Support parsing multiple levels descriptors (#325)

* [descriptor] fix parser to support multiple levels descriptors

* add andTokenSize constant

common/descriptor/expression.go

@@ -19,6 +19,10 @@ var (
 	ErrNotExpectedPolicy  = errors.New("not the expected policy")
 )
 
+const (
+	andTokenSize = len("and(")
+)
+
 type Expression interface {
 	Parse(policy string) error
 	Script(verify bool) (string, error)
@@ -156,28 +160,21 @@ func (e *And) Parse(policy string) error {
 		return ErrNotExpectedPolicy
 	}
 
-	index := strings.LastIndexByte(policy, ')')
+	parts, err := splitScriptTree(policy[andTokenSize : len(policy)-1])
-	if index == -1 {
+	if err != nil {
 		return ErrInvalidAndPolicy
 	}
 
-	childrenPolicy := policy[4:index]
+	if len(parts) != 2 {
-	if len(childrenPolicy) == 0 {
 		return ErrInvalidAndPolicy
 	}
 
-	children := strings.Split(childrenPolicy, ",")
+	first, err := parseExpression(parts[0])
-	if len(children) != 2 {
-		fmt.Println(children)
-		return ErrInvalidAndPolicy
-	}
-
-	first, err := parseExpression(children[0])
 	if err != nil {
 		return err
 	}
 
-	second, err := parseExpression(children[1])
+	second, err := parseExpression(parts[1])
 	if err != nil {
 		return err
 	}

common/descriptor/parser.go

@@ -11,6 +11,9 @@ const UnspendableKey = "0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f281
 
 func ParseTaprootDescriptor(desc string) (*TaprootDescriptor, error) {
 	desc = strings.ReplaceAll(desc, " ", "")
+	desc = strings.ReplaceAll(desc, "\n", "")
+	desc = strings.ReplaceAll(desc, "\t", "")
+	desc = strings.ReplaceAll(desc, "\r", "")
 
 	if !strings.HasPrefix(desc, "tr(") || !strings.HasSuffix(desc, ")") {
 		return nil, fmt.Errorf("invalid descriptor format")
@@ -93,6 +96,8 @@ func splitScriptTree(scriptTreeStr string) ([]string, error) {
 
 	for _, char := range scriptTreeStr {
 		switch char {
+		case '{', '}':
+			continue
 		case '(':
 			depth++
 			current.WriteRune(char)

common/descriptor/parser_test.go

@@ -179,6 +179,161 @@ func TestParseTaprootDescriptor(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name: "Multiple level descriptor",
+			desc: `
+			tr(
+				0250929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0,
+				{
+						{
+								{
+										and(and(pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465), pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465)), pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465)),
+										and(older(512), and(pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465), pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465)))
+								},
+								{
+										and(and(pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465), pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465)), pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465)),
+										and(older(1024), and(pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465), pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465)))
+								}
+						},
+						{
+								and(older(512), pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465)),
+								and(older(512), and(pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465), pk(873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465)))
+						}
+				}
+			)
+			`,
+			expected: descriptor.TaprootDescriptor{
+				InternalKey: descriptor.Key{Hex: "50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0"},
+				ScriptTree: []descriptor.Expression{
+					&descriptor.And{
+						First: &descriptor.And{
+							First: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+							Second: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+						},
+						Second: &descriptor.PK{
+							Key: descriptor.XOnlyKey{
+								descriptor.Key{
+									Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+								},
+							},
+						},
+					},
+					&descriptor.And{
+						First: &descriptor.Older{
+							Timeout: 512,
+						},
+						Second: &descriptor.And{
+							First: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+							Second: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+						},
+					},
+					&descriptor.And{
+						First: &descriptor.And{
+							First: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+							Second: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+						},
+						Second: &descriptor.PK{
+							Key: descriptor.XOnlyKey{
+								descriptor.Key{
+									Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+								},
+							},
+						},
+					},
+					&descriptor.And{
+						First: &descriptor.Older{
+							Timeout: 1024,
+						},
+						Second: &descriptor.And{
+							First: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+							Second: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+						},
+					},
+					&descriptor.And{
+						First: &descriptor.Older{
+							Timeout: 512,
+						},
+						Second: &descriptor.PK{
+							Key: descriptor.XOnlyKey{
+								descriptor.Key{
+									Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+								},
+							},
+						},
+					},
+					&descriptor.And{
+						First: &descriptor.Older{
+							Timeout: 512,
+						},
+						Second: &descriptor.And{
+							First: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+							Second: &descriptor.PK{
+								Key: descriptor.XOnlyKey{
+									descriptor.Key{
+										Hex: "873079a0091c9b16abd1f8c508320b07f0d50144d09ccd792ce9c915dac60465",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
 	}
 
 	for _, tt := range tests {