package vision

import (
	"image"
	"image/color/palette"
	"image/draw"
	"image/gif"

	"apigo.cc/go/file"
	"github.com/fogleman/gg"
)

// Animation 代表一个动画序列 (如 GIF)
type Animation struct {
	Frames []*Canvas
	Delays []int // 每帧延迟时间 (单位: 1/100 秒)
}

// NewAnimation 创建一个空动画
func NewAnimation() *Animation {
	return &Animation{
		Frames: make([]*Canvas, 0),
		Delays: make([]int, 0),
	}
}

// AddFrame 添加一帧到动画中
// delay: 延迟时间 (100 = 1秒)
func (a *Animation) AddFrame(c *Canvas, delay int) {
	a.Frames = append(a.Frames, c.Clone())
	a.Delays = append(a.Delays, delay)
}

// SaveGIF 将动画保存为 GIF 文件
func (a *Animation) SaveGIF(path string, loopCount int) error {
	out := &gif.GIF{
		LoopCount: loopCount,
	}

	for i, c := range a.Frames {
		img := c.dc.Image()
		bounds := img.Bounds()
		
		// 1. 使用 Plan9 标准调色板
		paletted := image.NewPaletted(bounds, palette.Plan9)
		
		// 2. 将图像绘制到调色板图像中
		draw.FloydSteinberg.Draw(paletted, bounds, img, image.Point{})
		
		out.Image = append(out.Image, paletted)
		out.Delay = append(out.Delay, a.Delays[i])
	}

	f, err := file.Create(path)
	if err != nil {
		return err
	}
	defer f.Close()

	return gif.EncodeAll(f, out)
}

// LoadGIF 从文件加载 GIF 动画
func LoadGIF(path string) (*Animation, error) {
	f, err := file.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	g, err := gif.DecodeAll(f)
	if err != nil {
		return nil, err
	}

	anim := NewAnimation()
	for i, img := range g.Image {
		canvas := &Canvas{
			dc: gg.NewContextForImage(img),
		}
		// 注意: GIF 帧可能是增量更新的，这里简化处理
		anim.AddFrame(canvas, g.Delay[i])
	}
	return anim, nil
}