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package reddit_background
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"github.com/nfnt/resize"
"github.com/silvasur/startpage/http_getter"
"github.com/silvasur/startpage/interval"
"image"
_ "image/gif"
"image/jpeg"
_ "image/png"
"io"
"log"
"mime"
"net/http"
"os"
"path"
"strings"
"time"
)
type redditList struct {
Data struct {
Children []struct {
Data *RedditImage `json:"data"`
} `json:"children"`
} `json:"data"`
}
type RedditImage struct {
Title string `json:"title"`
URL string `json:"url,omitempty"`
Permalink string `json:"permalink"`
Domain string `json:"domain"`
Saved bool `json:"-"`
Data []byte `json:"-"`
origdata []byte `json:"-"`
Mediatype string `json:"-"`
}
func GetRedditImage(maxsize int, subreddit string) (*RedditImage, error) {
subredditUrl := fmt.Sprintf("https://www.reddit.com/r/%s.json", subreddit)
resp, err := http_getter.Get(subredditUrl)
if err != nil {
return nil, err
}
defer resp.Body.Close()
var list redditList
dec := json.NewDecoder(resp.Body)
if err := dec.Decode(&list); err != nil {
return nil, err
}
for _, el := range list.Data.Children {
ri := el.Data
if ri.Domain == fmt.Sprintf("self.%s", subreddit) {
continue
}
if ri.URL == "" {
continue
}
if ri.fetch(maxsize) {
return ri, nil
}
}
return nil, errors.New("Could not get RedditImage: No image could be extracted")
}
func (ri *RedditImage) fetch(maxsize int) bool {
// TODO: We can do further processing here (e.g. if we get a link to flickr, extract the image).
// For now, we will simply test, if the URL points to an image.
resp, err := http.Get(ri.URL)
if err != nil {
return false
}
defer resp.Body.Close()
t := resp.Header.Get("Content-Type")
if t == "" {
log.Printf("could not get image of %s: no Content-Type", ri.Permalink)
return false
}
mt, _, err := mime.ParseMediaType(t)
if err != nil {
log.Printf("could not get image of %s: %s", ri.Permalink, err)
return false
}
if strings.Split(mt, "/")[0] != "image" {
log.Printf("could not get image of %s: not an image", ri.Permalink)
return false
}
buf := new(bytes.Buffer)
if _, err := io.Copy(buf, resp.Body); err != nil {
log.Printf("could not get image of %s: %s", ri.Permalink, err)
return false
}
ri.Mediatype = t
ri.origdata = buf.Bytes()
ri.Data = ri.origdata
ri.resize(maxsize)
return true
}
// resize resizes image, if it's very large
func (ri *RedditImage) resize(maxdim int) {
im, _, err := image.Decode(bytes.NewReader(ri.origdata))
if err != nil {
log.Printf("Failed decoding in resize(): %s", err)
return
}
size := im.Bounds().Size()
if !(size.X > maxdim || size.Y > maxdim) {
return
}
var w, h int
if size.X > size.Y {
h = maxdim * (size.Y / size.X)
w = maxdim
} else {
w = maxdim * (size.X / size.Y)
h = maxdim
}
im = resize.Resize(uint(w), uint(h), im, resize.Bicubic)
buf := new(bytes.Buffer)
if err := jpeg.Encode(buf, im, &jpeg.Options{Quality: 90}); err != nil {
log.Printf("Failed encoding in resize(): %s", err)
return
}
ri.Data = buf.Bytes()
ri.Mediatype = "image/jpeg"
}
var extensions = map[string]string{
"image/png": "png",
"image/jpeg": "jpg",
"image/gif": "gif",
"image/x-ms-bmp": "bmp",
"image/x-bmp": "bmp",
"image/bmp": "bmp",
"image/tiff": "tiff",
"image/tiff-fx": "tiff",
"image/x-targa": "tga",
"image/x-tga": "tga",
"image/webp": "webp",
}
const maxTitleLenInFilename = 100
func (p *RedditImage) Save(savepath string) error {
ext := extensions[p.Mediatype]
pp := strings.Split(p.Permalink, "/")
threadid := pp[len(pp)-3]
title := strings.Replace(p.Title, "/", "-", -1)
tRunes := []rune(title)
if len(tRunes) > maxTitleLenInFilename {
title = string(tRunes[0:maxTitleLenInFilename])
}
f, err := os.Create(path.Join(savepath, threadid+" - "+title+"."+ext))
if err != nil {
return fmt.Errorf("Could not save image: %s", err)
}
defer f.Close()
if _, err := f.Write(p.origdata); err != nil {
return fmt.Errorf("Could not save image: %s", err)
}
p.Saved = true
return nil
}
const (
UPDATE_INTERVAL = 30 * time.Minute
RETRY_INTERVAL = 1 * time.Minute
)
type RedditImageProvider struct {
intervalRunner *interval.IntervalRunner
maxsize int
subreddit string
image *RedditImage
}
func NewRedditImageProvider(maxsize int, subreddit string) *RedditImageProvider {
return &RedditImageProvider{
intervalRunner: interval.NewIntervalRunner(UPDATE_INTERVAL, RETRY_INTERVAL),
maxsize: maxsize,
subreddit: subreddit,
}
}
func (rip *RedditImageProvider) Image() *RedditImage {
rip.intervalRunner.Run(func() bool {
log.Printf("Getting new RedditImage")
var err error
rip.image, err = GetRedditImage(rip.maxsize, rip.subreddit)
if err == nil {
log.Printf("Successfully loaded RedditImage")
} else {
log.Printf("Failed loading RedditImage: %s", err)
}
return err == nil
})
return rip.image
}
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