// 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 Combine
import CoreData
import CoreGraphics
import SwiftUI

struct MapRenderView: View {

  var entities: [Wmap.Entity]
  @Binding var evolution: StageType

  @State private var lastEntityHash: Int = 0
  @AppStorage("showMapBackground") var showMapBackground: Bool = UserPreferences.Defaults
    .showMapBackground
  @AppStorage("useCustomFont") var useCustomFont: Bool = UserPreferences.Defaults.useCustomFont
  @AppStorage("customFontName") var customFontName: String = UserPreferences.Defaults.customFontName
  @AppStorage("useSmartLabelPositioning") private var useSmartLabelPositioning = UserPreferences
    .Defaults.useSmartLabelPositioning

  var stage: Stage {
    Stage.stages(evolution)
  }

  @State private var parsedMap: ParsedMap = ParsedMap.empty
  @State private var smartLabelPositions: [Int: CGPoint] = [:]
  @State private var parseTask: Task<Void, Never>?

  let mapSize = Dimensions.Map.size
  let padding = Dimensions.Map.padding

  let lineWidth = CGFloat(0.5)
  let vertexSize = CGSize(width: 25.0, height: 25.0)

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

  private func convertEntitiesInBackground() {

    parseTask?.cancel()
    let currentEntities = entities

    parseTask = Task {
      let parsed = await Task.detached(priority: .userInitiated) {
        convertEntitiesToParsedMap(currentEntities)
      }.value

      let positions = await Task.detached(priority: .userInitiated) {
        var positions: [Int: CGPoint] = [:]

        guard await useSmartLabelPositioning else { return positions }

        let axisLines = [
          Line(start: CGPoint(x: 0, y: 0), end: CGPoint(x: 0, y: mapSize.height)),
          Line(
            start: CGPoint(x: 0, y: mapSize.height),
            end: CGPoint(x: mapSize.width, y: mapSize.height)),
        ]

        for vertex in parsed.vertices {
          positions[vertex.id] = SmartLabelPositioning.calculateOptimalLabelPosition(
            for: vertex,
            mapSize: mapSize,
            vertexSize: vertexSize,
            edges: parsed.edges,
            opportunities: parsed.opportunities,
            inertias: parsed.inertias,
            axisLines: axisLines,
            allVertices: parsed.vertices,
            notes: parsed.notes
          )
        }

        return positions
      }.value

      if !Task.isCancelled {
        await MainActor.run {
          parsedMap = parsed
          smartLabelPositions = positions
        }
      }
    }
  }

  private nonisolated func convertEntitiesToParsedMap(_ entities: [Wmap.Entity]) -> ParsedMap {
    var vertices: [Vertex] = []
    var edges: [MapEdge] = []
    var inertias: [Inertia] = []
    var opportunities: [Opportunity] = []
    var notes: [Note] = []
    var stages: [CGFloat] = [25.0, 50.0, 75.0]  // default dimensions
    var groups: [[Vertex]] = []

    // Build a vertex lookup for edges, groups, etc.
    var vertexMap: [String: Vertex] = [:]
    var vertexIdCounter = 0

    for entity in entities {
      switch entity {
      case .vertex(let vertex):
        let newVertex = Vertex(
          id: vertexIdCounter,
          label: vertex.label,
          position: CGPoint(x: vertex.coordinates.0, y: vertex.coordinates.1),
          shape: convertShape(vertex.shape)
        )
        vertices.append(newVertex)
        vertexMap[vertex.label] = newVertex
        vertexIdCounter += 1

      case .note(let note):
        notes.append(
          Note(
            id: notes.count,
            position: CGPoint(x: note.coordinates.0, y: note.coordinates.1),
            text: note.text
          ))

      case .stage(let stage):
        let stageIndex = convertStageNumber(stage.number) - 1
        if stageIndex >= 0 && stageIndex < 3 {
          stages[stageIndex] = stage.value
        }

      default:
        continue
      }
    }

    // Second pass for entities that depend on vertices
    for entity in entities {
      switch entity {
      case .edge(let edge):
        if let fromVertex = vertexMap[edge.from],
          let toVertex = vertexMap[edge.to]
        {
          edges.append(
            MapEdge(
              id: edges.count,
              origin: fromVertex.position,
              destination: toVertex.position,
              arrowhead: edge.isDirected
            ))
        }

      case .inertia(let inertia):
        if let vertex = vertexMap[inertia.vertex] {
          inertias.append(
            Inertia(
              id: inertias.count,
              position: vertex.position
            ))
        }

      case .evolution(let evolution):
        if let vertex = vertexMap[evolution.vertex] {
          let direction: CGFloat = evolution.isPositive ? 1.0 : -1.0
          let destination = CGPoint(
            x: vertex.position.x + (direction * evolution.value),
            y: vertex.position.y
          )
          opportunities.append(
            Opportunity(
              id: opportunities.count,
              origin: vertex.position,
              destination: destination
            ))
        }

      case .group(let group):
        var groupVertices: [Vertex] = []
        for vertexName in group.vertices {
          if let vertex = vertexMap[vertexName] {
            groupVertices.append(vertex)
          }
        }
        if !groupVertices.isEmpty {
          groups.append(groupVertices)
        }

      default:
        continue
      }
    }

    return ParsedMap(
      vertices: vertices,
      edges: edges,
      inertias: inertias,
      opportunities: opportunities,
      notes: notes,
      stages: stages,
      groups: groups
    )
  }

  private nonisolated func convertShape(_ shape: String?) -> VertexShape {
    guard let shape = shape?.lowercased() else { return .circle }
    switch shape {
    case "square": return .square
    case "triangle": return .triangle
    case "x": return .x
    default: return .circle
    }
  }

  private nonisolated func convertStageNumber(_ stageNumber: String) -> Int {
    switch stageNumber.lowercased() {
    case "i": return 1
    case "ii": return 2
    case "iii": return 3
    case "iv": return 4
    default: return 1
    }
  }

  var body: some View {
    ZStack(alignment: .topLeading) {

      Path { path in
        path.addRect(
          CGRect(
            x: -padding, y: -padding, width: mapSize.width + padding * 2,
            height: mapSize.height + padding * 4))
      }.fill(.white)

      // The order Matters. Think of this as layers.

      if showMapBackground {
        MapBackground(mapSize: mapSize, lineWidth: lineWidth, stages: parsedMap.stages)
      }
      MapAxes(
        mapSize: mapSize, lineWidth: lineWidth, evolution: stage, stages: parsedMap.stages)
      Group {
        MapStages(mapSize: mapSize, lineWidth: lineWidth, stages: parsedMap.stages)
        MapEdges(
          mapSize: mapSize, lineWidth: lineWidth, vertexSize: vertexSize, edges: parsedMap.edges)
        MapOpportunities(
          mapSize: mapSize, lineWidth: lineWidth, vertexSize: vertexSize,
          opportunities: parsedMap.opportunities)
        MapIntertias(mapSize: mapSize, vertexSize: vertexSize, inertias: parsedMap.inertias)
      }.mask {
        MapMask(
          mapSize: mapSize, vertexSize: vertexSize, vertices: parsedMap.vertices,
          labelPositions: smartLabelPositions)
      }
      MapVertices(
        mapSize: mapSize, vertexSize: vertexSize, vertices: parsedMap.vertices,
        labelPositions: smartLabelPositions, onDragVertex: onDragVertex)
      MapGroups(mapSize: mapSize, vertexSize: vertexSize, groups: parsedMap.groups).drawingGroup(
        opaque: true
      ).opacity(0.1)
      MapNotes(
        mapSize: mapSize, lineWidth: lineWidth, notes: parsedMap.notes)
    }
    .id("\(useCustomFont)-\(customFontName)")
    .offset(x: padding, y: padding).frame(
      width: mapSize.width + 2 * padding,
      height: mapSize.height + 2 * padding, alignment: .topLeading
    )
    .onAppear {
      convertEntitiesInBackground()
    }
    .onChange(of: entities) { _, _ in
      convertEntitiesInBackground()
    }
    .onChange(of: useSmartLabelPositioning) {
      convertEntitiesInBackground()
    }
    .onDisappear {
      parseTask?.cancel()
    }
  }

  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))
  }
}

#Preview {
  MapRenderView(
    entities: [],
    evolution: Binding.constant(StageType.general)
  )
}