Refactored methods into pure functions.

README.md

@@ -96,7 +96,7 @@ event := events.Event{
 }
 
 // 2. Compute the event ID
-id, err := event.GetID()
+id, err := events.GetID(event)
 if err != nil {
     log.Fatal(err)
 }
@@ -114,7 +114,7 @@ event.Sig = sig
 
 ```go
 // Returns canonical JSON: [0, pubkey, created_at, kind, tags, content]
-serialized, err := event.Serialize()
+serialized, err := events.Serialize(event)
 if err != nil {
     log.Fatal(err)
 }
@@ -123,7 +123,7 @@ if err != nil {
 #### Compute event ID manually
 
 ```go
-id, err := event.GetID()
+id, err := events.GetID(event)
 if err != nil {
     log.Fatal(err)
 }
@@ -138,7 +138,7 @@ if err != nil {
 
 ```go
 // Checks structure, ID computation, and signature
-if err := event.Validate(); err != nil {
+if err := events.Validate(event); err != nil {
     log.Printf("Invalid event: %v", err)
 }
 ```
@@ -147,17 +147,17 @@ if err := event.Validate(); err != nil {
 
 ```go
 // Check field formats and lengths
-if err := event.ValidateStructure(); err != nil {
+if err := events.ValidateStructure(event); err != nil {
     log.Printf("Malformed structure: %v", err)
 }
 
 // Verify ID matches computed hash
-if err := event.ValidateID(); err != nil {
+if err := events.ValidateID(event); err != nil {
     log.Printf("ID mismatch: %v", err)
 }
 
 // Verify cryptographic signature
-if err := event.ValidateSignature(); err != nil {
+if err := events.ValidateSignature(event); err != nil {
     log.Printf("Invalid signature: %v", err)
 }
 ```
@@ -186,7 +186,7 @@ if err != nil {
 }
 
 // Validate after unmarshaling
-if err := event.Validate(); err != nil {
+if err := events.Validate(event); err != nil {
     log.Printf("Received invalid event: %v", err)
 }
 ```
@@ -250,7 +250,7 @@ filter := filters.Filter{
     Kinds:   []int{1},
 }
 
-if filter.Matches(&event) {
+if filters.Matches(filter, event) {
     // Event satisfies all filter conditions
 }
 ```
@@ -269,7 +269,7 @@ filter := filters.Filter{
 
 var matches []events.Event
 for _, event := range events {
-    if filter.Matches(&event) {
+    if filters.Matches(filter, event) {
         matches = append(matches, event)
     }
 }
@@ -293,7 +293,7 @@ filter := filters.Filter{
     },
 }
 
-jsonBytes, err := filter.MarshalJSON()
+jsonBytes, err := filters.MarshalJSON(filter)
 // Result: {"ids":["abc123"],"kinds":[1],"#e":["event-id"],"search":"nostr"}
 ```
 
@@ -309,7 +309,7 @@ jsonData := `{
 }`
 
 var filter filters.Filter
-err := filter.UnmarshalJSON([]byte(jsonData))
+err := filters.UnmarshalJSON([]byte(jsonData), &filter)
 if err != nil {
     log.Fatal(err)
 }

events/event_json_test.go

@@ -9,7 +9,7 @@ import (
 func TestUnmarshalEventJSON(t *testing.T) {
 	event := Event{}
 	json.Unmarshal(testEventJSONBytes, &event)
-	if err := event.Validate(); err != nil {
+	if err := Validate(event); err != nil {
 		t.Error("unmarshalled event is invalid")
 	}
 	expectEqualEvents(t, event, testEvent)
@@ -37,7 +37,7 @@ func TestEventJSONRoundTrip(t *testing.T) {
 	}
 	expectedJSON := `{"id":"86e856d0527dd08527498cd8afd8a7d296bde37e4757a8921f034f0b344df3ad","pubkey":"cfa87f35acbde29ba1ab3ee42de527b2cad33ac487e80cf2d6405ea0042c8fef","created_at":1760740551,"kind":1,"tags":[["a","value"],["b","value","optional"],["name","value","optional","optional"]],"content":"hello world","sig":"c05fe02a9c082ff56aad2b16b5347498a21665f02f050ba086dbe6bd593c8cd448505d2831d1c0340acc1793eaf89b7c0cb21bb696c71da6b8d6b857702bb557"}`
 
-	if err := event.Validate(); err != nil {
+	if err := Validate(event); err != nil {
 		t.Error("test event is invalid")
 	}
 	eventJSON, err := json.Marshal(event)
@@ -47,7 +47,7 @@ func TestEventJSONRoundTrip(t *testing.T) {
 	unmarshalledEvent := Event{}
 	json.Unmarshal(eventJSON, &unmarshalledEvent)
 
-	if err := unmarshalledEvent.Validate(); err != nil {
+	if err := Validate(unmarshalledEvent); err != nil {
 		t.Error("unmarshalled event is invalid")
 	}
 	expectEqualEvents(t, unmarshalledEvent, event)

events/id.go

@@ -8,7 +8,7 @@ import (
 
 // Serialize returns the canonical JSON array representation of the event.
 // used for ID computation: [0, pubkey, created_at, kind, tags, content].
-func (e *Event) Serialize() ([]byte, error) {
+func Serialize(e Event) ([]byte, error) {
 	serialized := []interface{}{
 		0,
 		e.PubKey,
@@ -27,8 +27,8 @@ func (e *Event) Serialize() ([]byte, error) {
 
 // GetID computes and returns the event ID as a lowercase, hex-encoded SHA-256 hash
 // of the serialized event.
-func (e *Event) GetID() (string, error) {
+func GetID(e Event) (string, error) {
-	bytes, err := e.Serialize()
+	bytes, err := Serialize(e)
 	if err != nil {
 		return "", err
 	}

events/id_test.go

@@ -196,7 +196,7 @@ var idTestCases = []IDTestCase{
 func TestEventGetId(t *testing.T) {
 	for _, tc := range idTestCases {
 		t.Run(tc.name, func(t *testing.T) {
-			actual, err := tc.event.GetID()
+			actual, err := GetID(tc.event)
 			assert.NoError(t, err)
 			assert.Equal(t, tc.expected, actual)
 		})

events/validate.go

@@ -9,21 +9,21 @@ import (
 
 // Validate performs a complete event validation: structure, ID computation,
 // and signature verification. Returns the first error encountered.
-func (e *Event) Validate() error {
+func Validate(e Event) error {
-	if err := e.ValidateStructure(); err != nil {
+	if err := ValidateStructure(e); err != nil {
 		return err
 	}
 
-	if err := e.ValidateID(); err != nil {
+	if err := ValidateID(e); err != nil {
 		return err
 	}
 
-	return e.ValidateSignature()
+	return ValidateSignature(e)
 }
 
 // ValidateStructure checks that all event fields conform to the protocol
 // specification: hex lengths, tag structure, and field formats.
-func (e *Event) ValidateStructure() error {
+func ValidateStructure(e Event) error {
 	if !Hex64Pattern.MatchString(e.PubKey) {
 		return errors.MalformedPubKey
 	}
@@ -46,8 +46,8 @@ func (e *Event) ValidateStructure() error {
 }
 
 // ValidateID recomputes the event ID and verifies it matches the stored ID field.
-func (e *Event) ValidateID() error {
+func ValidateID(e Event) error {
-	computedID, err := e.GetID()
+	computedID, err := GetID(e)
 	if err != nil {
 		return errors.FailedIDComp
 	}
@@ -62,7 +62,7 @@ func (e *Event) ValidateID() error {
 
 // ValidateSignature verifies the event signature is cryptographically valid
 // for the event ID and public key using Schnorr verification.
-func (e *Event) ValidateSignature() error {
+func ValidateSignature(e Event) error {
 	idBytes, err := hex.DecodeString(e.ID)
 	if err != nil {
 		return fmt.Errorf("invalid event id hex: %w", err)

events/validate_test.go

@@ -184,7 +184,7 @@ var structureTestCases = []ValidateEventTestCase{
 func TestValidateEventStructure(t *testing.T) {
 	for _, tc := range structureTestCases {
 		t.Run(tc.name, func(t *testing.T) {
-			err := tc.event.ValidateStructure()
+			err := ValidateStructure(tc.event)
 			assert.ErrorContains(t, err, tc.expectedError)
 		})
 	}
@@ -201,7 +201,7 @@ func TestValidateEventIDFailure(t *testing.T) {
 		Sig:       testEvent.Sig,
 	}
 
-	err := event.ValidateID()
+	err := ValidateID(event)
 	assert.ErrorContains(t, err, "does not match computed id")
 }
 
@@ -211,7 +211,7 @@ func TestValidateSignature(t *testing.T) {
 		PubKey: testEvent.PubKey,
 		Sig:    testEvent.Sig,
 	}
-	err := event.ValidateSignature()
+	err := ValidateSignature(event)
 
 	assert.NoError(t, err)
 }
@@ -222,7 +222,7 @@ func TestValidateInvalidSignature(t *testing.T) {
 		PubKey: testEvent.PubKey,
 		Sig:    "9e43cbcf7e828a21c53fa35371ee79bffbfd7a3063ae46fc05ec623dd3186667c57e3d006488015e19247df35eb41c61013e051aa87860e23fa5ffbd44120482",
 	}
-	err := event.ValidateSignature()
+	err := ValidateSignature(event)
 
 	assert.ErrorContains(t, err, "event signature is invalid")
 }
@@ -281,7 +281,7 @@ func TestValidateSignatureInvalidEventSignature(t *testing.T) {
 	for _, tc := range validateSignatureTestCases {
 		t.Run(tc.name, func(t *testing.T) {
 			event := Event{ID: tc.id, PubKey: tc.pubkey, Sig: tc.sig}
-			err := event.ValidateSignature()
+			err := ValidateSignature(event)
 			assert.ErrorContains(t, err, tc.expectedError)
 		})
 	}
@@ -301,6 +301,6 @@ func TestValidateEvent(t *testing.T) {
 		Sig:     "668a715f1eb983172acf230d17bd283daedb2598adf8de4290bcc7eb0b802fdb60669d1e7d1104ac70393f4dbccd07e8abf897152af6ce6c0a75499874e27f14",
 	}
 
-	err := event.Validate()
+	err := Validate(event)
 	assert.NoError(t, err)
 }

filters/filter.go

@@ -29,7 +29,7 @@ type Filter struct {
 
 // MarshalJSON converts the filter to JSON with standard fields, tag filters
 // (prefixed with "#"), and extensions merged into a single object.
-func (f *Filter) MarshalJSON() ([]byte, error) {
+func MarshalJSON(f Filter) ([]byte, error) {
 	outputMap := make(map[string]interface{})
 
 	// Add standard fields
@@ -86,7 +86,7 @@ func (f *Filter) MarshalJSON() ([]byte, error) {
 
 // UnmarshalJSON parses JSON into the filter, separating standard fields,
 // tag filters (keys starting with "#"), and extensions.
-func (f *Filter) UnmarshalJSON(data []byte) error {
+func UnmarshalJSON(data []byte, f *Filter) error {
 	// Decode into raw map
 	raw := make(FilterExtensions)
 	if err := json.Unmarshal(data, &raw); err != nil {
@@ -182,7 +182,7 @@ func (f *Filter) UnmarshalJSON(data []byte) error {
 // Matches returns true if the event satisfies all filter conditions.
 // Supports prefix matching for IDs and authors, and tag filtering.
 // Does not account for custom extensions.
-func (f *Filter) Matches(event *events.Event) bool {
+func Matches(f Filter, event events.Event) bool {
 	// Check ID
 	if len(f.IDs) > 0 {
 		if !matchesPrefix(event.ID, f.IDs) {

filters/filter_json_test.go

@@ -584,7 +584,7 @@ var roundTripTestCases = []FilterRoundTripTestCase{
 func TestFilterMarshalJSON(t *testing.T) {
 	for _, tc := range marshalTestCases {
 		t.Run(tc.name, func(t *testing.T) {
-			result, err := tc.filter.MarshalJSON()
+			result, err := MarshalJSON(tc.filter)
 			assert.NoError(t, err)
 
 			var expectedMap, actualMap map[string]interface{}
@@ -602,7 +602,7 @@ func TestFilterUnmarshalJSON(t *testing.T) {
 	for _, tc := range unmarshalTestCases {
 		t.Run(tc.name, func(t *testing.T) {
 			var result Filter
-			err := result.UnmarshalJSON([]byte(tc.input))
+			err := UnmarshalJSON([]byte(tc.input), &result)
 			assert.NoError(t, err)
 
 			expectEqualFilters(t, result, tc.expected)
@@ -613,11 +613,11 @@ func TestFilterUnmarshalJSON(t *testing.T) {
 func TestFilterRoundTrip(t *testing.T) {
 	for _, tc := range roundTripTestCases {
 		t.Run(tc.name, func(t *testing.T) {
-			jsonBytes, err := tc.filter.MarshalJSON()
+			jsonBytes, err := MarshalJSON(tc.filter)
 			assert.NoError(t, err)
 
 			var result Filter
-			err = result.UnmarshalJSON(jsonBytes)
+			err = UnmarshalJSON(jsonBytes, &result)
 			assert.NoError(t, err)
 
 			expectEqualFilters(t, result, tc.filter)

filters/filter_match_test.go

@@ -391,7 +391,7 @@ func TestEventFilterMatching(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			actualIDs := []string{}
 			for _, event := range testEvents {
-				if tc.filter.Matches(&event) {
+				if Matches(tc.filter, event) {
 					actualIDs = append(actualIDs, event.ID[:8])
 				}
 			}
@@ -416,5 +416,5 @@ func TestEventFilterMatchingSkipMalformedTags(t *testing.T) {
 		},
 	}
 
-	assert.True(t, filter.Matches(&event))
+	assert.True(t, Matches(filter, event))
 }