package feed

import (
	"fmt"
	"strings"
	"time"

	"golang.org/x/net/html"
)

const feedfmt = `<?xml version="1.0" encoding="utf-8"?>
    <rss version="2.0">
        <channel>
            <title>%s</title>
            <link>%s</link>
            <description>%s</description>%s
        </channel>
    </rss>`

const itemfmt = `
            <item>
                <title>Content Title</title>
                <link>%s</link>
                <guid>%s</guid>
                <pubDate>%s</pubDate>
                <description>
                    %s
                </description>
            </item>`

type RSSBuilder struct {
    Info    FeedInfo
    Items   []FeedItem
}

func GenerateRss(siteUrl, siteTitle, siteDesc string, pageUrls ...string) (string, error) {
    var items strings.Builder
    var errs strings.Builder
    var err error

    for _, u := range pageUrls {
        var formattedArticle strings.Builder
        var err error
        page, err := fetchPage(u)
        if err != nil {
            continue
        }
        article, atime, err := parseArticle(page)
        if err != nil && article == "" {
            errs.WriteString(fmt.Sprintf("error parsing article %s: %s", u, err.Error()))
            continue
        }
        for _, line := range strings.Split(article, "\n") {
            formattedArticle.WriteString(fmt.Sprintf("\t\t%s\n", html.EscapeString(line)))
        }
        if atime != nil {
            items.WriteString(fmt.Sprintf(itemfmt, u, u, atime.Format("Mon, 2 Jan 2006 15:04:05 MST"), formattedArticle.String()))
        } else {
            items.WriteString(fmt.Sprintf(itemfmt, u, u, time.Now().Format("Mon, 2 Jan 2006 15:04:05 MST"), formattedArticle.String()))
        }
    }

    return fmt.Sprintf(feedfmt, siteTitle, siteUrl, siteDesc, items.String()), err
}