package com.peachpasswords.codex

import androidx.camera.core.ImageProxy
import com.google.zxing.BinaryBitmap
import com.google.zxing.DecodeHintType
import com.google.zxing.PlanarYUVLuminanceSource
import com.google.zxing.aztec.AztecReader
import com.google.zxing.common.GlobalHistogramBinarizer
import com.google.zxing.common.HybridBinarizer

/**
 * Live-camera Aztec decode for the Codex restore camera path (D10).
 *
 * Distinct from [CodexAztec.decode], which decodes a tightly-cropped render of a
 * single PDF cell. A camera frame is a full scene that may contain one Aztec among
 * the printed 6×6 grid, so we use the scene detector (no PURE_BARCODE) and read the
 * Y plane directly — converting the YUV_420_888 frame to an ARGB bitmap every frame
 * would be wasteful at preview frame rates.
 */
object CodexAztecFrame {

    /**
     * Decode the first readable Aztec code from a CameraX [ImageProxy]
     * (YUV_420_888). Returns the raw text, or null if no code reads. Does NOT
     * close the proxy — the caller owns its lifecycle.
     */
    fun decode(image: ImageProxy): String? {
        val plane = image.planes.getOrNull(0) ?: return null
        val buffer = plane.buffer
        val data = ByteArray(buffer.remaining())
        buffer.get(data)

        val width = image.width
        val height = image.height
        val rowStride = plane.rowStride

        // PlanarYUVLuminanceSource expects a tightly-packed Y plane; when the
        // camera reports row padding (rowStride > width) we repack row by row.
        val luma: ByteArray = if (rowStride == width) {
            data
        } else {
            val packed = ByteArray(width * height)
            for (row in 0 until height) {
                System.arraycopy(data, row * rowStride, packed, row * width, width)
            }
            packed
        }

        val source = PlanarYUVLuminanceSource(
            luma, width, height, 0, 0, width, height, false,
        )
        val hints = mapOf(DecodeHintType.TRY_HARDER to true)
        // Cross both binarizers: Hybrid adapts to uneven lighting, Global handles
        // flat well-lit prints. Rotating the source covers codes shot sideways.
        val attempts = listOf(
            BinaryBitmap(HybridBinarizer(source)),
            BinaryBitmap(GlobalHistogramBinarizer(source)),
            BinaryBitmap(HybridBinarizer(source.rotateCounterClockwise())),
        )
        for (binary in attempts) {
            try {
                return AztecReader().decode(binary, hints).text
            } catch (_: Exception) {
                // try next strategy
            }
        }
        return null
    }
}