package main

import (
	"bufio"
	"bytes"
	"crypto/sha1"
	"encoding/gob"
	"encoding/hex"
	"encoding/xml"
	"flag"
	"fmt"
	"io"
	"os"
	"strconv"
	"time"

	"go.stargrave.org/rutrackerer"
)

func main() {
	doCSV := flag.Bool("csv", false, "Output CSV instead of gob")
	flag.Parse()
	br := bufio.NewReader(os.Stdin)
	d := xml.NewDecoder(br)
	var t xml.Token
	var err error
	var e xml.StartElement
	var ok bool
	for {
		t, err = d.Token()
		if err != nil {
			panic(err)
		}
		e, ok = t.(xml.StartElement)
		if ok && e.Name.Local == "torrents" {
			break
		}
	}
	var gobEnc *gob.Encoder
	bufStdout := bufio.NewWriter(os.Stdout)
	if !*doCSV {
		gobEnc = gob.NewEncoder(bufStdout)
	}
	emptyHash := make([]byte, sha1.Size)
	var torrent *rutrackerer.Torrent
	var c xml.CharData
	var attr xml.Attr
	for {
		t, err = d.Token()
		if err != nil {
			if err == io.EOF {
				break
			}
			panic(err)
		}
		e, ok = t.(xml.StartElement)
		if !ok {
			continue
		}
		switch e.Name.Local {
		case "title":
			t, err = d.Token()
			if err != nil {
				panic(err)
			}
			c, ok = t.(xml.CharData)
			if !ok {
				panic("non-character data after title")
			}
			torrent.Title = string(c)
		case "torrent":
			if len(e.Attr) < 3 {
				for _, attr = range e.Attr {
					if attr.Name.Local != "hash" {
						continue
					}
					if len(attr.Value) != sha1.Size*2 {
						panic("bad hash size")
					}
					_, err = hex.Decode(torrent.Hash[:], []byte(attr.Value))
					if err != nil {
						panic(err)
					}
				}
				continue
			}
			if torrent != nil {
				if torrent.Title == "" {
					panic("empty title")
				}
				if torrent.Id == 0 {
					panic("empty id")
				}
				if torrent.Size == 0 {
					panic("empty size")
				}
				if bytes.Compare(torrent.Hash[:], emptyHash) == 0 {
					panic("empty hash")
				}
				if *doCSV {
					fmt.Println(torrent.CSV())
				} else {
					if err = gobEnc.Encode(torrent); err != nil {
						panic(err)
					}
				}
			}
			torrent = new(rutrackerer.Torrent)
			for _, attr = range e.Attr {
				switch attr.Name.Local {
				case "id":
					torrent.Id, err = strconv.ParseInt(attr.Value, 10, 64)
					if err != nil {
						panic(err)
					}
					torrent.Offset = d.InputOffset()
				case "registred_at":
					torrent.Registered, err = time.Parse(
						"2006.01.02 15:04:05", attr.Value,
					)
					if err != nil {
						panic(err)
					}
				case "size":
					torrent.Size, err = strconv.ParseInt(attr.Value, 10, 64)
					if err != nil {
						panic(err)
					}
				}
			}
		}
	}
	if !*doCSV {
		if err = bufStdout.Flush(); err != nil {
			panic(err)
		}
	}
}