package caire

import (
	"image/color"
	"math"

	"gioui.org/f32"
	"gioui.org/op/clip"
	"gioui.org/op/paint"
	"github.com/esimov/caire/utils"
)

type ShapeType string

const (
	Circle ShapeType = "circle"
	Line   ShapeType = "line"
)

// DrawSeam visualizes the seam carver in action when the preview mode is activated.
// It receives as parameters the shape type, the seam (x,y) coordinates and it's thickness.
func (g *Gui) DrawSeam(shape ShapeType, x, y, thickness float32) {
	r := getRatio(g.cfg.window.width, g.cfg.window.height)

	switch shape {
	case Circle:
		g.drawCircle(x*r, y*r, thickness)
	case Line:
		g.drawLine(x*r, y*r, thickness)
	}
}

// drawCircle draws a circle at the seam (x,y) coordinate with the provided size.
func (g *Gui) drawCircle(x, y, radius float32) {
	var (
		sq   float64
		p1   f32.Point
		p2   f32.Point
		orig = g.point(x-radius, y)
	)

	sq = math.Sqrt(float64(radius*radius) - float64(radius*radius))
	p1 = g.point(x+float32(sq), y).Sub(orig)
	p2 = g.point(x-float32(sq), y).Sub(orig)

	col := utils.HexToRGBA(g.proc.SeamColor)
	g.setFillColor(col)

	var path clip.Path
	path.Begin(g.ctx.Ops)
	path.Move(orig)
	path.Arc(p1, p2, 2*math.Pi)
	path.Close()

	defer clip.Outline{Path: path.End()}.Op().Push(g.ctx.Ops).Pop()
	paint.ColorOp{Color: g.setColor(g.getFillColor())}.Add(g.ctx.Ops)
	paint.PaintOp{}.Add(g.ctx.Ops)
}

// drawLine draws a line at the seam (x,y) coordinate with the provided line thickness.
func (g *Gui) drawLine(x, y, thickness float32) {
	var (
		p1   = g.point(x, y)
		p2   = g.point(x, y+1)
		path clip.Path
	)

	path.Begin(g.ctx.Ops)
	path.Move(p1)
	path.Line(p2.Sub(path.Pos()))
	path.Close()

	col := utils.HexToRGBA(g.proc.SeamColor)
	g.setFillColor(col)

	defer clip.Stroke{Path: path.End(), Width: float32(thickness)}.Op().Push(g.ctx.Ops).Pop()
	paint.ColorOp{Color: g.setColor(g.getFillColor())}.Add(g.ctx.Ops)
	paint.PaintOp{}.Add(g.ctx.Ops)
}

// point converts the seam (x,y) coordinate to Gio f32.Point.
func (g *Gui) point(x, y float32) f32.Point {
	return f32.Point{
		X: x,
		Y: y,
	}
}

// setColor sets the seam color.
func (g *Gui) setColor(c color.Color) color.NRGBA {
	rc, gc, bc, ac := c.RGBA()
	return color.NRGBA{
		R: uint8(rc >> 8),
		G: uint8(gc >> 8),
		B: uint8(bc >> 8),
		A: uint8(ac >> 8),
	}
}

// setFillColor sets the paint fill color.
func (g *Gui) setFillColor(c color.Color) {
	g.cfg.color.fill = c
}

// getFillColor retrieve the paint fill color.
func (g *Gui) getFillColor() color.Color {
	return g.cfg.color.fill
}

// getRatio returns the image aspect ratio.
func getRatio(w, h float32) float32 {
	var r float32 = 1
	if w > maxScreenX && h > maxScreenY {
		wr := maxScreenX / float32(w) // width ratio
		hr := maxScreenY / float32(h) // height ratio

		r = utils.Max(wr, hr)
	}
	return r
}