Swiftgram/submodules/TelegramUI/Components/ChatFolderLinkPreviewScreen/Sources/ChatFolderLinkHeaderComponent.swift

import Foundation
import UIKit
import Display
import AsyncDisplayKit
import ComponentFlow
import AccountContext
import MultilineTextComponent
import TelegramPresentationData

final class ChatFolderLinkHeaderComponent: Component {
    let theme: PresentationTheme
    let strings: PresentationStrings
    let title: String
    let badge: String?
    
    init(
        theme: PresentationTheme,
        strings: PresentationStrings,
        title: String,
        badge: String?
    ) {
        self.theme = theme
        self.strings = strings
        self.title = title
        self.badge = badge
    }
    
    static func ==(lhs: ChatFolderLinkHeaderComponent, rhs: ChatFolderLinkHeaderComponent) -> Bool {
        if lhs.theme !== rhs.theme {
            return false
        }
        if lhs.strings !== rhs.strings {
            return false
        }
        if lhs.title != rhs.title {
            return false
        }
        if lhs.badge != rhs.badge {
            return false
        }
        return true
    }
    
    final class View: UIView {
        private let leftView = UIImageView()
        private let rightView = UIImageView()
        private let title = ComponentView<Empty>()
        private let separatorLayer = SimpleLayer()
        
        private var component: ChatFolderLinkHeaderComponent?
        
        override init(frame: CGRect) {
            super.init(frame: frame)
            
            self.addSubview(self.leftView)
            self.addSubview(self.rightView)
            self.layer.addSublayer(self.separatorLayer)
            
            self.separatorLayer.cornerRadius = 2.0
            self.separatorLayer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
        }
        
        required init?(coder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }
        
        func update(component: ChatFolderLinkHeaderComponent, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: Transition) -> CGSize {
            let themeUpdated = self.component?.theme !== component.theme
            
            self.component = component
            
            let height: CGFloat = 60.0
            let spacing: CGFloat = 16.0
            
            if themeUpdated {
                //TODO:localize
                let leftString = NSAttributedString(string: "All Chats", font: Font.semibold(14.0), textColor: component.theme.list.freeTextColor)
                let rightString = NSAttributedString(string: "Personal", font: Font.semibold(14.0), textColor: component.theme.list.freeTextColor)
                
                let leftStringBounds = leftString.boundingRect(with: CGSize(width: 200.0, height: 100.0), options: .usesLineFragmentOrigin, context: nil)
                let rightStringBounds = rightString.boundingRect(with: CGSize(width: 200.0, height: 100.0), options: .usesLineFragmentOrigin, context: nil)
                
                self.leftView.image = generateImage(leftStringBounds.size.integralFloor, rotatedContext: { size, context in
                    context.clear(CGRect(origin: CGPoint(), size: size))
                    UIGraphicsPushContext(context)
                    
                    leftString.draw(in: leftStringBounds)
                    
                    var colors: [UIColor] = []
                    var locations: [CGFloat] = []
                    for i in 0 ... 8 {
                        let t: CGFloat = CGFloat(i) / CGFloat(8)
                        let a: CGFloat = t * t
                        colors.append(UIColor(white: 1.0, alpha: a))
                        locations.append(t)
                    }
                    
                    if let image = generateGradientImage(size: CGSize(width: size.width * 0.8, height: 16.0), colors: colors, locations: locations, direction: .horizontal) {
                        image.draw(in: CGRect(origin: CGPoint(), size: CGSize(width: image.size.width, height: size.height)), blendMode: .destinationIn, alpha: 1.0)
                    }
                    
                    UIGraphicsPopContext()
                })
                self.leftView.alpha = 0.5
                
                self.rightView.image = generateImage(rightStringBounds.size.integralFloor, rotatedContext: { size, context in
                    context.clear(CGRect(origin: CGPoint(), size: size))
                    UIGraphicsPushContext(context)
                    
                    rightString.draw(in: rightStringBounds)
                    
                    var colors: [UIColor] = []
                    var locations: [CGFloat] = []
                    for i in 0 ... 8 {
                        let t: CGFloat = CGFloat(i) / CGFloat(8)
                        let a: CGFloat = 1.0 - t * t
                        colors.append(UIColor(white: 1.0, alpha: a))
                        locations.append(t)
                    }
                    
                    if let image = generateGradientImage(size: CGSize(width: size.width * 0.8, height: 16.0), colors: colors, locations: locations, direction: .horizontal) {
                        image.draw(in: CGRect(origin: CGPoint(x: size.width - image.size.width, y: 0.0), size: CGSize(width: image.size.width, height: size.height)), blendMode: .destinationIn, alpha: 1.0)
                    }
                    
                    UIGraphicsPopContext()
                })
                self.rightView.alpha = 0.5
                
                self.separatorLayer.backgroundColor = component.theme.list.itemAccentColor.cgColor
            }
            
            var contentWidth: CGFloat = 0.0
            if let leftImage = self.leftView.image {
                contentWidth += leftImage.size.width
            }
            contentWidth += spacing
            
            let titleSize = self.title.update(
                transition: .immediate,
                component: AnyComponent(Text(text: component.title, font: Font.semibold(17.0), color: component.theme.list.itemAccentColor)),
                environment: {},
                containerSize: CGSize(width: 200.0, height: 100.0)
            )
            contentWidth += titleSize.width
            
            contentWidth += spacing
            if let rightImage = self.rightView.image {
                contentWidth += rightImage.size.width
            }
            
            var contentOriginX: CGFloat = 0.0
            
            if let leftImage = self.leftView.image {
                transition.setFrame(view: self.leftView, frame: CGRect(origin: CGPoint(x: contentOriginX, y: floor((height - leftImage.size.height) / 2.0) - 1.0), size: leftImage.size))
                contentOriginX += leftImage.size.width
            }
            contentOriginX += spacing
            
            if let titleView = self.title.view {
                if titleView.superview == nil {
                    self.addSubview(titleView)
                }
                let titleFrame = CGRect(origin: CGPoint(x: contentOriginX, y: floor((height - titleSize.height) / 2.0)), size: titleSize)
                transition.setFrame(view: titleView, frame: titleFrame)
                
                transition.setFrame(layer: self.separatorLayer, frame: CGRect(origin: CGPoint(x: titleFrame.minX, y: titleFrame.maxY + 9.0), size: CGSize(width: titleFrame.width, height: 3.0)))
            }
            contentOriginX += titleSize.width
            contentOriginX += spacing
            
            if let rightImage = self.rightView.image {
                transition.setFrame(view: self.rightView, frame: CGRect(origin: CGPoint(x: contentOriginX, y: floor((height - rightImage.size.height) / 2.0) - 1.0), size: rightImage.size))
                contentOriginX += rightImage.size.width
            }
            
            return CGSize(width: contentWidth, height: height)
        }
    }
    
    func makeView() -> View {
        return View(frame: CGRect())
    }
    
    func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: Transition) -> CGSize {
        return view.update(component: self, availableSize: availableSize, state: state, environment: environment, transition: transition)
    }
}