package vision

import (
	"image/color"
	"math"

	"apigo.cc/go/rand"
)

// CaptchaOption 定义验证码生成选项
type CaptchaOption struct {
	Text       string
	Length     int
	Width      int
	Height     int
	NoiseLevel int // 1-10
}

// GenerateCaptcha 生成一个验证码画布
func GenerateCaptcha(opt *CaptchaOption) *Canvas {
	if opt == nil { opt = &CaptchaOption{} }
	if opt.Length == 0 { opt.Length = 4 }
	if opt.Width == 0 { opt.Width = 150 }
	if opt.Height == 0 { opt.Height = 50 }
	if opt.NoiseLevel == 0 { opt.NoiseLevel = 3 }
	if opt.Text == "" {
		chars := "ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnpqrstwxyz2345678"
		text := make([]byte, opt.Length)
		for i := 0; i < opt.Length; i++ {
			text[i] = chars[rand.Int(0, len(chars)-1)]
		}
		opt.Text = string(text)
	}

	c := New(opt.Width, opt.Height, "#FFFFFF")
	c.RandBG(opt.NoiseLevel)

	// 计算字体大小
	fontSize := math.Max(28, float64(opt.Height)*0.7)
	_ = c.SetFont(fontSize)

	// 绘制随机扭曲文本
	c.RandText(opt.Text)

	return c
}

// RandText 绘制随机扭曲文本 (用于验证码)
func (c *Canvas) RandText(text string) [][4]float64 {
	w, h := float64(c.Width()), float64(c.Height())
	fullWidth, _ := c.dc.MeasureString(text)

	x := (w - fullWidth) / 2
	y := h/2 + (c.dc.FontHeight()*0.7)/2

	charPositions := make([][4]float64, 0, len(text))
	for _, char := range text {
		charStr := string(char)
		charWidth, _ := c.dc.MeasureString(charStr)
		charHeight := c.dc.FontHeight()

		yOffset := rand.Float(0.0, 10.0) - 5
		angle := rand.Float(0.0, 0.4) - 0.2 // ±11°

		charPositions = append(charPositions, [4]float64{x, y + yOffset - charHeight, charWidth, charHeight})

		c.dc.Push()
		c.dc.RotateAbout(angle, x+charWidth/2, y+yOffset-charHeight/2)
		
		// 绘制阴影
		c.dc.SetColor(color.Gray{Y: 100})
		c.dc.DrawString(charStr, x+1, y+yOffset+1)
		
		// 绘制主体
		c.dc.SetColor(ParseColor(RandColor()))
		c.dc.DrawString(charStr, x, y+yOffset)
		c.dc.Pop()

		x += charWidth + rand.Float(0.0, 5.0)
	}

	return charPositions
}