#if canImport(UIKit)
import UIKit
#endif
import SwiftUI

#if canImport(UIKit)
typealias PlatformImage = UIImage
#elseif canImport(AppKit)
import AppKit
typealias PlatformImage = NSImage
#endif

#if canImport(UIKit) || canImport(AppKit)
actor ImageCache {
    static let shared = ImageCache()
    private var cache: [String:PlatformImage] = [:]

    func image(for id: String, in baseDir: URL) -> PlatformImage? {
        if let c = cache[id] { return c }
        let url = baseDir.appendingPathComponent("covers/\(id).jpg")
        #if canImport(UIKit)
        guard let img = PlatformImage(contentsOfFile: url.path) else { return nil }
        #elseif canImport(AppKit)
        guard let img = PlatformImage(contentsOf: url) else { return nil }
        #endif
        cache[id] = img
        return img
    }
}
#endif

#if os(iOS)
struct CoverImageView: View {
    let book: BookMeta
    let bundleDir: URL
    #if canImport(UIKit) || canImport(AppKit)
    @State private var uiImage: PlatformImage? = nil
    #endif

    var body: some View {
        ZStack {
            #if canImport(UIKit) || canImport(AppKit)
            if let img = uiImage {
                #if canImport(UIKit)
                Image(uiImage: img).resizable().scaledToFit().cornerRadius(6)
                #elseif canImport(AppKit)
                Image(nsImage: img).resizable().scaledToFit().cornerRadius(6)
                #endif
            } else {
                Rectangle().fill(Color.gray.opacity(0.2)).overlay(Text("No Cover").font(.caption))
            }
            #else
            Rectangle().fill(Color.gray.opacity(0.2)).overlay(Text("No Cover").font(.caption))
            #endif
        }
        #if canImport(UIKit) || canImport(AppKit)
        .task {
            if uiImage == nil, let img = await ImageCache.shared.image(for: book.id, in: bundleDir) {
                uiImage = img
            }
        }
        #endif
    }
}
#endif