import SwiftUI

struct LibraryGridView: View {
    let items: [LibraryItem]
    var onRefresh: (() async -> Void)? = nil
    var onSelect: (LibraryItem) -> Void

    @AppStorage("libraryCoverSize") private var coverSize: Double = Self.defaultCoverSize

    var body: some View {
        #if os(macOS)
        VStack(spacing: 0) {
            zoomBar
            gridContent
        }
        #else
        gridContent
        #endif
    }

    private var gridContent: some View {
        ScrollView {
            LazyVGrid(columns: gridColumns, spacing: gridSpacing) {
                ForEach(items) { item in
                    LibraryItemCell(item: item)
                        .onTapGesture { onSelect(item) }
                }
            }
            #if os(iOS)
            .padding(.horizontal, 8)
            .padding(.vertical, 4)
            #else
            .padding(20)
            #endif
        }
        #if os(iOS)
        .refreshable { await onRefresh?() }
        #endif
    }

    #if os(macOS)
    private var zoomBar: some View {
        HStack(spacing: 8) {
            Spacer()
            Image(systemName: "rectangle.grid.3x2")
                .font(.caption2)
                .foregroundStyle(.secondary)
            Slider(value: $coverSize, in: Self.minCoverSize...Self.maxCoverSize)
                .frame(maxWidth: 220)
            Image(systemName: "square")
                .font(.caption2)
                .foregroundStyle(.secondary)
        }
        .padding(.horizontal, 12)
        .padding(.vertical, 4)
    }
    #endif

    private var gridColumns: [GridItem] {
        [GridItem(.adaptive(minimum: CGFloat(coverSize)), spacing: gridSpacing)]
    }

    private var gridSpacing: CGFloat {
        #if os(iOS)
        return 8
        #else
        return 20
        #endif
    }

    // MARK: - Cover-Größen-Defaults (plattformabhängig)

    private static var defaultCoverSize: Double {
        #if os(iOS)
        return 110
        #else
        return 180
        #endif
    }

    private static var minCoverSize: Double {
        #if os(iOS)
        return 80
        #else
        return 120
        #endif
    }

    private static var maxCoverSize: Double {
        #if os(iOS)
        return 200
        #else
        return 320
        #endif
    }
}