feat: add Nostr protocol implementation (internal/nostr, internal/websocket)

1 files changed, 72 insertions, 0 deletions

diff --git a/internal/nostr/event.go b/internal/nostr/event.go
new file mode 100644
index 0000000..a8156bb
--- /dev/null
+++ b/internal/nostr/event.go
@@ -0,0 +1,72 @@
+package nostr
+
+import (
+        "crypto/sha256"
+        "encoding/hex"
+        "encoding/json"
+        "fmt"
+)
+
+// Event represents a Nostr event as defined in NIP-01.
+type Event struct {
+        ID        string `json:"id"`
+        PubKey    string `json:"pubkey"`
+        CreatedAt int64  `json:"created_at"`
+        Kind      int    `json:"kind"`
+        Tags      Tags   `json:"tags"`
+        Content   string `json:"content"`
+        Sig       string `json:"sig"`
+}
+
+// Serialize returns the canonical JSON serialization of the event for ID computation.
+// Format: [0, "pubkey", created_at, kind, tags, "content"]
+func (e *Event) Serialize() []byte {
+        // Use json.Marshal for proper escaping of content and tags
+        arr := []interface{}{
+                0,
+                e.PubKey,
+                e.CreatedAt,
+                e.Kind,
+                e.Tags,
+                e.Content,
+        }
+        data, _ := json.Marshal(arr)
+        return data
+}
+
+// ComputeID calculates the SHA256 hash of the serialized event.
+// Returns the 64-character hex-encoded ID.
+func (e *Event) ComputeID() string {
+        serialized := e.Serialize()
+        hash := sha256.Sum256(serialized)
+        return hex.EncodeToString(hash[:])
+}
+
+// SetID computes and sets the event ID.
+func (e *Event) SetID() {
+        e.ID = e.ComputeID()
+}
+
+// CheckID verifies that the event ID matches the computed ID.
+func (e *Event) CheckID() bool {
+        return e.ID == e.ComputeID()
+}
+
+// MarshalJSON implements json.Marshaler with empty tags as [] instead of null.
+func (e Event) MarshalJSON() ([]byte, error) {
+        type eventAlias Event
+        ea := eventAlias(e)
+        if ea.Tags == nil {
+                ea.Tags = Tags{}
+        }
+        return json.Marshal(ea)
+}
+
+// String returns a JSON representation of the event for debugging.
+func (e *Event) String() string {
+        data, err := json.MarshalIndent(e, "", "  ")
+        if err != nil {
+                return fmt.Sprintf("<Event error: %v>", err)
+        }
+        return string(data)
+}