init

internal/util/hash.go

@@ -0,0 +1,59 @@
+package util
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// ParseHex parses a hexadecimal value from the hash string
+// This implementation is shared between engine and jdenticon packages for consistency
+func ParseHex(hash string, startPosition, octets int) (int, error) {
+	// Handle negative indices (count from end like JavaScript)
+	if startPosition < 0 {
+		startPosition = len(hash) + startPosition
+	}
+	
+	// Ensure we don't go out of bounds
+	if startPosition < 0 || startPosition >= len(hash) {
+		return 0, fmt.Errorf("parseHex: position %d out of bounds for hash length %d", startPosition, len(hash))
+	}
+	
+	// If octets is 0 or negative, read from startPosition to end (like JavaScript default)
+	end := len(hash)
+	if octets > 0 {
+		end = startPosition + octets
+		if end > len(hash) {
+			end = len(hash)
+		}
+	}
+	
+	// Extract substring and parse as hexadecimal
+	substr := hash[startPosition:end]
+	if len(substr) == 0 {
+		return 0, fmt.Errorf("parseHex: empty substring at position %d", startPosition)
+	}
+	
+	result, err := strconv.ParseInt(substr, 16, 64)
+	if err != nil {
+		return 0, fmt.Errorf("parseHex: failed to parse hex '%s' at position %d: %w", substr, startPosition, err)
+	}
+	
+	return int(result), nil
+}
+
+// IsValidHash checks if a hash string is valid for jdenticon generation
+// This implementation is shared between engine and jdenticon packages for consistency
+func IsValidHash(hash string) bool {
+	if len(hash) < 11 {
+		return false
+	}
+	
+	// Check if all characters are valid hexadecimal
+	for _, r := range hash {
+		if !((r >= '0' && r <= '9') || (r >= 'a' && r <= 'f') || (r >= 'A' && r <= 'F')) {
+			return false
+		}
+	}
+	
+	return true
+}