feat: added DECR command support

echovault/api_generic_test.go

@@ -983,3 +983,67 @@ func TestEchoVault_INCR(t *testing.T) {
 		})
 	}
 }
+
+func TestEchoVault_DECR(t *testing.T) {
+	server := createEchoVault()
+
+	tests := []struct {
+		name         string
+		key          string
+		presetValues map[string]internal.KeyData
+		want         int
+		wantErr      bool
+	}{
+		{
+			name:         "1. Decrement non-existent key",
+			key:          "DecrKey1",
+			presetValues: nil,
+			want:         0,
+			wantErr:      false,
+		},
+		{
+			name: "2. Decrement existing key with integer value",
+			key:  "DecrKey2",
+			presetValues: map[string]internal.KeyData{
+				"DecrKey2": {Value: "5"},
+			},
+			want:    4,
+			wantErr: false,
+		},
+		{
+			name: "3. Decrement existing key with non-integer value",
+			key:  "DecrKey3",
+			presetValues: map[string]internal.KeyData{
+				"DecrKey3": {Value: "not_an_int"},
+			},
+			want:    0,
+			wantErr: true,
+		},
+		{
+			name: "4. Decrement existing key with int64 value",
+			key:  "DecrKey4",
+			presetValues: map[string]internal.KeyData{
+				"DecrKey4": {Value: int64(10)},
+			},
+			want:    9,
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.presetValues != nil {
+				for k, d := range tt.presetValues {
+					presetKeyData(server, context.Background(), k, d)
+				}
+			}
+			got, err := server.Incr(tt.key)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("TTL() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("TTL() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

internal/modules/generic/commands.go

@@ -430,6 +430,53 @@ func handleIncr(params internal.HandlerFuncParams) ([]byte, error) {
 	return []byte(fmt.Sprintf(":%d\r\n", newValue)), nil
 }
 
+func handleDecr(params internal.HandlerFuncParams) ([]byte, error) {
+	// Extract key from command
+	keys, err := decrKeyFunc(params.Command)
+	if err != nil {
+		return nil, err
+	}
+
+	key := keys.WriteKeys[0]
+	values := params.GetValues(params.Context, []string{key}) // Get the current values for the specified keys
+	currentValue, ok := values[key]                           // Check if the key exists
+
+	var newValue int64
+	var currentValueInt int64
+
+	// Check if the key exists and its current value
+	if !ok || currentValue == nil {
+		// If key does not exist, initialize it with 0
+		newValue = -1
+	} else {
+		// Use type switch to handle different types of currentValue
+		switch v := currentValue.(type) {
+		case string:
+			var err error
+			currentValueInt, err = strconv.ParseInt(v, 10, 64) // Parse the string to int64
+			if err != nil {
+				return nil, errors.New("value is not an integer or out of range")
+			}
+		case int:
+			currentValueInt = int64(v) // Convert int to int64
+		case int64:
+			currentValueInt = v // Use int64 value directly
+		default:
+			fmt.Printf("unexpected type for currentValue: %T\n", currentValue)
+			return nil, errors.New("unexpected type for currentValue") // Handle unexpected types
+		}
+		newValue = currentValueInt - 1 // Decrement the value
+	}
+
+	// Set the new incremented value
+	if err := params.SetValues(params.Context, map[string]interface{}{key: fmt.Sprintf("%d", newValue)}); err != nil {
+		return nil, err
+	}
+
+	// Prepare response with the actual new value
+	return []byte(fmt.Sprintf(":%d\r\n", newValue)), nil
+}
+
 func Commands() []internal.Command {
 	return []internal.Command{
 		{
@@ -607,5 +654,14 @@ LT - Only set the expiry time if the new expiry time is less than the current on
 			KeyExtractionFunc: incrKeyFunc,
 			HandlerFunc:       handleIncr,
 		},
+		{
+			Command:           "decr",
+			Module:            constants.GenericModule,
+			Categories:        []string{constants.KeyspaceCategory, constants.WriteCategory, constants.FastCategory},
+			Description:       `(DECR key) Decrements the number stored at key by one. If the key does not exist, it is set to 0 before performing the operation. An error is returned if the key contains a value of the wrong type or contains a string that cannot be represented as integer. This operation is limited to 64 bit signed integers.`,
+			Sync:              true,
+			KeyExtractionFunc: decrKeyFunc,
+			HandlerFunc:       handleDecr,
+		},
 	}
 }

internal/modules/generic/commands_test.go

@@ -2016,4 +2016,125 @@ func Test_Generic(t *testing.T) {
 			})
 		}
 	})
+
+	t.Run("Test_HandlerDECR", func(t *testing.T) {
+		t.Parallel()
+		conn, err := internal.GetConnection("localhost", port)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		defer func() {
+			_ = conn.Close()
+		}()
+		client := resp.NewConn(conn)
+
+		tests := []struct {
+			name             string
+			key              string
+			presetValue      interface{}
+			command          []resp.Value
+			expectedResponse int64
+			expectedError    error
+		}{
+			{
+				name:             "1. Increment non-existent key",
+				key:              "DecrKey1",
+				presetValue:      nil,
+				command:          []resp.Value{resp.StringValue("DECR"), resp.StringValue("DecrKey1")},
+				expectedResponse: -1,
+				expectedError:    nil,
+			},
+			{
+				name:             "2. Decrement existing key with integer value",
+				key:              "DecrKey2",
+				presetValue:      "5",
+				command:          []resp.Value{resp.StringValue("DECR"), resp.StringValue("DecrKey2")},
+				expectedResponse: 4,
+				expectedError:    nil,
+			},
+			{
+				name:             "3. Decrement existing key with non-integer value",
+				key:              "DecrKey3",
+				presetValue:      "not_an_int",
+				command:          []resp.Value{resp.StringValue("DECR"), resp.StringValue("DecrKey3")},
+				expectedResponse: 0,
+				expectedError:    errors.New("value is not an integer or out of range"),
+			},
+			{
+				name:             "4. Decrement existing key with int64 value",
+				key:              "DecrKey4",
+				presetValue:      int64(10),
+				command:          []resp.Value{resp.StringValue("DECR"), resp.StringValue("DecrKey4")},
+				expectedResponse: 11,
+				expectedError:    nil,
+			},
+			{
+				name:             "5. Command too short",
+				key:              "DencrKey5",
+				presetValue:      nil,
+				command:          []resp.Value{resp.StringValue("DECR")},
+				expectedResponse: 0,
+				expectedError:    errors.New(constants.WrongArgsResponse),
+			},
+			{
+				name:        "6. Command too long",
+				key:         "DecrKey6",
+				presetValue: nil,
+				command: []resp.Value{
+					resp.StringValue("DECR"),
+					resp.StringValue("DecrKey6"),
+					resp.StringValue("DecrKey6"),
+				},
+				expectedResponse: 0,
+				expectedError:    errors.New(constants.WrongArgsResponse),
+			},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				if test.presetValue != nil {
+					command := []resp.Value{resp.StringValue("SET"), resp.StringValue(test.key), resp.StringValue(fmt.Sprintf("%v", test.presetValue))}
+					if err = client.WriteArray(command); err != nil {
+						t.Error(err)
+					}
+					res, _, err := client.ReadValue()
+					if err != nil {
+						t.Error(err)
+					}
+					if !strings.EqualFold(res.String(), "ok") {
+						t.Errorf("expected preset response to be OK, got %s", res.String())
+					}
+				}
+
+				if err = client.WriteArray(test.command); err != nil {
+					t.Error(err)
+				}
+
+				res, _, err := client.ReadValue()
+				if err != nil {
+					t.Error(err)
+				}
+
+				if test.expectedError != nil {
+					if !strings.Contains(res.Error().Error(), test.expectedError.Error()) {
+						t.Errorf("expected error \"%s\", got \"%s\"", test.expectedError.Error(), err.Error())
+					}
+					return
+				}
+
+				if err != nil {
+					t.Error(err)
+				} else {
+					responseInt, err := strconv.ParseInt(res.String(), 10, 64)
+					if err != nil {
+						t.Errorf("error parsing response to int64: %s", err)
+					}
+					if responseInt != test.expectedResponse {
+						t.Errorf("expected response %d, got %d", test.expectedResponse, responseInt)
+					}
+				}
+			})
+		}
+	})
 }

internal/modules/generic/key_funcs.go

@@ -145,3 +145,12 @@ func incrKeyFunc(cmd []string) (internal.KeyExtractionFuncResult, error) {
 		WriteKeys: cmd[1:2],
 	}, nil
 }
+
+func decrKeyFunc(cmd []string) (internal.KeyExtractionFuncResult, error) {
+	if len(cmd) != 2 {
+		return internal.KeyExtractionFuncResult{}, errors.New("wrong number of arguments for INCR")
+	}
+	return internal.KeyExtractionFuncResult{
+		WriteKeys: cmd[1:2],
+	}, nil
+}