// SGBlog -- Git-backed CGI/UCSPI blogging/phlogging/gemlogging engine
// Copyright (C) 2020-2024 Sergey Matveev <stargrave@stargrave.org>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero 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 Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

// SGBlog -- Git-backed CGI/UCSPI blogging/phlogging/gemlogging engine
package sgblog

import (
	"bytes"
	"fmt"
	"io"
	"sort"
	"text/scanner"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
	"github.com/go-git/go-git/v5/plumbing/object"
	"go.cypherpunks.ru/recfile"
)

const (
	Version = "0.34.0"
	WhenFmt = "2006-01-02 15:04:05Z07:00"
)

func ParseComments(data []byte) []string {
	comments := []string{}
	r := recfile.NewReader(bytes.NewReader(data))
	for {
		fields, err := r.Next()
		if err != nil {
			break
		}
		if len(fields) != 3 ||
			fields[0].Name != "From" ||
			fields[1].Name != "Date" ||
			fields[2].Name != "Body" {
			continue
		}
		comments = append(comments, fmt.Sprintf(
			"%s: %s\n%s: %s\n%s",
			fields[0].Name, fields[0].Value,
			fields[1].Name, fields[1].Value,
			fields[2].Value,
		))
	}
	return comments
}

func ParseTopics(data []byte) []string {
	var s scanner.Scanner
	s.Init(bytes.NewBuffer(data))
	topics := []string{}
	for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
		topics = append(topics, s.TokenText())
	}
	sort.Strings(topics)
	return topics
}

func GetNote(repo *git.Repository, tree *object.Tree, what plumbing.Hash) []byte {
	if tree == nil {
		return nil
	}
	var entry *object.TreeEntry
	var err error
	paths := make([]string, 3)
	paths[0] = what.String()
	paths[1] = paths[0][:2] + "/" + paths[0][2:]
	paths[2] = paths[1][:4+1] + "/" + paths[1][4+1:]
	for _, p := range paths {
		entry, err = tree.FindEntry(p)
		if err == nil {
			break
		}
	}
	if entry == nil {
		return nil
	}
	blob, err := repo.BlobObject(entry.Hash)
	if err != nil {
		return nil
	}
	r, err := blob.Reader()
	if err != nil {
		return nil
	}
	data, err := io.ReadAll(r)
	if err != nil {
		return nil
	}
	return bytes.TrimSuffix(data, []byte{'\n'})
}