/*
meta4a -- Metalink 4.0 checker
Copyright (C) 2021-2023 Sergey Matveev <stargrave@stargrave.org>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

// Metalink 4.0 checker
package main

import (
	"bufio"
	"encoding/xml"
	"flag"
	"fmt"
	"io"
	"io/fs"
	"log"
	"os"
	"strings"

	"go.stargrave.org/meta4ra"
)

func main() {
	hashes := flag.String("hashes", strings.Join(meta4ra.HashesDefault, ","), "hash-name:command-s")
	extractSig := flag.Bool("extract-sig", false, "Extract signature files")
	log.SetFlags(log.Lshortfile)
	flag.Parse()
	bad := false
	for _, metaPath := range flag.Args() {
		data, err := os.ReadFile(metaPath)
		if err != nil {
			log.Fatalln(err)
		}
		var meta meta4ra.Metalink
		err = xml.Unmarshal(data, &meta)
		if err != nil {
			log.Fatalln(err)
		}
		for _, f := range meta.Files {
			if f.Signature != nil && *extractSig {
				if err = os.WriteFile(
					f.Name+".asc",
					[]byte(f.Signature.Signature),
					fs.FileMode(0666),
				); err != nil {
					fmt.Println("Error:", f.Name, "can not save signature:", err)
					bad = true
				}
			}
			hasher := meta4ra.NewHasher(*hashes)
			var hashTheir string
			var hashName string
			for i, name := range hasher.Names {
				for _, h := range f.Hashes {
					if h.Type == name {
						hasher.Names = []string{name}
						hasher.Cmds = append(hasher.Cmds[:0], hasher.Cmds[i])
						hasher.Ins = append(hasher.Ins[:0], hasher.Ins[i])
						hasher.Outs = append(hasher.Outs[:0], hasher.Outs[i])
						hashName = name
						hashTheir = h.Hash
						goto HashFound
					}
				}
			}
			log.Fatalln("no common hashes found for:", f.Name)
		HashFound:
			fd, err := os.Open(f.Name)
			if err != nil {
				continue
			}
			hasher.Start()
			_, err = io.Copy(hasher, bufio.NewReaderSize(fd, 1<<20))
			fd.Close()
			sums := hasher.Sums()
			if err != nil {
				fmt.Println("Error:", f.Name, err)
				bad = true
				continue
			}
			hashOur := sums[0].Hash
			if hashOur == hashTheir {
				fmt.Println(f.Name, hashName, "good")
			} else {
				fmt.Println(
					"Hash does not match:", f.Name, hashName,
					"our:", hashOur,
					"their:", hashTheir,
				)
				bad = true
				continue
			}
		}
	}
	if bad {
		os.Exit(1)
	}
}