import SwiftUI

struct CreatorChannelFanTalkTabView: View {
    let creatorId: Int
    let isOwnCreatorChannel: Bool
    @ObservedObject var viewModel: CreatorChannelFanTalkViewModel
    let onTapWrite: () -> Void
    let onTapEdit: (CreatorChannelFanTalkItemResponse) -> Void
    let onTapDetail: (CreatorChannelFanTalkItemResponse) -> Void

    @State private var actionPopupFanTalk: CreatorChannelFanTalkItemResponse?
    @State private var fanTalkItemFrames = [Int: CGRect]()

    var body: some View {
        ZStack(alignment: .topTrailing) {
            content

            actionPopupLayer
                .zIndex(1)
        }
            .coordinateSpace(name: Self.coordinateSpaceName)
            .background(Color.black)
            .onPreferenceChange(CreatorChannelFanTalkItemFramePreferenceKey.self) { frames in
                fanTalkItemFrames.merge(frames) { _, new in new }
            }
            .onAppear {
                if viewModel.hasLoaded == false {
                    viewModel.fetchFirstPage(creatorId: creatorId)
                }
            }
            .sodaToast(isPresented: $viewModel.isShowPopup, message: viewModel.errorMessage, autohideIn: 1)
            .overlay(reportDialog)
    }

    private var content: some View {
        VStack(spacing: 0) {
            CreatorChannelFanTalkCountBar(fanTalkCount: viewModel.fanTalkCount)

            if isEmptyState {
                CreatorChannelFanTalkEmptyView(
                    showsWriteButton: isOwnCreatorChannel == false,
                    onTapWrite: onTapWrite
                )
            } else {
                LazyVStack(spacing: 0) {
                    ForEach(viewModel.fanTalks) { fanTalk in
                        fanTalkItem(fanTalk)
                            .onAppear {
                                viewModel.fetchNextPageIfNeeded(
                                    creatorId: creatorId,
                                    currentItem: fanTalk
                                )
                            }
                    }

                    if viewModel.isLoadingNextPage {
                        ProgressView()
                            .padding(.vertical, SodaSpacing.s20)
                    }
                }
                .padding(.bottom, SodaSpacing.s20)
            }
        }
    }

    private func fanTalkItem(_ fanTalk: CreatorChannelFanTalkItemResponse) -> some View {
        let isMine = fanTalk.writerId == UserDefaults.int(forKey: .userId)

        return CreatorChannelFanTalkListItem(
            fanTalk: fanTalk,
            isMine: isMine,
            isOwnCreatorChannel: isOwnCreatorChannel,
            onTapReport: {
                actionPopupFanTalk = nil
                viewModel.presentReportDialog(fanTalkId: fanTalk.fanTalkId)
            },
            onTapMore: {
                actionPopupFanTalk = actionPopupFanTalk?.fanTalkId == fanTalk.fanTalkId ? nil : fanTalk
            },
            onTapDetail: {
                guard isOwnCreatorChannel else { return }
                actionPopupFanTalk = nil
                onTapDetail(fanTalk)
            }
        )
        .background {
            GeometryReader { proxy in
                Color.clear.preference(
                    key: CreatorChannelFanTalkItemFramePreferenceKey.self,
                    value: [fanTalk.fanTalkId: proxy.frame(in: .named(Self.coordinateSpaceName))]
                )
            }
        }
    }

    @ViewBuilder
    private var actionPopupLayer: some View {
        if let fanTalk = actionPopupFanTalk,
           let itemFrame = fanTalkItemFrames[fanTalk.fanTalkId] {
            let isMine = fanTalk.writerId == UserDefaults.int(forKey: .userId)

            CreatorChannelActionPopup(
                canEdit: isMine,
                canDelete: isMine || isOwnCreatorChannel,
                onTapEdit: {
                    actionPopupFanTalk = nil
                    onTapEdit(fanTalk)
                },
                onTapDelete: {
                    actionPopupFanTalk = nil
                    viewModel.presentDeleteDialog(fanTalkId: fanTalk.fanTalkId)
                },
                editTitle: I18n.Explorer.editAction,
                deleteTitle: I18n.Explorer.deleteAction
            )
            .padding(.top, itemFrame.minY + 44)
            .padding(.trailing, SodaSpacing.s14)
        }
    }

    private var isEmptyState: Bool {
        guard viewModel.hasLoaded else { return false }
        return viewModel.fanTalkCount == 0
    }

    @ViewBuilder
    private var reportDialog: some View {
        if viewModel.isShowReportDialog {
            CheersReportDialogView(
                isShowing: $viewModel.isShowReportDialog,
                confirmAction: { reason in
                    viewModel.report(reason: reason)
                }
            )
        }
    }


    private static let coordinateSpaceName = "CreatorChannelFanTalkTabView"
}

private struct CreatorChannelFanTalkItemFramePreferenceKey: PreferenceKey {
    static var defaultValue: [Int: CGRect] = [:]

    static func reduce(value: inout [Int: CGRect], nextValue: () -> [Int: CGRect]) {
        value.merge(nextValue()) { _, new in new }
    }
}