package rss

import (
	"encoding/xml"
	"fmt"
	"sync"
	"time"
)

type Channel struct {
	addCategory    chan string
	addItem        chan *Item
	XMLName        xml.Name `xml:"channel"`
	Title          string   `xml:"title"`
	Link           string   `xml:"link"`
	Description    string   `xml:"description"`
	Language       string   `xml:"language,omitempty"`
	Copyright      string   `xml:"copyright,omitempty"`
	ManagingEditor string   `xml:"managingEditor,omitempty"`
	WebMaster      string   `xml:"webMaster,omitempty"`
	PubDate        string   `xml:"pubDate,omitempty"`
	LastBuildDate  string   `xml:"lastBuildDate,omitempty"`
	Categories     []string `xml:"category,omitempty"`
	Generator      string   `xml:"generator,omitempty"`
	Docs           string   `xml:"docs,omitempty"`
	Cloud          string   `xml:"cloud,omitempty"`
	Image          *Image
	Rating         string `xml:"rating,omitempty"`
	TextInput      *TextInput
	SkipHours      []int `xml:"skipHours,omitempty"`
	SkipDays       []int `xml:"skipDays,omitempty"`
	Items          []*Item
	Ttl            int `xml:"ttl,omitempty"`
	wg             sync.WaitGroup
}

func (c *Channel) start() {
	c.wg.Done()

	for {
		select {
		case category := <-c.addCategory:
			c.Categories = append(c.Categories, category)
		case item := <-c.addItem:
			c.Items = append(c.Items, item)
		}

		c.LastBuildDate = time.Now().Format(time.RFC1123Z)
	}
}

func initChannel() *Channel {
	now := time.Now().Format(time.RFC1123Z)

	channel := &Channel{
		PubDate:       now,
		LastBuildDate: now,
	}

	channel.wg.Add(1)
	go channel.start()
	channel.wg.Wait()

	return channel
}

func (c *Channel) check() error {
	if len(c.Title) == 0 {
		return fmt.Errorf("error: title not set")
	}
	if len(c.Link) == 0 {
		return fmt.Errorf("error: link not set")
	}
	if len(c.Description) == 0 {
		return fmt.Errorf("error: description not set")
	}

	if err := c.Image.check(); err != nil {
		return fmt.Errorf("error checking image: %v", err)
	}
	if err := c.TextInput.check(); err != nil {
		return fmt.Errorf("error checking textInput: %v", err)
	}

	for _, item := range c.Items {
		if err := item.check(); err != nil {
			return fmt.Errorf("error checking item: %v", err)
		}
	}

	return nil
}

func NewChannel() *Channel {
	return initChannel()
}

func (c *Channel) AddCategory(category string) {
	c.addCategory <- category
}

func (c *Channel) AddItem(i *Item) {
	c.addItem <- i
}