import SwiftUI
import UIKit
import SwiftData

/// Wie `AsyncImage`, aber offline-fähig: zeigt zuerst ein lokal gecachtes Bild
/// (CachedImage in SwiftData); fehlt es, wird es remote geladen und dabei gleich
/// in den Offline-Cache geschrieben. `path` ist der relative Medienpfad
/// (z. B. "/media/routes/x.jpg"), die Basis-URL hängt OfflineCache an.
struct CachedAsyncImage<Content: View, Placeholder: View>: View {
    private let path: String?
    private let content: (Image) -> Content
    private let placeholder: () -> Placeholder

    @Environment(\.modelContext) private var ctx
    @State private var uiImage: UIImage?

    init(
        path: String?,
        @ViewBuilder content: @escaping (Image) -> Content,
        @ViewBuilder placeholder: @escaping () -> Placeholder
    ) {
        self.path = path
        self.content = content
        self.placeholder = placeholder
    }

    var body: some View {
        Group {
            if let uiImage {
                content(Image(uiImage: uiImage))
            } else {
                placeholder()
            }
        }
        .task(id: path) { await load() }
    }

    private func load() async {
        uiImage = nil
        guard let path, !path.isEmpty else { return }
        if let data = OfflineCache.imageData(path: path, in: ctx), let img = UIImage(data: data) {
            uiImage = img
            return
        }
        guard let url = URL(string: OfflineCache.mediaBase + path) else { return }
        if let (data, _) = try? await URLSession.shared.data(from: url), let img = UIImage(data: data) {
            uiImage = img
            OfflineCache.storeImage(path: path, data: data, in: ctx)
        }
    }
}