add nip34/git-natural-api, using the same approach as https://jsr.io/@fiatjaf/git-natural-api.

nip34/gitnaturalapi/commits.go

@@ -0,0 +1,106 @@
+package gitnaturalapi
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+type Person struct {
+	Name      string
+	Email     string
+	Timestamp int64
+	Timezone  string
+}
+
+type Commit struct {
+	Hash      string
+	Tree      string
+	Parents   []string
+	Author    Person
+	Committer Person
+	Message   string
+}
+
+func ParseCommit(data []byte, hash string) (*Commit, error) {
+	content := string(data)
+
+	headerEndIndex := strings.Index(content, "\n\n")
+	if headerEndIndex == -1 {
+		return nil, fmt.Errorf("invalid commit format for %s: no message separator found", hash)
+	}
+
+	header := content[:headerEndIndex]
+	message := content[headerEndIndex+2:]
+
+	lines := strings.Split(header, "\n")
+	result := &Commit{
+		Hash:    hash,
+		Parents: []string{},
+		Message: message,
+	}
+
+	for _, line := range lines {
+		if strings.HasPrefix(line, "tree ") {
+			result.Tree = line[5:]
+		} else if strings.HasPrefix(line, "parent ") {
+			result.Parents = append(result.Parents, line[7:])
+		} else if strings.HasPrefix(line, "author ") {
+			person, err := parsePerson(line[7:])
+			if err != nil {
+				return nil, fmt.Errorf("invalid author in commit %s: %w", hash, err)
+			}
+			result.Author = person
+		} else if strings.HasPrefix(line, "committer ") {
+			person, err := parsePerson(line[10:])
+			if err != nil {
+				return nil, fmt.Errorf("invalid committer in commit %s: %w", hash, err)
+			}
+			result.Committer = person
+		}
+	}
+
+	if result.Tree == "" {
+		return nil, fmt.Errorf("invalid commit format for %s: missing tree", hash)
+	}
+	if result.Author.Name == "" {
+		return nil, fmt.Errorf("invalid commit format for %s: missing author", hash)
+	}
+	if result.Committer.Name == "" {
+		return nil, fmt.Errorf("invalid commit format for %s: missing committer", hash)
+	}
+
+	return result, nil
+}
+
+func parsePerson(line string) (Person, error) {
+	emailStart := strings.Index(line, " <")
+	if emailStart == -1 {
+		return Person{}, fmt.Errorf("invalid person format: %s", line)
+	}
+	name := line[:emailStart]
+
+	emailEnd := strings.Index(line[emailStart+2:], ">")
+	if emailEnd == -1 {
+		return Person{}, fmt.Errorf("invalid person format: %s", line)
+	}
+	email := line[emailStart+2 : emailStart+2+emailEnd]
+
+	rest := strings.TrimSpace(line[emailStart+2+emailEnd+1:])
+	parts := strings.SplitN(rest, " ", 2)
+	if len(parts) != 2 {
+		return Person{}, fmt.Errorf("invalid person format: %s", line)
+	}
+
+	timestamp, err := strconv.ParseInt(parts[0], 10, 64)
+	if err != nil {
+		return Person{}, fmt.Errorf("invalid timestamp in person: %s", parts[0])
+	}
+
+	return Person{
+		Name:      name,
+		Email:     email,
+		Timestamp: timestamp,
+		Timezone:  parts[1],
+	}, nil
+}