Fix prefix distribution bug and add prefix length pages

- Fix GetPrefixDistribution to count unique prefixes using COUNT(DISTINCT prefix) instead of COUNT(*)
- Add /prefixlength/<length> route showing random sample of 500 prefixes
- Make prefix counts on status page clickable links to prefix length pages
- Add GetRandomPrefixesByLength database method
- Create prefix_length.html template with sortable table
- Show prefix age and origin AS with descriptions

internal/database/database.go

@@ -884,11 +884,11 @@ func (d *Database) DeleteLiveRoute(prefix string, originASN int, peerIP string)
 	return err
 }
 
-// GetPrefixDistribution returns the distribution of prefixes by mask length
+// GetPrefixDistribution returns the distribution of unique prefixes by mask length
 func (d *Database) GetPrefixDistribution() (ipv4 []PrefixDistribution, ipv6 []PrefixDistribution, err error) {
-	// IPv4 distribution
+	// IPv4 distribution - count unique prefixes, not routes
 	query := `
-		SELECT mask_length, COUNT(*) as count
+		SELECT mask_length, COUNT(DISTINCT prefix) as count
 		FROM live_routes
 		WHERE ip_version = 4
 		GROUP BY mask_length
@@ -908,9 +908,9 @@ func (d *Database) GetPrefixDistribution() (ipv4 []PrefixDistribution, ipv6 []Pr
 		ipv4 = append(ipv4, dist)
 	}
 
-	// IPv6 distribution
+	// IPv6 distribution - count unique prefixes, not routes
 	query = `
-		SELECT mask_length, COUNT(*) as count
+		SELECT mask_length, COUNT(DISTINCT prefix) as count
 		FROM live_routes
 		WHERE ip_version = 6
 		GROUP BY mask_length
@@ -1227,3 +1227,51 @@ func (d *Database) GetPrefixDetails(prefix string) ([]LiveRoute, error) {
 
 	return routes, nil
 }
+
+// GetRandomPrefixesByLength returns a random sample of prefixes with the specified mask length
+func (d *Database) GetRandomPrefixesByLength(maskLength, ipVersion, limit int) ([]LiveRoute, error) {
+	query := `
+		SELECT DISTINCT 
+			prefix, mask_length, ip_version, origin_asn, as_path, 
+			peer_ip, last_updated
+		FROM live_routes
+		WHERE mask_length = ? AND ip_version = ?
+		ORDER BY RANDOM()
+		LIMIT ?
+	`
+
+	rows, err := d.db.Query(query, maskLength, ipVersion, limit)
+	if err != nil {
+		return nil, fmt.Errorf("failed to query random prefixes: %w", err)
+	}
+	defer func() {
+		_ = rows.Close()
+	}()
+
+	var routes []LiveRoute
+	for rows.Next() {
+		var route LiveRoute
+		var pathJSON string
+		err := rows.Scan(
+			&route.Prefix,
+			&route.MaskLength,
+			&route.IPVersion,
+			&route.OriginASN,
+			&pathJSON,
+			&route.PeerIP,
+			&route.LastUpdated,
+		)
+		if err != nil {
+			continue
+		}
+
+		// Decode AS path
+		if err := json.Unmarshal([]byte(pathJSON), &route.ASPath); err != nil {
+			route.ASPath = []int{}
+		}
+
+		routes = append(routes, route)
+	}
+
+	return routes, nil
+}

internal/database/interface.go

@@ -54,6 +54,7 @@ type Store interface {
 	// AS and prefix detail operations
 	GetASDetails(asn int) (*ASN, []LiveRoute, error)
 	GetPrefixDetails(prefix string) ([]LiveRoute, error)
+	GetRandomPrefixesByLength(maskLength, ipVersion, limit int) ([]LiveRoute, error)
 
 	// Lifecycle
 	Close() error