//
//  SectionEventBannerView.swift
//  SodaLive
//
//  Created by klaus on 2023/08/09.
//

import SwiftUI
import Kingfisher

struct SectionEventBannerView: View {
    
    @State private var currentIndex = 0
    @State private var timer = Timer.publish(every: 4, on: .main, in: .common).autoconnect()
    @AppStorage("token") private var token: String = UserDefaults.string(forKey: UserDefaultsKey.token)
    
    let items: [EventItem]
    
    var body: some View {
        VStack(spacing: 16) {
            TabView(selection: $currentIndex) {
                ForEach(0..<items.count, id: \.self) { index in
                    let item = items[index]
                    SectionEventBannerPage(
                        item: item,
                        width: screenSize().width,
                        height: screenSize().width * 300 / 1000,
                        token: token
                    )
                    .tag(index)
                }
            }
            .tabViewStyle(PageTabViewStyle(indexDisplayMode: .never))
            .frame(
                width: screenSize().width,
                height: screenSize().width * 300 / 1000,
                alignment: .center
            )
            
            HStack(spacing: 8) {
                ForEach(0..<items.count, id: \.self) { index in
                    Capsule()
                        .foregroundColor(index == currentIndex ? .button : .gray77)
                        .frame(width: 10, height: 10)
                        .tag(index)
                }
            }
        }
        .onAppear {
            timer = Timer.publish(every: 4, on: .main, in: .common).autoconnect()
        }
        .onDisappear {
            timer.upstream.connect().cancel()
        }
        .onReceive(timer) { _ in
            DispatchQueue.main.async {
                withAnimation {
                    if currentIndex == items.count - 1 {
                        currentIndex = 0
                    } else {
                        currentIndex += 1
                    }
                }
            }
        }
    }
}

struct SectionEventBannerView_Previews: PreviewProvider {
    static var previews: some View {
        SectionEventBannerView(items: [])
    }
}

private struct SectionEventBannerPage: View {
    let item: EventItem
    let width: CGFloat
    let height: CGFloat
    let token: String
    @State private var boundURL: URL?
    
    var body: some View {
        Group {
            if let boundURL {
                KFImage(boundURL)
                    .cancelOnDisappear(true)
                    .downsampling(size: CGSize(width: width, height: height))
                    .resizable()
                    .scaledToFill()
                    .frame(width: width, height: height, alignment: .center)
            } else {
                Color.clear
                    .frame(width: width, height: height, alignment: .center)
            }
        }
        .contentShape(Rectangle())
        .onTapGesture {
            if !token.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
                if let _ = item.detailImageUrl {
                    AppState.shared.setAppStep(step: .eventDetail(event: item))
                } else if let link = item.link,
                          link.trimmingCharacters(in: .whitespaces).count > 0,
                          let url = URL(string: link),
                          UIApplication.shared.canOpenURL(url) {
                    UIApplication.shared.open(url)
                }
            } else {
                AppState.shared.setAppStep(step: .login)
            }
        }
        .onAppear {
            let urlString = item.thumbnailImageUrl.addingPercentEncoding(
                withAllowedCharacters: .urlQueryAllowed
            ) ?? item.thumbnailImageUrl
            boundURL = URL(string: urlString)
        }
        .onDisappear {
            boundURL = nil
        }
    }
}