Add stub database selection, and fix differences between pekoe and c-redis

- PUBSUB CHANNELS glob pattern matching
- Implement SELECT + max DB validation (0-15) (default db max is 16), for perl clients
- CLIENT KILL ID (single/range) + MAXAGE
- CLIENT INFO events + resp fields
- PUBSUB SHARDCHANNELS/SHARDNUMSUB stubs

internal/server/handlers.go

@@ -5,7 +5,9 @@ package server
 import (
 	"fmt"
 	"strings"
+	"time"
 
+	"github.com/eleksir/pekoe/internal/glob"
 	"github.com/eleksir/pekoe/internal/logger"
 	"github.com/eleksir/pekoe/internal/protocol"
 	"github.com/eleksir/pekoe/internal/pubsub"
@@ -132,12 +134,24 @@ func (s *Server) handlePubsub(args [][]byte, writer *ConnWriter) error {
 			pattern = string(args[1])
 		}
 		channels := s.channelList(pattern)
-		result := make([]protocol.Value, len(channels))
-		for i, ch := range channels {
-			result[i] = protocol.Bulk(ch)
+		result := make([]protocol.Value, 0, len(channels))
+		for _, ch := range channels {
+			if pattern == "" || glob.Match(pattern, ch) {
+				result = append(result, protocol.Bulk(ch))
+			}
 		}
 		writer.WriteArray(result)
 
+	case "shardchannels":
+		// PUBSUB SHARDCHANNELS [pattern] - List active sharded channels
+		// Pekoe doesn't support sharded pubsub, return empty list
+		writer.WriteArray(nil)
+
+	case "shardnumsub":
+		// PUBSUB SHARDNUMSUB [shardchannel ...] - Get subscriber count for sharded channels
+		// Pekoe doesn't support sharded pubsub, return empty array
+		writer.WriteArray(nil)
+
 	case "numpat":
 		// PUBSUB NUMPAT - Count of unique pattern subscriptions
 		writer.WriteInt(int64(s.hub.PatternCount()))
@@ -147,7 +161,9 @@ func (s *Server) handlePubsub(args [][]byte, writer *ConnWriter) error {
 		helpText := []string{
 			"PUBSUB <subcommand> [<argument> [<argument> ...]]>",
 			"  PUBSUB CHANNELS [pattern] - List active channels (optionally filtered by pattern)",
+			"  PUBSUB SHARDCHANNELS [pattern] - List active sharded channels (not supported)",
 			"  PUBSUB NUMSUB [channel ...] - Get subscriber count for channels",
+			"  PUBSUB SHARDNUMSUB [shardchannel ...] - Get subscriber count for sharded channels (not supported)",
 			"  PUBSUB NUMPAT - Get the number of pattern subscriptions",
 			"  PUBSUB HELP - Show this help message",
 		}
@@ -349,11 +365,15 @@ func (s *Server) buildClientList(args [][]byte) string {
 func (s *Server) handleClientKill(currentClient *pubsub.Client, args [][]byte) (int, error) {
 	clients := s.hub.GetAllClients()
 	killed := 0
+	var notFoundErr error
 
 	// Parse arguments
 	var killID uint64
+	var killIDMin uint64
+	var killIDMax uint64
 	var killAddr string
 	var skipMe = true
+	var maxAgeMs int64
 
 	for i := 0; i < len(args); i++ {
 		arg := strings.ToUpper(string(args[i]))
@@ -361,6 +381,12 @@ func (s *Server) handleClientKill(currentClient *pubsub.Client, args [][]byte) (
 		case "ID":
 			if i+2 < len(args) {
 				// ID min max format - kill all IDs in range
+				if _, err := fmt.Sscanf(string(args[i+1]), "%d", &killIDMin); err != nil {
+					return 0, fmt.Errorf("invalid client ID: %s", args[i+1])
+				}
+				if _, err := fmt.Sscanf(string(args[i+2]), "%d", &killIDMax); err != nil {
+					return 0, fmt.Errorf("invalid client ID: %s", args[i+2])
+				}
 				i += 2
 			} else if i+1 < len(args) {
 				// Single ID
@@ -374,14 +400,35 @@ func (s *Server) handleClientKill(currentClient *pubsub.Client, args [][]byte) (
 				killAddr = string(args[i+1])
 				i++
 			}
+		case "LADDR":
+			// LADDR not fully supported, just skip
+			if i+1 < len(args) {
+				i++
+			}
 		case "SKIPME":
 			if i+1 < len(args) {
 				skipMe = strings.ToUpper(string(args[i+1])) == "YES"
 				i++
 			}
+		case "MAXAGE":
+			if i+1 < len(args) {
+				if _, err := fmt.Sscanf(string(args[i+1]), "%d", &maxAgeMs); err != nil {
+					return 0, fmt.Errorf("invalid maxage: %s", args[i+1])
+				}
+				if maxAgeMs <= 0 {
+					return 0, fmt.Errorf("maxage must be greater than 0")
+				}
+				i++
+			}
+		case "TYPE":
+			// TYPE filter handled separately in handleClient
+			if i+1 < len(args) {
+				i++
+			}
 		}
 	}
 
+	now := time.Now()
 	for _, c := range clients {
 		// Skip current client if requested
 		if skipMe && c.ID() == currentClient.ID() {
@@ -390,11 +437,29 @@ func (s *Server) handleClientKill(currentClient *pubsub.Client, args [][]byte) (
 
 		shouldKill := false
 
-		if killID > 0 && c.ID() == killID {
-			shouldKill = true
+		// Check ID (single or range)
+		if killID > 0 {
+			shouldKill = c.ID() == killID
+		} else if killIDMin > 0 || killIDMax > 0 {
+			id := c.ID()
+			if killIDMin > 0 && id < killIDMin {
+				shouldKill = false
+			} else if killIDMax > 0 && id > killIDMax {
+				shouldKill = false
+			} else {
+				shouldKill = true
+			}
 		}
-		if killAddr != "" && c.RemoteAddr() == killAddr {
-			shouldKill = true
+
+		// Check ADDR
+		if !shouldKill && killAddr != "" {
+			shouldKill = c.RemoteAddr() == killAddr
+		}
+
+		// Check MAXAGE
+		if shouldKill && maxAgeMs > 0 {
+			age := now.Sub(c.CreatedAt()).Milliseconds()
+			shouldKill = age >= maxAgeMs
 		}
 
 		if shouldKill {
@@ -406,7 +471,39 @@ func (s *Server) handleClientKill(currentClient *pubsub.Client, args [][]byte) (
 		}
 	}
 
-	return killed, nil
+	// For single ID/ADDR that wasn't found, Redis returns error
+	if killed == 0 && (killID > 0 || killAddr != "") {
+		return 0, fmt.Errorf("No such client")
+	}
+
+	return killed, notFoundErr
+}
+
+// handleSelect processes SELECT command.
+// SELECT db - Switch to a different database (0-15).
+// For pekoe (pubsub-only), this only tracks the selected DB for client compatibility.
+// Redis default max DB is 16 (0-15), configurable via max-databases in config.
+func (s *Server) handleSelect(client *pubsub.Client, args [][]byte, writer *ConnWriter) error {
+	if len(args) != 1 {
+		writer.WriteError("ERR wrong number of arguments for 'select' command")
+		return nil
+	}
+
+	dbIndexStr := string(args[0])
+	var dbIndex int
+	if _, err := fmt.Sscanf(dbIndexStr, "%d", &dbIndex); err != nil {
+		writer.WriteError("ERR invalid DB index")
+		return nil
+	}
+
+	if dbIndex < 0 || dbIndex >= MaxDatabases {
+		writer.WriteError("ERR DB index is out of range")
+		return nil
+	}
+
+	client.SetSelectedDB(dbIndex)
+	writer.WriteStatus("OK")
+	return nil
 }
 
 // handlePsubscribe processes PSUBSCRIBE command.

internal/server/server.go

@@ -21,6 +21,8 @@ import (
 	"github.com/eleksir/pekoe/internal/pubsub"
 )
 
+const MaxDatabases = 16 // Redis default maximum databases (0-15)
+
 // Sentinel errors for connection handling
 var (
 	ErrQuit = errors.New("client quit")
@@ -276,6 +278,8 @@ func (s *Server) processCommand(client *pubsub.Client, cmd *Command, writer *Con
 		return s.handleQuit(client, writer)
 	case "client":
 		return s.handleClient(client, cmd.Args[1:], writer)
+	case "select":
+		return s.handleSelect(client, cmd.Args[1:], writer)
 	default:
 		// Check if client is in pubsub mode - only pubsub commands allowed
 		if client != nil && (client.SubsCount() > 0 || client.PatternSubsCount() > 0) {