package com.peachpasswords.ui.pairing

import android.Manifest
import android.content.pm.PackageManager
import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.result.contract.ActivityResultContracts
import androidx.camera.core.CameraSelector
import androidx.camera.core.ImageAnalysis
import androidx.camera.core.Preview
import androidx.camera.lifecycle.ProcessCameraProvider
import androidx.camera.view.PreviewView
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.compose.ui.viewinterop.AndroidView
import androidx.core.content.ContextCompat
import androidx.lifecycle.compose.LocalLifecycleOwner
import com.peachpasswords.ui.theme.PeachType
import com.peachpasswords.ui.theme.peachColors
import java.util.concurrent.Executors

@Composable
internal fun PairingQrCamera(
    onInvitation: (String) -> Unit,
    modifier: Modifier = Modifier,
) {
    val context = LocalContext.current
    var granted by remember {
        mutableStateOf(
            ContextCompat.checkSelfPermission(context, Manifest.permission.CAMERA) ==
                PackageManager.PERMISSION_GRANTED,
        )
    }
    val permission = rememberLauncherForActivityResult(
        ActivityResultContracts.RequestPermission(),
    ) { granted = it }
    LaunchedEffect(Unit) {
        if (!granted) permission.launch(Manifest.permission.CAMERA)
    }

    if (!granted) {
        Box(
            modifier
                .fillMaxWidth()
                .height(250.dp)
                .clip(RoundedCornerShape(16.dp))
                .background(peachColors.SurfaceElevated),
            contentAlignment = Alignment.Center,
        ) {
            Text(
                "Camera access is needed to scan.\nUse the manual invitation below instead.",
                color = peachColors.T2,
                fontFamily = PeachType.Mono,
                fontSize = 11.sp,
            )
        }
        return
    }

    val lifecycleOwner = LocalLifecycleOwner.current
    val executor = remember { Executors.newSingleThreadExecutor() }
    DisposableEffect(Unit) {
        onDispose { executor.shutdown() }
    }
    AndroidView(
        modifier = modifier
            .fillMaxWidth()
            .height(250.dp)
            .clip(RoundedCornerShape(16.dp)),
        factory = { viewContext ->
            PreviewView(viewContext).apply {
                scaleType = PreviewView.ScaleType.FILL_CENTER
                val previewView = this
                val provider = ProcessCameraProvider.getInstance(viewContext)
                provider.addListener({
                    val cameraProvider = provider.get()
                    val preview = Preview.Builder().build().also {
                        it.setSurfaceProvider(previewView.surfaceProvider)
                    }
                    val analysis = ImageAnalysis.Builder()
                        .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
                        .build()
                    analysis.setAnalyzer(executor) { proxy ->
                        try {
                            // This runs on a bare executor thread, so anything
                            // thrown here is an uncaught exception that kills
                            // the process. A frame that will not decode is
                            // normal; dropping it and waiting for the next one
                            // is always the right answer.
                            runCatching { PairingQrFrame.decode(proxy) }
                                .getOrNull()
                                ?.let(onInvitation)
                        } finally {
                            proxy.close()
                        }
                    }
                    runCatching {
                        cameraProvider.unbindAll()
                        cameraProvider.bindToLifecycle(
                            lifecycleOwner,
                            CameraSelector.DEFAULT_BACK_CAMERA,
                            preview,
                            analysis,
                        )
                    }
                }, ContextCompat.getMainExecutor(viewContext))
            }
        },
    )
}