import SwiftUI

struct MainHomeGenreCreatorSection: View {
    let items: [HomeGenreCreatorGroupItem]
    let isFollowAllCompleted: (String) -> Bool
    let isFollowAllLoading: (String) -> Bool
    let onTapCreator: (Int) -> Void
    let onTapFollowAll: ([Int], String) -> Void

    @State private var containerWidth = UIScreen.main.bounds.width

    init(
        items: [HomeGenreCreatorGroupItem],
        isFollowAllCompleted: @escaping (String) -> Bool = { _ in false },
        isFollowAllLoading: @escaping (String) -> Bool = { _ in false },
        onTapCreator: @escaping (Int) -> Void = { _ in },
        onTapFollowAll: @escaping ([Int], String) -> Void = { _, _ in }
    ) {
        self.items = items
        self.isFollowAllCompleted = isFollowAllCompleted
        self.isFollowAllLoading = isFollowAllLoading
        self.onTapCreator = onTapCreator
        self.onTapFollowAll = onTapFollowAll
    }

    var body: some View {
        if !items.isEmpty {
            ScrollView(.horizontal, showsIndicators: false) {
                LazyHStack(alignment: .top, spacing: SodaSpacing.s4) {
                    ForEach(Array(items.enumerated()), id: \.offset) { index, item in
                        let followKey = "genre-\(index)-\(item.genreName)"

                        MainHomeCreatorGroupSection(
                            title: item.genreName,
                            creators: item.creators,
                            isFollowAllCompleted: isFollowAllCompleted(followKey),
                            isFollowAllLoading: isFollowAllLoading(followKey),
                            onTapCreator: onTapCreator,
                            onTapFollowAll: {
                                onTapFollowAll(item.creators.map(\.creatorId), followKey)
                            }
                        )
                        .frame(width: cardWidth)
                    }
                }
                .padding(.leading, SodaSpacing.s14)
                .padding(.trailing, SodaSpacing.s20)
            }
            .background(widthReader)
        }
    }

    private var cardWidth: CGFloat {
        max(0, containerWidth - (SodaSpacing.s14 * 2))
    }

    private var widthReader: some View {
        GeometryReader { proxy in
            Color.clear
                .onAppear {
                    updateContainerWidth(proxy.size.width)
                }
                .onChange(of: proxy.size.width) { newWidth in
                    updateContainerWidth(newWidth)
                }
        }
    }

    private func updateContainerWidth(_ width: CGFloat) {
        guard width > 0, abs(containerWidth - width) > 0.5 else { return }

        containerWidth = width
    }
}

struct MainHomeCreatorGroupSection: View {
    private static let maxProfileSize: CGFloat = 75

    let title: String
    let showTitle: Bool
    let creators: [HomeCreatorItem]
    let isFollowAllCompleted: Bool
    let isFollowAllLoading: Bool
    let onTapCreator: (Int) -> Void
    let onTapFollowAll: () -> Void

    @State private var cardWidth = UIScreen.main.bounds.width - (SodaSpacing.s14 * 2)

    init(
        title: String,
        showTitle: Bool = true,
        creators: [HomeCreatorItem],
        isFollowAllCompleted: Bool = false,
        isFollowAllLoading: Bool = false,
        onTapCreator: @escaping (Int) -> Void = { _ in },
        onTapFollowAll: @escaping () -> Void = {}
    ) {
        self.title = title
        self.showTitle = showTitle
        self.creators = creators
        self.isFollowAllCompleted = isFollowAllCompleted
        self.isFollowAllLoading = isFollowAllLoading
        self.onTapCreator = onTapCreator
        self.onTapFollowAll = onTapFollowAll
    }

    var body: some View {
        let profileSize = profileSize(for: cardWidth)

        VStack(alignment: .leading, spacing: SodaSpacing.s14) {
            if showTitle {
                Text(title)
                    .appFont(.heading3)
                    .foregroundColor(.white)
                    .lineLimit(1)
                    .truncationMode(.tail)
            }

            LazyVGrid(columns: columns, alignment: .center, spacing: SodaSpacing.s14) {
                ForEach(creators.prefix(8), id: \.self) { creator in
                    CreatorProfileItem(
                        imageUrl: creator.creatorProfileImage,
                        name: creator.creatorNickname,
                        imageSize: CGSize(width: profileSize, height: profileSize),
                        spacing: SodaSpacing.s6
                    ) {
                        onTapCreator(creator.creatorId)
                    }
                    .frame(width: profileSize)
                }
            }

            FollowAllButton(
                isCompleted: isFollowAllCompleted,
                isLoading: isFollowAllLoading,
                action: onTapFollowAll
            )
        }
        .padding(SodaSpacing.s14)
        .frame(maxWidth: .infinity, alignment: .leading)
        .background(cardBackground)
        .background(widthReader)
        .clipShape(RoundedRectangle(cornerRadius: SodaSpacing.s14, style: .continuous))
    }

    private var columns: [GridItem] {
        Array(repeating: GridItem(.fixed(profileSize(for: cardWidth)), spacing: SodaSpacing.s14), count: 4)
    }

    private var widthReader: some View {
        GeometryReader { proxy in
            Color.clear
                .onAppear {
                    updateCardWidth(proxy.size.width)
                }
                .onChange(of: proxy.size.width) { newWidth in
                    updateCardWidth(newWidth)
                }
        }
    }

    private func updateCardWidth(_ width: CGFloat) {
        guard width > 0, abs(cardWidth - width) > 0.5 else { return }

        cardWidth = width
    }

    private func profileSize(for width: CGFloat) -> CGFloat {
        let contentWidth = width - (SodaSpacing.s14 * 2)
        let spacingWidth = SodaSpacing.s14 * 3
        let availableItemWidth = (contentWidth - spacingWidth) / 4

        return min(Self.maxProfileSize, max(0, availableItemWidth.rounded(.down)))
    }

    private var cardBackground: some View {
        LinearGradient(
            stops: [
                .init(color: Color.gray900, location: 0),
                .init(color: Color.gray900, location: 0.29327),
                .init(color: Color.soda700, location: 1)
            ],
            startPoint: .top,
            endPoint: .bottom
        )
    }
}

struct MainHomeGenreCreatorSection_Previews: PreviewProvider {
    private static let previewImageUrl = "https://picsum.photos/200/200"

    static var previews: some View {
        MainHomeGenreCreatorSection(
            items: [
                HomeGenreCreatorGroupItem(
                    genreName: I18n.HomeRecommendation.genreCreatorSectionTitle,
                    creators: (1...8).map {
                        HomeCreatorItem(
                            creatorId: $0,
                            creatorNickname: "크리에이터이름",
                            creatorProfileImage: previewImageUrl
                        )
                    }
                )
            ]
        )
        .padding(.vertical, SodaSpacing.s20)
        .background(Color.black)
        .previewLayout(.sizeThatFits)
    }
}