platform-ios/RainbowPlanet/RainbowPlanet/Modules/PublishModule/PublishMediaPicker/View/KSMediaPickerView.swift

//
//  KSMediaPickerView.swift
// 
//
//  Created by kinsun on 2019/3/1.
//

import UIKit

open class KSMediaPickerView: UIView {
    
    required public init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    public let albumNavigationView = KSMediaPickerView.navigationView()
    
    var jumpType: KSMediaPickerController.jumpType?

    
    public let collectionView = {() -> KSMediaPickerCollectionView in
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .vertical
        
        let collectionView = KSMediaPickerCollectionView(frame: .zero, collectionViewLayout: layout)
        collectionView.backgroundColor = .clear
        collectionView.alwaysBounceVertical = true
        collectionView.clipsToBounds = true
        collectionView.bounces = false
        if #available(iOS 11.0, *) {
            collectionView.contentInsetAdjustmentBehavior = .never
        }
        return collectionView
    }()
    
    public let previewView = KSMediaPickerPreviewView()
    
    private let _toolBarSafeAreaView = {() -> UIView in
        let toolBarSafeAreaView = UIView()
        toolBarSafeAreaView.backgroundColor = .clear
        return toolBarSafeAreaView
    }()
    
    private let _blackBackgroundLayer = {() -> CALayer in
        let blackBackgroundLayer = CALayer()
        blackBackgroundLayer.opacity = 0.0
        blackBackgroundLayer.backgroundColor = UIColor.ks_black.cgColor
        return blackBackgroundLayer
    }()
    
    override public init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .ks_white
        layer.addSublayer(_blackBackgroundLayer)
        
        addSubview(collectionView)
        addSubview(previewView)
        albumNavigationView.nextButton.isEnabled = false
        addSubview(albumNavigationView)
        
        collectionView.handlePanCallback = {[weak self] (pan) in
            self?._collectionView(did: pan)
        }
        collectionView.scrollViewDidScrollCallback = {[weak self] (scrollView) in
            self?._collectionViewDidScroll(scrollView)
        }
        collectionView.scrollViewDidEndDraggingCallback = {[weak self] (scrollView, decelerate) in
            self?._collectionViewDidEndDragging(scrollView, decelerate: decelerate)
        }
    }
    
    override open func layoutSublayers(of layer: CALayer) {
        super.layoutSublayers(of: layer)
        _blackBackgroundLayer.frame = layer.bounds
    }
    
    override open func layoutSubviews() {
        super.layoutSubviews()
        let bounds = self.bounds
        let safeArea = UIEdgeInsets.safeAreaInsets
        
        let windowSize = bounds.size
        let windowWidth = windowSize.width
        let windowHeight = windowSize.height
        let floatZore = CGFloat(0.0)
        let safeBottomMargin = safeArea.bottom        
        
        var viewW = windowWidth
        var viewH = safeBottomMargin+48.0
        var viewX = floatZore
        var viewY = windowHeight-viewH
        _toolBarSafeAreaView.frame = CGRect(x: viewX, y: viewY, width: viewW, height: viewH)
                
        let margin = CGFloat(3.0)
        let columnCount = UInt(4)
        let itemW = floor((windowWidth-margin*CGFloat(columnCount-1))/CGFloat(columnCount))
        let layout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout
        layout.itemSize = CGSize(width: itemW, height: itemW)
        layout.minimumLineSpacing = margin
        layout.minimumInteritemSpacing = margin
        layout.sectionInset = .zero
        
        viewX = floatZore
        viewY = floatZore
        viewW = windowWidth
        viewH = UIView.statusBarNavigationBarSize.height
        albumNavigationView.frame = CGRect(x: viewX, y: viewY, width: viewW, height: viewH)
        
        let navHeight = albumNavigationView.frame.maxY
        let baseY = previewView.frame.origin.y
        viewX = floatZore
        if baseY == 0 {
            viewY = navHeight
            _baseY = viewY
        } else {
            viewY = baseY
        }
        viewW = windowWidth
        viewH = viewW
        previewView.frame = CGRect(x: viewX, y: viewY, width: viewW, height: viewH)
        
        let previewViewFrameMaxY = previewView.frame.maxY
        viewY = floatZore
        viewH = previewViewFrameMaxY+20.0
        _previewGestureCorrespondingArea = CGRect(x: viewX, y: viewY, width: viewW, height: viewH)
        
        let toolBarSafeAreaViewHeight = _toolBarSafeAreaView.bounds.size.height
        
        viewX = floatZore
        viewY = floatZore
        viewW = windowWidth
        viewH = windowHeight-toolBarSafeAreaViewHeight
        
        if jumpType == .publishEdit {
            let frame = CGRect(x: viewX, y: viewY, width: viewW, height: viewH + kTabBarTotalHeight)
            collectionView.frame = frame
        }else {

            let frame = CGRect(x: viewX, y: viewY, width: viewW, height: viewH)
            collectionView.frame = frame
        }
        
        let conetntInset = UIEdgeInsets(top: previewViewFrameMaxY+3.0, left: 0.0, bottom: 0.0, right: 0.0)
        collectionView.contentInset = conetntInset
        collectionView.scrollIndicatorInsets = conetntInset
        
    }
    
    private var _baseY: CGFloat?
    private var _previewGestureCorrespondingArea: CGRect?
    private var _isInGestureCorrespondingArea = false
    
    private var _panBeginLocationY = CGFloat(0)
    private var _isScrollDown = false
    private var _isRetract = false {
        didSet {
            if albumNavigationView.isHidden != _isRetract {
                let trans = CATransition()
                trans.duration = 0.2
                trans.type = .push
                trans.subtype = _isRetract ? .fromTop : .fromBottom
                albumNavigationView.isHidden = _isRetract
                albumNavigationView.layer.add(trans, forKey: nil)
            }
        }
    }
    
    private func _collectionView(did pan: UIPanGestureRecognizer) {
        switch pan.state {
        case .began:
            _panBeginLocationY = pan.location(in: self).y
            break
        case .changed:
            // FIXME: preview视图收起展示逻辑
//            guard let baseY = _baseY else {
//                return
//            }
//            let location = pan.location(in: self)
//            let locationY = location.y
//            _isScrollDown = locationY > _panBeginLocationY
//            _isInGestureCorrespondingArea = _previewGestureCorrespondingArea != nil && _previewGestureCorrespondingArea!.contains(location)
//            if _isInGestureCorrespondingArea {
//                var previewFrame = previewView.frame
//                var y = locationY-previewFrame.size.height
//                if y >= baseY {
//                    y = baseY
//                }
//                previewFrame.origin.y = y
//                previewView.frame = previewFrame
//
//                _previewGestureCorrespondingArea!.size.height = previewFrame.maxY+20.0
//            }
//            _panBeginLocationY = locationY
            break
        case .cancelled, .ended, .failed:
            guard _isInGestureCorrespondingArea, let baseY = _baseY else {
                return
            }
            var previewFrame = previewView.frame
            let maxY = previewFrame.maxY
            let boundary = (previewFrame.size.height+baseY)*(_isScrollDown ? 0.2 : 0.8)
            if maxY < boundary {
                _isRetract = true
                previewFrame.origin.y = baseY-previewFrame.size.height
            } else {
                _isRetract = false
                previewFrame.origin.y = baseY
            }
            
            let height = previewFrame.maxY
            _previewGestureCorrespondingArea!.size.height = height+20.0
            
            var topPoint: CGPoint? = nil
            let offsetY = -collectionView.contentOffset.y
            if offsetY > height {
                topPoint = CGPoint(x: 0.0, y: -(height+3.0))
            }
            UIView.animate(withDuration: 0.2, animations: {[weak self, weak previewView] in
                previewView?.frame = previewFrame
                guard let k_topPoint = topPoint else {
                    return
                }
                self?.collectionView.contentOffset = k_topPoint
            })
            break
        default:
            break
        }
    }
    
    private func _collectionViewDidScroll(_ scrollView: KSMediaPickerCollectionView) {
        guard !_isInGestureCorrespondingArea, _isScrollDown, _isRetract, let baseY = _baseY else {
            return
        }
        let offsetY = -(scrollView.contentOffset.y)
        if offsetY >= baseY {
            var previewFrame = previewView.frame
            var y = offsetY-previewFrame.size.height
            if y >= baseY {
                y = baseY
            }
            previewFrame.origin.y = y
            previewView.frame = previewFrame
            
            _previewGestureCorrespondingArea!.size.height = previewFrame.maxY+20.0
        }
    }
    
    private func _collectionViewDidEndDragging(_ scrollView: KSMediaPickerCollectionView, decelerate: Bool) {
        var previewFrame = previewView.frame
        let maxY = previewFrame.maxY
        guard scrollView.contentOffset.y <= -maxY, !_isInGestureCorrespondingArea, let baseY = _baseY else {
            return
        }
        let boundary = (previewFrame.size.height+baseY)*(_isScrollDown ? 0.2 : 0.8)
        if maxY < boundary && !_isRetract {
            _isRetract = true
            previewFrame.origin.y = baseY-previewFrame.size.height
        } else if _isRetract {
            _isRetract = false
            previewFrame.origin.y = baseY
        } else {
            return
        }
        
        let height = previewFrame.maxY
        _previewGestureCorrespondingArea!.size.height = height+20.0
        
        let topPoint = CGPoint(x: 0.0, y: -(height+3.0))
        UIView.animate(withDuration: 0.2, animations: {[weak self, weak previewView] in
            previewView?.frame = previewFrame
            self?.collectionView.contentOffset = topPoint
        })
    }
    
    public func showPreview(_ animated: Bool) {
        var previewFrame = previewView.frame
        previewFrame.origin.y = _baseY ?? 0
        _isRetract = false
        if animated {
            UIView.animate(withDuration: 0.2, animations: {[weak self] in
                self?.previewView.frame = previewFrame
            }) {[weak self] (finish) in
                self?.setNeedsLayout()
            }
        } else {
            setNeedsLayout()
        }
    }
    
    public func collectionViewScrollToTop() {
        let point = CGPoint(x: 0.0, y: -collectionView.contentInset.top)
        if !point.equalTo(collectionView.contentOffset) {
            collectionView.setContentOffset(point, animated: false)
            showPreview(false)
        }
    }
    
}