feat: with base envelope

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/crunch-envelope/src/json_envelope.rs

@@ -0,0 +1,39 @@
+use base64::{engine::general_purpose, Engine};
+use serde::{Deserialize, Serialize};
+
+use crate::EnvelopeError;
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct Envelope {
+    content: String,
+    metadata: Metadata,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct Metadata {
+    domain: String,
+    entity: String,
+}
+
+pub fn wrap<'a>(domain: &'a str, entity: &'a str, content: &'a [u8]) -> Vec<u8> {
+    let output = serde_json::to_vec(&Envelope {
+        content: general_purpose::URL_SAFE_NO_PAD.encode(content),
+        metadata: Metadata {
+            domain: domain.to_string(),
+            entity: entity.to_string(),
+        },
+    })
+    .unwrap();
+
+    output
+}
+pub fn unwrap<'a>(message: &'a [u8]) -> Result<(Vec<u8>, Metadata), EnvelopeError> {
+    let envelope: Envelope = serde_json::from_slice(message).map_err(EnvelopeError::JsonError)?;
+
+    Ok((
+        general_purpose::URL_SAFE_NO_PAD
+            .decode(envelope.content)
+            .map_err(EnvelopeError::Base64Error)?,
+        envelope.metadata,
+    ))
+}