import SwiftUI

struct MapVertices: View {

  let mapSize: CGSize
  let vertexSize: CGSize
  let vertices: [Vertex]
  let padding = CGFloat(5.0)

  var onDragVertex: (Vertex, CGFloat, CGFloat) -> Void = { _, _, _ in }

  var body: some View {
    ZStack(alignment: .topLeading) {
      ForEach(vertices, id: \.id) { vertex in
        ZStack(alignment: .topLeading) {
          getVertexShape(vertex).fill(Color.map.vertexColor)
          Text(vertex.label.replacingOccurrences(of: "\\n", with: "\n")).font(.theme.vertexLabel)
            .foregroundColor(.map.labelColor)
            .shadow(color: .white, radius: 0, x: -0.5, y: -0.5)
            .shadow(color: .white, radius: 0, x: 0.5, y: 0.5)
            .offset(
              CGSize(
                width: w(vertex.position.x) + vertexSize.width + padding,
                height: h(vertex.position.y) + 7.0))
        }.gesture(
          DragGesture()
            .onChanged { value in
              let deltaX = value.startLocation.x - value.location.x
              let deltaY = value.startLocation.y - value.location.y
              onDragVertex(vertex, deltaX, deltaY)
            }
        )
      }
    }
  }

  func h(_ dimension: CGFloat) -> CGFloat {
    max(0.0, min(mapSize.height, dimension * mapSize.height / 100.0))
  }

  func w(_ dimension: CGFloat) -> CGFloat {
    max(0.0, min(mapSize.width, dimension * mapSize.width / 100.0))
  }

  func getVertexShape(_ vertex: Vertex) -> Path {
    switch vertex.shape {
    case .circle:
      return Path { path in
        path.addEllipse(
          in: CGRect(
            origin: CGPoint(x: w(vertex.position.x), y: h(vertex.position.y)), size: vertexSize
          ))
      }
    case .square:
      return Path { path in
        path.addRect(
          CGRect(
            x: w(vertex.position.x), y: h(vertex.position.y), width: vertexSize.width,
            height: vertexSize.height
          ))
      }
    case .triangle:
      return Path { path in
        path.move(to: CGPoint(x: w(vertex.position.x), y: h(vertex.position.y) + vertexSize.height))
        path.addLine(
          to: CGPoint(
            x: w(vertex.position.x) + vertexSize.width, y: h(vertex.position.y) + vertexSize.height)
        )
        path.addLine(
          to: CGPoint(x: w(vertex.position.x) + vertexSize.width / 2.0, y: h(vertex.position.y)))
        path.addLine(
          to: CGPoint(x: w(vertex.position.x), y: h(vertex.position.y) + vertexSize.height))
        path.closeSubpath()
      }
    case .x:
      return Path { path in
        path.move(to: CGPoint(x: w(vertex.position.x), y: h(vertex.position.y)))
        path.addLine(
          to: CGPoint(
            x: w(vertex.position.x) + vertexSize.width, y: h(vertex.position.y) + vertexSize.height)
        )
        path.closeSubpath()
        path.move(to: CGPoint(x: w(vertex.position.x) + vertexSize.width, y: h(vertex.position.y)))
        path.addLine(
          to: CGPoint(x: w(vertex.position.x), y: h(vertex.position.y) + vertexSize.height))
        path.closeSubpath()
      }.strokedPath(StrokeStyle(lineWidth: 2.0, lineCap: .butt))
    }
  }
}

#Preview {
  MapVertices(
    mapSize: CGSize(width: 400.0, height: 400.0), vertexSize: CGSize(width: 25.0, height: 25.0),
    vertices: [
      Vertex(id: 0, label: "A Circle", position: CGPoint(x: 50.0, y: 50.0)),
      Vertex(id: 1, label: "A Square", position: CGPoint(x: 10.0, y: 20.0), shape: .square),
      Vertex(id: 2, label: "A triangle", position: CGPoint(x: 25, y: 32.0), shape: .triangle),
      Vertex(id: 3, label: "An X", position: CGPoint(x: 70.0, y: 70.0), shape: .x),
    ])
}