Add support for cap, a pow captcha, and implement on contact form

src/lib/cap.ts

@@ -0,0 +1,85 @@
+import Cap, { type ChallengeData } from "@cap.js/server";
+import { db, eq, and, gt, lte, Cap_Challenges, Cap_Tokens } from "astro:db";
+
+const cap = new Cap({
+  storage: {
+    challenges: {
+      store: async (token: string, challengeData: ChallengeData) => {
+        const expires = challengeData.expires;
+        const data = challengeData.challenge;
+        await db
+          .insert(Cap_Challenges)
+          .values({ token: token, data: data, expires: expires })
+          .onConflictDoUpdate({
+            target: Cap_Challenges.token,
+            set: { data: data, expires: expires },
+          });
+      },
+      read: async (token) => {
+        const result = await db
+          .select({
+            challenge: Cap_Challenges.data,
+            expires: Cap_Challenges.expires,
+          })
+          .from(Cap_Challenges)
+          .where(
+            and(
+              eq(Cap_Challenges.token, token),
+              gt(Cap_Challenges.expires, Date.now()),
+            ),
+          )
+          .limit(1);
+
+        const data = result[0] as ChallengeData;
+
+        return result ? data : null;
+      },
+
+      delete: async (token) => {
+        await db.delete(Cap_Challenges).where(eq(Cap_Challenges.token, token));
+      },
+
+      deleteExpired: async () => {
+        await db
+          .delete(Cap_Challenges)
+          .where(lte(Cap_Challenges.expires, Date.now()));
+      },
+    },
+    tokens: {
+      store: async (tokenKey, expires) => {
+        await db
+          .insert(Cap_Tokens)
+          .values({ key: tokenKey, expires: expires })
+          .onConflictDoUpdate({
+            target: Cap_Tokens.key,
+            set: { expires: expires },
+          });
+      },
+
+      get: async (tokenKey) => {
+        const result = await db
+          .select({ expires: Cap_Tokens.expires })
+          .from(Cap_Tokens)
+          .where(
+            and(
+              eq(Cap_Tokens.key, tokenKey),
+              gt(Cap_Tokens.expires, Date.now()),
+            ),
+          )
+          .limit(1);
+
+        return result ? result[0].expires : null;
+      },
+
+      delete: async (tokenKey) => {
+        await db.delete(Cap_Tokens).where(eq(Cap_Tokens.key, tokenKey));
+      },
+
+      deleteExpired: async () => {
+        await db.delete(Cap_Tokens).where(lte(Cap_Tokens.expires, Date.now()));
+      },
+    },
+  },
+});
+
+export default cap;