package main

import (
	e "codeberg.org/pebbe/errors"

	"encoding/xml"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"time"
)

type Rss struct {
	XMLName xml.Name `xml:"rss"`
	Items   []ItemT  `xml:"channel>item"`
}

type ItemT struct {
	PubDate  string `xml:"pubDate"`
	UnixTime int64  `xml:"unixTime"`
	Link     string `xml:"link"`
	Guid     string `xml:"guid"`
	Data     []byte `xml:",innerxml"`
}

var (
	p     = e.PanicErr
	agent = "AhrefsBot/7.0"
)

func exists(filename string) bool {
	_, err := os.Stat(filename)
	return err == nil
}

func main() {
	defer func() {
		if e.Panicked {
			_ = recover()
			os.Exit(1)
		}
	}()

	myLock := "/net/corpora/nlnieuws/Oog/lock"
	mkLock(myLock)
	defer func() {
		_ = os.Remove(myLock)
	}()

	req, err := http.NewRequest("GET", "https://www.oogtv.nl/feed/", nil)
	p(err)
	req.Header.Set("User-Agent", agent)

	client := &http.Client{}
	resp, err := client.Do(req)
	p(err)
	body, err := io.ReadAll(resp.Body)
	p(err)
	p(resp.Body.Close())

	var rss Rss
	p(xml.Unmarshal(body, &rss))

	if len(rss.Items) == 0 {
		p(fmt.Errorf("len(rss.Items) == 0"))
	}

	for _, item := range rss.Items {
		t, err := time.Parse(time.RFC1123Z, item.PubDate)
		if err != nil {
			t, err = time.Parse(time.RFC1123, item.PubDate)
		}
		p(err)
		year, week := t.ISOWeek()
		dirname := fmt.Sprintf("/net/corpora/nlnieuws/Oog/%d/%02d", year, week)
		if exists(dirname + "/lock") {
			continue
		}
		basename := strings.TrimPrefix(item.Guid, "https://www.oogtv.nl/?p=")
		if i := strings.LastIndex(basename, "/"); i > 0 {
			basename = basename[:i]
		}
		filename := dirname + "/" + url.PathEscape(basename)

		p(os.MkdirAll(dirname, 0777))
		func() {
			var ok bool
			defer func() {
				if e.Panicked {
					fmt.Fprintln(os.Stderr, "----", filename)
					fmt.Fprintln(os.Stderr, "----", item.Link)
				}
				if !ok {
					_ = os.Remove(filename + ".xml")
				}
			}()
			fp, err := os.Create(filename + ".xml")
			p(err)
			p(fp.WriteString("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<item>\n"))
			p(fmt.Fprintf(fp, "<unixTime>%d</unixTime>", t.Unix()))
			p(fp.Write(item.Data))
			p(fp.WriteString("</item>\n"))
			p(fp.Close())
			p(os.Chtimes(filename+".xml", t, t))
			ok = true
		}()
	}

}

func mkLock(filename string) {
	pid := os.Getpid()
	link := fmt.Sprintf("%s.%d", filepath.Base(filename), pid)
	p(os.Symlink(link, filename))

	name, err := os.Readlink(filename)
	p(err)

	if name != link {
		p(fmt.Errorf("wrong lock name %q, should be %q", name, link))
	}
}