import Foundation
import Combine

class NewHomeTabViewModel: ObservableObject {
    @Published var posts: [Post] = []
    @Published var isLoading = true
    @Published var isRefreshing = false
    @Published var isLoadingPage = false
    
    @Published var canLoadMorePages = true
    
    private var currentPage = 0
    private let postsPerPage = 10
    
    func fetchDataIfNeeded() {
        guard posts.isEmpty else { return }
        fetchPosts()
    }
    
    func refreshData() {
        guard !isRefreshing else { return }
        
        isRefreshing = true
        currentPage = 0
        canLoadMorePages = true
        
        fetchPosts(isRefresh: true)
    }
    
    func loadMoreContentIfNeeded(currentItem item: Post?) {
        guard let item = item else {
            fetchPosts()
            return
        }
        
        let thresholdIndex = posts.index(posts.endIndex, offsetBy: -5)
        if posts.firstIndex(where: { $0.id == item.id }) == thresholdIndex {
            fetchPosts()
        }
    }
    
    private func fetchPosts(isRefresh: Bool = false) {
        guard !isLoadingPage, canLoadMorePages else {
            if isRefresh {
                DispatchQueue.main.async {
                    self.isRefreshing = false
                }
            }
            return
        }
        
        isLoadingPage = true
        if isRefresh {
            currentPage = 0
        } else {
            currentPage += 1
        }
        
        PostService.shared.fetchAllPosts(page: currentPage, limit: postsPerPage) { [weak self] fetchedPosts in
            guard let self = self else { return }
            
            DispatchQueue.main.async {
                if isRefresh {
                    self.posts = fetchedPosts
                } else {
                    self.posts.append(contentsOf: fetchedPosts)
                }
                
                self.canLoadMorePages = !fetchedPosts.isEmpty
                self.isLoading = false
                self.isLoadingPage = false
                self.isRefreshing = false
            }
        }
    }
}