// vi:ts=4:sts=4:sw=4:noet:tw=72
//
// This code is mostly derived from the example code by Jim Teeuwen
// and is subject to the CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
// license.

package modules

import (
	"bufio"
	"errors"
	"flag"
	"fmt"
	"io"
	"os"
	"time"

	gorss "git.dnix.de/an/go-pkg-rss"
	xmlx "git.dnix.de/an/go-pkg-xmlx"
	"git.dnix.de/an/xlog"
)

var hideOutput = true
var rssFeeds = flag.String("rss_feeds", "feeds.txt", "Feed list file")
var rssChannel = flag.String("rss_channel", "", "Target channel")

func init() {
	MsgFuncs["rss"] = rssHandleMessage
	RunFuncs["rss"] = rssRun
}

func rssRun() {
	time.Sleep(5 * time.Second)
	file, err := os.Open(*rssFeeds)
	if err != nil {
		xlog.Fatal(err.Error())
	}
	defer file.Close()
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		go rssPollFeed(scanner.Text(), 5, rssCharsetReader)
	}
	if err := scanner.Err(); err != nil {
		xlog.Fatal(err.Error())
	}
	go func() {
		// Suppress output of new items for 15 minutes after startup
		// in order to prevent spam.
		time.Sleep(15 * time.Minute)
		hideOutput = false
	}()
}

func rssHandleMessage(m *Message) {
}

func rssPollFeed(uri string, timeout int, cr xmlx.CharsetFunc) {
	feed := gorss.New(timeout, true, rssChanHandler, rssItemHandler)
	for {
		xlog.Info("Polling feed: %s", uri)
		if err := feed.Fetch(uri, cr); err != nil {
			xlog.Error("Feed error: %s: %s", "*", uri, err)
		}
		xlog.Info("Polled %s, next poll in %d seconds", uri, feed.SecondsTillUpdate())
		<-time.After(time.Duration(feed.SecondsTillUpdate() * 1e9))
	}
}

func rssChanHandler(feed *gorss.Feed, newchannels []*gorss.Channel) {
	//SayCh <- fmt.Sprintf("%s\n[RSS] %d new channel(s) in %s", "*", len(newchannels), feed.Url)
}

func rssItemHandler(feed *gorss.Feed, ch *gorss.Channel, newitems []*gorss.Item) {
	if hideOutput {
		return
	}
	for _, ni := range newitems {
		ti := ni.Title
		short := ""
		if len(ti) > 80 {
			runes := []rune(ti)
			short = string(runes[0:80]) + " [...]"
		} else {
			short = ti
		}
		SayCh <- fmt.Sprintf("%s\n[RSS] %v - %v", *rssChannel, short, ni.Links[0].Href)
	}
}

func rssCharsetReader(charset string, r io.Reader) (io.Reader, error) {
	if charset == "ISO-8859-1" || charset == "iso-8859-1" {
		return r, nil
	}
	return nil, errors.New("Unsupported character set encoding: " + charset)
}