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

/**
 * @file BowlingCameraActivity.kt
 * @brief Camera screen Activity: owns the ViewModel, wires user actions to the camera controller, and reflects state onto views.
 */
package com.example.jnicpp.bowling

import android.content.pm.ActivityInfo
import android.net.Uri
import android.os.Bundle
import android.util.Log
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 androidx.core.content.ContextCompat
import com.example.jnicpp.R
import com.example.jnicpp.databinding.ActivityBowlingCameraBinding
import com.google.mlkit.vision.pose.PoseLandmark
import kotlinx.coroutines.flow.combine
import kotlinx.coroutines.launch
import java.util.Locale
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors

/**
 * @brief 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 {

    companion object {
        private const val TAG = "BowlingCameraActivity"
    }

    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

    // Throttled diagnostic for step-count troubleshooting: confirms whether
    // ankles are actually clearing PoseSkeletonRenderer.MIN_LIKELIHOOD, since
    // LiveStepDetector silently sees nothing for a foot until they do.
    private var lastLandmarkLogMs = 0L

    // Richer, un-throttled per-frame trace of the same troubleshooting data,
    // written to a file instead of Logcat -- see DebugSessionLogger's class
    // doc. Open only while a recording is in progress.
    private lateinit var debugSessionLogger: DebugSessionLogger

    // class for FeedbackUI
    private lateinit var feedbackUI: FeedbackUI
    private val stepLabels = listOf(
        R.string.starting_position,
        R.string.first_step,
        R.string.second_step,
        R.string.third_step,
        R.string.fourth_step,
        R.string.end_position
    )
    private var currentStepIndex = 0

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

    /**
     * @brief Standard Activity entry point: inflates the layout, wires up
     *        click listeners and ViewModel observers, and starts the
     *        camera if permissions already allow it.
     * @param savedInstanceState Previous saved state, if this is a re-creation; unused.
     */
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityBowlingCameraBinding.inflate(layoutInflater)
        setContentView(binding.root)

        cameraExecutor = Executors.newSingleThreadExecutor()
        cameraXController = CameraXController(applicationContext, cameraExecutor)
        debugSessionLogger = DebugSessionLogger(applicationContext)
        feedbackUI = FeedbackUI(this, binding.root)

        binding.poseOverlay.attachFeedback(feedbackUI)
        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() }
        binding.btnShowStep.setOnClickListener { onStepIncrease() }

        observeViewModel()

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

    /** @brief Binds the CameraX use cases to this Activity's lifecycle using the current [lensFacing]. */
    private fun startCamera() {
        cameraXController.bindToLifecycle(
            lifecycleOwner = this,
            previewView = binding.cameraPreview,
            callback = this,
            lensFacing = lensFacing,
            feedbackUi = feedbackUI
        )
    }

    /** @brief Handles the record button: starts or stops recording depending on current state. */
    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()
        }
    }

    /** @brief Handles the switch-camera button: toggles [lensFacing] and rebinds, unless a recording is in progress. */
    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()
        }
    }

    /** @brief Collects every [CameraViewModel] StateFlow/SharedFlow and reflects each onto the views. */
    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()
                    }
                }
                launch {
                    viewModel.stepEvents.collect { events ->
                        binding.textStepCount.text = getString(R.string.step_count_format, events.size)
                        if (events.isNotEmpty()) {
                            Log.d(TAG, "Step ${events.size}: ${events.last()}")
                        }
                    }
                }
                // Deliberately its own collector, independent of stepEvents
                // above -- delivery-phase feedback and step counting are
                // separate concerns (see PosePhaseDetector's class doc).
                // Combined with poseEnabled (rather than posePhase alone) so
                // the label can tell "pose off" (hidden) apart from "pose on
                // but not yet in the target posture" (amber prompt) -- both
                // cases otherwise report a null phase.
                launch {
                    combine(viewModel.poseEnabled, viewModel.posePhase) { enabled, phase -> enabled to phase }
                        .collect { (enabled, phase) -> renderPosePhase(enabled, phase) }
                }
                // Raw angle readout backing the label above -- its own
                // collector since it's driven by a separate StateFlow
                // (poseMetrics is null on its own whenever pose detection is
                // off, so no need to combine with poseEnabled here).
                launch {
                    viewModel.poseMetrics.collect { metrics -> renderPoseMetrics(metrics) }
                }
            }
        }
    }

    /**
     * @brief Reflects [state] onto the record button, pose toggle, recording
     *        indicator/timer, and screen-orientation lock.
     *
     * 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.
     *
     * @param state The recording state to render.
     */
    private fun renderRecordingState(state: CameraViewModel.RecordingState) {
        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
                // Feedback UI - buttons only shown when recording
                binding.btnShowStep.isEnabled = false
            }
            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
                binding.btnShowStep.isEnabled = true
                binding.btnShowStep.setText(R.string.starting_position)
            }
            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)
                binding.btnShowStep.isEnabled = true
            }
        }
    }

    /**
     * @brief Shows or hides the delivery-phase feedback label, and colors/labels
     *        it for whether [phase] currently validates.
     *
     * Visible for the entire time [poseEnabled] is on -- not just at the
     * moment a phase is confirmed -- so the bowler gets a continuous
     * "not yet"/"confirmed" signal to line themselves up against, rather
     * than a label that silently disappears whenever they drift out of
     * position. Independent of [renderRecordingState]/the step counter --
     * see [PosePhaseDetector]'s class doc for why phase feedback and step
     * counting are kept as separate concerns.
     *
     * @param poseEnabled Whether pose detection is currently on at all.
     * @param phase The bowler's current delivery phase, or null if none currently validates.
     */
    private fun renderPosePhase(poseEnabled: Boolean, phase: BowlingPhase?) {
        if (!poseEnabled) {
            binding.textPoseFeedback.visibility = View.GONE
            return
        }
        binding.textPoseFeedback.visibility = View.VISIBLE
        // Every other BowlingPhase falls back to the "waiting" message too --
        // see PosePhaseDetector's class doc, only STARTING_STANCE is detected today.
        if (phase == BowlingPhase.STARTING_STANCE) {
            binding.textPoseFeedback.text = getString(R.string.pose_phase_starting_stance)
            binding.textPoseFeedback.setBackgroundColor(ContextCompat.getColor(this, R.color.pose_feedback_ready))
        } else {
            binding.textPoseFeedback.text = getString(R.string.pose_phase_waiting)
            binding.textPoseFeedback.setBackgroundColor(ContextCompat.getColor(this, R.color.pose_feedback_waiting))
        }
    }

    /**
     * @brief Shows or hides the raw torso/knee/elbow angle readout backing [renderPosePhase]'s label.
     * @param metrics This frame's angle readings, or null to hide the readout (pose detection off).
     */
    private fun renderPoseMetrics(metrics: PosePhaseDetector.Metrics?) {
        if (metrics == null) {
            binding.textPoseMetrics.visibility = View.GONE
            return
        }
        binding.textPoseMetrics.visibility = View.VISIBLE
        binding.textPoseMetrics.text = getString(
            R.string.pose_metrics_format,
            angleText(metrics.torsoTiltDegrees),
            angleText(metrics.leftKneeAngleDegrees),
            angleText(metrics.rightKneeAngleDegrees),
            angleText(metrics.leftElbowAngleDegrees),
            angleText(metrics.rightElbowAngleDegrees)
        )
    }

    /**
     * @brief Formats one angle reading for display.
     * @param degrees The angle in degrees, or null if that landmark wasn't confidently detected this frame.
     * @return e.g. "12°", or "--" if [degrees] is null.
     */
    private fun angleText(degrees: Float?): String =
        if (degrees == null) "--" else "${degrees.toInt()}°"

    /** @brief Hides the permission-rationale screen, revealing the camera UI underneath. */
    private fun showCameraUi() {
        binding.layoutPermissionRationale.visibility = View.GONE
    }

    /**
     * @brief Shows the permission-rationale screen with either the initial
     *        ask or the post-denial message.
     * @param showAsDenied true to show the "permission denied" message, false for the initial rationale.
     */
    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 -----

    /** @brief Hides the permission-rationale screen once the camera is bound and ready. */
    override fun onCameraReady() {
        showCameraUi()
    }

    /** @brief Surfaces a camera-binding failure to the ViewModel. @param message Human-readable failure reason. */
    override fun onCameraError(message: String) {
        viewModel.postError(getString(R.string.error_camera_unavailable, message))
    }

    /** @brief Forwards the "recording actually started" event to the ViewModel and opens the debug trace file. */
    override fun onRecordingStarted() {
        viewModel.onRecordingStarted()
        debugSessionLogger.start()
    }

    /**
     * @brief Forwards the "recording finished" event to the ViewModel,
     *        closes the debug trace file, and shows the saved video's name.
     * @param outputUri Location of the saved video.
     */
    override fun onRecordingFinalized(outputUri: Uri) {
        viewModel.onRecordingStopped()
        debugSessionLogger.stop()
        Toast.makeText(
            this,
            "${outputUri.lastPathSegment ?: outputUri.toString()} (debug trace saved to Downloads/bowling)",
            Toast.LENGTH_LONG
        ).show()
    }

    /** @brief Surfaces a recording failure to the ViewModel and closes the debug trace file. @param message Human-readable failure reason. */
    override fun onRecordingError(message: String) {
        viewModel.postError(getString(R.string.error_recording_failed, message))
        debugSessionLogger.stop()
    }

    /**
     * @brief Surfaces a pose-detector failure without disrupting an in-progress recording.
     *
     * Detector hiccups on a single frame shouldn't interrupt an
     * in-progress recording -- just surface it, don't reset state.
     *
     * @param message Human-readable failure reason.
     */
    override fun onPoseDetectorError(message: String) {
        Toast.makeText(this, getString(R.string.error_pose_detector, message), Toast.LENGTH_SHORT).show()
    }

    /**
     * @brief Receives each analyzed frame's pose result: updates the live
     *        overlay, forwards it to the ViewModel for buffering/step
     *        detection, and periodically logs landmark confidence for
     *        troubleshooting.
     *
     * 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.
     *
     * @param result The current frame's landmarks, angles, and image metadata.
     */
    override fun onPoseResult(result: PoseAnalyzer.PoseFrameResult) {
        binding.poseOverlay.update(result)
        viewModel.onPoseFrameUpdated(result.landmarks, result.angles)

        val frameTimestampMs = System.currentTimeMillis()
        debugSessionLogger.log(result.landmarks, frameTimestampMs, viewModel.stepEvents.value.size)

        if (frameTimestampMs - lastLandmarkLogMs >= 1000) {
            lastLandmarkLogMs = frameTimestampMs
            val leftAnkle = result.landmarks[PoseLandmark.LEFT_ANKLE]
            val rightAnkle = result.landmarks[PoseLandmark.RIGHT_ANKLE]
            val leftHip = result.landmarks[PoseLandmark.LEFT_HIP]
            val rightHip = result.landmarks[PoseLandmark.RIGHT_HIP]
            val leftShoulder = result.landmarks[PoseLandmark.LEFT_SHOULDER]
            val rightShoulder = result.landmarks[PoseLandmark.RIGHT_SHOULDER]
            Log.d(
                TAG,
                "Likelihood (need >= ${PoseSkeletonRenderer.MIN_LIKELIHOOD}) -- " +
                    "ankle L=${leftAnkle?.inFrameLikelihood} R=${rightAnkle?.inFrameLikelihood}, " +
                    "hip L=${leftHip?.inFrameLikelihood} R=${rightHip?.inFrameLikelihood}, " +
                    "shoulder L=${leftShoulder?.inFrameLikelihood} R=${rightShoulder?.inFrameLikelihood}"
            )
        }
    }

    /** @brief Releases the camera controller, shuts down the analysis executor, and closes any open debug trace file. */
    override fun onDestroy() {
        super.onDestroy()
        cameraXController.release()
        cameraExecutor.shutdown()
        debugSessionLogger.stop()
    }

    /**
     * @brief Advances the step index and updates the step button label.
     *
     * This method increments the current step index, cycling back to zero
     * once the end of the [stepLabels] list is reached. It then updates the
     * `btnShowStep` text to reflect the new step, ensuring the UI button
     * always displays the correct label for the current position in the
     * sequence.
     */
    fun onStepIncrease() {
        currentStepIndex = (currentStepIndex + 1) % stepLabels.size
        binding.btnShowStep.setText(stepLabels[currentStepIndex])
    }
}