import Foundation

@Observable
final class BrowseViewModel {
    var items: [ContentItem] = []
    var category: ContentCategory = .movie
    var filter = FilterState()
    var currentPage = 1
    var totalPages = 1
    var isLoading = false
    var isLoadingMore = false
    var error: String?

    private var cacheKey: String {
        "\(category.rawValue)_\(filter.sort)_\(filter.genre)_\(filter.region)_\(filter.year)"
    }

    var hasData: Bool {
        !items.isEmpty
    }

    @MainActor
    func loadContentIfNeeded() async {
        if hasData && !ContentCache.shared.isExpired(key: cacheKey) {
            return
        }
        await loadContent()
    }

    @MainActor
    func loadContent() async {
        isLoading = true
        error = nil
        currentPage = 1
        totalPages = 1
        items = []

        do {
            let html = try await APIClient.shared.fetchCategoryPage(
                category: category,
                page: 1,
                filter: filter
            )
            let newItems = try HTMLParser.parseContentList(html: html, defaultCategory: category)
            let pagination = try HTMLParser.parsePagination(html: html)

            self.items = newItems
            self.currentPage = pagination.current
            self.totalPages = pagination.total

            ContentCache.shared.markFresh(key: cacheKey)
        } catch is CancellationError {
        } catch let error as URLError where error.code == .cancelled {
        } catch {
            self.error = error.localizedDescription
        }

        isLoading = false
    }

    @MainActor
    func loadMore() async {
        guard !isLoadingMore, !isLoading, currentPage < totalPages else { return }
        isLoadingMore = true

        let nextPage = currentPage + 1
        do {
            let html = try await APIClient.shared.fetchCategoryPage(
                category: category,
                page: nextPage,
                filter: filter
            )
            let newItems = try HTMLParser.parseContentList(html: html, defaultCategory: category)
            let pagination = try HTMLParser.parsePagination(html: html)

            self.items.append(contentsOf: newItems)
            self.currentPage = pagination.current
            self.totalPages = pagination.total
        } catch is CancellationError {
        } catch let error as URLError where error.code == .cancelled {
        } catch {
            // 加载更多失败不显示全局错误，允许重试
        }

        isLoadingMore = false
    }

    func changeCategory(_ newCategory: ContentCategory) async {
        category = newCategory
        filter = FilterState()
        await loadContentIfNeeded()
    }

    func applyFilter(_ newFilter: FilterState) async {
        filter = newFilter
        await loadContent()
    }
}