import SwiftUI

struct BrowseView: View {
    let category: ContentCategory
    @Bindable var viewModel: BrowseViewModel

    var body: some View {
        Group {
            if !viewModel.hasData && viewModel.error == nil {
                VStack(spacing: 0) {
                    FilterBarView(filter: $viewModel.filter) {
                        Task { await viewModel.applyFilter(viewModel.filter) }
                    }
                    .padding(.vertical, 8)

                    ProgressView()
                        .frame(maxWidth: .infinity, maxHeight: .infinity)
                }
            } else {
                ScrollView {
                    VStack(spacing: 0) {
                        FilterBarView(filter: $viewModel.filter) {
                            Task { await viewModel.applyFilter(viewModel.filter) }
                        }
                        .padding(.vertical, 8)

                        if let error = viewModel.error {
                            errorView(error)
                        } else if viewModel.items.isEmpty {
                            emptyView
                        } else {
                            ContentGridView(items: viewModel.items) {
                                Task { await viewModel.loadMore() }
                            }
                            .padding(.horizontal)
                            .padding(.top, 8)

                            if viewModel.isLoadingMore {
                                ProgressView()
                                    .padding()
                            }
                        }
                    }
                }
            }
        }
        .navigationTitle(category.displayName)
        .navigationDestination(for: ContentItem.self) { item in
            DetailView(item: item)
        }
        .refreshable {
            await viewModel.loadContent()
        }
        .task {
            viewModel.category = category
            await viewModel.loadContentIfNeeded()
        }
    }

    private func errorView(_ message: String) -> some View {
        VStack(spacing: 16) {
            Image(systemName: "exclamationmark.triangle")
                .font(.system(size: 48))
                .foregroundStyle(.secondary)
            Text(message)
                .foregroundStyle(.secondary)
            Button("重试") {
                Task { await viewModel.loadContent() }
            }
        }
        .frame(maxWidth: .infinity, minHeight: 300)
    }

    private var emptyView: some View {
        VStack(spacing: 12) {
            Image(systemName: "film.stack")
                .font(.system(size: 48))
                .foregroundStyle(.secondary)
            Text("暂无内容")
                .foregroundStyle(.secondary)
        }
        .frame(maxWidth: .infinity, minHeight: 300)
    }
}