141 lines
3.2 KiB
Go
141 lines
3.2 KiB
Go
package main
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import (
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"encoding/json"
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"fmt"
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"image"
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"image/draw"
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"image/png"
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"io/ioutil"
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"log"
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"net/http"
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"os"
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"os/exec"
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"path"
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"time"
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)
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const (
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level = 4
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width = 550
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delay = 8 // delay in hours, so that I can see daylight on my wallpaper during the day!
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)
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type latestData struct {
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Date string `json:"date"`
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File string `json:"file"`
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}
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func main() {
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// Define work directory and files
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var (
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home = os.Getenv("HOME")
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workDir = path.Join(home, ".himawari")
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imageFile = path.Join(workDir, "/latest.png")
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dataFile = path.Join(workDir, "/data")
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data []byte
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err error
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oldData = new(latestData)
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initData = new(latestData)
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t time.Time
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location *time.Location
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output *image.RGBA
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out *os.File
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)
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// Read the last date from dataFile if it exists
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data, err = ioutil.ReadFile(dataFile)
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if err != nil {
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data = nil
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} else {
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err = json.Unmarshal(data, oldData)
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if err != nil {
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oldData = nil
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}
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}
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// Get the data about the last image
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err = getJSON("http://himawari8-dl.nict.go.jp/himawari8/img/D531106/latest.json", initData)
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if err != nil {
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log.Fatal("error getting json data from himawari server: ", err)
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}
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location, err = time.LoadLocation("Asia/Tokyo")
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if err != nil {
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log.Fatal("error loading Asia/Tokyo time zone data: ", err)
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}
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t, _ = time.ParseInLocation("2006-01-02 15:04:05", initData.Date, location)
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if oldData != nil && oldData.Date == initData.Date {
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log.Print("No new image, keeping the old one")
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os.Exit(0)
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}
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t = t.Add(time.Duration(-delay) * time.Hour)
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// Get all the chunks from the latest image and assemble them
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output = image.NewRGBA(image.Rect(0, 0, level*width, level*width))
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for x := 0; x < level; x++ {
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for y := 0; y < level; y++ {
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url := fmt.Sprintf("http://himawari8.nict.go.jp/img/D531106/%dd/%d/%s_%d_%d.png",
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level, width, t.Format("2006/01/02/150405"), x, y)
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var buff image.Image
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err = getPNG(url, &buff)
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if err != nil {
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err = getPNG(url, &buff)
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if err != nil {
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log.Fatal("Error getting png :", url)
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}
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}
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draw.Draw(output, image.Rect(x*width, y*width, (x+1)*width, (y+1)*width), buff, image.Point{0, 0}, draw.Src)
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}
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}
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// Write output to file
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out, err = os.Create(imageFile)
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if err != nil {
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err := os.Mkdir(workDir, 0755)
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if err != nil {
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log.Fatal("error creating output directory:", err)
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}
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out, err = os.Create(imageFile)
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if err != nil {
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log.Fatal("error creating output file:", err)
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}
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}
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defer out.Close()
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err = png.Encode(out, output)
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if err != nil {
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log.Fatal("Error writing output file:", err)
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}
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// Write dat file
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buff, err := json.Marshal(initData)
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ioutil.WriteFile(dataFile, buff, 0644)
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// Exec feh
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cmd := exec.Command("feh", "--bg-max", imageFile)
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err = cmd.Run()
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if err != nil {
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log.Fatal("Error launching feh :", err)
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}
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}
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func getJSON(url string, target interface{}) (err error) {
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var r *http.Response
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r, err = http.Get(url)
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if err == nil {
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defer r.Body.Close()
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err = json.NewDecoder(r.Body).Decode(target)
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}
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return
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}
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func getPNG(url string, image *image.Image) (err error) {
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var r *http.Response
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r, err = http.Get(url)
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if err == nil {
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defer r.Body.Close()
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*image, err = png.Decode(r.Body)
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}
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return
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}
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