feat(auth): integrate user registration route, frontend form, and server validation

app/(auth)/login/page.tsx

@@ -37,8 +37,10 @@ export default function LoginPage() {
     const formData = new FormData(e.currentTarget);
     const email = formData.get("email") as string;
     const password = formData.get("password") as string;
+    const defaultErrorMessage = "An unexpected error has occurred.";
 
     try {
+      // Attempt to sign in using Auth.js credentials provider
       const res = await signIn("credentials", {
         email,
         password,
@@ -46,18 +48,26 @@ export default function LoginPage() {
       });
 
       if (res?.error) {
+        // Handle specific authentication errors
         if (res.error === "CredentialsSignin") {
           setError("Incorrect email address or password.");
         } else {
-          setError("An unexpected error has occurred.");
+          setError(defaultErrorMessage);
         }
-        setLoading(false);
       } else {
+        // Redirect user and refresh router cache on success
         router.push("/");
         router.refresh();
+        return;
       }
-    } catch {
-      setError("Connection error. Please try again later.");
+    } catch (err: any) {
+      // Handle network or connection errors vs unexpected errors
+      if (err?.message?.includes("fetch") || err?.name === "TypeError") {
+        setError("Server error: API endpoint not available");
+      } else {
+        setError(defaultErrorMessage);
+      }
+    } finally {
       setLoading(false);
     }
   };

app/(auth)/register/page.tsx

@@ -0,0 +1,131 @@
+/**
+ * @file RegisterPage.tsx
+ * @description Client component providing a user registration interface for creating a new account.
+ */
+
+"use client";
+
+import Link from "next/link";
+import { useState } from "react";
+import { useRouter } from "next/navigation";
+
+/**
+ * Renders the registration page featuring a sign-up form, error feedback,
+ * and routing logic to the login page upon successful account creation.
+ *
+ * @returns {JSX.Element} The rendered registration page component.
+ */
+export default function RegisterPage() {
+  const [error, setError] = useState<string | null>(null);
+  const [loading, setLoading] = useState(false);
+  const router = useRouter();
+
+  /**
+   * Handles the submission of the registration form, sends user data to the API,
+   * creates the account, auto-logins the user, and redirects to the main view on success.
+   *
+   * @async
+   * @param {React.SubmitEvent<HTMLFormElement>} event - The form submission event.
+   * @returns {Promise<void>}
+   */
+  async function handleSubmit(event: React.SubmitEvent<HTMLFormElement>) {
+    event.preventDefault();
+    setError(null);
+    setLoading(true);
+
+    const formData = new FormData(event.currentTarget);
+    const email = formData.get("email");
+    const password = formData.get("password");
+
+    try {
+      // Send registration request to the API
+      const response = await fetch("/api/auth/register", {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ email, password }),
+      });
+
+      // Ensure the response is valid JSON before parsing
+      const contentType = response.headers.get("content-type");
+      let data;
+      if (contentType && contentType.includes("application/json")) {
+        data = await response.json();
+      } else {
+        throw new Error("Server error: API endpoint not available");
+      }
+
+      // Handle non-successful status codes
+      if (!response.ok) {
+        throw new Error(data.message || "Something went wrong.");
+      }
+
+      // Redirect user and refresh router cache on success
+      router.push("/");
+      router.refresh();
+    } catch (err: any) {
+      setError(err.message);
+    } finally {
+      setLoading(false);
+    }
+  }
+
+  return (
+    <div className="flex h-dvh w-full items-center justify-center">
+      {/* Login Card Container */}
+      <div className="w-full max-w-sm p-6 space-y-6 border border-border rounded-xl bg-card backdrop-blur-md">
+        {/* Header Section */}
+        <div className="space-y-2 text-center">
+          <h1 className="text-2xl font-bold tracking-tight">
+            Create an Account
+          </h1>
+          <p className="text-sm text-muted">
+            Get started with your Flowstate Workspace.
+          </p>
+        </div>
+
+        {/* Error Notification Banner */}
+        {error && (
+          <div
+            className="p-3 text-xs font-medium text-destructive bg-destructive-bg border border-destructive-border rounded-lg text-center"
+            role="alert"
+          >
+            {error}
+          </div>
+        )}
+
+        {/* Credentials Form */}
+        <form onSubmit={handleSubmit} className="space-y-4">
+          <input
+            name="email"
+            type="email"
+            placeholder="Email"
+            required
+            className="w-full px-3 py-2 text-sm rounded-lg border border-border bg-background focus:outline-none focus:border-foreground"
+          />
+          <input
+            name="password"
+            type="password"
+            placeholder="Password"
+            required
+            className="w-full px-3 py-2 text-sm rounded-lg border border-border bg-background focus:outline-none focus:border-foreground"
+          />
+          <button
+            type="submit"
+            disabled={loading}
+            className="w-full py-2 text-sm font-medium rounded-lg bg-foreground text-background hover:opacity-70 transition-opacity disabled:opacity-20 cursor-pointer disabled:cursor-auto"
+          >
+            {loading ? "Being created..." : "Sign Up"}
+          </button>
+        </form>
+
+        {/* Back Link Footer */}
+        <div className="text-center text-xs text-muted">
+          Already have an account?{" "}
+          <Link href="/login" className="text-foreground hover:underline">
+            Sign In
+          </Link>
+        </div>
+      </div>
+    </div>
+  );
+}

app/api/auth/register/route.ts

@@ -0,0 +1,109 @@
+/**
+ * @file route.ts
+ * @description API route handler for user registration, managing email normalization, credential validation, secure password hashing, and auto sign-in.
+ */
+
+import { NextResponse } from "next/server";
+import { db } from "@/db";
+import { usersTable } from "@/db/schema";
+import { eq } from "drizzle-orm";
+import bcrypt from "bcryptjs";
+import { signIn } from "@/auth";
+
+/**
+ * Handles POST requests to register a new user.
+ * Parses and validates the request body, normalizes the email address, enforces security rules,
+ * checks for existing records, stores the hashed password in the database, and attempts an automatic sign-in.
+ *
+ * @async
+ * @param {Request} request - The incoming HTTP request containing the registration data.
+ * @returns {Promise<NextResponse>} A JSON response with status details indicating success or failure.
+ */
+export async function POST(request: Request) {
+  try {
+    // Parse incoming JSON body safely
+    const body = await request.json().catch(() => null);
+
+    if (!body) {
+      return NextResponse.json(
+        { message: "Invalid JSON payload" },
+        { status: 400 },
+      );
+    }
+
+    const { email: rawEmail, password } = body;
+
+    // Ensure types and presence of required fields
+    if (
+      !rawEmail ||
+      typeof rawEmail !== "string" ||
+      !password ||
+      typeof password !== "string"
+    ) {
+      return NextResponse.json(
+        { message: "Email and password are required" },
+        { status: 400 },
+      );
+    }
+
+    // Normalize email (lowercase and trim)
+    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+    const email = rawEmail.toLowerCase().trim();
+
+    if (!emailRegex.test(email)) {
+      return NextResponse.json(
+        { message: "Please provide a valid email address" },
+        { status: 400 },
+      );
+    }
+
+    // Enforce minimum password length security constraint
+    if (password.length < 8) {
+      return NextResponse.json(
+        { message: "Password must be at least 8 characters long" },
+        { status: 400 },
+      );
+    }
+
+    // Check if user with this email already exists
+    const existing = await db.query.usersTable.findFirst({
+      where: eq(usersTable.email, email),
+    });
+
+    if (existing) {
+      return NextResponse.json(
+        { message: "Mail is already in use" },
+        { status: 409 },
+      );
+    }
+
+    // Hash password securely with bcrypt before storing
+    const hashedPassword = await bcrypt.hash(password, 10);
+    await db.insert(usersTable).values({ email, password: hashedPassword });
+
+    // Automatically authenticate the user after successful registration
+    const signInResult = await signIn("credentials", {
+      email,
+      password,
+      redirect: false,
+    });
+
+    if (signInResult?.error) {
+      return NextResponse.json(
+        {
+          message:
+            "Registration successful, but auto sign-in failed. Please log in manually.",
+        },
+        { status: 500 },
+      );
+    }
+
+    return NextResponse.json(
+      { message: "Registration successful" },
+      { status: 201 },
+    );
+  } catch (error) {
+    console.error("Register Error:", error);
+    return NextResponse.json({ message: "Server error" }, { status: 500 });
+  }
+}