import Siesta
import SwiftUI

struct ChannelPlaylistView: View {
    #if os(iOS)
        static let hiddenOffset = max(UIScreen.main.bounds.height, UIScreen.main.bounds.width) + 100
    #endif

    var playlist: ChannelPlaylist?

    @State private var presentingShareSheet = false
    @State private var shareURL: URL?

    #if os(iOS)
        @State private var viewVerticalOffset = Self.hiddenOffset
    #endif

    @StateObject private var store = Store<ChannelPlaylist>()

    @Environment(\.colorScheme) private var colorScheme
    @Environment(\.navigationStyle) private var navigationStyle

    @EnvironmentObject<AccountsModel> private var accounts
    @EnvironmentObject<NavigationModel> private var navigation
    @EnvironmentObject<PlayerModel> private var player
    @EnvironmentObject<RecentsModel> private var recents

    private var items: [ContentItem] {
        ContentItem.array(of: store.item?.videos ?? [])
    }

    private var presentedPlaylist: ChannelPlaylist? {
        playlist ?? recents.presentedPlaylist
    }

    private var resource: Resource? {
        guard let playlist = presentedPlaylist else {
            return nil
        }

        let resource = accounts.api.channelPlaylist(playlist.id)
        resource?.addObserver(store)

        return resource
    }

    var body: some View {
        if navigationStyle == .tab {
            NavigationView {
                BrowserPlayerControls {
                    content
                }
            }
            #if os(iOS)
            .onChange(of: navigation.presentingPlaylist) { newValue in
                if newValue {
                    store.clear()
                    viewVerticalOffset = 0
                    resource?.load()
                } else {
                    viewVerticalOffset = Self.hiddenOffset
                }
            }
            .offset(y: viewVerticalOffset)
            .opacity(viewVerticalOffset == Self.hiddenOffset ? 0 : 1)
            .animation(.easeIn(duration: 0.2), value: viewVerticalOffset)
            #endif
        } else {
            BrowserPlayerControls {
                content
            }
        }
    }

    var content: some View {
        VStack(alignment: .leading) {
            #if os(tvOS)
                HStack {
                    Text(playlist.title)
                        .font(.title2)
                        .frame(alignment: .leading)

                    Spacer()

                    FavoriteButton(item: FavoriteItem(section: .channelPlaylist(playlist.id, playlist.title)))
                        .labelStyle(.iconOnly)

                    playButton
                        .labelStyle(.iconOnly)
                    shuffleButton
                        .labelStyle(.iconOnly)
                }
            #endif
            VerticalCells(items: items)
                .environment(\.inChannelPlaylistView, true)
        }
        #if os(iOS)
        .sheet(isPresented: $presentingShareSheet) {
            if let shareURL = shareURL {
                ShareSheet(activityItems: [shareURL])
            }
        }
        #endif
        .onAppear {
            resource?.loadIfNeeded()
        }
        #if os(tvOS)
        .background(Color.background(scheme: colorScheme))
        #else
        .toolbar {
            ToolbarItem(placement: .navigation) {
                if navigationStyle == .tab {
                    Button("Done") {
                        navigation.presentingPlaylist = false
                    }
                }
            }

            ToolbarItem(placement: playlistButtonsPlacement) {
                HStack {
                    ShareButton(
                        contentItem: contentItem,
                        presentingShareSheet: $presentingShareSheet,
                        shareURL: $shareURL
                    )

                    if let playlist = presentedPlaylist {
                        FavoriteButton(item: FavoriteItem(section: .channelPlaylist(playlist.id, playlist.title)))
                    }

                    playButton
                    shuffleButton
                }
            }
        }
        .navigationTitle(presentedPlaylist?.title ?? "")
        #endif
    }

    private var playlistButtonsPlacement: ToolbarItemPlacement {
        #if os(iOS)
            .navigationBarTrailing
        #else
            .automatic
        #endif
    }

    private var playButton: some View {
        Button {
            player.play(videos)
        } label: {
            Label("Play All", systemImage: "play")
        }
    }

    private var shuffleButton: some View {
        Button {
            player.play(videos, shuffling: true)
        } label: {
            Label("Shuffle", systemImage: "shuffle")
        }
    }

    private var videos: [Video] {
        items.compactMap(\.video)
    }

    private var contentItem: ContentItem {
        ContentItem(playlist: playlist)
    }
}

struct ChannelPlaylistView_Previews: PreviewProvider {
    static var previews: some View {
        ChannelPlaylistView(playlist: ChannelPlaylist.fixture)
            .injectFixtureEnvironmentObjects()
    }
}