package vision

import (
	"fmt"
)

// StreamProcessor 定义帧处理器函数
type StreamProcessor func(frame *Canvas, frameIndex int) error

// ProcessVideoFrames 模拟视频帧处理 (通过一系列图片或自定义逻辑)
// 这是一个为未来视频流处理预留的语义化接口
func ProcessVideoFrames(totalFrames int, provider func(int) (*Canvas, error), processor StreamProcessor) error {
	for i := 0; i < totalFrames; i++ {
		frame, err := provider(i)
		if err != nil {
			return fmt.Errorf("provider failed at frame %d: %w", i, err)
		}
		
		if err := processor(frame, i); err != nil {
			return fmt.Errorf("processor failed at frame %d: %w", i, err)
		}
	}
	return nil
}

// DiffFrames 计算两帧之间的差异 (简单运动检测基础)
func DiffFrames(prev, curr *Canvas) float64 {
	pImg := prev.dc.Image()
	cImg := curr.dc.Image()
	
	bounds := pImg.Bounds()
	w, h := bounds.Dx(), bounds.Dy()
	
	var diffTotal uint64
	// 采样计算
	for y := 0; y < h; y += 4 {
		for x := 0; x < w; x += 4 {
			pr, pg, pb, _ := pImg.At(x, y).RGBA()
			cr, cg, cb, _ := cImg.At(x, y).RGBA()
			
			dr := int(pr>>8) - int(cr>>8)
			dg := int(pg>>8) - int(cg>>8)
			db := int(pb>>8) - int(cb>>8)
			
			if dr < 0 { dr = -dr }
			if dg < 0 { dg = -dg }
			if db < 0 { db = -db }
			
			diffTotal += uint64(dr + dg + db)
		}
	}
	
	// 归一化差异百分比
	maxDiff := uint64(w/4 * h/4 * 255 * 3)
	if maxDiff == 0 { return 0 }
	return float64(diffTotal) / float64(maxDiff)
}