very dumb adapter from redis GET, PUT, DEL to SELECT, INSERT ON CONFLICT UPDATE, DELETE

src/adapt.go

@@ -1,13 +1,143 @@
 package src
 
 import (
+	"bufio"
+	"bytes"
 	"context"
+	"fmt"
 	"io"
+	"log"
 	"net"
+	"strconv"
 )
 
 func adapt(ctx context.Context, config Config, conn net.Conn) error {
+	reader := bufio.NewReader(conn)
+
 	for ctx.Err() == nil {
+		message, err := readMessage(reader)
+		if err != nil {
+			if err == io.EOF {
+				return nil
+			}
+			return err
+		}
+
+		if len(message) > 0 {
+			var reply string
+			switch message[0] {
+			case "hello":
+				reply = "*0\r\n"
+			case "client":
+				reply = "+OK\r\n"
+			case "ping":
+				reply = "+PONG\r\n"
+			case "set":
+				k := message[1].(string)
+				v := message[2]
+				reply = "+OK\r\n"
+				switch v2 := v.(type) {
+				case []byte:
+					if err := config.db.Put(ctx, 1, k, string(v2)); err != nil {
+						reply = "-" + err.Error() + "\r\n"
+					}
+				case string:
+					if err := config.db.Put(ctx, 1, k, v2); err != nil {
+						reply = "-" + err.Error() + "\r\n"
+					}
+				default:
+					log.Fatalf("not impl: set %T", v)
+				}
+			case "del":
+				k := message[1].(string)
+				reply = "+OK\r\n"
+				if err := config.db.Del(ctx, 1, k); err != nil {
+					reply = "-" + err.Error() + "\r\n"
+				}
+			case "get":
+				v, err := Select[any](ctx, 1, fmt.Sprint(message[1]))
+				if err != nil {
+					reply = "-" + err.Error()
+				} else if v == nil || *v == nil {
+					reply = "_\r\n" // RESP3 null
+				} else {
+					switch v2 := (*v).(type) {
+					case []byte:
+						reply = fmt.Sprintf("+%s\r\n", v2)
+					case string:
+						reply = fmt.Sprintf("+%s\r\n", v2)
+					default:
+						log.Fatalf("not impl: get type %T", v2)
+						return nil
+					}
+				}
+			default:
+				log.Fatalf("unhandled: %+v", message)
+			}
+			log.Printf("replying: %q", reply)
+			if _, err := fmt.Fprintf(conn, reply); err != nil {
+				return err
+			}
+		}
+
+		log.Println()
 	}
+
 	return io.EOF
 }
+
+func readMessage(reader *bufio.Reader) ([]any, error) {
+	firstLine, _, err := reader.ReadLine()
+	log.Printf("%q", firstLine)
+	if err != nil {
+		return nil, err
+	}
+	firstLine = bytes.TrimSuffix(firstLine, []byte("\r\n"))
+	if len(firstLine) == 0 {
+		return nil, nil
+	}
+
+	switch firstLine[0] {
+	case '+': // simple string, like +OK
+		return []any{string(firstLine[1:])}, nil
+	case '-': // simple error, like -message
+		return nil, fmt.Errorf("error: %s", firstLine[1:])
+	case ':': // number, like /[+-][0-9]+/
+		firstLine = bytes.TrimPrefix(firstLine[1:], []byte("+"))
+		n, err := strconv.Atoi(string(firstLine[1:]))
+		return []any{n}, err
+	case '$': // long string, like $-1 for nil, like $LEN\r\nSTRING\r\n
+		if firstLine[1] == '-' {
+			return []any{nil}, nil
+		}
+		nextLine, _, err := reader.ReadLine()
+		log.Printf("%q", nextLine)
+		nextLine = bytes.TrimSuffix(nextLine, []byte("\r\n"))
+		return []any{string(nextLine)}, err
+	case '*': // array, like *-1 for nil, like *4 for [1,2,3,4]
+		n, err := strconv.Atoi(string(firstLine[1:]))
+		if err != nil {
+			return nil, err
+		} else if n == -1 {
+			return nil, nil
+		}
+		var result []any
+		for i := 0; i < n; i++ {
+			more, err := readMessage(reader)
+			if err != nil {
+				return nil, err
+			}
+			result = append(result, more...)
+		}
+		return result, nil
+	case '_': // nil
+		return nil, nil
+	case '#': // boolean, like #t or #f
+		return []any{firstLine[1] == 't'}, nil
+	case ',': // double
+		log.Fatal("not impl")
+	}
+
+	log.Fatalf("not impl: %q", firstLine)
+	return nil, nil
+}

src/db.go

@@ -36,7 +36,7 @@ func (db DB) setup(ctx context.Context) error {
 		return err
 	}
 	if _, err := db.ExecContext(ctx, `
-		CREATE TABLE data (
+		CREATE TABLE IF NOT EXISTS data (
 			database INTEGER
 			, key TEXT
 			, value TEXT