Add JSON lines parser implementation with IP extraction support

parser/json_lines.go

@@ -0,0 +1,59 @@
+package parser
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+)
+
+type jsonLinesExtract func(item json.RawMessage) (string, error)
+
+type jsonLinesParser struct {
+	extract jsonLinesExtract
+}
+
+func NewJsonLines(extract jsonLinesExtract) (Parser, error) {
+	if extract == nil {
+		return nil, fmt.Errorf("json lines extract is nil")
+	}
+
+	return &jsonLinesParser{
+		extract: extract,
+	}, nil
+}
+
+func (p *jsonLinesParser) Parse(body io.Reader, validator IPValidator, limit uint) (IPs, error) {
+	decoder := json.NewDecoder(body)
+	ips := make(IPs, 0)
+	for {
+		var item json.RawMessage
+		if err := decoder.Decode(&item); err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, fmt.Errorf("decode json item: %w", err)
+		}
+
+		if item == nil {
+			continue
+		}
+
+		ip, err := p.extract(item)
+		if err != nil {
+			return nil, fmt.Errorf("extract ip: %w", err)
+		}
+
+		ip = strings.TrimSpace(ip)
+		if !validator.IsValid(ip) {
+			continue
+		}
+
+		ips = append(ips, ip)
+		if limit > 0 && uint(len(ips)) >= limit {
+			break
+		}
+	}
+
+	return ips, nil
+}