import Foundation
import UIKit
import Display
import ComponentFlow
import TelegramPresentationData
import MultilineTextComponent

final class SectionHeaderComponent: Component {
    let theme: PresentationTheme
    let sideInset: CGFloat
    let title: String
    
    init(
        theme: PresentationTheme,
        sideInset: CGFloat,
        title: String
    ) {
        self.theme = theme
        self.sideInset = sideInset
        self.title = title
    }
    
    static func ==(lhs: SectionHeaderComponent, rhs: SectionHeaderComponent) -> Bool {
        if lhs.theme !== rhs.theme {
            return false
        }
        if lhs.sideInset != rhs.sideInset {
            return false
        }
        if lhs.title != rhs.title {
            return false
        }
        return true
    }
    
    final class View: UIView {        
        private let title = ComponentView<Empty>()
        private let backgroundView: BlurredBackgroundView
        
        private var component: SectionHeaderComponent?
        private weak var state: EmptyComponentState?
        
        override init(frame: CGRect) {            
            self.backgroundView = BlurredBackgroundView(color: .clear, enableBlur: true)
            
            super.init(frame: frame)
            
            self.addSubview(self.backgroundView)
        }
        
        required init?(coder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }
        
        func update(component: SectionHeaderComponent, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: Transition) -> CGSize {
            let themeUpdated = self.component?.theme !== component.theme
            
            self.component = component
            self.state = state
            
            let height: CGFloat = 28.0
            let leftInset: CGFloat = component.sideInset
            let rightInset: CGFloat = component.sideInset
            
            let previousTitleFrame = self.title.view?.frame
            
            if themeUpdated {
                self.backgroundView.updateColor(color: component.theme.rootController.navigationBar.blurredBackgroundColor, transition: .immediate)
            }
            
            let titleSize = self.title.update(
                transition: .immediate,
                component: AnyComponent(MultilineTextComponent(
                    text: .plain(NSAttributedString(string: component.title, font: Font.regular(13.0), textColor: component.theme.list.itemSecondaryTextColor))
                )),
                environment: {},
                containerSize: CGSize(width: availableSize.width - leftInset - rightInset, height: 100.0)
            )
            
            let titleFrame = CGRect(origin: CGPoint(x: leftInset, y: floor((height - titleSize.height) / 2.0)), size: titleSize)
            if let titleView = self.title.view {
                if titleView.superview == nil {
                    titleView.isUserInteractionEnabled = false
                    self.addSubview(titleView)
                }
                titleView.frame = titleFrame
                if let previousTitleFrame, previousTitleFrame.origin.x != titleFrame.origin.x {
                    transition.animatePosition(view: titleView, from: CGPoint(x: previousTitleFrame.origin.x - titleFrame.origin.x, y: 0.0), to: CGPoint(), additive: true)
                }
            }
            
            let size = CGSize(width: availableSize.width, height: height)
            
            transition.setFrame(view: self.backgroundView, frame: CGRect(origin: CGPoint(), size: size))
            self.backgroundView.update(size: size, transition: transition.containedViewLayoutTransition)
            
            return size
        }
    }
    
    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)
    }
}