sed replacement in message box.

src/components/common/messaging/MessageBox.tsx

@@ -106,6 +106,9 @@ const Action = styled.div`
     }
 `;
 
+// For sed replacement
+const SED_REGEX = new RegExp("^s/([^])+/([^])+$");
+
 // ! FIXME: add to app config and load from app config
 export const CAN_UPLOAD_AT_ONCE = 4;
 
@@ -198,9 +201,34 @@ export default observer(({ channel }: Props) => {
         stopTyping();
         setMessage();
         setReplies([]);
+        const nonce = ulid();
+
+        // sed style message editing.
+        // If the user types for example `s/abc/def`, the string "abc"
+        // will be replaced with "def" in their last sent message.
+        if (SED_REGEX.test(content)) {
+            renderer.messages.reverse();
+            const msg = renderer.messages.find(
+                (msg) => msg.author_id === client.user!._id,
+            );
+            renderer.messages.reverse();
+
+            if (msg) {
+                const [_, toReplace, newText, flags] =
+                    content.split(/(?<!\\)\//);
+                const newContent = msg.content
+                    .toString()
+                    .replace(new RegExp(toReplace, flags), newText);
+
+                if (newContent != msg.content) {
+                    msg.edit({
+                        content: newContent.substr(0, 2000),
+                    }).catch(console.warn);
+                }
+            }
+        } else {
             playSound("outbound");
 
-        const nonce = ulid();
             dispatch({
                 type: "QUEUE_ADD",
                 nonce,
@@ -231,6 +259,7 @@ export default observer(({ channel }: Props) => {
                 });
             }
         }
+    }
 
     async function sendFile(content: string) {
         if (uploadState.type !== "attached") return;