package main
import (
    "fmt"
    "github.com/nfnt/resize"
    "image"
    "image/draw"
    "image/jpeg"
    "image/png"
    "io/ioutil"
    "log"
    "math/rand"
    "os"
    "runtime"
    "strconv"
    "strings"
    "time"
)
func main() {
    runtime.GOMAXPROCS(runtime.NumCPU())
    cmd("data/")
    fmt.Println("OK!")
}
// 執行操作
func cmd(path string) {
    files, _ := ioutil.ReadDir(path)
    for _, file := range files {
        if file.IsDir() {
            fmt.Println("目錄" + file.Name())
            cmd(path + file.Name() + "/")
        } else {
            if strings.Contains(strings.ToLower(file.Name()), ".jpg") {
                // 隨機名稱
                to := path + random_name() + ".jpg"
                origin := path + file.Name()
                fmt.Println("正在處理" + origin + ">>>" + to)
                cmd_resize(origin, 2048, 0, to)
                defer os.Remove(origin)
            }
        }
    }
}
// 改變大小
func cmd_resize(file string, width uint, height uint, to string) {
    // 打開圖片并解碼
    file_origin, _ := os.Open(file)
    origin, _ := jpeg.Decode(file_origin)
    defer file_origin.Close()
    canvas := resize.Resize(width, height, origin, resize.Lanczos3)
    file_out, err := os.Create(to)
    if err != nil {
        log.Fatal(err)
    }
    defer file_out.Close()
    jpeg.Encode(file_out, canvas, jpeg.Options{80})
    // cmd_watermark(to, strings.Replace(to, ".jpg", "@big.jpg", 1))
    cmd_thumbnail(to, 480, 360, strings.Replace(to, ".jpg", "@small.jpg", 1))
}
func cmd_thumbnail(file string, width uint, height uint, to string) {
    // 打開圖片并解碼
    file_origin, _ := os.Open(file)
    origin, _ := jpeg.Decode(file_origin)
    defer file_origin.Close()
    canvas := resize.Thumbnail(width, height, origin, resize.Lanczos3)
    file_out, err := os.Create(to)
    if err != nil {
        log.Fatal(err)
    }
    defer file_out.Close()
    jpeg.Encode(file_out, canvas, jpeg.Options{80})
}
// 水印
func cmd_watermark(file string, to string) {
    // 打開圖片并解碼
    file_origin, _ := os.Open(file)
    origin, _ := jpeg.Decode(file_origin)
    defer file_origin.Close()
    // 打開水印圖并解碼
    file_watermark, _ := os.Open("watermark.png")
    watermark, _ := png.Decode(file_watermark)
    defer file_watermark.Close()
    //原始圖界限
    origin_size := origin.Bounds()
    //創建新圖層
    canvas := image.NewNRGBA(origin_size)
    // 貼原始圖
    draw.Draw(canvas, origin_size, origin, image.ZP, draw.Src)
    // 貼水印圖
    draw.Draw(canvas, watermark.Bounds().Add(image.Pt(30, 30)), watermark, image.ZP, draw.Over)
    //生成新圖片
    create_image, _ := os.Create(to)
    jpeg.Encode(create_image, canvas, jpeg.Options{95})
    defer create_image.Close()
}
// 隨機生成文件名
func random_name() string {
    rand.Seed(time.Now().UnixNano())
    return strconv.Itoa(rand.Int())
}