114 lines
2.4 KiB
Go
114 lines
2.4 KiB
Go
package rss
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import (
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"context"
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"net/http"
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"sync"
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"time"
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log "github.com/go-pkgz/lgr"
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"github.com/mmcdole/gofeed"
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"github.com/pkg/errors"
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)
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// Notify on RSS change
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type Notify struct {
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Feed string
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Duration time.Duration
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Timeout time.Duration
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once sync.Once
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ctx context.Context
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cancel context.CancelFunc
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}
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// Event from RSS
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type Event struct {
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ChanTitle string
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Title string
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Link string
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Text string
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guid string
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}
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// Go starts notifier and returns events channel
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func (n *Notify) Go(ctx context.Context) <-chan Event {
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log.Printf("[INFO] start notifier for %s, every %s", n.Feed, n.Duration)
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n.once.Do(func() { n.ctx, n.cancel = context.WithCancel(ctx) })
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ch := make(chan Event)
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// wait for duration, can be terminated by ctx
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waitOrCancel := func(ctx context.Context) bool {
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select {
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case <-ctx.Done():
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return false
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case <-time.After(n.Duration):
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return true
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}
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}
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go func() {
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defer func() {
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close(ch)
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n.cancel()
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}()
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fp := gofeed.NewParser()
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fp.Client = &http.Client{Timeout: n.Timeout}
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log.Printf("[DEBUG] notifier uses http timeout %v", n.Timeout)
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lastGUID := ""
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for {
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feedData, err := fp.ParseURL(n.Feed)
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if err != nil {
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log.Printf("[WARN] failed to fetch/parse url from %s, %v", n.Feed, err)
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if !waitOrCancel(n.ctx) {
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return
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}
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continue
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}
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event, err := n.feedEvent(feedData)
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if lastGUID != event.guid && err == nil {
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if lastGUID != "xyz" { // don't notify on initial change
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log.Printf("[INFO] new event %s - %s", event.guid, event.Title)
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ch <- event
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} else {
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log.Printf("[INFO] ignore first event %s - %s", event.guid, event.Title)
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}
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lastGUID = event.guid
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}
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if !waitOrCancel(n.ctx) {
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log.Print("[WARN] notifier canceled")
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return
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}
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}
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}()
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return ch
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}
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// Shutdown notifier
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func (n *Notify) Shutdown() {
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log.Print("[DEBUG] shutdown initiated")
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n.cancel()
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<-n.ctx.Done()
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}
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// feedEvent gets latest item from rss feed
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func (n *Notify) feedEvent(feed *gofeed.Feed) (e Event, err error) {
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if len(feed.Items) == 0 {
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return e, errors.New("no items in rss feed")
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}
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if feed.Items[0].GUID == "" {
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return e, errors.Errorf("no guid for rss entry %+v", feed.Items[0])
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}
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e.ChanTitle = feed.Title
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e.Title = feed.Items[0].Title
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e.Link = feed.Items[0].Link
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e.Text = feed.Items[0].Description
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e.guid = feed.Items[0].GUID
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return e, nil
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}
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