import Foundation
import UIKit
import Display
import AsyncDisplayKit
import ComponentFlow
import SwiftSignalKit
import AccountContext
import TelegramCore
import MultilineTextComponent
import AvatarNode
import TelegramPresentationData
import CheckNode
import TelegramStringFormatting

private let avatarFont = avatarPlaceholderFont(size: 15.0)

final class PeerListItemComponent: Component {
    enum SelectionState: Equatable {
        case none
        case editing(isSelected: Bool, isTinted: Bool)
    }
    
    let context: AccountContext
    let theme: PresentationTheme
    let strings: PresentationStrings
    let sideInset: CGFloat
    let title: String
    let peer: EnginePeer?
    let subtitle: String?
    let selectionState: SelectionState
    let hasNext: Bool
    let action: (EnginePeer) -> Void
    
    init(
        context: AccountContext,
        theme: PresentationTheme,
        strings: PresentationStrings,
        sideInset: CGFloat,
        title: String,
        peer: EnginePeer?,
        subtitle: String?,
        selectionState: SelectionState,
        hasNext: Bool,
        action: @escaping (EnginePeer) -> Void
    ) {
        self.context = context
        self.theme = theme
        self.strings = strings
        self.sideInset = sideInset
        self.title = title
        self.peer = peer
        self.subtitle = subtitle
        self.selectionState = selectionState
        self.hasNext = hasNext
        self.action = action
    }
    
    static func ==(lhs: PeerListItemComponent, rhs: PeerListItemComponent) -> Bool {
        if lhs.context !== rhs.context {
            return false
        }
        if lhs.theme !== rhs.theme {
            return false
        }
        if lhs.strings !== rhs.strings {
            return false
        }
        if lhs.sideInset != rhs.sideInset {
            return false
        }
        if lhs.title != rhs.title {
            return false
        }
        if lhs.peer != rhs.peer {
            return false
        }
        if lhs.subtitle != rhs.subtitle {
            return false
        }
        if lhs.selectionState != rhs.selectionState {
            return false
        }
        if lhs.hasNext != rhs.hasNext {
            return false
        }
        return true
    }
    
    final class View: UIView {
        private let containerButton: HighlightTrackingButton
        
        private let title = ComponentView<Empty>()
        private let label = ComponentView<Empty>()
        private let separatorLayer: SimpleLayer
        private let avatarNode: AvatarNode
        
        private var checkLayer: CheckLayer?
        
        private var component: PeerListItemComponent?
        private weak var state: EmptyComponentState?
        
        override init(frame: CGRect) {
            self.separatorLayer = SimpleLayer()
            
            self.containerButton = HighlightTrackingButton()
            
            self.avatarNode = AvatarNode(font: avatarFont)
            self.avatarNode.isLayerBacked = true
            
            super.init(frame: frame)
            
            self.layer.addSublayer(self.separatorLayer)
            self.addSubview(self.containerButton)
            self.containerButton.layer.addSublayer(self.avatarNode.layer)
            
            self.containerButton.addTarget(self, action: #selector(self.pressed), for: .touchUpInside)
        }
        
        required init?(coder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }
        
        @objc private func pressed() {
            guard let component = self.component, let peer = component.peer else {
                return
            }
            component.action(peer)
        }
        
        func update(component: PeerListItemComponent, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
            let themeUpdated = self.component?.theme !== component.theme
            
            var hasSelectionUpdated = false
            if let previousComponent = self.component {
                switch previousComponent.selectionState {
                case .none:
                    if case .none = component.selectionState {
                    } else {
                        hasSelectionUpdated = true
                    }
                case .editing:
                    if case .editing = component.selectionState {
                    } else {
                        hasSelectionUpdated = true
                    }
                }
            }
            
            self.component = component
            self.state = state
            
            let contextInset: CGFloat = 0.0
            
            let height: CGFloat = 60.0
            let verticalInset: CGFloat = 1.0
            var leftInset: CGFloat = 62.0 + component.sideInset
            let rightInset: CGFloat = contextInset * 2.0 + 8.0 + component.sideInset
            var avatarLeftInset: CGFloat = component.sideInset + 10.0
            
            if case let .editing(isSelected, isTinted) = component.selectionState {
                leftInset += 44.0
                avatarLeftInset += 44.0
                let checkSize: CGFloat = 22.0
                
                let checkLayer: CheckLayer
                if let current = self.checkLayer {
                    checkLayer = current
                    if themeUpdated {
                        var theme = CheckNodeTheme(theme: component.theme, style: .plain)
                        if isTinted {
                            theme.backgroundColor = theme.backgroundColor.mixedWith(component.theme.list.itemBlocksBackgroundColor, alpha: 0.5)
                        }
                        checkLayer.theme = theme
                    }
                    checkLayer.setSelected(isSelected, animated: !transition.animation.isImmediate)
                } else {
                    var theme = CheckNodeTheme(theme: component.theme, style: .plain)
                    if isTinted {
                        theme.backgroundColor = theme.backgroundColor.mixedWith(component.theme.list.itemBlocksBackgroundColor, alpha: 0.5)
                    }
                    checkLayer = CheckLayer(theme: theme)
                    self.checkLayer = checkLayer
                    self.containerButton.layer.addSublayer(checkLayer)
                    checkLayer.frame = CGRect(origin: CGPoint(x: -checkSize, y: floor((height - verticalInset * 2.0 - checkSize) / 2.0)), size: CGSize(width: checkSize, height: checkSize))
                    checkLayer.setSelected(isSelected, animated: false)
                    checkLayer.setNeedsDisplay()
                }
                transition.setFrame(layer: checkLayer, frame: CGRect(origin: CGPoint(x: floor((54.0 - checkSize) * 0.5), y: floor((height - verticalInset * 2.0 - checkSize) / 2.0)), size: CGSize(width: checkSize, height: checkSize)))
            } else {
                if let checkLayer = self.checkLayer {
                    self.checkLayer = nil
                    transition.setPosition(layer: checkLayer, position: CGPoint(x: -checkLayer.bounds.width * 0.5, y: checkLayer.position.y), completion: { [weak checkLayer] _ in
                        checkLayer?.removeFromSuperlayer()
                    })
                }
            }
            
            let avatarSize: CGFloat = 40.0
            
            let avatarFrame = CGRect(origin: CGPoint(x: avatarLeftInset, y: floor((height - verticalInset * 2.0 - avatarSize) / 2.0)), size: CGSize(width: avatarSize, height: avatarSize))
            if self.avatarNode.bounds.isEmpty {
                self.avatarNode.frame = avatarFrame
            } else {
                transition.setFrame(layer: self.avatarNode.layer, frame: avatarFrame)
            }
            if let peer = component.peer {
                let clipStyle: AvatarNodeClipStyle
                if case let .channel(channel) = peer, channel.flags.contains(.isForum) {
                    clipStyle = .roundedRect
                } else {
                    clipStyle = .round
                }
                if peer.id == component.context.account.peerId {
                    self.avatarNode.setPeer(context: component.context, theme: component.theme, peer: peer, overrideImage: .savedMessagesIcon, clipStyle: clipStyle, displayDimensions: CGSize(width: avatarSize, height: avatarSize))
                } else {
                    self.avatarNode.setPeer(context: component.context, theme: component.theme, peer: peer, clipStyle: clipStyle, displayDimensions: CGSize(width: avatarSize, height: avatarSize))
                }
            }
            
            let labelData: (String, Bool)
            if let subtitle = component.subtitle {
                labelData = (subtitle, false)
            } else if case .legacyGroup = component.peer {
                labelData = (component.strings.Group_Status, false)
            } else if case let .channel(channel) = component.peer {
                if case .group = channel.info {
                    labelData = (component.strings.Group_Status, false)
                } else {
                    labelData = (component.strings.Channel_Status, false)
                }
            } else {
                labelData = (component.strings.Group_Status, false)
            }
            
            let labelSize = self.label.update(
                transition: .immediate,
                component: AnyComponent(MultilineTextComponent(
                    text: .plain(NSAttributedString(string: labelData.0, font: Font.regular(15.0), textColor: labelData.1 ? component.theme.list.itemAccentColor : component.theme.list.itemSecondaryTextColor))
                )),
                environment: {},
                containerSize: CGSize(width: availableSize.width - leftInset - rightInset, height: 100.0)
            )
            
            let previousTitleFrame = self.title.view?.frame
            var previousTitleContents: UIView?
            if hasSelectionUpdated && !"".isEmpty {
                previousTitleContents = self.title.view?.snapshotView(afterScreenUpdates: false)
            }
            
            let titleSize = self.title.update(
                transition: .immediate,
                component: AnyComponent(MultilineTextComponent(
                    text: .plain(NSAttributedString(string: component.title, font: Font.semibold(17.0), textColor: component.theme.list.itemPrimaryTextColor))
                )),
                environment: {},
                containerSize: CGSize(width: availableSize.width - leftInset - rightInset, height: 100.0)
            )
            
            let titleSpacing: CGFloat = 1.0
            let centralContentHeight: CGFloat = titleSize.height + labelSize.height + titleSpacing
            
            let titleFrame = CGRect(origin: CGPoint(x: leftInset, y: floor((height - verticalInset * 2.0 - centralContentHeight) / 2.0)), size: titleSize)
            if let titleView = self.title.view {
                if titleView.superview == nil {
                    titleView.isUserInteractionEnabled = false
                    self.containerButton.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)
                }
                
                if let previousTitleFrame, let previousTitleContents, previousTitleFrame.size != titleSize {
                    previousTitleContents.frame = CGRect(origin: previousTitleFrame.origin, size: previousTitleFrame.size)
                    self.addSubview(previousTitleContents)
                    
                    transition.setFrame(view: previousTitleContents, frame: CGRect(origin: titleFrame.origin, size: previousTitleFrame.size))
                    transition.setAlpha(view: previousTitleContents, alpha: 0.0, completion: { [weak previousTitleContents] _ in
                        previousTitleContents?.removeFromSuperview()
                    })
                    transition.animateAlpha(view: titleView, from: 0.0, to: 1.0)
                }
            }
            if let labelView = self.label.view {
                if labelView.superview == nil {
                    labelView.isUserInteractionEnabled = false
                    self.containerButton.addSubview(labelView)
                }
                transition.setFrame(view: labelView, frame: CGRect(origin: CGPoint(x: titleFrame.minX, y: titleFrame.maxY + titleSpacing), size: labelSize))
            }
            
            if themeUpdated {
                self.separatorLayer.backgroundColor = component.theme.list.itemPlainSeparatorColor.cgColor
            }
            transition.setFrame(layer: self.separatorLayer, frame: CGRect(origin: CGPoint(x: leftInset, y: height), size: CGSize(width: availableSize.width - leftInset, height: UIScreenPixel)))
            self.separatorLayer.isHidden = !component.hasNext
            
            let containerFrame = CGRect(origin: CGPoint(x: contextInset, y: verticalInset), size: CGSize(width: availableSize.width - contextInset * 2.0, height: height - verticalInset * 2.0))
            transition.setFrame(view: self.containerButton, frame: containerFrame)
            
            return CGSize(width: availableSize.width, height: height)
        }
    }
    
    func makeView() -> View {
        return View(frame: CGRect())
    }
    
    func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
        return view.update(component: self, availableSize: availableSize, state: state, environment: environment, transition: transition)
    }
}