// Command icongen 根据一张图片快速生成当前项目的托盘图标与打包图标，
// 已存在的图标文件会被直接覆盖。
//
// 用法（在项目根目录执行）：
//
//	go run ./pkg/icongen -src /path/to/image.png
//
// 可选参数：
//
//	go run ./pkg/icongen -src logo.jpg -root . -appicon 1024 -tray 256
package main

import (
	"bytes"
	"encoding/binary"
	"flag"
	"fmt"
	"image"
	imagedraw "image/draw"
	"image/png"
	"log"
	"os"
	"path/filepath"

	"golang.org/x/image/draw"
	_ "golang.org/x/image/webp"
	_ "image/gif"
	_ "image/jpeg"
)

// ico 文件中包含的尺寸
var icoSizes = []int{256, 128, 64, 48, 32, 16}

func main() {
	src := flag.String("src", "", "源图片路径（png/jpg/jpeg/gif/bmp/webp）")
	root := flag.String("root", ".", "项目根目录")
	appicon := flag.Int("appicon", 1024, "build/appicon.png 尺寸")
	icon := flag.Int("icon", 1024, "build/icon.png 尺寸")
	tray := flag.Int("tray", 256, "trayicons/assets 图标尺寸")
	flag.Parse()

	if *src == "" {
		log.Fatal("[-src] 源图片路径不能为空")
	}

	f, err := os.Open(*src)
	if err != nil {
		log.Fatalf("打开源图片失败: %v", err)
	}
	defer f.Close()

	srcImg, _, err := image.Decode(f)
	if err != nil {
		log.Fatalf("解码源图片失败（支持 png/jpg/gif/bmp/webp）: %v", err)
	}
	log.Printf("源图片: %s (%dx%d)", *src, srcImg.Bounds().Dx(), srcImg.Bounds().Dy())

	cropped := centerCrop(srcImg)

	// PNG 目标：源图居中裁剪后缩放
	writePNG(filepath.Join(*root, "build", "appicon.png"), cropped, *appicon)
	writePNG(filepath.Join(*root, "build", "icon.png"), cropped, *icon)
	writePNG(filepath.Join(*root, "assets", "icon.png"), cropped, *tray)
	writePNG(filepath.Join(*root, "trayicons", "icon.png"), cropped, *tray)

	// ICO 目标：Windows exe / 托盘图标（多尺寸）
	writeICO(filepath.Join(*root, "build", "windows", "icon.ico"), cropped, icoSizes)

	log.Println("完成，所有图标已按需覆盖。")
}

// centerCrop 从图像中心裁剪出正方形区域。
func centerCrop(srcImg image.Image) image.Image {
	b := srcImg.Bounds()
	w, h := b.Dx(), b.Dy()
	side := w
	if h < side {
		side = h
	}
	x0 := b.Min.X + (w-side)/2
	y0 := b.Min.Y + (h-side)/2
	rect := image.Rect(0, 0, side, side)
	out := image.NewRGBA(rect)
	imagedraw.Draw(out, rect, srcImg, image.Pt(x0, y0), imagedraw.Src)
	return out
}

// writePNG 按 size 缩放后写出 PNG 文件。
func writePNG(path string, cropped image.Image, size int) {
	dst := image.NewRGBA(image.Rect(0, 0, size, size))
	draw.CatmullRom.Scale(dst, dst.Bounds(), cropped, cropped.Bounds(), draw.Over, nil)

	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		log.Fatalf("创建目录失败 %s: %v", filepath.Dir(path), err)
	}
	out, err := os.Create(path)
	if err != nil {
		log.Fatalf("创建文件失败 %s: %v", path, err)
	}
	defer out.Close()
	if err := png.Encode(out, dst); err != nil {
		log.Fatalf("编码 PNG 失败 %s: %v", path, err)
	}
	fmt.Printf("  [ok] %s (%dx%d)\n", path, size, size)
}

// writeICO 写出多尺寸 ICO（Windows 图标，PNG 条目压缩，Vista+ 支持）。
func writeICO(path string, cropped image.Image, sizes []int) {
	type entry struct {
		w, h byte
		data []byte
	}
	entries := make([]entry, 0, len(sizes))
	for _, s := range sizes {
		dst := image.NewRGBA(image.Rect(0, 0, s, s))
		draw.CatmullRom.Scale(dst, dst.Bounds(), cropped, cropped.Bounds(), draw.Over, nil)

		var pngBuf bytes.Buffer
		if err := png.Encode(&pngBuf, dst); err != nil {
			log.Fatalf("编码 ICO 条目失败 (%dpx): %v", s, err)
		}
		w, h := byte(s), byte(s)
		if s == 256 {
			w, h = 0, 0 // 0 表示 256
		}
		entries = append(entries, entry{w: w, h: h, data: pngBuf.Bytes()})
	}

	var buf bytes.Buffer
	// ICONDIR（6 字节头）
	binary.Write(&buf, binary.LittleEndian, uint16(0)) // Reserved
	binary.Write(&buf, binary.LittleEndian, uint16(1)) // Type: icon
	binary.Write(&buf, binary.LittleEndian, uint16(len(entries)))

	// ICONDIRENTRY（16 字节 x N）
	cur := 6 + 16*len(entries)
	for _, e := range entries {
		binary.Write(&buf, binary.LittleEndian, e.w)
		binary.Write(&buf, binary.LittleEndian, e.h)
		binary.Write(&buf, binary.LittleEndian, uint8(0))  // 颜色数（忽略）
		binary.Write(&buf, binary.LittleEndian, uint8(0))  // 保留
		binary.Write(&buf, binary.LittleEndian, uint16(1)) // 平面数
		binary.Write(&buf, binary.LittleEndian, uint16(32))
		binary.Write(&buf, binary.LittleEndian, uint32(len(e.data)))
		binary.Write(&buf, binary.LittleEndian, uint32(cur))
		cur += len(e.data)
	}
	// PNG 图像数据
	for _, e := range entries {
		buf.Write(e.data)
	}

	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		log.Fatalf("创建目录失败 %s: %v", filepath.Dir(path), err)
	}
	if err := os.WriteFile(path, buf.Bytes(), 0o644); err != nil {
		log.Fatalf("写入 ICO 失败 %s: %v", path, err)
	}
	fmt.Printf("  [ok] %s (ico %v)\n", path, sizes)
}