import SwiftUI

struct HomeView: View {
    var viewModel: HomeViewModel
    @State private var searchText = ""
    @State private var searchViewModel = SearchViewModel()

    private var showingSearchResults: Bool {
        searchViewModel.hasSearched
    }

    var body: some View {
        Group {
            if !viewModel.hasData && viewModel.error == nil && !showingSearchResults {
                ProgressView()
                    .frame(maxWidth: .infinity, maxHeight: .infinity)
            } else if showingSearchResults && searchViewModel.isSearching {
                ProgressView()
                    .frame(maxWidth: .infinity, maxHeight: .infinity)
            } else {
                ScrollView {
                    if showingSearchResults {
                        searchContent
                    } else {
                        homeContent
                    }
                }
            }
        }
        .navigationTitle("低端影视")
        .navigationDestination(for: ContentItem.self) { item in
            DetailView(item: item)
        }
        .searchable(text: $searchText, prompt: "搜索电影、电视剧...")
        .onSubmit(of: .search) {
            let trimmed = searchText.trimmingCharacters(in: .whitespacesAndNewlines)
            guard !trimmed.isEmpty else { return }
            Task {
                searchViewModel.query = trimmed
                await searchViewModel.search()
            }
        }
        .onChange(of: searchText) { _, newValue in
            if newValue.isEmpty {
                searchViewModel.clear()
            }
        }
        .refreshable {
            if showingSearchResults {
                await searchViewModel.search()
            } else {
                await viewModel.loadHome()
            }
        }
        .task {
            await viewModel.loadHomeIfNeeded()
        }
    }

    // MARK: - 首页内容

    @ViewBuilder
    private var homeContent: some View {
        if let error = viewModel.error {
            errorView(error)
        } else {
            LazyVStack(alignment: .leading, spacing: 24) {
                if !viewModel.recommendedItems.isEmpty {
                    sectionHeader("热门推荐")
                    ScrollView(.horizontal, showsIndicators: false) {
                        LazyHStack(spacing: 12) {
                            ForEach(viewModel.recommendedItems) { item in
                                NavigationLink(value: item) {
                                    ContentCardView(item: item)
                                }
                                .buttonStyle(.plain)
                            }
                        }
                        .padding(.horizontal)
                    }
                }

                if !viewModel.latestItems.isEmpty {
                    sectionHeader("最新更新")
                    ContentGridView(items: viewModel.latestItems)
                        .padding(.horizontal)
                }
            }
            .padding(.vertical)
        }
    }

    // MARK: - 搜索结果

    @ViewBuilder
    private var searchContent: some View {
        if let error = searchViewModel.error {
            VStack(spacing: 16) {
                Image(systemName: "exclamationmark.triangle")
                    .font(.system(size: 48))
                    .foregroundStyle(.secondary)
                Text(error)
                    .foregroundStyle(.secondary)
                Button("重试") {
                    Task { await searchViewModel.search() }
                }
            }
            .frame(maxWidth: .infinity, minHeight: 300)
        } else if searchViewModel.results.isEmpty {
            VStack(spacing: 12) {
                Image(systemName: "magnifyingglass")
                    .font(.system(size: 48))
                    .foregroundStyle(.secondary)
                Text("未找到「\(searchViewModel.query)」的相关内容")
                    .foregroundStyle(.secondary)
            }
            .frame(maxWidth: .infinity, minHeight: 300)
        } else {
            LazyVStack(alignment: .leading, spacing: 16) {
                Text("搜索结果")
                    .font(.title2)
                    .fontWeight(.bold)
                    .padding(.horizontal)

                ContentGridView(items: searchViewModel.results) {
                    Task { await searchViewModel.loadMore() }
                }
                .padding(.horizontal)

                if searchViewModel.isLoadingMore {
                    ProgressView()
                        .frame(maxWidth: .infinity)
                        .padding()
                }
            }
            .padding(.vertical)
        }
    }

    private func sectionHeader(_ title: String) -> some View {
        Text(title)
            .font(.title2)
            .fontWeight(.bold)
            .padding(.horizontal)
    }

    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.loadHome() }
            }
        }
        .frame(maxWidth: .infinity, minHeight: 300)
    }
}