package utils

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"golang.org/x/image/bmp"
	"golang.org/x/image/tiff"
	"image"
	"image/color"
	"image/draw"
	"image/jpeg"
	"image/png"
	"math"
	"path"
	"strings"
)

func BuffToImage(in []byte) image.Image {
	buff := bytes.NewBuffer(in)
	m, _, _ := image.Decode(buff)
	return m
}

// Clip 图片裁剪
func Clip(buff *bytes.Buffer, wi, hi int, equalProportion bool) (out image.Image, imageType string, err error) {
	//buff := bytes.NewBuffer(in)
	m, imgType, err := image.Decode(buff)
	if err != nil {
		return nil, "", err
	}
	if equalProportion {
		w := m.Bounds().Max.X
		h := m.Bounds().Max.Y
		if w > 0 && h > 0 && wi > 0 && hi > 0 {
			wi, hi = fixSize(w, h, wi, hi)
		}
	}
	switch imgType {
	case "jpeg", "jpg":
		rgbImg := m.(*image.YCbCr)
		return rgbImg.SubImage(image.Rect(0, 0, wi, hi)), imgType, nil
	case "bmp":
		img := m.(*image.RGBA)
		if equalProportion {

		}
		return img.SubImage(image.Rect(0, 0, wi, hi)).(*image.RGBA), imageType, nil
	case "png":
		switch m.(type) {
		case *image.NRGBA:
			img := m.(*image.NRGBA)
			subImg := img.SubImage(image.Rect(0, 0, wi, hi)).(*image.NRGBA)

			return subImg, imageType, nil
		case *image.RGBA:
			img := m.(*image.RGBA)
			subImg := img.SubImage(image.Rect(0, 0, wi, hi)).(*image.RGBA)
			return subImg, imageType, nil
		}
	case "gif":
		img := m.(*image.Paletted)
		subImg := img.SubImage(image.Rect(0, 0, wi, hi)).(*image.Paletted)
		return subImg, imageType, nil
	}
	return nil, "", fmt.Errorf("未知的图片格式")

}

func fixSize(img1W, img2H, wi, hi int) (new1W, new2W int) {
	var ( //为了方便计算，将图片的宽转为 float64
		imgWidth, imgHeight = float64(img1W), float64(img2H)
		ratio               float64
	)
	if imgWidth >= imgHeight {
		ratio = imgWidth / float64(wi)
		return int(imgWidth * ratio), int(imgHeight * ratio)
	}
	ratio = imgHeight / float64(hi)
	return int(imgWidth * ratio), int(imgHeight * ratio)
}

func Gray(buff *bytes.Buffer) (out image.Image, err error) {
	m, _, _ := image.Decode(buff)
	bounds := m.Bounds()
	dx := bounds.Dx()
	dy := bounds.Dy()
	newRgba := image.NewRGBA(bounds)
	for i := 0; i < dx; i++ {
		for j := 0; j < dy; j++ {
			colorRgb := m.At(i, j)
			_, g, _, a := colorRgb.RGBA()
			gUint8 := uint8(g >> 8)
			aUint8 := uint8(a >> 8)
			newRgba.SetRGBA(i, j, color.RGBA{R: gUint8, G: gUint8, B: gUint8, A: aUint8})
		}
	}
	r := image.Rect(0, 0, dx, dy)
	return newRgba.SubImage(r), nil
}

func Rotate90(buff *bytes.Buffer) image.Image {
	m, _, _ := image.Decode(buff)
	rotate90 := image.NewRGBA(image.Rect(0, 0, m.Bounds().Dy(), m.Bounds().Dx()))
	// 矩阵旋转
	for x := m.Bounds().Min.Y; x < m.Bounds().Max.Y; x++ {
		for y := m.Bounds().Max.X - 1; y >= m.Bounds().Min.X; y-- {
			//  设置像素点
			rotate90.Set(m.Bounds().Max.Y-x, y, m.At(y, x))
		}
	}
	return rotate90
}

// Rotate180 旋转180度
func Rotate180(buff *bytes.Buffer) image.Image {
	m, _, _ := image.Decode(buff)
	rotate180 := image.NewRGBA(image.Rect(0, 0, m.Bounds().Dx(), m.Bounds().Dy()))
	// 矩阵旋转
	for x := m.Bounds().Min.X; x < m.Bounds().Max.X; x++ {
		for y := m.Bounds().Min.Y; y < m.Bounds().Max.Y; y++ {
			//  设置像素点
			rotate180.Set(m.Bounds().Max.X-x, m.Bounds().Max.Y-y, m.At(x, y))
		}
	}
	return rotate180
}

// Rotate270 旋转270度
func Rotate270(buff *bytes.Buffer) image.Image {
	m, _, _ := image.Decode(buff)
	rotate270 := image.NewRGBA(image.Rect(0, 0, m.Bounds().Dy(), m.Bounds().Dx()))
	// 矩阵旋转
	for x := m.Bounds().Min.Y; x < m.Bounds().Max.Y; x++ {
		for y := m.Bounds().Max.X - 1; y >= m.Bounds().Min.X; y-- {
			// 设置像素点
			rotate270.Set(x, m.Bounds().Max.X-y, m.At(y, x))
		}
	}
	return rotate270

}

func ImageToBase64(img image.Image, imgType string) string {
	buff := ImageToBuff(img, imgType)
	return base64.StdEncoding.EncodeToString(buff.Bytes())
}

func ImageToBuff(img image.Image, imgType string) *bytes.Buffer {
	buff := bytes.NewBuffer(nil)
	switch imgType {
	case "bmp":
		imgType = "bmp"
		_ = bmp.Encode(buff, img)
	case "png":
		imgType = "png"
		_ = png.Encode(buff, img)
	case "tiff", "tif":
		imgType = "tiff"
		_ = tiff.Encode(buff, img, nil)
	default:
		imgType = "jpeg"
		_ = jpeg.Encode(buff, img, &jpeg.Options{
			Quality: 100,
		})
	}
	return buff
}
func SplitImage(buff *bytes.Buffer, w, h int) []image.Image {
	img, _, _ := image.Decode(buff)
	list := make([]image.Image, 0)
	newWidth := int(math.Ceil(float64(img.Bounds().Dx()) / float64(w)))
	newHeight := int(math.Ceil(float64(img.Bounds().Dy()) / float64(h)))
	rect := image.Rect(0, 0, newWidth*w, newHeight*h)
	newImage := image.NewRGBA(rect)
	black := color.RGBA{A: 255}
	draw.Draw(newImage, newImage.Bounds(), &image.Uniform{C: black}, image.Point{}, draw.Src)
	draw.Draw(newImage, img.Bounds(), img, newImage.Bounds().Min, draw.Over)
	sp := splitPattern(newImage, w, h)
	spLen := len(sp)
	var (
		square image.Rectangle
	)
	for i := 0; i < spLen; i++ {
		square = image.Rect(sp[i][0], sp[i][1], sp[i][2], sp[i][3])
		imgPart := img.(interface {
			SubImage(r image.Rectangle) image.Image
		}).SubImage(square)
		list = append(list, imgPart)
	}
	return list
}
func splitPattern(img image.Image, w, h int) [][]int {
	ret := make([][]int, 0)
	vOffSet := width(img) / w
	hOffSet := height(img) / h
	for r := 0; r < hOffSet; r++ {
		for c := 0; c < vOffSet; c++ {
			//行偏移,仅应用在x
			x1 := w * c
			y1 := h * r

			x2 := w * (c + 1)
			y2 := (r + 1) * h
			el := []int{x1, y1, x2, y2}
			ret = append(ret, el)
		}
	}
	return ret
}

func width(i image.Image) int {
	return i.Bounds().Max.X - i.Bounds().Min.X
}

func height(i image.Image) int {
	return i.Bounds().Max.Y - i.Bounds().Min.Y
}

func IsImage(fileName string) bool {
	fileType := path.Ext(fileName)
	return InSlice([]string{".png", ".jpg", ".jpeg", ".bmp", ".tif", ".tiff"}, strings.ToLower(fileType))
}

// InSlice 判断字符串是否在 slice 中。
func InSlice(items []string, item string) bool {
	for _, eachItem := range items {
		if eachItem == item {
			return true
		}
	}
	return false
}