYBetweenOfMinYAndDefaultY {
                    currentY = minY
                }

                ges.panGesValue.translationY = 0
                break
            default:
                currentY = viewFrame.origin.y
                break
            }
        }
     }
    
    func baseAction(duration: TimeInterval,baseActionHandler: (_ viewFrame: CGRect, _ minY: CGFloat, _ defaultY: CGFloat, _ maxY: CGFloat,_ currentY: inout CGFloat) -> Void) {
        guard let superView = view?.superview else {
            assert(false,"父类都没有，拖什么拖")
            return
        }

        let superViewFrame = superView.frame
        let viewFrame = view?.frame ?? .zero
        let superViewH = superViewFrame.size.height
        let viewH = viewFrame.size.height

        switch panGesValue.from {
        case .bottom:
            /// 拖动的view的最小y值，这个值和view的高度有关，view的最大y值要和它的superView的最大y值相等，所以minY可能等于deltaH
            var minY = superViewH - panGesValue.maxDisplayHeight
            let deltaH = superViewH - viewH
            if deltaH > minY {
               minY = deltaH
            }

            /// 拖动的view的最大y值
            var maxY = superViewH - panGesValue.minDisplayHeight
            if deltaH > maxY {
               maxY = deltaH
            }

            /// 默认弹出的y值
            var defaultY = superViewH - panGesValue.defaultDisplayHeight
            if deltaH > defaultY {
                defaultY = deltaH
            }
            
            var currentY : CGFloat = 0.0

            /// 计算值
            baseActionHandler(viewFrame,minY,defaultY,maxY,&currentY)

            /// 当到达最小y值时返回
            if currentY < minY {
                return
            }
            
            /// 当到达最大y值时返回
            if currentY > maxY {
                return
            }
            
            /// 记录当前的currentY
            panGesValue.currentY = currentY

            /// 上一次expandLevel
            let oldExpandLevel = panGesValue.expandLevel
            
            /// 记录当前的expandLevel
            if panGesValue.currentY == minY {
                panGesValue.expandLevel = .max
            }else if panGesValue.currentY == maxY {
                panGesValue.expandLevel = .min
            }else if panGesValue.currentY == defaultY {
                panGesValue.expandLevel = .default
            }

            /// 新的expandLevel
            let newExpandLevel = panGesValue.expandLevel
            
            /// expandLevel改变时回调
            if oldExpandLevel != newExpandLevel {
                if let expandLevelChangedHandler = expandLevelChangedHandler {
                    expandLevelChangedHandler(oldExpandLevel,newExpandLevel)
                }
            }
            
            UIView.animate(withDuration: duration, animations: {[weak self] in
               self?.view?.frame = CGRectMake(viewFrame.origin.x, currentY, viewFrame.size.width, viewFrame.size.height)
            })
            break
        default:
            break
        }
    }
    
    public func expand(_ expand: ExpandLevel) {
        baseAction(duration: 0.25) { viewFrame, minY, defaultY, maxY, currentY in
            if expand == .max {
                currentY = minY
            }else if expand == .min {
                currentY = maxY
            }else if expand == .default {
                currentY = defaultY
            }
        }
    }
}