Swiftgram/submodules/ItemListUI/Sources/Items/ItemListPlaceholderItem.swift

import Foundation
import UIKit
import Display
import AsyncDisplayKit
import SwiftSignalKit
import TelegramPresentationData

public class ItemListPlaceholderItem: ListViewItem, ItemListItem {
    let theme: PresentationTheme
    let text: String
    public let sectionId: ItemListSectionId
    let style: ItemListStyle
    public let tag: ItemListItemTag?
    
    public init(theme: PresentationTheme, text: String, sectionId: ItemListSectionId, style: ItemListStyle, tag: ItemListItemTag? = nil) {
        self.theme = theme
        self.text = text
        self.sectionId = sectionId
        self.style = style
        self.tag = tag
    }
    
    public func nodeConfiguredForParams(async: @escaping (@escaping () -> Void) -> Void, params: ListViewItemLayoutParams, synchronousLoads: Bool, previousItem: ListViewItem?, nextItem: ListViewItem?, completion: @escaping (ListViewItemNode, @escaping () -> (Signal<Void, NoError>?, (ListViewItemApply) -> Void)) -> Void) {
        async {
            let node = ItemListPlaceholderItemNode()
            let (layout, apply) = node.asyncLayout()(self, params, itemListNeighbors(item: self, topItem: previousItem as? ItemListItem, bottomItem: nextItem as? ItemListItem))
            
            node.contentSize = layout.contentSize
            node.insets = layout.insets
            
            Queue.mainQueue().async {
                completion(node, {
                    return (nil, { _ in apply() })
                })
            }
        }
    }
    
    public func updateNode(async: @escaping (@escaping () -> Void) -> Void, node: @escaping () -> ListViewItemNode, params: ListViewItemLayoutParams, previousItem: ListViewItem?, nextItem: ListViewItem?, animation: ListViewItemUpdateAnimation, completion: @escaping (ListViewItemNodeLayout, @escaping (ListViewItemApply) -> Void) -> Void) {
        Queue.mainQueue().async {
            if let nodeValue = node() as? ItemListPlaceholderItemNode {
                let makeLayout = nodeValue.asyncLayout()
                
                async {
                    let (layout, apply) = makeLayout(self, params, itemListNeighbors(item: self, topItem: previousItem as? ItemListItem, bottomItem: nextItem as? ItemListItem))
                    Queue.mainQueue().async {
                        completion(layout, { _ in
                            apply()
                        })
                    }
                }
            }
        }
    }
    
    public let selectable = false
}

private let textFont = Font.regular(15.0)

public class ItemListPlaceholderItemNode: ListViewItemNode, ItemListItemNode {
    private let backgroundNode: ASDisplayNode
    private let topStripeNode: ASDisplayNode
    private let bottomStripeNode: ASDisplayNode
    private let maskNode: ASImageNode
    
    public let textNode: TextNode
    
    private var item: ItemListPlaceholderItem?
    
    override public var canBeSelected: Bool {
        return false
    }
    
    public var tag: ItemListItemTag? {
        return self.item?.tag
    }
    
    public init() {
        self.backgroundNode = ASDisplayNode()
        self.backgroundNode.isLayerBacked = true
        self.backgroundNode.backgroundColor = .white
        
        self.maskNode = ASImageNode()
        self.maskNode.isUserInteractionEnabled = false
        
        self.topStripeNode = ASDisplayNode()
        self.topStripeNode.isLayerBacked = true
        
        self.bottomStripeNode = ASDisplayNode()
        self.bottomStripeNode.isLayerBacked = true
        
        self.textNode = TextNode()
        self.textNode.isUserInteractionEnabled = false
        
        super.init(layerBacked: false, dynamicBounce: false)
        
        self.addSubnode(self.textNode)
    }
    
    public func asyncLayout() -> (_ item: ItemListPlaceholderItem, _ params: ListViewItemLayoutParams, _ insets: ItemListNeighbors) -> (ListViewItemNodeLayout, () -> Void) {
        let makeTextLayout = TextNode.asyncLayout(self.textNode)
        
        let currentItem = self.item
        
        return { item, params, neighbors in
            var updatedTheme: PresentationTheme?
            if currentItem?.theme !== item.theme {
                updatedTheme = item.theme
            }
        
            let contentSize: CGSize
            let insets: UIEdgeInsets
            let separatorHeight = UIScreenPixel
            let itemBackgroundColor: UIColor
            let itemSeparatorColor: UIColor
            
            let leftInset = 16.0 + params.leftInset
            let rightInset = 16.0 + params.rightInset
            
            let textColor = item.theme.list.itemSecondaryTextColor
            
            let (textLayout, textApply) = makeTextLayout(TextNodeLayoutArguments(attributedString: NSAttributedString(string: item.text, font: textFont, textColor: textColor), backgroundColor: nil, maximumNumberOfLines: 0, truncationType: .end, constrainedSize: CGSize(width: params.width - leftInset - rightInset, height: CGFloat.greatestFiniteMagnitude), alignment: .center, cutout: nil, insets: UIEdgeInsets()))
            
            let height: CGFloat = 42.0 + textLayout.size.height
            
            switch item.style {
                case .plain:
                    itemBackgroundColor = item.theme.list.plainBackgroundColor
                    itemSeparatorColor = item.theme.list.itemPlainSeparatorColor
                    contentSize = CGSize(width: params.width, height: height)
                    insets = itemListNeighborsPlainInsets(neighbors)
                case .blocks:
                    itemBackgroundColor = item.theme.list.itemBlocksBackgroundColor
                    itemSeparatorColor = item.theme.list.itemBlocksSeparatorColor
                    contentSize = CGSize(width: params.width, height: height)
                    insets = itemListNeighborsGroupedInsets(neighbors, params)
            }
            
            return (ListViewItemNodeLayout(contentSize: contentSize, insets: insets), { [weak self] in
                if let strongSelf = self {
                    strongSelf.item = item
                    
                    if let _ = updatedTheme {
                        strongSelf.topStripeNode.backgroundColor = itemSeparatorColor
                        strongSelf.bottomStripeNode.backgroundColor = itemSeparatorColor
                        strongSelf.backgroundNode.backgroundColor = itemBackgroundColor
                    }
                    
                    let _ = textApply()
                    
                    switch item.style {
                        case .plain:
                            if strongSelf.backgroundNode.supernode != nil {
                                strongSelf.backgroundNode.removeFromSupernode()
                            }
                            if strongSelf.topStripeNode.supernode != nil {
                                strongSelf.topStripeNode.removeFromSupernode()
                            }
                            if strongSelf.bottomStripeNode.supernode == nil {
                                strongSelf.insertSubnode(strongSelf.bottomStripeNode, at: 0)
                            }
                            if strongSelf.maskNode.supernode != nil {
                                strongSelf.maskNode.removeFromSupernode()
                            }
                            strongSelf.bottomStripeNode.frame = CGRect(origin: CGPoint(x: leftInset, y: contentSize.height - separatorHeight), size: CGSize(width: params.width - leftInset, height: separatorHeight))
                        case .blocks:
                            if strongSelf.backgroundNode.supernode == nil {
                                strongSelf.insertSubnode(strongSelf.backgroundNode, at: 0)
                            }
                            if strongSelf.topStripeNode.supernode == nil {
                                strongSelf.insertSubnode(strongSelf.topStripeNode, at: 1)
                            }
                            if strongSelf.bottomStripeNode.supernode == nil {
                                strongSelf.insertSubnode(strongSelf.bottomStripeNode, at: 2)
                            }
                            if strongSelf.maskNode.supernode == nil {
                                strongSelf.insertSubnode(strongSelf.maskNode, at: 3)
                            }
                            let hasCorners = itemListHasRoundedBlockLayout(params)
                            var hasTopCorners = false
                            var hasBottomCorners = false
                            switch neighbors.top {
                                case .sameSection(false):
                                    strongSelf.topStripeNode.isHidden = true
                                default:
                                    hasTopCorners = true
                                    strongSelf.topStripeNode.isHidden = hasCorners
                            }
                            let bottomStripeInset: CGFloat
                            switch neighbors.bottom {
                                case .sameSection(false):
                                    bottomStripeInset = leftInset
                                    strongSelf.bottomStripeNode.isHidden = false
                                default:
                                    bottomStripeInset = 0.0
                                    hasBottomCorners = true
                                    strongSelf.bottomStripeNode.isHidden = hasCorners
                            }
                            
                            strongSelf.maskNode.image = hasCorners ? PresentationResourcesItemList.cornersImage(item.theme, top: hasTopCorners, bottom: hasBottomCorners) : nil
                        
                            strongSelf.backgroundNode.frame = CGRect(origin: CGPoint(x: 0.0, y: -min(insets.top, separatorHeight)), size: CGSize(width: params.width, height: contentSize.height + min(insets.top, separatorHeight) + min(insets.bottom, separatorHeight)))
                            strongSelf.maskNode.frame = strongSelf.backgroundNode.frame.insetBy(dx: params.leftInset, dy: 0.0)
                            strongSelf.topStripeNode.frame = CGRect(origin: CGPoint(x: 0.0, y: -min(insets.top, separatorHeight)), size: CGSize(width: params.width, height: separatorHeight))
                            strongSelf.bottomStripeNode.frame = CGRect(origin: CGPoint(x: bottomStripeInset, y: contentSize.height - separatorHeight), size: CGSize(width: params.width - bottomStripeInset, height: separatorHeight))
                    }
                    
                    strongSelf.textNode.frame = CGRect(origin: CGPoint(x: floorToScreenPixels((params.width - textLayout.size.width) / 2.0), y: floorToScreenPixels((height - textLayout.size.height) / 2.0)), size: textLayout.size)
                }
            })
        }
    }
    
    override public func animateInsertion(_ currentTimestamp: Double, duration: Double, options: ListViewItemAnimationOptions) {
        self.layer.animateAlpha(from: 0.0, to: 1.0, duration: 0.4)
    }
    
    override public func animateAdded(_ currentTimestamp: Double, duration: Double) {
        self.layer.animateAlpha(from: 0.0, to: 1.0, duration: 0.2)
    }
    
    override public func animateRemoved(_ currentTimestamp: Double, duration: Double) {
        self.layer.animateAlpha(from: 1.0, to: 0.0, duration: 0.15, removeOnCompletion: false)
    }
}