Chat history.

client/public/index.html

@@ -31,8 +31,8 @@
                 <div id="bottom_text">
                     <i>COMS</i> by Jacob Signorovitch.
                     <a href="#" id="help">Help</a> |
-                    <a href="//signorovitch.org">Code</a> |
+                    <a href="//git.signorovitch.org/jacob/coms">Code</a> |
-                    <a href="//signorovitch.org">API</a>
+                    <a href="#">API</a>
                 </div>
             </div>
         </div>

client/public/wsModule.js

@@ -12,6 +12,7 @@ import {
   updateUser,
   getGroupedUsers,
   setMyId,
+  clearData,
   users,
   setFocused,
   setReplyTo,
@@ -49,11 +50,25 @@ export function initWebSocket(username, chatEl, inputContainer, usersListEl) {
       case "welcome": {
         // Initial user list.
         const myId = packet.data.you;
+        clearData();
         setMyId(myId);
         const users = packet.data.users || [];
         users.forEach(({ id, username }) => addUser(id, username));
         const groups = getGroupedUsers();
         usersListEl.innerHTML = "Online: " + groups.join(", ");
+        // Replay chat history.
+        const history = packet.data.history || [];
+        history.forEach((raw) => {
+          try {
+            const histPkt = JSON.parse(raw);
+            if (histPkt.type === "msg-event") {
+              const { id, username: u, content, ts, parent } = histPkt.data;
+              addMessage({ id, username: u, content, ts, parent });
+            }
+          } catch (e) {
+            console.error("Invalid history entry", raw);
+          }
+        });
         //addNotice(`<i>Users online: ${groups.join(", ")}</i>`);
         break;
       }

server/src/chat.c

@@ -12,6 +12,13 @@
 
 static size_t next_msg_id = 1;
 
+// History buffer for last 100 messages.
+#define HISTORY_SIZE 100
+static char* history[HISTORY_SIZE];
+static size_t history_len[HISTORY_SIZE];
+static size_t history_pos = 0;
+static size_t history_count = 0;
+
 #define CHAT_BUF_SIZE SESSION_CHAT_BUF_SIZE
 
 /*
@@ -92,6 +99,7 @@ int cb_chat(
                         if (session_has_username(s)) {
                             yyjson_mut_val* uobj = yyjson_mut_obj(wdoc);
                             yyjson_mut_arr_add_val(wusers, uobj);
+                            yyjson_mut_arr_add_val(wusers, uobj);
                             yyjson_mut_obj_add_uint(
                                 wdoc, uobj, "id", session_get_id(s)
                             );
@@ -100,6 +108,19 @@ int cb_chat(
                             );
                         }
                     }
+                    // Include last 100 messages in the welcome history array.
+                    yyjson_mut_val* whist = yyjson_mut_arr(wdoc);
+                    yyjson_mut_obj_add_val(wdoc, wdata, "history", whist);
+                    for (size_t i = 0; i < history_count; ++i) {
+                        size_t idx =
+                            (history_pos + HISTORY_SIZE - history_count + i) %
+                            HISTORY_SIZE;
+                        // Append raw JSON string into history array.
+                        yyjson_mut_val* raw = yyjson_mut_strn(
+                            wdoc, history[idx], history_len[idx]
+                        );
+                        yyjson_mut_arr_add_val(whist, raw);
+                    }
 
                     size_t out_len;
                     char* out = yyjson_mut_write(wdoc, 0, &out_len);
@@ -291,6 +312,15 @@ int cb_chat(
 
                 size_t out_len;
                 char* out = yyjson_mut_write(mdoc, 0, &out_len);
+                /* Store this msg-event JSON in the circular history buffer */
+                if (history_count == HISTORY_SIZE) {
+                    free(history[history_pos]);
+                } else {
+                    history_count++;
+                }
+                history[history_pos] = strdup(out);
+                history_len[history_pos] = out_len;
+                history_pos = (history_pos + 1) % HISTORY_SIZE;
                 size_t copy_len = out_len < SESSION_CHAT_BUF_SIZE
                                       ? out_len
                                       : SESSION_CHAT_BUF_SIZE;