import Foundation
import AVKit
import Combine
@MainActor
class SightViewModel: ObservableObject {
    @Published var sightName: String = "Загрузка..."
    @Published var allArticles: [Article] = []
    @Published var selectedArticle: Article?
    @Published var articleHeading: String = ""
    @Published var articleBody: String = ""
    @Published var mediaState: MediaState = .loading
    
    private var sightModel: SightModel?
    private var selectedLanguage: String = "ru"  // по умолчанию

    enum MediaState {
        case loading
        case image(URL)
        case video(AVPlayer)
        case error
    }

    func setLanguage(_ language: String) {
        self.selectedLanguage = language
    }

    func loadInitialData(sightId: Int) async {
        do {
            async let sightModelTask = fetchJSON(
                from: "https://white-nights.krbl.ru/services/content/sight/\(sightId)?lang=\(selectedLanguage)",
                type: SightModel.self
            )
            async let articlesTask = fetchJSON(
                from: "https://white-nights.krbl.ru/services/content/sight/\(sightId)/article?lang=\(selectedLanguage)",
                type: [Article].self
            )

            let (fetchedSightModel, fetchedArticles) = try await (sightModelTask, articlesTask)
            
            self.sightModel = fetchedSightModel
            self.sightName = fetchedSightModel.name
            
            let reviewArticle = Article(id: -1, body: "", heading: "Обзор", isReviewArticle: true)
            self.allArticles = [reviewArticle] + fetchedArticles
            
            selectArticle(reviewArticle)

        } catch {
            print("Ошибка начальной загрузки данных: \(error)")
            self.mediaState = .error
        }
    }
    
    func selectArticle(_ article: Article) {
        guard selectedArticle != article else { return }
        
        self.selectedArticle = article
        self.articleHeading = article.heading
        self.articleBody = article.body
        
        Task {
            await updateMedia(for: article)
        }
    }

    private func updateMedia(for article: Article) async {
        self.mediaState = .loading
        
        if article.isReviewArticle == true {
            guard let sight = sightModel else {
                self.mediaState = .error
                return
            }

            if let videoPreviewId = sight.video_preview,
               let url = URL(string: "https://white-nights.krbl.ru/services/content/media/\(videoPreviewId)/download?lang=\(selectedLanguage)") {
                let player = AVPlayer(url: url)
                player.play()
                self.mediaState = .video(player)
            } else if let url = URL(string: "https://white-nights.krbl.ru/services/content/media/\(sight.preview_media)/download?lang=\(selectedLanguage)") {
                self.mediaState = .image(url)
            } else {
                self.mediaState = .error
            }
        } else {
            do {
                let mediaItems = try await fetchJSON(
                    from: "https://white-nights.krbl.ru/services/content/article/\(article.id)/media?lang=\(selectedLanguage)",
                    type: [ArticleMedia].self
                )
                if let firstMedia = mediaItems.first,
                   let url = URL(string: "https://white-nights.krbl.ru/services/content/media/\(firstMedia.id)/download?lang=\(selectedLanguage)") {
                    self.mediaState = .image(url)
                } else {
                    self.mediaState = .error
                }
            } catch {
                print("Ошибка загрузки медиа для статьи '\(article.heading)': \(error)")
                self.mediaState = .error
            }
        }
    }

    private func fetchJSON<T: Decodable>(from urlString: String, type: T.Type) async throws -> T {
        guard let url = URL(string: urlString) else {
            throw URLError(.badURL)
        }
        let (data, _) = try await URLSession.shared.data(from: url)
        return try JSONDecoder().decode(T.self, from: data)
    }
}