import AzureCommunicationCalling
import CoreVideo
import Foundation

/// Fresh Swift sender on ACS iOS RawOutgoingVideoStream + CVPixelBuffer.
/// No RealWear code (they have no iOS equivalent).
final class AcsFrameSender: NSObject {
    private var stream: VirtualOutgoingVideoStream?
    private var running = false
    private var lastSent: CFTimeInterval = 0
    private let sendGate = VideoSendGate()
    private let stateLock = NSLock()

    func attach(_ stream: VirtualOutgoingVideoStream) {
        detach()
        stateLock.lock()
        self.stream = stream
        lastSent = 0
        stateLock.unlock()
        stream.delegate = self
    }

    /// True when the frame was handed to ACS; false when readiness, pacing or the send gate dropped it.
    @discardableResult
    func send(_ pixelBuffer: CVPixelBuffer) -> Bool {
        stateLock.lock()
        guard running, let stream else {
            stateLock.unlock()
            return false
        }
        let fps = stream.format.framesPerSecond
        let now = CFAbsoluteTimeGetCurrent()
        if lastSent > 0, now - lastSent < 1.0 / Double(max(fps, 1)) {
            stateLock.unlock()
            return false
        }
        guard let token = sendGate.acquire() else {
            stateLock.unlock()
            return false
        }
        lastSent = now
        stateLock.unlock()
        let frame = RawVideoFrameBuffer()
        frame.buffer = pixelBuffer
        frame.streamFormat = stream.format
        frame.timestampInTicks = stream.timestampInTicks
        stream.send(frame: frame) { [sendGate] error in
            // Keep the source pixels alive until ACS finishes reading the frame.
            withExtendedLifetime(pixelBuffer) { frame.dispose() }
            sendGate.release(token)
            if let error { NSLog("ACS-SPIKE send frame failed: \(error)") }
        }
        return true
    }

    func detach() {
        stateLock.lock()
        running = false
        // Drop the delegate on the previous stream so a late STOPPED from a prior
        // call cannot freeze outgoing video for the current meeting.
        let previous = stream
        stream = nil
        sendGate.reset()
        stateLock.unlock()
        previous?.delegate = nil
    }
}

extension AcsFrameSender: VirtualOutgoingVideoStreamDelegate {
    func virtualOutgoingVideoStream(_ virtualOutgoingVideoStream: VirtualOutgoingVideoStream, didChangeState _: VideoStreamStateChangedEventArgs) {
        stateLock.lock()
        defer { stateLock.unlock() }
        guard virtualOutgoingVideoStream === stream else { return }
        running = virtualOutgoingVideoStream.state == .started
        NSLog("ACS-SPIKE iOS raw video state=\(virtualOutgoingVideoStream.state)")
    }
}