import Foundation
import UIKit
import Display
import AsyncDisplayKit
import TelegramPresentationData
import LegacyComponents
import ComponentFlow

public final class SliderComponent: Component {
    public let valueCount: Int
    public let value: Int
    public let trackBackgroundColor: UIColor
    public let trackForegroundColor: UIColor
    public let valueUpdated: (Int) -> Void
    public let isTrackingUpdated: ((Bool) -> Void)?
    
    public init(
        valueCount: Int,
        value: Int,
        trackBackgroundColor: UIColor,
        trackForegroundColor: UIColor,
        valueUpdated: @escaping (Int) -> Void,
        isTrackingUpdated: ((Bool) -> Void)? = nil
    ) {
        self.valueCount = valueCount
        self.value = value
        self.trackBackgroundColor = trackBackgroundColor
        self.trackForegroundColor = trackForegroundColor
        self.valueUpdated = valueUpdated
        self.isTrackingUpdated = isTrackingUpdated
    }
    
    public static func ==(lhs: SliderComponent, rhs: SliderComponent) -> Bool {
        if lhs.valueCount != rhs.valueCount {
            return false
        }
        if lhs.value != rhs.value {
            return false
        }
        if lhs.trackBackgroundColor != rhs.trackBackgroundColor {
            return false
        }
        if lhs.trackForegroundColor != rhs.trackForegroundColor {
            return false
        }
        return true
    }
    
    public final class View: UIView {
        private var sliderView: TGPhotoEditorSliderView?
        
        private var component: SliderComponent?
        private weak var state: EmptyComponentState?
        
        override public init(frame: CGRect) {
            super.init(frame: frame)
        }
        
        required public init?(coder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }
                
        func update(component: SliderComponent, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: Transition) -> CGSize {
            self.component = component
            self.state = state
            
            let size = CGSize(width: availableSize.width, height: 44.0)
            
            var internalIsTrackingUpdated: ((Bool) -> Void)?
            if let isTrackingUpdated = component.isTrackingUpdated {
                internalIsTrackingUpdated = { [weak self] isTracking in
                    if let self {
                        if isTracking {
                            self.sliderView?.bordered = true
                        } else {
                            DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.1, execute: { [weak self] in
                                self?.sliderView?.bordered = false
                            })
                        }
                        isTrackingUpdated(isTracking)
                    }
                }
            }
                        
            let sliderView: TGPhotoEditorSliderView
            if let current = self.sliderView {
                sliderView = current
            } else {
                sliderView = TGPhotoEditorSliderView()
                sliderView.enablePanHandling = true
                sliderView.trackCornerRadius = 2.0
                sliderView.lineSize = 4.0
                sliderView.dotSize = 5.0
                sliderView.minimumValue = 0.0
                sliderView.startValue = 0.0
                sliderView.disablesInteractiveTransitionGestureRecognizer = true
                sliderView.maximumValue = CGFloat(component.valueCount)
                sliderView.positionsCount = component.valueCount + 1
                sliderView.useLinesForPositions = true
                
                sliderView.backgroundColor = nil
                sliderView.isOpaque = false
                sliderView.backColor = component.trackBackgroundColor
                sliderView.startColor = component.trackBackgroundColor
                sliderView.trackColor = component.trackForegroundColor
                sliderView.knobImage = generateImage(CGSize(width: 40.0, height: 40.0), rotatedContext: { size, context in
                    context.clear(CGRect(origin: CGPoint(), size: size))
                    context.setShadow(offset: CGSize(width: 0.0, height: -3.0), blur: 12.0, color: UIColor(white: 0.0, alpha: 0.25).cgColor)
                    context.setFillColor(UIColor.white.cgColor)
                    context.fillEllipse(in: CGRect(origin: CGPoint(x: 6.0, y: 6.0), size: CGSize(width: 28.0, height: 28.0)))
                })
                
                sliderView.frame = CGRect(origin: CGPoint(x: 0.0, y: 0.0), size: size)
                sliderView.hitTestEdgeInsets = UIEdgeInsets(top: -sliderView.frame.minX, left: 0.0, bottom: 0.0, right: -sliderView.frame.minX)
                
                
                sliderView.disablesInteractiveTransitionGestureRecognizer = true
                sliderView.addTarget(self, action: #selector(self.sliderValueChanged), for: .valueChanged)
                sliderView.layer.allowsGroupOpacity = true
                self.sliderView = sliderView
                self.addSubview(sliderView)
            }
            sliderView.value = CGFloat(component.value)
            sliderView.interactionBegan = {
                internalIsTrackingUpdated?(true)
            }
            sliderView.interactionEnded = {
                internalIsTrackingUpdated?(false)
            }
            
            transition.setFrame(view: sliderView, frame: CGRect(origin: CGPoint(x: 0.0, y: 0.0), size: CGSize(width: availableSize.width, height: 44.0)))
            sliderView.hitTestEdgeInsets = UIEdgeInsets(top: 0.0, left: 0.0, bottom: 0.0, right: 0.0)
            
            return size
        }
        
        @objc private func sliderValueChanged() {
            guard let component = self.component, let sliderView = self.sliderView else {
                return
            }
            component.valueUpdated(Int(sliderView.value))
        }
    }

    public func makeView() -> View {
        return View(frame: CGRect())
    }
    
    public 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)
    }
}