import SwiftUI

struct SheetPreview: Decodable, Hashable, Sendable {
  let Rows: Int
  let Cols: Int
  let Empty: Bool
  let Cells: [SheetPreviewCell]?
}
struct SheetPreviewCell: Decodable, Hashable, Sendable {
  let R: Int
  let C: Int
  let Fill: String
  let Bold: Bool
}

/// Renders shape metadata only: no cell text, web view, or external image fetch.
struct SheetThumbnail: View {
  private let preview: SheetPreview?
  var width: CGFloat = 52
  var height: CGFloat = 68
  init(_ preview: SheetPreview?, width: CGFloat = 52, height: CGFloat = 68) { self.preview = preview; self.width = width; self.height = height }

  var body: some View {
    Canvas { context, size in
      let border = Path(roundedRect: CGRect(origin: .zero, size: size).insetBy(dx: 0.5, dy: 0.5), cornerRadius: 3)
      context.fill(border, with: .color(.primary.opacity(0.025)))
      context.stroke(border, with: .color(.secondary.opacity(0.3)), lineWidth: 1)
      guard let preview, !preview.Empty, (1...12).contains(preview.Rows),
        (1...8).contains(preview.Cols) else { return }
      let width = (size.width - 8) / Double(preview.Cols)
      let height = (size.height - 8) / Double(preview.Rows)
      for cell in (preview.Cells ?? []).prefix(96) {
        guard (0..<preview.Rows).contains(cell.R), (0..<preview.Cols).contains(cell.C) else { continue }
        let rect = CGRect(x: 4 + Double(cell.C) * width, y: 4 + Double(cell.R) * height, width: width, height: height)
        if !cell.Fill.isEmpty {
          let fill = cell.Fill
          let isHex = fill.count == 7 && fill.hasPrefix("#") && UInt64(fill.dropFirst(), radix: 16) != nil
          context.fill(Path(rect), with: .color(isHex ? Color(hex: fill) : .accentColor.opacity(0.15)))
        }
        let mark = CGRect(x: rect.minX + width * 0.15, y: rect.minY + height * 0.35,
          width: width * 0.7, height: height * 0.3)
        context.fill(Path(roundedRect: mark, cornerRadius: 0.5),
          with: .color(.secondary.opacity(cell.Bold ? 0.8 : 0.4)))
      }
    }
    .frame(width: width, height: height)
    .accessibilityHidden(true)
  }
}