import ARHeadsetKit
import Metal
import QuartzCore

class MyRenderer: CustomRenderer {
  unowned let renderer: MainRenderer
  var startTime: Double?
  var endTime: Double?
  
  required init(renderer: MainRenderer, library: MTLLibrary!) {
    self.renderer = renderer
  }
  
  func updateResources() {
    guard let startTime = self.startTime else {
      self.startTime = CACurrentMediaTime()
      return
    }
    if self.endTime != nil {
      // Already exported once; don't do it again.
      return
    }
    
    // Automatically export after 30 seconds (you can adjust the duration).
    let timerDuration: Double = 30.0
    let currentTime = CACurrentMediaTime()
    guard currentTime - startTime > timerDuration else { return }
    self.endTime = currentTime
    
    let exporter = ARDataExporter(renderer: self.renderer)
    let data = exporter.exportMesh(includeColor: true)
    
    // Do something with the `Data` object, like inspecting it in some Swift
    // code you write. You don't have to export it via 'ActivityViewController'
    // (ref: https://github.com/philipturner/lidar-scanning-app/blob/main/LiDARScanningApp/ActivityViewController.swift)
    // just to debug the exporter.
    print("Number of bytes: \(data.count)")
    
    let rawMemory = malloc(data.count)!
    defer { free(rawMemory) }
    data.copyBytes(
      to: rawMemory.assumingMemoryBound(to: UInt8.self), count: data.count)
    
    let header = rawMemory.assumingMemoryBound(to: UInt32.self)
    let numSmallTriangles = Int(header[0])
    let numLargeTriangles = Int(header[1])
    print("Number of small triangles: \(numSmallTriangles)")
    print("Number of large triangles: \(numLargeTriangles)")
    
    if numSmallTriangles > 0 {
      let smallTriangles = rawMemory + 64
      for i in 0..<min(numSmallTriangles, 10) {
        // Address of the i-th triangle.
        _ = smallTriangles + i * 320
      }
    }
  }
  
  func drawGeometry(renderEncoder: ARMetalRenderCommandEncoder) { }
}