package rss

import (
	"fmt"
	"sync"
	"time"

	"github.com/influxdata/telegraf"
	"github.com/influxdata/telegraf/plugins/inputs"
	"github.com/mmcdole/gofeed"
)

var ts = time.Now()

type RSS struct {
	URLs []string `toml:"urls"`
}

func (r *RSS) Description() string {
	return "Reads RSS Feeds Description"
}

var sampleConfig = `
  ## One or more URLs from which to read rss feed
  urls = [
    "http://localhost/rss/feed"
  ]

  ## Reduce traffic. Do not run too frequently.
  interval = '10m'
`

func (r *RSS) SampleConfig() string {
	return sampleConfig
}

func (r *RSS) Gather(acc telegraf.Accumulator) error {
	var wg sync.WaitGroup
	for _, u := range r.URLs {
		wg.Add(1)
		go func(url string) {
			defer wg.Done()
			if err := r.gatherFeed(acc, url, ts); err != nil {
				acc.AddError(fmt.Errorf("[url=%s]: %s", url, err))
			}
		}(u)
	}

	// remember last time started
	ts = time.Now()

	wg.Wait()

	return nil
}

func (r *RSS) gatherFeed(acc telegraf.Accumulator, url string, ts time.Time) error {
	fp := gofeed.NewParser()
	feed, err := fp.ParseURL(url)
	if err != nil {
		return err
	}

	fields := make(map[string]interface{})
	tags := make(map[string]string)

	tags["url"] = url
	tags["feed_type"] = feed.FeedType
	tags["feed_version"] = feed.FeedVersion

	for _, item := range feed.Items {
		time := item.PublishedParsed
		if time.Before(ts) {
			continue
		}

		fields["title"] = item.Title
		fields["description"] = item.Description

		acc.AddFields("rss", fields, tags, *time)
	}

	return nil
}

func init() {
	inputs.Add("rss", func() telegraf.Input { return &RSS{} })
}