Add Discord verification option for users without email

src/lib/auth.ts

@@ -117,24 +117,38 @@ export const { handlers, signIn, signOut, auth } = NextAuth({
   callbacks: {
     async signIn({ user, account }) {
       if (account?.provider === "credentials") return true;
-      // OAuth: only allow if a hotel account with this email already exists.
+      // OAuth: try to match by email first.
       const email = user.email;
-      if (!email) return "/login?error=NoEmail";
-      try {
-        const dbUser = await prisma.user.findFirst({
-          where: { mail: email },
-          select: { id: true },
-        });
-        return dbUser ? true : "/login?error=NoAccount";
-      } catch {
-        return "/login?error=Unavailable";
+      if (email) {
+        try {
+          const dbUser = await prisma.user.findFirst({
+            where: { mail: email },
+            select: { id: true },
+          });
+          if (dbUser) return true;
+        } catch {
+          return "/login?error=Unavailable";
+        }
       }
+      // If email didn't match, try Discord ID via SocialAccounts.
+      if (account?.provider === "discord" && account.providerAccountId) {
+        try {
+          const linked = await prisma.socialAccounts.findUnique({
+            where: { provider_providerId: { provider: "discord", providerId: account.providerAccountId } },
+            select: { userId: true },
+          });
+          if (linked) return true;
+        } catch {
+          return "/login?error=Unavailable";
+        }
+      }
+      return "/login?error=NoAccount";
     },
     async jwt({ token, user, account }) {
       if (user && account?.provider === "credentials") {
         token.rank = (user as { rank?: number }).rank;
       } else if (user?.email) {
-        // OAuth: bind the session to the matching hotel account.
+        // OAuth with email: bind to matching hotel account.
         try {
           const dbUser = await prisma.user.findFirst({
             where: { mail: user.email },
@@ -149,6 +163,27 @@ export const { handlers, signIn, signOut, auth } = NextAuth({
           // leave token as-is on lookup failure
         }
       }
+      // OAuth without email match: try Discord ID via SocialAccounts.
+      if (!token.sub && account?.provider === "discord" && account.providerAccountId) {
+        try {
+          const linked = await prisma.socialAccounts.findUnique({
+            where: { provider_providerId: { provider: "discord", providerId: account.providerAccountId } },
+          });
+          if (linked) {
+            const dbUser = await prisma.user.findUnique({
+              where: { id: Number(linked.userId) },
+              select: { id: true, rank: true, username: true },
+            });
+            if (dbUser) {
+              token.sub = String(dbUser.id);
+              token.rank = dbUser.rank;
+              token.name = dbUser.username;
+            }
+          }
+        } catch {
+          // leave token as-is on lookup failure
+        }
+      }
       return token;
     },
     session({ session, token }) {