package data

import (
	"encoding/gob"
	"fmt"
	"os"

	"github.com/gorilla/feeds"
)

type Feed struct {
	addCh  chan *feeds.Item
	openCh chan feeds.Feed
	saveCh chan feeds.Feed
	showCh chan feeds.Feed
	feed   feeds.Feed
}

func (f *Feed) start() {
	for {
		select {
		case item := <-f.addCh:
			f.feed.Items = append(f.feed.Items, item)
		case f.saveCh <- f.feed:
		case tmpFeed := <-f.openCh:
			f.feed = tmpFeed
		case f.showCh <- f.feed:
		}
	}
}

func NewFeed(title, link, desc string) *Feed {
	feed := &Feed{
		addCh:  make(chan *feeds.Item),
		openCh: make(chan feeds.Feed),
		saveCh: make(chan feeds.Feed),
		showCh: make(chan feeds.Feed),
		feed: feeds.Feed{
			Title:       title,
			Link:        &feeds.Link{Href: link},
			Description: desc,
		},
	}
	go feed.start()
	return feed
}

func OpenFeed(filename string) (*Feed, error) {
	feed := new(Feed)
	go feed.start()

	file, err := os.Open(filename)
	if err != nil {
		return nil, fmt.Errorf("error opening file %v: %v", filename, err)
	}
	defer file.Close()

	decoder := gob.NewDecoder(file)
	tmpFeed := new(feeds.Feed)
	err = decoder.Decode(tmpFeed)
	if err != nil {
		return nil, fmt.Errorf("error decoding file %v: %v", filename, err)
	}

	feed.openCh <- *tmpFeed

	return feed, nil
}

func (f *Feed) Save(filename string) error {
	file, err := os.Create(filename)
	if err != nil {
		return fmt.Errorf("error creating file %v: %v", filename, err)
	}
	defer file.Close()

	encoder := gob.NewEncoder(file)
	feed := <-f.saveCh
	err = encoder.Encode(feed)
	if err != nil {
		return fmt.Errorf("error encoding file %v: %v", filename, err)
	}

	return nil
}

func (f *Feed) Add(i *feeds.Item) {
	f.addCh <- i
}

func (f *Feed) Show() feeds.Feed {
	return <-f.showCh
}