package aluminum

import "io"
import "image"
import "git.tebibyte.media/tomo/tomo"
import "git.tebibyte.media/tomo/tomo/theme"
import "git.tebibyte.media/tomo/tomo/canvas"

type iconIndex interface {
	~int | ~string
}

type iconEntry[T iconIndex] struct {
	position image.Point
	index T
}

func i[T iconIndex] (x, y int, index T) iconEntry[T] {
	return iconEntry[T] {
		position: image.Pt(x, y),
		index:    index,
	}
}

type iconSet[T iconIndex] struct {
	icons map[theme.IconSize] map[T] canvas.Texture
}

func (this *iconSet[T]) Get (index T,size theme.IconSize) canvas.Texture {
	return this.icons[size][index]
}

func (this *iconSet[T]) Init (
	small, medium, large io.Reader,
	rows, columns        int,
	icons                ...iconEntry[T],
) {
	this.icons = make(map[theme.IconSize] map[T] canvas.Texture)
	this.initFor(theme.IconSizeSmall,  small,  rows, columns, icons...)
	this.initFor(theme.IconSizeMedium, medium, rows, columns, icons...)
	this.initFor(theme.IconSizeLarge,  large,  rows, columns, icons...)
}

func (this *iconSet[T]) initFor (
	size          theme.IconSize,
	file          io.Reader,
	rows, columns int,
	icons         ...iconEntry[T],
) {
	if file == nil { return }
	
	atlasImage, _, err := image.Decode(file)
	if err != nil { panic(err) }
	atlas := tomo.NewTexture(atlasImage)
	cellW := atlasImage.Bounds().Dx() / columns
	cellH := atlasImage.Bounds().Dy() / rows
	cellSize := image.Rect(0, 0, cellW, cellH)

	this.icons[size] = make(map[T] canvas.Texture)
	for _, icon := range icons {
		offset := image.Pt (
			icon.position.X * cellW,
			icon.position.Y * cellH)
		this.icons[size][icon.index] = atlas.Clip(cellSize.Add(offset))
	}
}