// Copyright (C) 2024 Rubén Beltrán del Río

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see https://map.tranquil.systems.
import SwiftUI

struct MapVertices: View {

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

  @State private var offset = CGSize.zero
  @State private var draggingVertex: Vertex? = nil

  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.Theme.Map.vertexColor)
            .offset(
              x: vertex == draggingVertex ? offset.width : 0,
              y: vertex == draggingVertex ? offset.height : 0)

          // Drag Hit box. Path bounds seem to be infinite.
          Rectangle()
            .fill(Color.black.opacity(0.001))
            .frame(width: vertexSize.width, height: vertexSize.height)
            .offset(x: w(vertex.position.x), y: h(vertex.position.y))
            .onHover { isHovering in
              if isHovering {
                NSCursor.pointingHand.set()
              } else {
                NSCursor.arrow.set()
              }
            }
            .gesture(
              DragGesture()
                .onChanged { value in
                  offset = value.translation
                  draggingVertex = vertex
                  NSCursor.closedHand.set()
                }
                .onEnded { value in
                  let newX = mw(w(vertex.position.x) + value.translation.width)
                  let newY = mh(h(vertex.position.y) + value.translation.height)

                  onDragVertex(vertex, newX, newY)

                  NSCursor.pointingHand.set()
                }
            )

          Text(vertex.label.replacingOccurrences(of: "\\n", with: "\n"))
            .font(.Theme.Map.vertexLabel)
            .lineSpacing(
              Dimensions.LineHeight.Map.vertexLabel - Dimensions.FontSize.Map.vertexLabel
            )
            .foregroundColor(.Theme.Map.labelColor)
            .offset(
              CGSize(
                width: labelPositions[vertex.id]?.x
                  ?? (w(vertex.position.x) + vertexSize.width + padding),
                height: labelPositions[vertex.id]?.y ?? (h(vertex.position.y) + 7.0))
            )
            .offset(
              x: vertex == draggingVertex ? offset.width : 0,
              y: vertex == draggingVertex ? offset.height : 0)
        }
      }
    }
  }

  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 mh(_ dimension: CGFloat) -> CGFloat {
    max(0.0, min(100, dimension * 100 / mapSize.height))
  }

  func mw(_ dimension: CGFloat) -> CGFloat {
    max(0.0, min(100, dimension * 100 / mapSize.width))
  }

  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 .xMark:
      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: .xMark),
    ],
    labelPositions: [:])
}