import SwiftUI

struct CreatorChannelView: View {
    let creatorId: Int
    
    @StateObject private var viewModel = CreatorChannelViewModel()
    @Environment(\.dismiss) private var dismiss
    @State private var tabBarMinY: CGFloat = .greatestFiniteMagnitude

    private let titleBarHeight: CGFloat = 56
    private let tabBarHeight: CGFloat = 52
    
    init(creatorId: Int, viewModel: CreatorChannelViewModel = CreatorChannelViewModel()) {
        self.creatorId = creatorId
        _viewModel = StateObject(wrappedValue: viewModel)
    }
    
    var body: some View {
        GeometryReader { proxy in
            let titleBarBottomY = proxy.safeAreaInsets.top + titleBarHeight
            let backgroundProgress = clamp(1 - ((tabBarMinY - titleBarBottomY) / titleBarHeight))
            let isTabBarSticky = tabBarMinY <= titleBarBottomY

            ZStack(alignment: .top) {
                Color.black.ignoresSafeArea()

                ScrollView(.vertical, showsIndicators: false) {
                    VStack(spacing: 0) {
                        headerSection

                        tabBar
                            .background(
                                GeometryReader { geometry in
                                    let minY = geometry.frame(in: .global).minY
                                    Color.clear
                                        .onAppear {
                                            updateTabBarMinY(minY)
                                        }
                                        .onChange(of: minY) { value in
                                            updateTabBarMinY(value)
                                        }
                                }
                            )
                            .opacity(isTabBarSticky ? 0 : 1)

                        selectedTabContent
                    }
                }
                .ignoresSafeArea(.container, edges: .vertical)

                if isTabBarSticky {
                    tabBar
                        .frame(height: tabBarHeight)
                        .offset(y: titleBarHeight)
                }
                
                VStack(spacing: 0) {
                    Color.black
                        .opacity(backgroundProgress)
                        .frame(height: proxy.safeAreaInsets.top)
                    titleBar(backgroundProgress: backgroundProgress)
                    }
                    .ignoresSafeArea(.container, edges: .top)

                if viewModel.isLoading {
                    LoadingView()
                }
            }
        }
        .navigationBarBackButtonHidden(true)
        .onAppear {
            if viewModel.hasLoaded == false {
                viewModel.fetchHome(creatorId: creatorId)
            }
        }
        .sodaToast(isPresented: $viewModel.isShowPopup, message: viewModel.errorMessage, autohideIn: 1)
    }
    
    private func titleBar(backgroundProgress: CGFloat) -> some View {
        CreatorChannelTitleBar(
            nickname: viewModel.response?.creator.nickname ?? "",
            isFollow: viewModel.response?.creator.isFollow ?? false,
            isNotify: viewModel.response?.creator.isNotify ?? false,
            backgroundProgress: backgroundProgress,
            onTapBack: {
                dismiss()
            },
            onTapFollow: {
                viewModel.creatorFollow(follow: true, notify: true)
            },
            onTapUnfollow: {
                viewModel.creatorFollow(follow: false, notify: false)
            },
            onTapNotify: {
                viewModel.creatorFollow(follow: true, notify: true)
            },
            onTapUnnotify: {
                viewModel.creatorFollow(follow: true, notify: false)
            },
            onTapMore: {}
        )
    }
    
    @ViewBuilder
    private var headerSection: some View {
        if let creator = viewModel.response?.creator {
            CreatorChannelHeaderSection(creator: creator)
        }
    }
    
    private var tabBar: some View {
        CreatorChannelTabBar(selectedTab: $viewModel.selectedTab)
    }
    
    private func clamp(_ value: CGFloat) -> CGFloat {
        max(0, min(value, 1))
    }

    private func updateTabBarMinY(_ value: CGFloat) {
        guard tabBarMinY != value else { return }
        DispatchQueue.main.async {
            tabBarMinY = value
        }
    }

    @ViewBuilder
    private var selectedTabContent: some View {
        if viewModel.selectedTab != .home {
            CreatorChannelPlaceholderTabView(title: viewModel.selectedTab.title)
        } else if let response = viewModel.response {
            CreatorChannelHomeView(
                response: response,
                onSelectTab: selectTab
            )
        } else {
            CreatorChannelPlaceholderTabView(title: viewModel.selectedTab.title)
        }
    }

    private func selectTab(_ tab: CreatorChannelTab) {
        switch tab {
        case .audio:
            viewModel.selectedTab = .audio
        case .series:
            viewModel.selectedTab = .series
        case .community:
            viewModel.selectedTab = .community
        case .fanTalk:
            viewModel.selectedTab = .fanTalk
        case .donation:
            viewModel.selectedTab = .donation
        default:
            viewModel.selectedTab = tab
        }
    }
}

struct CreatorChannelView_Previews: PreviewProvider {
    static var previews: some View {
        CreatorChannelView(creatorId: 1, viewModel: sampleViewModel)
    }
    
    private static var sampleViewModel: CreatorChannelViewModel {
        let viewModel = CreatorChannelViewModel()
        viewModel.response = CreatorChannelHomeResponse(
            creator: CreatorChannelCreatorResponse(
                creatorId: 1,
                characterId: 10,
                nickname: "Soda Creator",
                profileImageUrl: "https://picsum.photos/600",
                followerCount: 12345,
                isAiChatAvailable: true,
                isDmAvailable: false,
                isFollow: true,
                isNotify: true
            ),
            currentLive: nil,
            latestAudioContent: nil,
            channelDonations: [],
            notices: [],
            schedules: [],
            audioContents: [],
            series: [],
            communities: [],
            fanTalk: CreatorChannelFanTalkSummaryResponse(totalCount: 0, latestFanTalk: nil),
            introduce: "",
            activity: CreatorChannelActivityResponse(
                debutDateUtc: nil,
                dday: "D+1",
                liveCount: 0,
                liveDurationHours: 0,
                liveContributorCount: 0,
                audioContentCount: 0,
                seriesCount: 0
            ),
            sns: CreatorChannelSnsResponse(
                instagramUrl: "",
                fancimmUrl: "",
                xurl: "",
                youtubeUrl: "",
                kakaoOpenChatUrl: ""
            )
        )
        viewModel.hasLoaded = true
        return viewModel
    }
}