feat(auth): implement custom credentials provider with session management

src/lib/auth.ts

@@ -1,9 +1,90 @@
+import bcrypt from "bcrypt";
+import { ZodError } from "zod";
 import NextAuth from "next-auth";
 import prisma from "@/lib/prisma";
+import { v4 as uuid } from "uuid";
+import { authSchema } from "@/lib/zod";
+import { encode } from "next-auth/jwt";
 import GitHub from "next-auth/providers/github";
 import { PrismaAdapter } from "@auth/prisma-adapter";
+import Credentials from "next-auth/providers/credentials";
 
-export const { handlers, auth, signIn, signOut } = NextAuth({
-  adapter: PrismaAdapter(prisma),
-  providers: [GitHub],
+const adapter = PrismaAdapter(prisma);
+
+// Constant for session expiry time (30 days)
+const SESSION_EXPIRY_MS = 30 * 24 * 60 * 60 * 1000; // 30 days in milliseconds
+
+// Helper function to create a session and return the session token
+const createSession = async (userId: string) => {
+  const sessionToken = uuid();
+  const createdSession = await adapter?.createSession?.({
+    sessionToken,
+    userId,
+    expires: new Date(Date.now() + SESSION_EXPIRY_MS),
+  });
+
+  if (!createdSession) {
+    throw new Error("Failed to create session");
+  }
+
+  return sessionToken;
+};
+
+// NextAuth configuration
+export const { auth, handlers, signIn, signOut } = NextAuth({
+  adapter,
+  providers: [
+    GitHub,
+    Credentials({
+      credentials: {
+        email: {},
+        password: {},
+      },
+      authorize: async (credentials) => {
+        try {
+          // Parse credentials using authSchema for validation
+          const { email, password } = await authSchema.parseAsync(credentials);
+
+          // Find user by email
+          const user = await prisma.user.findUnique({
+            where: { email },
+          });
+
+          // Check if the user exists and validate password
+          if (!user || !user.password || !(await bcrypt.compare(password, user.password))) {
+            throw new Error("Invalid credentials.");
+          }
+
+          // Return the user object if credentials are valid
+          return user;
+        } catch (error) {
+          if (error instanceof ZodError) {
+            // Return null if validation fails
+            return null;
+          }
+          console.error(error); // Log other errors for debugging
+          return null;
+        }
+      },
+    }),
+  ],
+  callbacks: {
+    async jwt({ token, account }) {
+      if (account?.provider === "credentials") {
+        token.credentials = true; // Add flag to token for credentials provider
+      }
+      return token;
+    },
+  },
+  jwt: {
+    encode: async function (params) {
+      if (params.token?.credentials) {
+        if (!params.token?.sub) {
+          throw new Error("No user ID found in token");
+        }
+        return await createSession(params.token.sub); // Create session for the user and return session token
+      }
+      return encode(params); // Default encoding for JWT
+    },
+  },
 });