package main
import (
"fmt"
"log"
"net/http"
"os"
"path/filepath"
"sync"
"time"
"github.com/gorilla/feeds"
)
type RssEntry struct {
title string
url string
descripiton string
time time.Time
}
type Parser interface {
Parse() []*RssEntry
Title() string
Description() string
RootUrl() string
ImageUrl() string
ServerUrl() string
CacheName() string
CacheTimeout() int
}
type ParserFeed struct {
parser Parser
rss string
mutex *sync.Mutex
time time.Time
}
func (this ParserFeed) CachePath() string {
return "./_cache/" + this.parser.CacheName() + ".rss"
}
func (this *ParserFeed) ReadCache() bool {
path := this.CachePath()
stat, err := os.Stat(path)
if err != nil {
return true
}
data, err := os.ReadFile(this.CachePath())
if err != nil {
return true
}
this.SetFeed(string(data))
this.time = stat.ModTime()
return time.Now().Sub(this.time).Seconds() > float64(this.parser.CacheTimeout())
}
func (this *ParserFeed) ParseAndUpdateCache() {
feed := &feeds.Feed{
Title: this.parser.Title(),
Link: &feeds.Link{Href: this.parser.RootUrl()},
Description: this.parser.Description(),
Created: time.Now(),
Image: &feeds.Image{
Url: this.parser.ImageUrl(),
Title: this.parser.Title(),
Link: this.parser.RootUrl(),
},
}
entities := this.parser.Parse()
for _, re := range entities {
feed.Items = append(feed.Items, &feeds.Item{
Id: re.url,
Title: re.title,
Link: &feeds.Link{Href: re.url},
Description: re.descripiton,
Created: re.time,
})
}
rssFeed, err := feed.ToRss()
if err != nil {
fmt.Println(err)
}
dir := filepath.Dir(this.CachePath())
os.MkdirAll(dir, os.ModePerm)
os.WriteFile(this.CachePath(), []byte(rssFeed), os.ModePerm)
this.mutex.Lock()
this.rss = rssFeed
this.time = time.Now()
this.mutex.Unlock()
}
func (this *ParserFeed) RunWorker() {
if this.ReadCache() {
this.ParseAndUpdateCache()
}
for {
nextmark := this.time.Add(time.Second * time.Duration(this.parser.CacheTimeout()))
sleepfor := nextmark.Unix() - time.Now().Unix()
if sleepfor > 0 {
time.Sleep(time.Second * time.Duration(sleepfor))
}
this.ParseAndUpdateCache()
}
}
func (this *ParserFeed) SetFeed(feed string) {
this.mutex.Lock()
this.rss = feed
this.mutex.Unlock()
}
func (this *ParserFeed) GetFeed() string {
this.mutex.Lock()
rss := this.rss
this.mutex.Unlock()
return rss
}
func main() {
parsers := []*ParserFeed{
{parser: NvidiaParser{}, mutex: &sync.Mutex{}},
}
for _, p := range parsers {
go p.RunWorker()
}
rootPage :=
`
RSS index page
RSS index page
Custom generators of RSS feed from different blogs
`
for _, p := range parsers {
rootPage += fmt.Sprintf("%v", p.parser.ServerUrl(), p.parser.Title())
}
rootPage += ""
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
if r.URL.Path != "/" {
w.WriteHeader(404)
return
}
fmt.Fprintf(w, rootPage)
})
for _, p := range parsers {
http.HandleFunc(p.parser.ServerUrl(), func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/xml")
fmt.Fprint(w, p.GetFeed())
})
}
log.Fatal(http.ListenAndServe(":3500", nil))
}