package scorecard

import (
	"image"
	"image/color"
	"image/draw"
	"strconv"

	"golang.org/x/image/font"
	"golang.org/x/image/font/basicfont"
	"golang.org/x/image/math/fixed"
)

type DrawContext struct {
	Img   *image.RGBA
	Scale int
}

func NewDrawContext(img *image.RGBA, scale int) *DrawContext {
	return &DrawContext{Img: img, Scale: scale}
}

func (dc *DrawContext) S(v int) int {
	return v * dc.Scale
}

func (dc *DrawContext) FillRect(x, y, w, h int, c color.RGBA) {
	for dy := 0; dy < h; dy++ {
		for dx := 0; dx < w; dx++ {
			px, py := x+dx, y+dy
			if px >= 0 && px < dc.Img.Bounds().Dx() && py >= 0 && py < dc.Img.Bounds().Dy() {
				dc.Img.Set(px, py, c)
			}
		}
	}
}

func (dc *DrawContext) DrawRect(x1, y1, x2, y2 int, c color.RGBA, width int) {
	for i := 0; i < width; i++ {
		dc.DrawHLine(x1, y1+i, x2, c)
		dc.DrawHLine(x1, y2-i, x2, c)
		dc.DrawVLine(x1+i, y1, y2, c)
		dc.DrawVLine(x2-i, y1, y2, c)
	}
}

func (dc *DrawContext) DrawHLine(x1, y, x2 int, c color.RGBA) {
	if y < 0 || y >= dc.Img.Bounds().Dy() {
		return
	}
	if x1 > x2 {
		x1, x2 = x2, x1
	}
	for x := x1; x <= x2; x++ {
		if x >= 0 && x < dc.Img.Bounds().Dx() {
			dc.Img.Set(x, y, c)
		}
	}
}

func (dc *DrawContext) DrawVLine(x, y1, y2 int, c color.RGBA) {
	if x < 0 || x >= dc.Img.Bounds().Dx() {
		return
	}
	if y1 > y2 {
		y1, y2 = y2, y1
	}
	for y := y1; y <= y2; y++ {
		if y >= 0 && y < dc.Img.Bounds().Dy() {
			dc.Img.Set(x, y, c)
		}
	}
}

func (dc *DrawContext) DrawRoundedRect(x, y, w, h, r int, c color.RGBA) {
	dc.FillRect(x+r, y, w-2*r, h, c)
	dc.FillRect(x, y+r, w, h-2*r, c)
	for dy := -r; dy <= 0; dy++ {
		for dx := -r; dx <= 0; dx++ {
			if dx*dx+dy*dy >= r*r {
				continue
			}
			dc.Img.Set(x+r+dx, y+r+dy, c)
			dc.Img.Set(x+w-r-1-dx, y+r+dy, c)
			dc.Img.Set(x+r+dx, y+h-r-1-dy, c)
			dc.Img.Set(x+w-r-1-dx, y+h-r-1-dy, c)
		}
	}
}

func (dc *DrawContext) DrawRoundedRectWithOutline(x, y, w, h, r int, fill, outline color.RGBA, outlineWidth int) {
	dc.DrawRoundedRect(x, y, w, h, r, fill)
	rr := r - outlineWidth
	if rr < 0 {
		rr = 0
	}
	for i := 0; i < outlineWidth; i++ {
		ri := r - i
		if ri < 0 {
			ri = 0
		}
		dc.DrawHLine(x+ri, y+i, x+w-ri-1, outline)
		dc.DrawHLine(x+ri, y+h-i-1, x+w-ri-1, outline)
		dc.DrawVLine(x+i, y+ri, y+h-ri-1, outline)
		dc.DrawVLine(x+w-i-1, y+ri, y+h-ri-1, outline)
	}
}

func (dc *DrawContext) DrawDiamond(cx, cy, size int, c color.RGBA) {
	for dy := -size; dy <= size; dy++ {
		for dx := -size; dx <= size; dx++ {
			if abs(dx)+abs(dy) <= size {
				px, py := cx+dx, cy+dy
				if px >= 0 && px < dc.Img.Bounds().Dx() && py >= 0 && py < dc.Img.Bounds().Dy() {
					dc.Img.Set(px, py, c)
				}
			}
		}
	}
}

func (dc *DrawContext) DrawRuleWithOrnament(y, x1, x2, cx int, lineColor, ornamentColor color.RGBA) {
	gap := dc.S(8)
	dc.DrawHLine(x1, y, cx-gap, lineColor)
	dc.DrawHLine(cx+gap, y, x2, lineColor)
	dc.DrawDiamond(cx, y, dc.S(3), ornamentColor)
}

func (dc *DrawContext) DrawVertRuleWithOrnament(x, y1, y2, cy int, lineColor, ornamentColor color.RGBA) {
	gap := dc.S(8)
	dc.DrawVLine(x, y1, cy-gap, lineColor)
	dc.DrawVLine(x, cy+gap, y2, lineColor)
	dc.DrawDiamond(x, cy, dc.S(3), ornamentColor)
}

func (dc *DrawContext) DrawText(text string, x, y int, face font.Face, c color.RGBA) {
	d := font.Drawer{
		Dst:  dc.Img,
		Src:  &image.Uniform{c},
		Face: face,
		Dot:  fixed.Point26_6{X: fixed.I(x), Y: fixed.I(y)},
	}
	d.DrawString(text)
}

func (dc *DrawContext) DrawCenteredText(text string, cx, y int, face font.Face, c color.RGBA) {
	advance := font.MeasureString(face, text)
	x := cx - (advance.Ceil() / 2)
	dc.DrawText(text, x, y, face, c)
}

func (dc *DrawContext) DrawRightAlignedText(text string, rx, y int, face font.Face, c color.RGBA) {
	advance := font.MeasureString(face, text)
	x := rx - advance.Ceil()
	dc.DrawText(text, x, y, face, c)
}

func (dc *DrawContext) FillBackground(c color.RGBA) {
	draw.Draw(dc.Img, dc.Img.Bounds(), &image.Uniform{c}, image.Point{}, draw.Src)
}

func (dc *DrawContext) DrawDoubleFrame(x1, y1, x2, y2 int, outerColor, innerColor color.RGBA, outerWidth, innerWidth int) {
	dc.DrawRect(x1, y1, x2, y2, outerColor, outerWidth)
	innerX1 := x1 + outerWidth + 2
	innerY1 := y1 + outerWidth + 2
	innerX2 := x2 - outerWidth - 2
	innerY2 := y2 - outerWidth - 2
	dc.DrawRect(innerX1, innerY1, innerX2, innerY2, innerColor, innerWidth)
}

func (dc *DrawContext) TextWidth(text string, face font.Face) int {
	return font.MeasureString(face, text).Ceil()
}

func (dc *DrawContext) TextBounds(text string, face font.Face) (width, height, offsetY int) {
	advance := font.MeasureString(face, text)
	width = advance.Ceil()
	metrics := face.Metrics()
	height = (metrics.Ascent + metrics.Descent).Ceil()
	offsetY = -metrics.Ascent.Ceil()
	return
}

func (dc *DrawContext) TruncateText(text string, maxWidth int, face font.Face) string {
	if dc.TextWidth(text, face) <= maxWidth {
		return text
	}
	ellipsis := "…"
	ellipsisWidth := dc.TextWidth(ellipsis, face)
	for len(text) > 0 {
		text = text[:len(text)-1]
		if dc.TextWidth(text, face)+ellipsisWidth <= maxWidth {
			return text + ellipsis
		}
	}
	return ellipsis
}

func GetFont() font.Face {
	return basicfont.Face7x13
}

func FmtScore(score float64) string {
	if score == float64(int(score)) {
		return strconv.Itoa(int(score))
	}
	return strconv.FormatFloat(score, 'f', 1, 64)
}

func abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}