package com.example.jnicpp.bowling

import android.Manifest
import android.content.ContentValues
import android.content.Context
import android.content.pm.PackageManager
import android.graphics.Color
import android.graphics.Paint
import android.graphics.PorterDuff
import android.net.Uri
import android.os.Build
import android.os.Environment
import android.os.Handler
import android.os.HandlerThread
import android.provider.MediaStore
import androidx.camera.core.CameraEffect
import androidx.camera.core.CameraSelector
import androidx.camera.core.ImageAnalysis
import androidx.camera.core.Preview
import androidx.camera.core.UseCaseGroup
import androidx.camera.effects.OverlayEffect
import androidx.camera.lifecycle.ProcessCameraProvider
import androidx.camera.video.FallbackStrategy
import androidx.camera.video.MediaStoreOutputOptions
import androidx.camera.video.Quality
import androidx.camera.video.QualitySelector
import androidx.camera.video.Recorder
import androidx.camera.video.Recording
import androidx.camera.video.VideoCapture
import androidx.camera.video.VideoRecordEvent
import androidx.camera.view.PreviewView
import androidx.core.content.ContextCompat
import androidx.lifecycle.LifecycleOwner
import com.example.jnicpp.R
import java.text.SimpleDateFormat
import java.util.Locale

/**
 * Owns all CameraX use-case binding and recording control. Deliberately not
 * an Activity/Fragment/View: it only needs a [Context], a [LifecycleOwner]
 * and a couple of Android views handed to it, which keeps the CameraX wiring
 * isolated from Android component lifecycle boilerplate and easy to reason
 * about (and to fake out behind [Callback] in tests that don't need a real
 * camera).
 */
class CameraXController(
    private val appContext: Context,
    private val cameraExecutor: java.util.concurrent.Executor
) {

    interface Callback {
        fun onCameraReady() {}
        fun onCameraError(message: String)
        fun onRecordingStarted() {}
        fun onRecordingFinalized(outputUri: Uri) {}
        fun onRecordingError(message: String)
        fun onPoseDetectorError(message: String) {}
        fun onPoseResult(result: PoseAnalyzer.PoseFrameResult)
    }

    private var cameraProvider: ProcessCameraProvider? = null
    private var videoCapture: VideoCapture<Recorder>? = null
    private var imageAnalysis: ImageAnalysis? = null
    private var poseAnalyzer: PoseAnalyzer? = null
    private var activeRecording: Recording? = null
    private var currentLensFacing: Int = CameraSelector.LENS_FACING_BACK
    private var callback: Callback? = null

    // Whether the pose analyzer should be attached to the analysis stream,
    // and whether the skeleton should be composited into recorded frames.
    // Survives across bindToLifecycle() calls (e.g. switching cameras) so
    // the mode chosen via setPoseDetectionEnabled() isn't lost on rebind.
    private var poseDetectionEnabled = false

    // Latest pose result, consumed by the OverlayEffect draw listener (see
    // below) to composite the skeleton into recorded video frames. Read on
    // the effect's GL/handler thread, written on the main thread from
    // PoseAnalyzer's callback -- both just replace the whole reference, so
    // no extra locking is needed.
    @Volatile
    private var latestPoseFrame: PoseAnalyzer.PoseFrameResult? = null

    // Bakes the skeleton into VIDEO_CAPTURE output only (not PREVIEW) --
    // the live preview keeps using PoseOverlayView, which is already proven
    // to draw correctly; this only needs to affect what actually gets
    // encoded into the saved file.
    private var overlayEffect: OverlayEffect? = null
    private var overlayHandlerThread: HandlerThread? = null
    private val overlayBonePaint by lazy {
        Paint(Paint.ANTI_ALIAS_FLAG).apply {
            color = ContextCompat.getColor(appContext, R.color.skeleton_bone)
            style = Paint.Style.STROKE
            strokeWidth = PoseSkeletonRenderer.STROKE_WIDTH
        }
    }
    private val overlayJointPaint by lazy {
        Paint(Paint.ANTI_ALIAS_FLAG).apply {
            color = ContextCompat.getColor(appContext, R.color.skeleton_joint)
            style = Paint.Style.FILL
        }
    }

    val isRecording: Boolean
        get() = activeRecording != null

    /**
     * Binds Preview + VideoCapture (Recorder) + ImageAnalysis to a single
     * camera lifecycle, all at once, so the same camera stream feeds the
     * on-screen preview, the video file being recorded, and the pose
     * detector simultaneously. Also attaches an [OverlayEffect] to the
     * VideoCapture output so [setPoseDetectionEnabled] can bake the
     * skeleton into the recorded file, not just the live preview.
     */
    fun bindToLifecycle(
        lifecycleOwner: LifecycleOwner,
        previewView: PreviewView,
        callback: Callback,
        lensFacing: Int = CameraSelector.LENS_FACING_BACK
    ) {
        this.callback = callback
        this.currentLensFacing = lensFacing

        val providerFuture = ProcessCameraProvider.getInstance(appContext)
        providerFuture.addListener({
            try {
                val provider = providerFuture.get()
                cameraProvider = provider

                val preview = Preview.Builder().build().also {
                    it.surfaceProvider = previewView.surfaceProvider
                }

                val recorder = Recorder.Builder()
                    .setQualitySelector(
                        QualitySelector.from(
                            Quality.FHD,
                            FallbackStrategy.higherQualityOrLowerThan(Quality.SD)
                        )
                    )
                    .build()
                val videoCapture = VideoCapture.withOutput(recorder)
                this.videoCapture = videoCapture

                poseAnalyzer?.close()
                val analyzer = PoseAnalyzer(
                    isFrontCamera = { currentLensFacing == CameraSelector.LENS_FACING_FRONT },
                    onResult = { result ->
                        latestPoseFrame = result
                        callback.onPoseResult(result)
                    },
                    onError = { e -> callback.onPoseDetectorError(e.message ?: "Pose detector error") }
                )
                poseAnalyzer = analyzer

                // Analyzer is deliberately not attached here -- whether it's
                // attached at all is controlled by setPoseDetectionEnabled()
                // below, so the analysis stream stays idle (no inference
                // cost) whenever pose detection isn't the active mode.
                val imageAnalysis = ImageAnalysis.Builder()
                    // We only ever care about the freshest frame; if the
                    // detector falls behind, drop stale frames instead of
                    // queueing them, so pose overlay latency can't grow
                    // unbounded relative to what's on screen.
                    .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
                    .build()
                this.imageAnalysis = imageAnalysis

                val cameraSelector = CameraSelector.Builder()
                    .requireLensFacing(lensFacing)
                    .build()

                val useCaseGroup = UseCaseGroup.Builder()
                    .addUseCase(preview)
                    .addUseCase(videoCapture)
                    .addUseCase(imageAnalysis)
                    .addEffect(getOrCreateOverlayEffect())
                    .build()

                provider.unbindAll()
                provider.bindToLifecycle(lifecycleOwner, cameraSelector, useCaseGroup)
                applyPoseDetectionEnabled()
                callback.onCameraReady()
            } catch (e: Exception) {
                callback.onCameraError(e.message ?: "Camera unavailable")
            }
        }, ContextCompat.getMainExecutor(appContext))
    }

    private fun getOrCreateOverlayEffect(): OverlayEffect {
        overlayEffect?.let { return it }

        val handlerThread = HandlerThread("PoseOverlayEffect").apply { start() }
        overlayHandlerThread = handlerThread

        val effect = OverlayEffect(
            CameraEffect.VIDEO_CAPTURE,
            /* queueDepth = */ 2,
            Handler(handlerThread.looper)
        ) { throwable ->
            callback?.onPoseDetectorError(throwable.message ?: "Pose overlay compositing error")
        }
        effect.setOnDrawListener { frame ->
            val poseFrame = latestPoseFrame
            val canvas = frame.overlayCanvas
            // Always clear first: with no pose mode active (or no pose
            // result yet), this leaves the canvas fully transparent, so the
            // recorded frame passes through untouched.
            canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)
            if (poseDetectionEnabled && poseFrame != null) {
                val frameSize = frame.size
                // Mirrors the same raw-buffer-dimensions-plus-rotation-degrees
                // convention CameraX uses for ImageAnalysis/ImageProxy (see
                // PoseSkeletonRenderer.computeTransform's source-side handling).
                val targetWidth: Int
                val targetHeight: Int
                if (frame.rotationDegrees == 90 || frame.rotationDegrees == 270) {
                    targetWidth = frameSize.height
                    targetHeight = frameSize.width
                } else {
                    targetWidth = frameSize.width
                    targetHeight = frameSize.height
                }
                val transform = PoseSkeletonRenderer.computeTransform(
                    sourceWidth = poseFrame.imageWidth,
                    sourceHeight = poseFrame.imageHeight,
                    sourceRotationDegrees = poseFrame.rotationDegrees,
                    targetWidth = targetWidth,
                    targetHeight = targetHeight,
                    mirror = frame.isMirroring
                )
                PoseSkeletonRenderer.draw(canvas, poseFrame.pose, transform, overlayBonePaint, overlayJointPaint)
            }
            true
        }
        overlayEffect = effect
        return effect
    }

    /**
     * Attaches/detaches the pose analyzer from the analysis stream, and
     * turns skeleton compositing into the recorded video on/off, without
     * needing a full unbind/rebind of the camera use cases. Cheap and
     * synchronous, so it's safe to call right before [startRecording] to
     * pick the mode for that recording (plain video vs. with pose baked in).
     */
    fun setPoseDetectionEnabled(enabled: Boolean) {
        poseDetectionEnabled = enabled
        if (!enabled) {
            latestPoseFrame = null
        }
        applyPoseDetectionEnabled()
    }

    private fun applyPoseDetectionEnabled() {
        val analysis = imageAnalysis ?: return
        val analyzer = poseAnalyzer ?: return
        if (poseDetectionEnabled) {
            analysis.setAnalyzer(cameraExecutor, analyzer)
        } else {
            analysis.clearAnalyzer()
        }
    }

    fun startRecording() {
        val cb = callback ?: return
        val capture = videoCapture
        if (capture == null) {
            cb.onRecordingError("Camera is not ready yet")
            return
        }
        if (activeRecording != null) return

        try {
            val fileName = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(java.util.Date())
            val contentValues = ContentValues().apply {
                put(MediaStore.Video.Media.DISPLAY_NAME, "bowling_$fileName.mp4")
                put(MediaStore.Video.Media.MIME_TYPE, "video/mp4")
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
                    // Public Movies/bowling collection so the recording shows up in the
                    // Gallery/Photos app rather than app-private storage.
                    put(MediaStore.Video.Media.RELATIVE_PATH, "${Environment.DIRECTORY_MOVIES}/bowling")
                }
            }
            val outputOptions = MediaStoreOutputOptions.Builder(
                appContext.contentResolver,
                MediaStore.Video.Media.EXTERNAL_CONTENT_URI
            )
                .setContentValues(contentValues)
                .build()

            var pendingRecording = capture.output.prepareRecording(appContext, outputOptions)
            if (ContextCompat.checkSelfPermission(appContext, Manifest.permission.RECORD_AUDIO)
                == PackageManager.PERMISSION_GRANTED
            ) {
                pendingRecording = pendingRecording.withAudioEnabled()
            }

            activeRecording = pendingRecording.start(ContextCompat.getMainExecutor(appContext)) { event ->
                when (event) {
                    is VideoRecordEvent.Start -> cb.onRecordingStarted()
                    is VideoRecordEvent.Finalize -> {
                        activeRecording = null
                        if (event.hasError()) {
                            cb.onRecordingError(
                                event.cause?.message ?: "Recording error code=${event.error}"
                            )
                        } else {
                            cb.onRecordingFinalized(event.outputResults.outputUri)
                        }
                    }
                    else -> Unit
                }
            }
        } catch (e: Exception) {
            cb.onRecordingError(e.message ?: "Failed to start recording")
        }
    }

    fun stopRecording() {
        activeRecording?.stop()
        activeRecording = null
    }

    /** Unbinds all use cases and releases the pose detector. Call from onDestroy. */
    fun release() {
        activeRecording?.stop()
        activeRecording = null
        cameraProvider?.unbindAll()
        poseAnalyzer?.close()
        poseAnalyzer = null
        overlayEffect?.close()
        overlayEffect = null
        overlayHandlerThread?.quitSafely()
        overlayHandlerThread = null
        callback = null
    }
}