From 295a83ea7049ab8b039f6f6f7c59f4e3e156dcfc Mon Sep 17 00:00:00 2001
From: Etienne Donneger <etienne@pinax.network>
Date: Tue, 30 Apr 2024 10:07:59 -0400
Subject: [PATCH] Add new endpoint `/head`

---
 src/fetch/GET.ts     |  2 ++
 src/fetch/head.ts    | 10 ++++++++++
 src/fetch/openapi.ts | 22 ++++++++++++++++++++--
 3 files changed, 32 insertions(+), 2 deletions(-)
 create mode 100644 src/fetch/head.ts

diff --git a/src/fetch/GET.ts b/src/fetch/GET.ts
index 26dbc10..40f78dd 100644
--- a/src/fetch/GET.ts
+++ b/src/fetch/GET.ts
@@ -1,6 +1,7 @@
 import { registry } from "../prometheus.js";
 import openapi from "./openapi.js";
 import health from "./health.js";
+import head from "./head.js";
 import balance from "./balance.js";
 import supply from "./supply.js";
 import * as prometheus from "../prometheus.js";
@@ -26,6 +27,7 @@ export default async function (req: Request) {
     if (pathname === "/version") return toJSON({ version: APP_VERSION.split('+')[0], commit: APP_VERSION.split('+')[1] });
     
     // Token endpoints
+    if (pathname === "/head") return head(req);
     if (pathname === "/supply") return supply(req);
     if (pathname === "/balance") return balance(req);
     if (pathname === "/transfers") return transfers(req);
diff --git a/src/fetch/head.ts b/src/fetch/head.ts
new file mode 100644
index 0000000..0a56bac
--- /dev/null
+++ b/src/fetch/head.ts
@@ -0,0 +1,10 @@
+import { addMetadata, toJSON } from "./utils.js"; 
+import { makeQuery } from "../clickhouse/makeQuery.js";
+
+export default async function (req: Request) {
+	return toJSON(
+		addMetadata(
+			await makeQuery("SELECT block_num FROM cursors ORDER BY block_num DESC LIMIT 1")
+		)
+	);
+}
\ No newline at end of file
diff --git a/src/fetch/openapi.ts b/src/fetch/openapi.ts
index a3623d6..2881d36 100644
--- a/src/fetch/openapi.ts
+++ b/src/fetch/openapi.ts
@@ -17,6 +17,17 @@ const timestampExamplesArrayFilter = ["greater_or_equals_by_timestamp", "greater
 const blockExamplesArrayFilter = ["greater_or_equals_by_block", "greater_by_block", "less_or_equals_by_block", "less_by_block"];
 const amountExamplesArrayFilter = ["amount_greater_or_equals", "amount_greater", "amount_less_or_equals", "amount_less"];
 
+const head_example = addMetadata({
+    meta: [],
+    data: [{ block_num: "107439534" }],
+    rows: 0,
+    rows_before_limit_at_least: 0,
+    statistics: {
+        elapsed: 0.00132,
+        rows_read: 4,
+        bytes_read: 32
+    }
+});
 const supply_example = await makeQuery(getTotalSupply(new URLSearchParams({ limit: "1" }), true)).then(res => addMetadata(res, 1, 1));
 const balance_example = await makeQuery(getBalanceChanges(new URLSearchParams({ limit: "2" }), true)).then(res => addMetadata(res, 2, 1));
 const transfers_example = await makeQuery(getTransfers(new URLSearchParams({ limit: "5" }), true)).then(res => addMetadata(res, 5, 1));
@@ -164,11 +175,18 @@ export default new OpenApiBuilder()
             responses: { 200: { description: "OK", content: { "text/plain": { example: "OK" } } } },
         },
     })
+    .addPath("/head", {
+        get: {
+            tags: [TAGS.MONITORING],
+            summary: "Information about the current head block in the database",
+            responses: { 200: { description: "Information about the current head block in the database", content: { "application/json": { example: head_example } } } },
+        },
+    })
     .addPath("/metrics", {
         get: {
             tags: [TAGS.MONITORING],
-            summary: "Prometheus metrics",
-            responses: { 200: { description: "Prometheus metrics", content: { "text/plain": { example: await registry.metrics(), schema: { type: "string" } } } } },
+            summary: "Prometheus metrics for the API",
+            responses: { 200: { description: "Prometheus metrics for the API", content: { "text/plain": { example: await registry.metrics(), schema: { type: "string" } } } } },
         },
     })
     .addPath("/openapi", {