tilt-shift-camera/app/src/main/java/no/naiv/tiltshift/camera/ImageCaptureHandler.kt

package no.naiv.tiltshift.camera

import android.content.Context
import android.graphics.Bitmap
import android.graphics.BitmapFactory
import android.graphics.Canvas
import android.graphics.Matrix
import android.graphics.Paint
import android.graphics.RenderEffect
import android.graphics.Shader
import android.location.Location
import android.os.Build
import android.view.Surface
import androidx.camera.core.ImageCapture
import androidx.camera.core.ImageCaptureException
import androidx.camera.core.ImageProxy
import androidx.exifinterface.media.ExifInterface
import kotlinx.coroutines.suspendCancellableCoroutine
import no.naiv.tiltshift.effect.BlurParameters
import no.naiv.tiltshift.storage.PhotoSaver
import no.naiv.tiltshift.storage.SaveResult
import no.naiv.tiltshift.util.OrientationDetector
import java.io.File
import java.util.concurrent.Executor
import kotlin.coroutines.resume
import kotlin.math.cos
import kotlin.math.sin

/**
 * Handles capturing photos with the tilt-shift effect applied.
 */
class ImageCaptureHandler(
    private val context: Context,
    private val photoSaver: PhotoSaver
) {

    /**
     * Captures a photo and applies the tilt-shift effect.
     */
    suspend fun capturePhoto(
        imageCapture: ImageCapture,
        executor: Executor,
        blurParams: BlurParameters,
        deviceRotation: Int,
        location: Location?,
        isFrontCamera: Boolean
    ): SaveResult = suspendCancellableCoroutine { continuation ->

        imageCapture.takePicture(
            executor,
            object : ImageCapture.OnImageCapturedCallback() {
                override fun onCaptureSuccess(imageProxy: ImageProxy) {
                    try {
                        // Get rotation from ImageProxy (sensor orientation)
                        val imageRotation = imageProxy.imageInfo.rotationDegrees

                        // Convert ImageProxy to Bitmap
                        var bitmap = imageProxyToBitmap(imageProxy)
                        imageProxy.close()

                        if (bitmap == null) {
                            continuation.resume(SaveResult.Error("Failed to convert image"))
                            return
                        }

                        // Rotate bitmap to correct orientation
                        // Camera sensor is landscape, we need to rotate for portrait
                        bitmap = rotateBitmap(bitmap, imageRotation, isFrontCamera)

                        // Apply tilt-shift effect to the correctly oriented image
                        val processedBitmap = applyTiltShiftEffect(bitmap, blurParams)
                        bitmap.recycle()

                        // Save with EXIF orientation as NORMAL (bitmap is already rotated)
                        kotlinx.coroutines.runBlocking {
                            val result = photoSaver.saveBitmap(
                                processedBitmap,
                                ExifInterface.ORIENTATION_NORMAL,
                                location
                            )
                            processedBitmap.recycle()
                            continuation.resume(result)
                        }
                    } catch (e: Exception) {
                        continuation.resume(SaveResult.Error("Capture failed: ${e.message}", e))
                    }
                }

                override fun onError(exception: ImageCaptureException) {
                    continuation.resume(
                        SaveResult.Error("Capture failed: ${exception.message}", exception)
                    )
                }
            }
        )
    }

    /**
     * Rotates a bitmap to the correct orientation.
     */
    private fun rotateBitmap(bitmap: Bitmap, rotationDegrees: Int, isFrontCamera: Boolean): Bitmap {
        if (rotationDegrees == 0 && !isFrontCamera) {
            return bitmap
        }

        val matrix = Matrix()

        // Apply rotation
        if (rotationDegrees != 0) {
            matrix.postRotate(rotationDegrees.toFloat())
        }

        // Mirror for front camera
        if (isFrontCamera) {
            matrix.postScale(-1f, 1f)
        }

        val rotated = Bitmap.createBitmap(
            bitmap, 0, 0, bitmap.width, bitmap.height, matrix, true
        )

        if (rotated != bitmap) {
            bitmap.recycle()
        }

        return rotated
    }

    private fun imageProxyToBitmap(imageProxy: ImageProxy): Bitmap? {
        val buffer = imageProxy.planes[0].buffer
        val bytes = ByteArray(buffer.remaining())
        buffer.get(bytes)
        return BitmapFactory.decodeByteArray(bytes, 0, bytes.size)
    }

    /**
     * Applies tilt-shift blur effect to a bitmap.
     * This is a software fallback - on newer devices we could use RenderScript/RenderEffect.
     */
    private fun applyTiltShiftEffect(source: Bitmap, params: BlurParameters): Bitmap {
        val width = source.width
        val height = source.height

        // Create output bitmap
        val result = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
        val canvas = Canvas(result)

        // For performance, we use a scaled-down version for blur and composite
        val scaleFactor = 4 // Blur a 1/4 size image for speed
        val blurredWidth = width / scaleFactor
        val blurredHeight = height / scaleFactor

        // Create scaled bitmap for blur
        val scaled = Bitmap.createScaledBitmap(source, blurredWidth, blurredHeight, true)

        // Apply stack blur (fast approximation)
        val blurred = stackBlur(scaled, (params.blurAmount * 25).toInt().coerceIn(1, 25))
        scaled.recycle()

        // Scale blurred back up
        val blurredFullSize = Bitmap.createScaledBitmap(blurred, width, height, true)
        blurred.recycle()

        // Create gradient mask based on tilt-shift parameters
        val mask = createGradientMask(width, height, params)

        // Composite: blend original with blurred based on mask
        val paint = Paint(Paint.ANTI_ALIAS_FLAG)
        val pixels = IntArray(width * height)
        val blurredPixels = IntArray(width * height)
        val maskPixels = IntArray(width * height)

        source.getPixels(pixels, 0, width, 0, 0, width, height)
        blurredFullSize.getPixels(blurredPixels, 0, width, 0, 0, width, height)
        mask.getPixels(maskPixels, 0, width, 0, 0, width, height)

        blurredFullSize.recycle()
        mask.recycle()

        for (i in pixels.indices) {
            val maskAlpha = (maskPixels[i] and 0xFF) / 255f
            val origR = (pixels[i] shr 16) and 0xFF
            val origG = (pixels[i] shr 8) and 0xFF
            val origB = pixels[i] and 0xFF
            val blurR = (blurredPixels[i] shr 16) and 0xFF
            val blurG = (blurredPixels[i] shr 8) and 0xFF
            val blurB = blurredPixels[i] and 0xFF

            val r = (origR * (1 - maskAlpha) + blurR * maskAlpha).toInt()
            val g = (origG * (1 - maskAlpha) + blurG * maskAlpha).toInt()
            val b = (origB * (1 - maskAlpha) + blurB * maskAlpha).toInt()

            pixels[i] = (0xFF shl 24) or (r shl 16) or (g shl 8) or b
        }

        result.setPixels(pixels, 0, width, 0, 0, width, height)
        return result
    }

    /**
     * Creates a gradient mask for the tilt-shift effect.
     */
    private fun createGradientMask(width: Int, height: Int, params: BlurParameters): Bitmap {
        val mask = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
        val pixels = IntArray(width * height)

        val centerX = width * params.positionX
        val centerY = height * params.positionY
        val focusHalfHeight = height * params.size * 0.5f
        val transitionHeight = focusHalfHeight * 0.5f

        val cosAngle = cos(params.angle)
        val sinAngle = sin(params.angle)

        for (y in 0 until height) {
            for (x in 0 until width) {
                // Rotate point around focus center
                val dx = x - centerX
                val dy = y - centerY
                val rotatedY = -dx * sinAngle + dy * cosAngle

                // Calculate blur amount based on distance from focus line
                val dist = kotlin.math.abs(rotatedY)
                val blurAmount = when {
                    dist < focusHalfHeight -> 0f
                    dist < focusHalfHeight + transitionHeight -> {
                        (dist - focusHalfHeight) / transitionHeight
                    }
                    else -> 1f
                }

                val gray = (blurAmount * 255).toInt().coerceIn(0, 255)
                pixels[y * width + x] = (0xFF shl 24) or (gray shl 16) or (gray shl 8) or gray
            }
        }

        mask.setPixels(pixels, 0, width, 0, 0, width, height)
        return mask
    }

    /**
     * Fast stack blur algorithm.
     */
    private fun stackBlur(bitmap: Bitmap, radius: Int): Bitmap {
        if (radius < 1) return bitmap.copy(Bitmap.Config.ARGB_8888, true)

        val w = bitmap.width
        val h = bitmap.height
        val pix = IntArray(w * h)
        bitmap.getPixels(pix, 0, w, 0, 0, w, h)

        val wm = w - 1
        val hm = h - 1
        val wh = w * h
        val div = radius + radius + 1

        val r = IntArray(wh)
        val g = IntArray(wh)
        val b = IntArray(wh)
        var rsum: Int
        var gsum: Int
        var bsum: Int
        var x: Int
        var y: Int
        var i: Int
        var p: Int
        var yp: Int
        var yi: Int
        var yw: Int
        val vmin = IntArray(maxOf(w, h))

        var divsum = (div + 1) shr 1
        divsum *= divsum
        val dv = IntArray(256 * divsum)
        for (i2 in 0 until 256 * divsum) {
            dv[i2] = (i2 / divsum)
        }

        yi = 0
        yw = 0

        val stack = Array(div) { IntArray(3) }
        var stackpointer: Int
        var stackstart: Int
        var sir: IntArray
        var rbs: Int
        val r1 = radius + 1
        var routsum: Int
        var goutsum: Int
        var boutsum: Int
        var rinsum: Int
        var ginsum: Int
        var binsum: Int

        for (y2 in 0 until h) {
            rinsum = 0
            ginsum = 0
            binsum = 0
            routsum = 0
            goutsum = 0
            boutsum = 0
            rsum = 0
            gsum = 0
            bsum = 0
            for (i2 in -radius..radius) {
                p = pix[yi + minOf(wm, maxOf(i2, 0))]
                sir = stack[i2 + radius]
                sir[0] = (p and 0xff0000) shr 16
                sir[1] = (p and 0x00ff00) shr 8
                sir[2] = (p and 0x0000ff)
                rbs = r1 - kotlin.math.abs(i2)
                rsum += sir[0] * rbs
                gsum += sir[1] * rbs
                bsum += sir[2] * rbs
                if (i2 > 0) {
                    rinsum += sir[0]
                    ginsum += sir[1]
                    binsum += sir[2]
                } else {
                    routsum += sir[0]
                    goutsum += sir[1]
                    boutsum += sir[2]
                }
            }
            stackpointer = radius

            for (x2 in 0 until w) {
                r[yi] = dv[rsum]
                g[yi] = dv[gsum]
                b[yi] = dv[bsum]

                rsum -= routsum
                gsum -= goutsum
                bsum -= boutsum

                stackstart = stackpointer - radius + div
                sir = stack[stackstart % div]

                routsum -= sir[0]
                goutsum -= sir[1]
                boutsum -= sir[2]

                if (y2 == 0) {
                    vmin[x2] = minOf(x2 + radius + 1, wm)
                }
                p = pix[yw + vmin[x2]]

                sir[0] = (p and 0xff0000) shr 16
                sir[1] = (p and 0x00ff00) shr 8
                sir[2] = (p and 0x0000ff)

                rinsum += sir[0]
                ginsum += sir[1]
                binsum += sir[2]

                rsum += rinsum
                gsum += ginsum
                bsum += binsum

                stackpointer = (stackpointer + 1) % div
                sir = stack[(stackpointer) % div]

                routsum += sir[0]
                goutsum += sir[1]
                boutsum += sir[2]

                rinsum -= sir[0]
                ginsum -= sir[1]
                binsum -= sir[2]

                yi++
            }
            yw += w
        }
        for (x2 in 0 until w) {
            rinsum = 0
            ginsum = 0
            binsum = 0
            routsum = 0
            goutsum = 0
            boutsum = 0
            rsum = 0
            gsum = 0
            bsum = 0
            yp = -radius * w
            for (i2 in -radius..radius) {
                yi = maxOf(0, yp) + x2

                sir = stack[i2 + radius]

                sir[0] = r[yi]
                sir[1] = g[yi]
                sir[2] = b[yi]

                rbs = r1 - kotlin.math.abs(i2)

                rsum += r[yi] * rbs
                gsum += g[yi] * rbs
                bsum += b[yi] * rbs

                if (i2 > 0) {
                    rinsum += sir[0]
                    ginsum += sir[1]
                    binsum += sir[2]
                } else {
                    routsum += sir[0]
                    goutsum += sir[1]
                    boutsum += sir[2]
                }

                if (i2 < hm) {
                    yp += w
                }
            }
            yi = x2
            stackpointer = radius
            for (y2 in 0 until h) {
                pix[yi] = (0xff000000.toInt() and pix[yi]) or (dv[rsum] shl 16) or (dv[gsum] shl 8) or dv[bsum]

                rsum -= routsum
                gsum -= goutsum
                bsum -= boutsum

                stackstart = stackpointer - radius + div
                sir = stack[stackstart % div]

                routsum -= sir[0]
                goutsum -= sir[1]
                boutsum -= sir[2]

                if (x2 == 0) {
                    vmin[y2] = minOf(y2 + r1, hm) * w
                }
                p = x2 + vmin[y2]

                sir[0] = r[p]
                sir[1] = g[p]
                sir[2] = b[p]

                rinsum += sir[0]
                ginsum += sir[1]
                binsum += sir[2]

                rsum += rinsum
                gsum += ginsum
                bsum += binsum

                stackpointer = (stackpointer + 1) % div
                sir = stack[stackpointer]

                routsum += sir[0]
                goutsum += sir[1]
                boutsum += sir[2]

                rinsum -= sir[0]
                ginsum -= sir[1]
                binsum -= sir[2]

                yi += w
            }
        }

        val result = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888)
        result.setPixels(pix, 0, w, 0, 0, w, h)
        return result
    }
}