package no.naiv.tiltshift.ui

import android.content.Intent
import android.graphics.Bitmap
import android.graphics.SurfaceTexture
import android.location.Location
import android.net.Uri
import android.opengl.GLSurfaceView
import android.view.Surface
import androidx.compose.animation.AnimatedVisibility
import androidx.compose.animation.fadeIn
import androidx.compose.animation.fadeOut
import androidx.compose.animation.scaleIn
import androidx.compose.foundation.background
import androidx.compose.foundation.border
import androidx.compose.foundation.clickable
import androidx.compose.foundation.systemGestureExclusion
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.navigationBarsPadding
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.layout.statusBarsPadding
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.result.PickVisualMediaRequest
import androidx.activity.result.contract.ActivityResultContracts
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Check
import androidx.compose.material.icons.filled.Close
import androidx.compose.material.icons.filled.FlipCameraAndroid
import androidx.compose.material.icons.filled.PhotoLibrary
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.Slider
import androidx.compose.material3.SliderDefaults
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.collectAsState
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.runtime.rememberUpdatedState
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.foundation.Image
import androidx.compose.ui.draw.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.asImageBitmap
import androidx.compose.ui.layout.ContentScale
import androidx.compose.ui.platform.LocalContext
import androidx.lifecycle.compose.LocalLifecycleOwner
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.compose.ui.viewinterop.AndroidView
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.collectLatest
import kotlinx.coroutines.launch
import no.naiv.tiltshift.camera.CameraManager
import no.naiv.tiltshift.camera.ImageCaptureHandler
import no.naiv.tiltshift.effect.BlurMode
import no.naiv.tiltshift.effect.BlurParameters
import no.naiv.tiltshift.effect.TiltShiftRenderer
import no.naiv.tiltshift.storage.PhotoSaver
import no.naiv.tiltshift.storage.SaveResult
import no.naiv.tiltshift.util.HapticFeedback
import no.naiv.tiltshift.util.LocationProvider
import no.naiv.tiltshift.util.OrientationDetector

/**
 * Main camera screen with tilt-shift controls.
 */
@Composable
fun CameraScreen(
    modifier: Modifier = Modifier
) {
    val context = LocalContext.current
    val lifecycleOwner = LocalLifecycleOwner.current
    val scope = rememberCoroutineScope()

    // Camera and effect state
    val cameraManager = remember { CameraManager(context) }
    val photoSaver = remember { PhotoSaver(context) }
    val captureHandler = remember { ImageCaptureHandler(context, photoSaver) }
    val haptics = remember { HapticFeedback(context) }
    val orientationDetector = remember { OrientationDetector(context) }
    val locationProvider = remember { LocationProvider(context) }

    // State
    var blurParams by remember { mutableStateOf(BlurParameters.DEFAULT) }
    var surfaceTexture by remember { mutableStateOf<SurfaceTexture?>(null) }
    var renderer by remember { mutableStateOf<TiltShiftRenderer?>(null) }
    var glSurfaceView by remember { mutableStateOf<GLSurfaceView?>(null) }

    var isCapturing by remember { mutableStateOf(false) }
    var showSaveSuccess by remember { mutableStateOf(false) }
    var showSaveError by remember { mutableStateOf<String?>(null) }
    var showControls by remember { mutableStateOf(false) }

    // Thumbnail state for last captured photo
    var lastSavedUri by remember { mutableStateOf<Uri?>(null) }
    var lastThumbnailBitmap by remember { mutableStateOf<Bitmap?>(null) }

    // Gallery preview mode: non-null means we're previewing a gallery image
    var galleryBitmap by remember { mutableStateOf<Bitmap?>(null) }
    var galleryImageUri by remember { mutableStateOf<Uri?>(null) }
    val isGalleryPreview = galleryBitmap != null

    var currentRotation by remember { mutableStateOf(Surface.ROTATION_0) }
    var currentLocation by remember { mutableStateOf<Location?>(null) }

    // Gallery picker: load image for interactive preview before processing
    val galleryLauncher = rememberLauncherForActivityResult(
        contract = ActivityResultContracts.PickVisualMedia()
    ) { uri ->
        if (uri != null && !isCapturing && !isGalleryPreview) {
            scope.launch {
                val bitmap = captureHandler.loadGalleryImage(uri)
                if (bitmap != null) {
                    galleryBitmap = bitmap
                    galleryImageUri = uri
                } else {
                    haptics.error()
                    showSaveError = "Failed to load image"
                    delay(2000)
                    showSaveError = null
                }
            }
        }
    }

    val zoomRatio by cameraManager.zoomRatio.collectAsState()
    val minZoom by cameraManager.minZoomRatio.collectAsState()
    val maxZoom by cameraManager.maxZoomRatio.collectAsState()
    val isFrontCamera by cameraManager.isFrontCamera.collectAsState()
    val cameraError by cameraManager.error.collectAsState()

    // Show camera errors via the existing error UI
    LaunchedEffect(cameraError) {
        cameraError?.let { message ->
            showSaveError = message
            cameraManager.clearError()
            delay(2000)
            showSaveError = null
        }
    }

    // Collect orientation updates
    LaunchedEffect(Unit) {
        orientationDetector.orientationFlow().collectLatest { rotation ->
            currentRotation = rotation
        }
    }

    // Collect location updates
    LaunchedEffect(Unit) {
        locationProvider.locationFlow().collectLatest { location ->
            currentLocation = location
        }
    }

    // Update renderer with blur params
    LaunchedEffect(blurParams) {
        renderer?.updateParameters(blurParams)
        glSurfaceView?.requestRender()
    }

    // Update renderer when camera switches (front/back)
    LaunchedEffect(isFrontCamera) {
        renderer?.setFrontCamera(isFrontCamera)
        glSurfaceView?.requestRender()
    }

    // Start camera when surface texture is available
    LaunchedEffect(surfaceTexture) {
        surfaceTexture?.let {
            cameraManager.startCamera(lifecycleOwner) { surfaceTexture }
        }
    }

    // Cleanup
    DisposableEffect(Unit) {
        onDispose {
            cameraManager.release()
            renderer?.release()
            lastThumbnailBitmap?.recycle()
            galleryBitmap?.recycle()
        }
    }

    Box(
        modifier = modifier
            .fillMaxSize()
            .background(Color.Black)
    ) {
        // Main view: gallery preview image or camera GL surface
        if (isGalleryPreview) {
            galleryBitmap?.let { bmp ->
                Image(
                    bitmap = bmp.asImageBitmap(),
                    contentDescription = "Gallery preview",
                    contentScale = ContentScale.Fit,
                    modifier = Modifier
                        .fillMaxSize()
                        .background(Color.Black)
                )
            }
        } else {
            // OpenGL Surface for camera preview with effect
            AndroidView(
                factory = { ctx ->
                    GLSurfaceView(ctx).apply {
                        setEGLContextClientVersion(2)

                        val newRenderer = TiltShiftRenderer(ctx) { st ->
                            surfaceTexture = st
                        }
                        renderer = newRenderer

                        setRenderer(newRenderer)
                        renderMode = GLSurfaceView.RENDERMODE_CONTINUOUSLY

                        glSurfaceView = this
                    }
                },
                modifier = Modifier.fillMaxSize()
            )
        }

        // Tilt-shift overlay (gesture handling + visualization)
        TiltShiftOverlay(
            params = blurParams,
            onParamsChange = { newParams ->
                blurParams = newParams
                haptics.tick()
            },
            onZoomChange = { zoomDelta ->
                if (!isGalleryPreview) {
                    val newZoom = (zoomRatio * zoomDelta).coerceIn(minZoom, maxZoom)
                    cameraManager.setZoom(newZoom)
                }
            },
            modifier = Modifier.fillMaxSize()
        )

        // Top bar with controls
        Column(
            modifier = Modifier
                .fillMaxWidth()
                .statusBarsPadding()
                .padding(16.dp)
        ) {
            Row(
                modifier = Modifier.fillMaxWidth(),
                horizontalArrangement = Arrangement.SpaceBetween,
                verticalAlignment = Alignment.CenterVertically
            ) {
                if (!isGalleryPreview) {
                    // Zoom indicator
                    ZoomIndicator(currentZoom = zoomRatio)
                } else {
                    Spacer(modifier = Modifier.width(1.dp))
                }

                Row(verticalAlignment = Alignment.CenterVertically) {
                    if (!isGalleryPreview) {
                        // Camera flip button
                        IconButton(
                            onClick = {
                                cameraManager.switchCamera()
                                haptics.click()
                            }
                        ) {
                            Icon(
                                imageVector = Icons.Default.FlipCameraAndroid,
                                contentDescription = "Switch Camera",
                                tint = Color.White
                            )
                        }
                    }

                    // Toggle controls button
                    IconButton(
                        onClick = {
                            showControls = !showControls
                            haptics.tick()
                        }
                    ) {
                        Text(
                            text = if (showControls) "Hide" else "Ctrl",
                            color = Color.White,
                            fontSize = 12.sp
                        )
                    }
                }
            }

            // Mode toggle
            Row(
                modifier = Modifier
                    .fillMaxWidth()
                    .padding(top = 8.dp),
                horizontalArrangement = Arrangement.Center
            ) {
                ModeToggle(
                    currentMode = blurParams.mode,
                    onModeChange = { mode ->
                        blurParams = blurParams.copy(mode = mode)
                        haptics.click()
                    }
                )
            }
        }

        // Control panel (sliders)
        AnimatedVisibility(
            visible = showControls,
            enter = fadeIn(),
            exit = fadeOut(),
            modifier = Modifier
                .align(Alignment.CenterEnd)
                .padding(end = 16.dp)
        ) {
            ControlPanel(
                params = blurParams,
                onParamsChange = { newParams ->
                    blurParams = newParams
                }
            )
        }

        // Bottom controls
        Column(
            modifier = Modifier
                .align(Alignment.BottomCenter)
                .navigationBarsPadding()
                .padding(bottom = 48.dp)
                .systemGestureExclusion(),
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            if (isGalleryPreview) {
                // Gallery preview mode: Cancel | Apply
                Row(
                    verticalAlignment = Alignment.CenterVertically,
                    horizontalArrangement = Arrangement.spacedBy(48.dp)
                ) {
                    // Cancel button
                    IconButton(
                        onClick = {
                            galleryBitmap?.recycle()
                            galleryBitmap = null
                            galleryImageUri = null
                        },
                        modifier = Modifier
                            .size(56.dp)
                            .clip(CircleShape)
                            .background(Color(0x80000000))
                    ) {
                        Icon(
                            imageVector = Icons.Default.Close,
                            contentDescription = "Cancel",
                            tint = Color.White,
                            modifier = Modifier.size(28.dp)
                        )
                    }

                    // Apply button
                    IconButton(
                        onClick = {
                            val uri = galleryImageUri ?: return@IconButton
                            if (!isCapturing) {
                                isCapturing = true
                                haptics.heavyClick()
                                scope.launch {
                                    val result = captureHandler.processExistingImage(
                                        imageUri = uri,
                                        blurParams = blurParams,
                                        location = currentLocation
                                    )
                                    when (result) {
                                        is SaveResult.Success -> {
                                            haptics.success()
                                            lastThumbnailBitmap?.recycle()
                                            lastThumbnailBitmap = result.thumbnail
                                            lastSavedUri = result.uri
                                            showSaveSuccess = true
                                            delay(1500)
                                            showSaveSuccess = false
                                        }
                                        is SaveResult.Error -> {
                                            haptics.error()
                                            showSaveError = result.message
                                            delay(2000)
                                            showSaveError = null
                                        }
                                    }
                                    galleryBitmap?.recycle()
                                    galleryBitmap = null
                                    galleryImageUri = null
                                    isCapturing = false
                                }
                            }
                        },
                        enabled = !isCapturing,
                        modifier = Modifier
                            .size(56.dp)
                            .clip(CircleShape)
                            .background(Color(0xFFFFB300))
                    ) {
                        Icon(
                            imageVector = Icons.Default.Check,
                            contentDescription = "Apply effect",
                            tint = Color.Black,
                            modifier = Modifier.size(28.dp)
                        )
                    }
                }
            } else {
                // Camera mode: Zoom presets + Gallery | Capture | Spacer
                // Zoom presets (only show for back camera)
                if (!isFrontCamera) {
                    ZoomControl(
                        currentZoom = zoomRatio,
                        minZoom = minZoom,
                        maxZoom = maxZoom,
                        onZoomSelected = { zoom ->
                            cameraManager.setZoom(zoom)
                            haptics.click()
                        }
                    )

                    Spacer(modifier = Modifier.height(24.dp))
                }

                // Gallery button | Capture button | Spacer for symmetry
                Row(
                    verticalAlignment = Alignment.CenterVertically,
                    horizontalArrangement = Arrangement.spacedBy(24.dp)
                ) {
                    // Gallery picker button
                    IconButton(
                        onClick = {
                            if (!isCapturing) {
                                galleryLauncher.launch(
                                    PickVisualMediaRequest(ActivityResultContracts.PickVisualMedia.ImageOnly)
                                )
                            }
                        },
                        enabled = !isCapturing,
                        modifier = Modifier.size(52.dp)
                    ) {
                        Icon(
                            imageVector = Icons.Default.PhotoLibrary,
                            contentDescription = "Pick from gallery",
                            tint = Color.White,
                            modifier = Modifier.size(28.dp)
                        )
                    }

                    // Capture button
                    CaptureButton(
                        isCapturing = isCapturing,
                        onClick = {
                            if (!isCapturing) {
                                isCapturing = true
                                haptics.heavyClick()

                                scope.launch {
                                    val imageCapture = cameraManager.imageCapture
                                    if (imageCapture != null) {
                                        val result = captureHandler.capturePhoto(
                                            imageCapture = imageCapture,
                                            executor = cameraManager.getExecutor(),
                                            blurParams = blurParams,
                                            deviceRotation = currentRotation,
                                            location = currentLocation,
                                            isFrontCamera = isFrontCamera
                                        )

                                        when (result) {
                                            is SaveResult.Success -> {
                                                haptics.success()
                                                lastThumbnailBitmap?.recycle()
                                                lastThumbnailBitmap = result.thumbnail
                                                lastSavedUri = result.uri
                                                showSaveSuccess = true
                                                delay(1500)
                                                showSaveSuccess = false
                                            }
                                            is SaveResult.Error -> {
                                                haptics.error()
                                                showSaveError = result.message
                                                delay(2000)
                                                showSaveError = null
                                            }
                                        }
                                    }
                                    isCapturing = false
                                }
                            }
                        }
                    )

                    // Spacer for visual symmetry with gallery button
                    Spacer(modifier = Modifier.size(52.dp))
                }
            }
        }

        // Last captured photo thumbnail (hidden in gallery preview mode)
        if (!isGalleryPreview) LastPhotoThumbnail(
            thumbnail = lastThumbnailBitmap,
            onTap = {
                lastSavedUri?.let { uri ->
                    val intent = Intent(Intent.ACTION_VIEW).apply {
                        setDataAndType(uri, "image/jpeg")
                        addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
                    }
                    context.startActivity(intent)
                }
            },
            modifier = Modifier
                .align(Alignment.BottomEnd)
                .navigationBarsPadding()
                .padding(bottom = 48.dp, end = 16.dp)
        )

        // Success indicator
        AnimatedVisibility(
            visible = showSaveSuccess,
            enter = fadeIn(),
            exit = fadeOut(),
            modifier = Modifier.align(Alignment.Center)
        ) {
            Box(
                modifier = Modifier
                    .size(80.dp)
                    .clip(CircleShape)
                    .background(Color(0xFF4CAF50)),
                contentAlignment = Alignment.Center
            ) {
                Icon(
                    imageVector = Icons.Default.Check,
                    contentDescription = "Saved",
                    tint = Color.White,
                    modifier = Modifier.size(48.dp)
                )
            }
        }

        // Error indicator
        AnimatedVisibility(
            visible = showSaveError != null,
            enter = fadeIn(),
            exit = fadeOut(),
            modifier = Modifier
                .align(Alignment.Center)
                .padding(32.dp)
        ) {
            Column(
                horizontalAlignment = Alignment.CenterHorizontally,
                modifier = Modifier
                    .clip(RoundedCornerShape(16.dp))
                    .background(Color(0xFFF44336))
                    .padding(24.dp)
            ) {
                Icon(
                    imageVector = Icons.Default.Close,
                    contentDescription = "Error",
                    tint = Color.White,
                    modifier = Modifier.size(32.dp)
                )
                Spacer(modifier = Modifier.height(8.dp))
                Text(
                    text = showSaveError ?: "Error",
                    color = Color.White,
                    fontSize = 14.sp
                )
            }
        }
    }
}

/**
 * Mode toggle for Linear / Radial blur modes.
 */
@Composable
private fun ModeToggle(
    currentMode: BlurMode,
    onModeChange: (BlurMode) -> Unit,
    modifier: Modifier = Modifier
) {
    Row(
        modifier = modifier
            .clip(RoundedCornerShape(20.dp))
            .background(Color(0x80000000))
            .padding(4.dp),
        horizontalArrangement = Arrangement.Center
    ) {
        ModeButton(
            text = "Linear",
            isSelected = currentMode == BlurMode.LINEAR,
            onClick = { onModeChange(BlurMode.LINEAR) }
        )
        Spacer(modifier = Modifier.width(4.dp))
        ModeButton(
            text = "Radial",
            isSelected = currentMode == BlurMode.RADIAL,
            onClick = { onModeChange(BlurMode.RADIAL) }
        )
    }
}

@Composable
private fun ModeButton(
    text: String,
    isSelected: Boolean,
    onClick: () -> Unit
) {
    Box(
        modifier = Modifier
            .clip(RoundedCornerShape(16.dp))
            .background(if (isSelected) Color(0xFFFFB300) else Color.Transparent)
            .clickable(onClick = onClick)
            .padding(horizontal = 16.dp, vertical = 8.dp),
        contentAlignment = Alignment.Center
    ) {
        Text(
            text = text,
            color = if (isSelected) Color.Black else Color.White,
            fontSize = 14.sp
        )
    }
}

/**
 * Control panel with sliders for blur parameters.
 */
@Composable
private fun ControlPanel(
    params: BlurParameters,
    onParamsChange: (BlurParameters) -> Unit,
    modifier: Modifier = Modifier
) {
    // Use rememberUpdatedState to avoid stale closure capture during slider drags
    val currentParams by rememberUpdatedState(params)
    val currentOnParamsChange by rememberUpdatedState(onParamsChange)

    Column(
        modifier = modifier
            .width(200.dp)
            .clip(RoundedCornerShape(16.dp))
            .background(Color(0xCC000000))
            .padding(16.dp),
        verticalArrangement = Arrangement.spacedBy(16.dp)
    ) {
        // Blur intensity slider
        SliderControl(
            label = "Blur",
            value = params.blurAmount,
            valueRange = BlurParameters.MIN_BLUR..BlurParameters.MAX_BLUR,
            onValueChange = { currentOnParamsChange(currentParams.copy(blurAmount = it)) }
        )

        // Falloff slider
        SliderControl(
            label = "Falloff",
            value = params.falloff,
            valueRange = BlurParameters.MIN_FALLOFF..BlurParameters.MAX_FALLOFF,
            onValueChange = { currentOnParamsChange(currentParams.copy(falloff = it)) }
        )

        // Aspect ratio slider (radial mode only)
        if (params.mode == BlurMode.RADIAL) {
            SliderControl(
                label = "Shape",
                value = params.aspectRatio,
                valueRange = BlurParameters.MIN_ASPECT..BlurParameters.MAX_ASPECT,
                onValueChange = { currentOnParamsChange(currentParams.copy(aspectRatio = it)) }
            )
        }

    }
}

@Composable
private fun SliderControl(
    label: String,
    value: Float,
    valueRange: ClosedFloatingPointRange<Float>,
    onValueChange: (Float) -> Unit
) {
    Column {
        Row(
            modifier = Modifier.fillMaxWidth(),
            horizontalArrangement = Arrangement.SpaceBetween
        ) {
            Text(
                text = label,
                color = Color.White,
                fontSize = 12.sp
            )
            Text(
                text = "${(value * 100).toInt()}%",
                color = Color.White.copy(alpha = 0.7f),
                fontSize = 12.sp
            )
        }
        Slider(
            value = value,
            onValueChange = onValueChange,
            valueRange = valueRange,
            colors = SliderDefaults.colors(
                thumbColor = Color(0xFFFFB300),
                activeTrackColor = Color(0xFFFFB300),
                inactiveTrackColor = Color.White.copy(alpha = 0.3f)
            ),
            modifier = Modifier.height(24.dp)
        )
    }
}

/**
 * Capture button with animation for capturing state.
 */
@Composable
private fun CaptureButton(
    isCapturing: Boolean,
    onClick: () -> Unit,
    modifier: Modifier = Modifier
) {
    val outerSize = 72.dp
    val innerSize = if (isCapturing) 48.dp else 60.dp

    Box(
        modifier = modifier
            .size(outerSize)
            .clip(CircleShape)
            .border(4.dp, Color.White, CircleShape)
            .clickable(enabled = !isCapturing, onClick = onClick),
        contentAlignment = Alignment.Center
    ) {
        Box(
            modifier = Modifier
                .size(innerSize)
                .clip(CircleShape)
                .background(if (isCapturing) Color(0xFFFFB300) else Color.White)
        )
    }
}

/**
 * Rounded thumbnail of the last captured photo.
 * Tapping opens the image in the default photo viewer.
 */
@Composable
private fun LastPhotoThumbnail(
    thumbnail: Bitmap?,
    onTap: () -> Unit,
    modifier: Modifier = Modifier
) {
    AnimatedVisibility(
        visible = thumbnail != null,
        enter = fadeIn() + scaleIn(initialScale = 0.6f),
        exit = fadeOut(),
        modifier = modifier
    ) {
        thumbnail?.let { bmp ->
            Image(
                bitmap = bmp.asImageBitmap(),
                contentDescription = "Last captured photo",
                contentScale = ContentScale.Crop,
                modifier = Modifier
                    .size(52.dp)
                    .clip(RoundedCornerShape(10.dp))
                    .border(2.dp, Color.White, RoundedCornerShape(10.dp))
                    .clickable(onClick = onTap)
            )
        }
    }
}