/*
 * Copyright 2023 LiveKit, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.livekit.android.videoencodedecode

import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.size
import androidx.compose.material.Icon
import androidx.compose.material.Surface
import androidx.compose.runtime.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.layout.onGloballyPositioned
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.semantics.semantics
import androidx.compose.ui.semantics.testTag
import androidx.compose.ui.unit.dp
import androidx.compose.ui.viewinterop.AndroidView
import io.livekit.android.renderer.TextureViewRenderer
import io.livekit.android.room.Room
import io.livekit.android.room.participant.Participant
import io.livekit.android.room.track.RemoteVideoTrack
import io.livekit.android.room.track.Track
import io.livekit.android.room.track.VideoTrack
import io.livekit.android.util.flow
import io.livekit.android.videoencodedecode.ui.ComposeVisibility
import kotlinx.coroutines.flow.*

/**
 * Widget for displaying a VideoTrack. Handles the Compose <-> AndroidView interop needed to use
 * [TextureViewRenderer].
 */
@Composable
fun VideoItem(
    room: Room,
    videoTrack: VideoTrack,
    modifier: Modifier = Modifier
) {
    val videoSinkVisibility = remember(room, videoTrack) { ComposeVisibility() }
    var boundVideoTrack by remember { mutableStateOf<VideoTrack?>(null) }
    var videoView: TextureViewRenderer? by remember { mutableStateOf(null) }
    var receivedVideoFrames by remember { mutableStateOf(false) }

    fun cleanupVideoTrack() {
        videoView?.let { boundVideoTrack?.removeRenderer(it) }
        boundVideoTrack = null
    }

    fun setupVideoIfNeeded(videoTrack: VideoTrack, view: TextureViewRenderer) {
        if (boundVideoTrack == videoTrack) {
            return
        }

        cleanupVideoTrack()

        boundVideoTrack = videoTrack
        if (videoTrack is RemoteVideoTrack) {
            videoTrack.addRenderer(view, videoSinkVisibility)
        } else {
            videoTrack.addRenderer(view)
        }
    }

    DisposableEffect(room, videoTrack) {
        onDispose {
            videoSinkVisibility.onDispose()
            cleanupVideoTrack()
        }
    }

    DisposableEffect(currentCompositeKeyHash.toString()) {
        onDispose {
            videoView?.release()
        }
    }

    Box(
        modifier = modifier
    ) {
        AndroidView(
            factory = { context ->
                TextureViewRenderer(context).apply {
                    room.initVideoRenderer(this)
                    setupVideoIfNeeded(videoTrack, this)
                    this.addFrameListener({
                        if (!receivedVideoFrames) {
                            receivedVideoFrames = true
                        }
                    }, 0f)
                    videoView = this
                }
            },
            update = { view ->
                setupVideoIfNeeded(videoTrack, view)
            },
            modifier = Modifier
                .fillMaxSize()
                .onGloballyPositioned { videoSinkVisibility.onGloballyPositioned(it) },
        )

        // Frame Indicator
        if (receivedVideoFrames) {
            val frameIndicatorColor = Color.Green
            Surface(
                color = frameIndicatorColor,
                modifier = Modifier
                    .size(40.dp)
                    .semantics { testTag = VIDEO_FRAME_INDICATOR }
            ) {}
        }
    }
}

const val VIDEO_FRAME_INDICATOR = "frame_indicator"

/**
 * This widget primarily serves as a way to observe changes in [videoTracks].
 */
@Composable
fun VideoItemTrackSelector(
    room: Room,
    participant: Participant,
    modifier: Modifier = Modifier
) {
    val videoTrackMap by participant::videoTracks.flow.collectAsState(initial = emptyList())
    val videoPubs = videoTrackMap.filter { (pub) -> pub.subscribed }
        .map { (pub) -> pub }
    val videoTrack = videoPubs.firstOrNull { pub -> pub.source == Track.Source.SCREEN_SHARE }?.track as? VideoTrack
        ?: videoPubs.firstOrNull { pub -> pub.source == Track.Source.CAMERA }?.track as? VideoTrack
        ?: videoPubs.firstOrNull()?.track as? VideoTrack

    if (videoTrack != null) {
        VideoItem(
            room = room,
            videoTrack = videoTrack,
            modifier = modifier
        )
    } else {
        Box(modifier = modifier) {
            Icon(
                painter = painterResource(id = io.livekit.android.sample.common.R.drawable.outline_videocam_off_24),
                contentDescription = null,
                tint = Color.White,
                modifier = Modifier.align(Alignment.Center)
            )
        }
    }
}