package uts.sdk.modules.masCodeScan

import android.graphics.Rect
import android.graphics.RectF
import kotlin.math.max
import kotlin.math.min

/**
 * 相对于实时预览层的有效扫码区域配置。
 * 由 Activity 统一校验后同时用于扫描框绘制和条码结果过滤。
 */
data class ScanRegionConfig(
    val enabled: Boolean,
    val widthRatio: Float = DEFAULT_SIZE_RATIO,
    val heightRatio: Float = DEFAULT_SIZE_RATIO,
    val centerXRatio: Float = DEFAULT_CENTER_RATIO,
    val centerYRatio: Float = DEFAULT_CENTER_RATIO
) {
    companion object {
        const val DEFAULT_SIZE_RATIO = 0.74f
        const val DEFAULT_CENTER_RATIO = 0.5f
        private const val MIN_SIZE_RATIO = 0.1f
        private const val MAX_SIZE_RATIO = 1f

        fun safe(
            enabled: Boolean,
            widthRatio: Float,
            heightRatio: Float,
            centerXRatio: Float,
            centerYRatio: Float
        ): ScanRegionConfig {
            val safeWidth = widthRatio.sanitize(DEFAULT_SIZE_RATIO).coerceIn(MIN_SIZE_RATIO, MAX_SIZE_RATIO)
            val safeHeight = heightRatio.sanitize(DEFAULT_SIZE_RATIO).coerceIn(MIN_SIZE_RATIO, MAX_SIZE_RATIO)
            return ScanRegionConfig(
                enabled = enabled,
                widthRatio = safeWidth,
                heightRatio = safeHeight,
                centerXRatio = centerXRatio.sanitize(DEFAULT_CENTER_RATIO).coerceIn(0f, 1f),
                centerYRatio = centerYRatio.sanitize(DEFAULT_CENTER_RATIO).coerceIn(0f, 1f)
            )
        }

        private fun Float.sanitize(defaultValue: Float): Float {
            return if (isFinite()) this else defaultValue
        }
    }

    /** 返回扫描框在预览 View 坐标系中的实际位置，越界部分会收敛到 View 内。 */
    fun resolveViewRect(viewWidth: Int, viewHeight: Int): RectF {
        if (viewWidth <= 0 || viewHeight <= 0) return RectF()
        // width / height 都以预览宽度为基准，并使用同一缩放因子收敛，确保始终保持配置比例。
        val desiredWidth = viewWidth * widthRatio
        val desiredHeight = viewWidth * heightRatio
        val sizeScale = min(1f, min(viewWidth / desiredWidth, viewHeight / desiredHeight))
        val frameWidth = desiredWidth * sizeScale
        val frameHeight = desiredHeight * sizeScale
        val wantedLeft = viewWidth * centerXRatio - frameWidth / 2f
        val wantedTop = viewHeight * centerYRatio - frameHeight / 2f
        val left = wantedLeft.coerceIn(0f, max(0f, viewWidth - frameWidth))
        val top = wantedTop.coerceIn(0f, max(0f, viewHeight - frameHeight))
        return RectF(left, top, left + frameWidth, top + frameHeight)
    }
}

/**
 * 将 PreviewView 的扫描框映射到 ML Kit 返回 boundingBox 所在的旋转后图像坐标。
 * PreviewView 使用 FILL_CENTER，因此必须补偿等比填充产生的裁剪偏移。
 */
object ScanRegionMapper {
    fun mapViewRectToImage(
        viewRect: RectF,
        viewWidth: Int,
        viewHeight: Int,
        imageWidth: Int,
        imageHeight: Int,
        cropRect: Rect,
        rotationDegrees: Int
    ): Rect? {
        if (viewRect.isEmpty || viewWidth <= 0 || viewHeight <= 0 || imageWidth <= 0 || imageHeight <= 0) {
            return null
        }
        val visualCrop = YuvFrames.rectToVisualSpace(cropRect, imageWidth, imageHeight, rotationDegrees)
        val cropWidth = visualCrop.width()
        val cropHeight = visualCrop.height()
        if (cropWidth <= 0 || cropHeight <= 0) return null

        val scale = max(viewWidth.toFloat() / cropWidth, viewHeight.toFloat() / cropHeight)
        if (!scale.isFinite() || scale <= 0f) return null
        val offsetX = (viewWidth - cropWidth * scale) / 2f
        val offsetY = (viewHeight - cropHeight * scale) / 2f
        val mapped = Rect(
            ((viewRect.left - offsetX) / scale).toInt() + visualCrop.left,
            ((viewRect.top - offsetY) / scale).toInt() + visualCrop.top,
            ((viewRect.right - offsetX) / scale).toInt() + visualCrop.left,
            ((viewRect.bottom - offsetY) / scale).toInt() + visualCrop.top
        )
        return mapped.apply {
            left = left.coerceIn(visualCrop.left, visualCrop.right)
            top = top.coerceIn(visualCrop.top, visualCrop.bottom)
            right = right.coerceIn(left, visualCrop.right)
            bottom = bottom.coerceIn(top, visualCrop.bottom)
        }.takeIf { it.width() > 0 && it.height() > 0 }
    }

    fun containsBarcodeCenter(region: Rect, barcodeBox: Rect): Boolean {
        return region.contains(barcodeBox.centerX(), barcodeBox.centerY())
    }
}