RTCVideoWrapper.swift

//
//  RTCVideoWrapper.swift
//  Neuro App
//
//  Created by David Ferrufino on 8/27/24.
//

import Foundation
import WebRTC
import UIKit

class RTCVideoWrapper: UIView, RTCVideoRenderer {

    private let videoView: RTCMTLVideoView
    private var aspectRatioConstraint: NSLayoutConstraint?

    override init(frame: CGRect) {
        self.videoView = RTCMTLVideoView(frame: frame)
        super.init(frame: frame)

        // Apply horizontal flip for front-facing camera (mirroring)
        self.videoView.transform = CGAffineTransform(scaleX: -1.0, y: 1.0)

        self.videoView.contentMode = .scaleAspectFit // Maintain aspect ratio
        self.addSubview(videoView)
        setupConstraints()
    }

    required init?(coder: NSCoder) {
        self.videoView = RTCMTLVideoView(frame: .zero)
        super.init(coder: coder)

        // Apply horizontal flip for front-facing camera (mirroring)
        self.videoView.transform = CGAffineTransform(scaleX: -1.0, y: 1.0)

        self.videoView.contentMode = .scaleAspectFit // Maintain aspect ratio
        self.addSubview(videoView)
        setupConstraints()
    }

    func setSize(_ size: CGSize) {
        updateAspectRatioConstraint(size: size)
    }

    func renderFrame(_ frame: RTCVideoFrame?) {
        guard let frame = frame else {
            print("Received nil frame, not rendering.")
            return
        }
        // Update aspect ratio whenever a new frame is rendered
        let videoSize = CGSize(width: CGFloat(frame.width), height: CGFloat(frame.height))
        updateAspectRatioConstraint(size: videoSize)
        videoView.renderFrame(frame)
    }

    private func setupConstraints() {
        videoView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            videoView.leadingAnchor.constraint(equalTo: self.leadingAnchor),
            videoView.trailingAnchor.constraint(equalTo: self.trailingAnchor),
            videoView.topAnchor.constraint(equalTo: self.topAnchor),
            videoView.bottomAnchor.constraint(equalTo: self.bottomAnchor)
        ])
    }

    private func updateAspectRatioConstraint(size: CGSize) {
        DispatchQueue.main.async { [weak self] in
            guard let self = self else { return }

            // Remove the existing aspect ratio constraint
            if let aspectRatioConstraint = self.aspectRatioConstraint {
                self.removeConstraint(aspectRatioConstraint)
            }

            // Calculate and apply the new aspect ratio
            let aspectRatio = size.width / size.height
            self.aspectRatioConstraint = self.videoView.widthAnchor.constraint(equalTo: self.videoView.heightAnchor, multiplier: aspectRatio)
            self.aspectRatioConstraint?.isActive = true
        }
    }
}