package vision

import (
	"fmt"
	"image/color"
	"sort"

	"github.com/disintegration/imaging"
)

// ColorCount 记录颜色及其出现的频率
type ColorCount struct {
	Color color.Color
	Hex   string
	Count int
}

// ExtractPalette 从图像中提取调色板（主要颜色）
// n: 提取的前 n 种颜色
func (c *Canvas) ExtractPalette(n int) []ColorCount {
	img := c.dc.Image()
	// 为了性能，先缩小图片
	resized := imaging.Resize(img, 100, 100, imaging.NearestNeighbor)
	bounds := resized.Bounds()
	
	counts := make(map[uint32]int)
	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
		for x := bounds.Min.X; x < bounds.Max.X; x++ {
			r, g, b, a := resized.At(x, y).RGBA()
			// 忽略透明度较高的像素
			if a < 32768 { continue }
			
			// 简单的颜色量化，减少颜色数量
			r >>= 12
			g >>= 12
			b >>= 12
			key := (r << 8) | (g << 4) | b
			counts[key]++
		}
	}

	palette := make([]ColorCount, 0, len(counts))
	for key, count := range counts {
		r := uint8((key >> 8) & 0xF) * 17
		g := uint8((key >> 4) & 0xF) * 17
		b := uint8(key & 0xF) * 17
		c := color.RGBA{r, g, b, 255}
		palette = append(palette, ColorCount{
			Color: c,
			Hex:   RGBAToHex(c),
			Count: count,
		})
	}

	sort.Slice(palette, func(i, j int) bool {
		return palette[i].Count > palette[j].Count
	})

	if len(palette) > n {
		palette = palette[:n]
	}
	return palette
}

// RGBAToHex 将 RGBA 转换为 Hex 字符串
func RGBAToHex(c color.RGBA) string {
	return fmt.Sprintf("#%02X%02X%02X", c.R, c.G, c.B)
}

// GetAverageColor 计算画布的平均颜色
func (c *Canvas) GetAverageColor() color.Color {
	img := c.dc.Image()
	bounds := img.Bounds()
	var r, g, b, a uint64
	w, h := bounds.Dx(), bounds.Dy()
	
	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
		for x := bounds.Min.X; x < bounds.Max.X; x++ {
			pr, pg, pb, pa := img.At(x, y).RGBA()
			r += uint64(pr)
			g += uint64(pg)
			b += uint64(pb)
			a += uint64(pa)
		}
	}
	
	total := uint64(w * h)
	if total == 0 { return color.Transparent }
	
	return color.RGBA64{
		R: uint16(r / total),
		G: uint16(g / total),
		B: uint16(b / total),
		A: uint16(a / total),
	}
}