package main

import (
	"fmt"
	"image"
	"image/color"
	"image/draw"
	"image/jpeg"
	"os"
	"path/filepath"

	"github.com/nfnt/resize"
	"golang.org/x/image/font"
	"golang.org/x/image/font/opentype"
	"golang.org/x/image/math/fixed"
)

func addWatermark(img *image.RGBA, text string, textColor color.Color, bgColor color.Color) {
	fontData, err := os.ReadFile("/System/Library/Fonts/Courier.ttc")
	if err != nil {
		fmt.Println("Error loading font:", err)
		return
	}
	ttCollection, err := opentype.ParseCollection(fontData)
	if err != nil {
		fmt.Println("Error parsing font collection:", err)
		return
	}
	ttFont, err := ttCollection.Font(0)
	if err != nil {
		fmt.Println("Error getting font from collection:", err)
		return
	}
	fontSize := 20.0
	face, err := opentype.NewFace(ttFont, &opentype.FaceOptions{
		Size:    fontSize,
		DPI:     72,
		Hinting: font.HintingFull,
	})
	if err != nil {
		fmt.Println("Error creating face:", err)
		return
	}

	// 计算文字尺寸
	d := &font.Drawer{
		Dst:  img,
		Src:  image.NewUniform(textColor),
		Face: face,
		Dot:  fixed.Point26_6{},
	}
	textBounds := d.MeasureString(text)
	textWidth := int(textBounds.Ceil())
	textHeight := int(face.Metrics().Height.Ceil())

	// 设置水印文字的位置为右下角，添加内边距
	padding := 8
	x := img.Bounds().Max.X - textWidth - padding
	y := img.Bounds().Max.Y - padding - textHeight/2 + 4

	// 绘制背景矩形（上下左右居中于文字）
	bgRect := image.Rect(x-padding/2, y-textHeight/2-padding/2+4, x+textWidth+padding/2, y+textHeight/2+padding/2)
	draw.Draw(img, bgRect, image.NewUniform(bgColor), image.Point{}, draw.Src)

	// 绘制文字
	d.Dot = fixed.Point26_6{X: fixed.I(x), Y: fixed.I(y + 8)}
	d.DrawString(text)
}

func scaleAndAddWatermark(inputImagePath, outputImagePath string, scaleSize int, watermarkText string) {
	file, err := os.Open(inputImagePath)
	if err != nil {
		fmt.Println("Error opening file:", err)
		return
	}
	defer file.Close()

	img, _, err := image.Decode(file)
	if err != nil {
		fmt.Println("Error decoding image:", err)
		return
	}

	bounds := img.Bounds()
	width := bounds.Max.X
	height := bounds.Max.Y
	fmt.Printf("Image %s, width: %d, height: %d\n", inputImagePath, width, height)

	var resizedImg image.Image
	if width > scaleSize && height > scaleSize {
		if width < height {
			resizedImg = resize.Resize(uint(scaleSize), 0, img, resize.Lanczos3)
		} else {
			resizedImg = resize.Resize(0, uint(scaleSize), img, resize.Lanczos3)
		}
	} else {
		resizedImg = img
	}

	// 将图片转换为 RGBA 格式以便添加水印
	rgbaImg := image.NewRGBA(resizedImg.Bounds())
	if rgbaImg.Stride != rgbaImg.Rect.Size().X*4 {
		fmt.Println("Unsupported image format")
		return
	}
	for y := rgbaImg.Rect.Min.Y; y < rgbaImg.Rect.Max.Y; y++ {
		for x := rgbaImg.Rect.Min.X; x < rgbaImg.Rect.Max.X; x++ {
			rgbaImg.Set(x, y, resizedImg.At(x, y))
		}
	}

	// 添加水印（使用柔和的深灰色文字和米白色背景）
	softTextColor := color.RGBA{R: 60, G: 60, B: 60, A: 255}
	softBgColor := color.RGBA{R: 250, G: 250, B: 245, A: 255}
	addWatermark(rgbaImg, watermarkText, softTextColor, softBgColor)

	outFile, err := os.Create(outputImagePath)
	if err != nil {
		fmt.Println("Error creating file:", err)
		return
	}
	defer outFile.Close()

	err = jpeg.Encode(outFile, rgbaImg, &jpeg.Options{
		Quality: 95,
	})
	if err != nil {
		fmt.Println("Error encoding image:", err)
		return
	}

	fmt.Println("Image processed and saved as", filepath.Base(outputImagePath))
}

func main() {
	inputImagePath := "input.jpg"   // 输入图片路径
	outputImagePath := "output.jpg" // 输出图片路径

	imageSize := 1200 // 默认尺寸

	scaleAndAddWatermark(inputImagePath, outputImagePath, imageSize, "email@example.com")
}