// godlighty -- highly-customizable HTTP, HTTP/2, HTTPS server
// Copyright (C) 2021-2024 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/>.

package meta4

import (
	"encoding/hex"
	"encoding/xml"
)

var KnownHashes = map[string]string{
	"blake3-256":   "BLAKE3-256",
	"blake2b-512":  "BLAKE2b-512",
	"blake2b-256":  "BLAKE2b-256",
	"sha-256":      "SHA-256",
	"sha-512":      "SHA-512",
	"shake128":     "SHAKE128",
	"shake256":     "SHAKE256",
	"skein-256":    "Skein-256",
	"skein-512":    "Skein-512",
	"streebog-256": "Streebog-256",
	"streebog-512": "Streebog-512",
	"xxh3-128":     "XXH3-128",
}

type ForHTTP struct {
	Hashes   map[string][]byte
	URLs     []string
	Torrents []string
}

func Parse(fn string, data []byte) (*ForHTTP, error) {
	var meta Metalink
	err := xml.Unmarshal(data, &meta)
	if err != nil {
		return nil, err
	}
	for _, f := range meta.Files {
		if f.Name != fn {
			continue
		}
		forHTTP := ForHTTP{Hashes: make(map[string][]byte)}
		for _, h := range f.Hashes {
			name := KnownHashes[h.Type]
			if name == "" {
				continue
			}
			digest, err := hex.DecodeString(h.Hash)
			if err != nil {
				return nil, err
			}
			forHTTP.Hashes[name] = digest
		}
		for _, u := range f.URLs {
			forHTTP.URLs = append(forHTTP.URLs, u.URL)
		}
		for _, m := range f.MetaURLs {
			if m.MediaType == "torrent" {
				forHTTP.Torrents = append(forHTTP.Torrents, m.URL)
			}
		}
		return &forHTTP, nil
	}
	return nil, nil
}