// Package classify 提供纯函数的分辨率归类规则，不依赖任何状态。
package classify

import "strings"

// Orientation 画面方向
type Orientation int

const (
	OrientationSquare Orientation = iota
	OrientationHorizontal
	OrientationVertical
)

// OrientationOf 由宽高判定画面方向
func OrientationOf(width, height int) Orientation {
	switch {
	case width > height:
		return OrientationHorizontal
	case width < height:
		return OrientationVertical
	default:
		return OrientationSquare
	}
}

func (o Orientation) String() string {
	switch o {
	case OrientationHorizontal:
		return "横屏"
	case OrientationVertical:
		return "竖屏"
	default:
		return "等比"
	}
}

// ImageDir 返回图片归类子目录名，如 "图片_横屏_1080P-dark_100" / "图片_GIF"。
// darkScore/lightScore 用于明暗分类（GIF 不做明暗分类，忽略这两项）。
func ImageDir(ext string, width, height int, darkScore, lightScore float64) string {
	if strings.EqualFold(ext, ".gif") {
		return "图片_GIF"
	}
	dir := resolutionDir("图片", ext, width, height)
	return dir + "-" + BrightnessName(darkScore, lightScore)
}

// VideoDir 返回视频归类子目录名，如 "视频_竖屏_4k" / "视频_横屏_GIF"
func VideoDir(ext string, width, height int) string {
	return resolutionDir("视频", ext, width, height)
}

func resolutionDir(kind, ext string, width, height int) string {
	ori := OrientationOf(width, height).String()
	if strings.EqualFold(ext, ".gif") {
		return kind + "_" + ori + "_GIF"
	}
	if suffix := matchStandard(width, height); suffix != "" {
		return kind + "_" + ori + "_" + suffix
	}
	overflow := "原图"
	if kind == "视频" {
		overflow = "原画质"
	}
	return kind + "_" + ori + "_" + levelName(longEdge(width, height), overflow)
}

// longEdge 返回长边像素
func longEdge(w, h int) int {
	if w > h {
		return w
	}
	return h
}