PinPoint/app/src/main/java/com/example/jnicpp/bowling/BowlingCameraActivity.kt

package com.example.jnicpp.bowling

import android.content.pm.ActivityInfo
import android.net.Uri
import android.os.Bundle
import android.view.View
import android.widget.Toast
import androidx.activity.result.contract.ActivityResultContracts
import androidx.activity.viewModels
import androidx.appcompat.app.AppCompatActivity
import androidx.camera.core.CameraSelector
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.lifecycleScope
import androidx.lifecycle.repeatOnLifecycle
import com.example.jnicpp.R
import com.example.jnicpp.databinding.ActivityBowlingCameraBinding
import kotlinx.coroutines.launch
import java.util.Locale
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors

/**
 * Screen that records video and runs real-time pose detection on the same
 * camera stream. This is a standalone entry point for now (see the plan
 * this was built from) -- it isn't wired into a menu/game-state system yet.
 *
 * This class intentionally does *not* contain any CameraX/ML Kit binding
 * logic itself -- that lives in [CameraXController] (use-case binding) and
 * [PoseAnalyzer] (per-frame inference), both plain classes that don't touch
 * Android component lifecycle. This class's job is just: own the executor,
 * own the ViewModel, wire user actions to the controller, and reflect
 * [CameraViewModel]'s state back onto the views.
 */
class BowlingCameraActivity : AppCompatActivity(), CameraXController.Callback {

    private lateinit var binding: ActivityBowlingCameraBinding
    private val viewModel: CameraViewModel by viewModels()

    private lateinit var cameraExecutor: ExecutorService
    private lateinit var cameraXController: CameraXController
    private var lensFacing = CameraSelector.LENS_FACING_BACK

    private val permissionLauncher =
        registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) { _ ->
            val granted = CameraPermissions.allGranted(this)
            viewModel.onPermissionsResult(granted)
            if (granted) {
                showCameraUi()
                startCamera()
            } else {
                showPermissionRationale(showAsDenied = true)
            }
        }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityBowlingCameraBinding.inflate(layoutInflater)
        setContentView(binding.root)

        cameraExecutor = Executors.newSingleThreadExecutor()
        cameraXController = CameraXController(applicationContext, cameraExecutor)

        binding.btnGrantPermissions.setOnClickListener {
            permissionLauncher.launch(CameraPermissions.REQUIRED)
        }
        binding.btnRecord.setOnClickListener { onRecordClicked() }
        binding.switchPose.setOnCheckedChangeListener { _, isChecked -> viewModel.onPoseToggled(isChecked) }
        binding.btnSwitchCamera.setOnClickListener { onSwitchCameraClicked() }
        binding.btnBack.setOnClickListener { finish() }

        observeViewModel()

        val granted = CameraPermissions.allGranted(this)
        viewModel.onPermissionsResult(granted)
        if (granted) {
            showCameraUi()
            startCamera()
        } else {
            showPermissionRationale(showAsDenied = false)
        }
    }

    private fun startCamera() {
        cameraXController.bindToLifecycle(
            lifecycleOwner = this,
            previewView = binding.cameraPreview,
            callback = this,
            lensFacing = lensFacing
        )
    }

    private fun onRecordClicked() {
        if (cameraXController.isRecording) {
            cameraXController.stopRecording()
        } else {
            // Pose mode for this recording is whatever switch_pose is
            // already set to -- see the poseEnabled collector in
            // observeViewModel(), which keeps cameraXController's live pose
            // state in sync with the toggle as it's flipped.
            viewModel.onRecordingStarting()
            cameraXController.startRecording()
        }
    }

    private fun onSwitchCameraClicked() {
        if (cameraXController.isRecording) {
            Toast.makeText(this, R.string.switch_camera_while_recording, Toast.LENGTH_SHORT).show()
            return
        }
        lensFacing = if (lensFacing == CameraSelector.LENS_FACING_BACK) {
            CameraSelector.LENS_FACING_FRONT
        } else {
            CameraSelector.LENS_FACING_BACK
        }
        // CameraXController.bindToLifecycle() unbinds all use cases before
        // rebinding, so calling it again with the flipped lensFacing is
        // enough to switch cameras cleanly.
        if (CameraPermissions.allGranted(this)) {
            startCamera()
        }
    }

    private fun observeViewModel() {
        lifecycleScope.launch {
            repeatOnLifecycle(Lifecycle.State.STARTED) {
                launch {
                    viewModel.recordingState.collect { state -> renderRecordingState(state) }
                }
                launch {
                    viewModel.poseEnabled.collect { enabled ->
                        // Also drives the switch's checked state (idempotent
                        // if the user just flipped it themselves), so it
                        // reflects viewModel state after an Activity
                        // recreation, e.g. on rotation.
                        if (binding.switchPose.isChecked != enabled) {
                            binding.switchPose.isChecked = enabled
                        }
                        cameraXController.setPoseDetectionEnabled(enabled)
                        if (!enabled) binding.poseOverlay.clear()
                    }
                }
                launch {
                    viewModel.errorEvents.collect { message ->
                        Toast.makeText(this@BowlingCameraActivity, message, Toast.LENGTH_LONG).show()
                    }
                }
            }
        }
    }

    private fun renderRecordingState(state: CameraViewModel.RecordingState) {
        // The screen now rotates freely (see res/layout-land/), which
        // recreates this Activity on rotation - that would orphan an
        // in-progress recording, since the CameraXController instance
        // holding the active Recording gets torn down with it. Locking to
        // whichever orientation we're already in while Starting/Recording
        // (and releasing the lock once Idle again) keeps recordings from
        // being interrupted by a rotation mid-shot.
        requestedOrientation = if (state is CameraViewModel.RecordingState.Idle) {
            ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED
        } else {
            ActivityInfo.SCREEN_ORIENTATION_LOCKED
        }
        when (state) {
            is CameraViewModel.RecordingState.Idle -> {
                binding.layoutRecordingIndicator.visibility = View.GONE
                binding.btnRecord.isEnabled = true
                binding.btnRecord.setText(R.string.record)
                // Pose mode can only be changed between recordings, not
                // mid-flight -- see setPoseDetectionEnabled()'s doc comment.
                binding.switchPose.isEnabled = true
            }
            is CameraViewModel.RecordingState.Starting -> {
                // Can't stop a recording that hasn't started yet, and pose
                // mode for it is already locked in.
                binding.btnRecord.isEnabled = false
                binding.switchPose.isEnabled = false
            }
            is CameraViewModel.RecordingState.Recording -> {
                binding.btnRecord.isEnabled = true
                binding.btnRecord.setText(R.string.stop_recording)
                binding.switchPose.isEnabled = false
                binding.layoutRecordingIndicator.visibility = View.VISIBLE
                val minutes = state.elapsedSeconds / 60
                val seconds = state.elapsedSeconds % 60
                binding.textTimer.text = String.format(Locale.US, "%02d:%02d", minutes, seconds)
            }
        }
    }

    private fun showCameraUi() {
        binding.layoutPermissionRationale.visibility = View.GONE
    }

    private fun showPermissionRationale(showAsDenied: Boolean) {
        binding.layoutPermissionRationale.visibility = View.VISIBLE
        binding.textPermissionMessage.setText(
            if (showAsDenied) R.string.permission_denied_message else R.string.permission_rationale_message
        )
    }

    // ----- CameraXController.Callback -----

    override fun onCameraReady() {
        showCameraUi()
    }

    override fun onCameraError(message: String) {
        viewModel.postError(getString(R.string.error_camera_unavailable, message))
    }

    override fun onRecordingStarted() {
        viewModel.onRecordingStarted()
    }

    override fun onRecordingFinalized(outputUri: Uri) {
        viewModel.onRecordingStopped()
        Toast.makeText(this, outputUri.lastPathSegment ?: outputUri.toString(), Toast.LENGTH_LONG).show()
    }

    override fun onRecordingError(message: String) {
        viewModel.postError(getString(R.string.error_recording_failed, message))
    }

    override fun onPoseDetectorError(message: String) {
        // Detector hiccups on a single frame shouldn't interrupt an
        // in-progress recording -- just surface it, don't reset state.
        Toast.makeText(this, getString(R.string.error_pose_detector, message), Toast.LENGTH_SHORT).show()
    }

    override fun onPoseResult(result: PoseAnalyzer.PoseFrameResult) {
        // Safe to touch the view directly here: ML Kit's Task listeners
        // (see PoseAnalyzer) deliver on the main thread by default even
        // though inference itself runs on the background camera executor.
        binding.poseOverlay.update(result)
        viewModel.onPoseAnglesUpdated(result.angles)
    }

    override fun onDestroy() {
        super.onDestroy()
        cameraXController.release()
        cameraExecutor.shutdown()
    }
}