/*
 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 MapEditor: View {
  @Binding var document: MapDocument
  var url: URL?
  @State var selectedEvolution: StageType = .behavior

  @AppStorage("viewStyle") var viewStyle: ViewStyle = .horizontal

  let zoomRange = Constants.kMinZoom...Constants.kMaxZoom
  @AppStorage("zoom") var zoom = 1.0
  @State var lastZoom = 1.0

  var body: some View {
    VStack(spacing: 0) {
      adaptiveStack {
        ZStack(alignment: .topLeading) {
          MapTextEditor(document: $document)
            .background(Color.ui.background)
            .foregroundColor(Color.ui.foreground)
            .frame(minHeight: 96.0)
        }.padding(.top, 8.0).padding(.leading, 8.0).background(Color.ui.background).cornerRadius(
          5.0)
        GeometryReader { geometry in
          ScrollView([.horizontal, .vertical]) {
            MapRenderView(
              document: $document, evolution: $selectedEvolution, onDragVertex: onDragVertex
            ).scaleEffect(zoom, anchor: .center).frame(
              width: (Dimensions.mapSize.width + 2 * Dimensions.mapPadding) * zoom,
              height: (Dimensions.mapSize.height + 2 * Dimensions.mapPadding) * zoom)
          }.background(Color.ui.background)
            .gesture(
              MagnificationGesture()
                .onChanged { value in
                  let delta = value / lastZoom
                  lastZoom = value
                  zoom = min(max(zoom * delta, zoomRange.lowerBound), zoomRange.upperBound)
                }
                .onEnded { _ in
                  lastZoom = 1.0
                }
            )
        }
      }
      Divider()
      HStack {
        Spacer()
        Slider(
          value: $zoom, in: zoomRange, step: 0.1,
          label: {
            Text(formatZoom(zoom))
              .font(.theme.smallControl)
          },
          minimumValueLabel: {
            Image(systemName: "minus.magnifyingglass")
              .font(.theme.smallControl)
              .help("Zoom Out (⌘-)")
          },
          maximumValueLabel: {
            Image(systemName: "plus.magnifyingglass")
              .font(.theme.smallControl)
              .help("Zoom In (⌘+)")
          }
        ).frame(width: 200).padding(.trailing, 10.0)
      }.padding(4.0)
    }.toolbar {
      HStack {
        Button(action: saveImage) {
          Image(systemName: "photo")
        }
        .help("Export Image (⌘E)")
        .padding(.vertical, 4.0).padding(.leading, 4.0).padding(.trailing, 8.0)
      }
      EvolutionPicker(selectedEvolution: $selectedEvolution)
    }
  }

  @ViewBuilder
  func adaptiveStack<Content: View>(@ViewBuilder content: () -> Content) -> some View {
    if viewStyle == .horizontal {
      VSplitView {
        content()
      }
    } else {
      HSplitView {
        content()
      }
    }
  }

  private func formatZoom(_ number: CGFloat) -> String {
    let formatter = NumberFormatter()
    formatter.numberStyle = .decimal
    formatter.maximumFractionDigits = 1
    formatter.minimumFractionDigits = 1
    return (formatter.string(from: NSNumber(value: number)) ?? "") + "x"
  }

  private func onDragVertex(vertex: Vertex, x: CGFloat, y: CGFloat) {
  }

  private func saveImage() {
    if let image = document.exportAsImage(withEvolution: selectedEvolution) {

      let filename = url?.deletingPathExtension().lastPathComponent ?? "Untitled"

      let savePanel = NSSavePanel()
      savePanel.allowedContentTypes = [.png]
      savePanel.canCreateDirectories = true
      savePanel.isExtensionHidden = false
      savePanel.title = "Save \(filename) as image"
      savePanel.message = "Choose a location to save the image"
      savePanel.nameFieldStringValue = "\(filename).png"
      savePanel.begin { result in
        if result == .OK, let url = savePanel.url {
          if let tiffRepresentation = image.tiffRepresentation {
            let bitmapImage = NSBitmapImageRep(data: tiffRepresentation)
            let pngData = bitmapImage?.representation(using: .png, properties: [:])
            do {
              try pngData?.write(to: url)
            } catch {
              return
            }
          }
        }
      }
    }
  }
}

#Preview {
  MapEditor(document: .constant(MapDocument()), url: URL(filePath: "test.png")!)
}