package canvas

import (
	"image"
	"math"
)

// path 路径结构
type path struct {
	points []image.Point
	start  image.Point
}

// BeginPath 开始新路径
func (c *Context) BeginPath() {
	c.path = &path{}
}

// MoveTo 移动到指定位置
func (c *Context) MoveTo(x, y float64) {
	pt := c.transformPoint(x, y)
	c.path.points = append(c.path.points, pt)
	c.path.start = pt
}

// LineTo 绘制线段到指定位置
func (c *Context) LineTo(x, y float64) {
	if len(c.path.points) == 0 {
		c.MoveTo(x, y)
		return
	}
	c.path.points = append(c.path.points, c.transformPoint(x, y))
}

// Rect 绘制矩形路径
func (c *Context) Rect(x, y, width, height float64) {
	c.MoveTo(x, y)
	c.LineTo(x+width, y)
	c.LineTo(x+width, y+height)
	c.LineTo(x, y+height)
	c.ClosePath()
}

// Arc 绘制圆弧路径
func (c *Context) Arc(x, y, radius, startAngle, endAngle float64) {
	// 确保角度在0-2π之间
	for startAngle < 0 {
		startAngle += 2 * math.Pi
	}
	for endAngle < 0 {
		endAngle += 2 * math.Pi
	}

	// 确定步数
	angleRange := endAngle - startAngle
	if angleRange < 0 {
		angleRange += 2 * math.Pi
	}
	steps := int(math.Ceil(angleRange * 10)) // 每弧度10步

	for i := 0; i <= steps; i++ {
		t := float64(i) / float64(steps)
		angle := startAngle + t*angleRange
		px := x + radius*math.Cos(angle)
		py := y + radius*math.Sin(angle)
		if i == 0 {
			c.MoveTo(px, py)
		} else {
			c.LineTo(px, py)
		}
	}
}

// ClosePath 闭合路径
func (c *Context) ClosePath() {
	if len(c.path.points) > 0 {
		c.LineTo(float64(c.path.start.X), float64(c.path.start.Y))
	}
}