feat: add contact page with form handling and validation

- Implemented a contact page with a form for user inquiries.
- Added validation for form fields using Zod schema.
- Integrated PostgreSQL database for storing contact messages.
- Created necessary API endpoints for form submission.
- Added admin authentication and session management.
- Developed CGU, cookies policy, privacy policy, and legal mentions pages.
- Set up Docker configuration for PostgreSQL and application services.
- Enhanced UI with responsive design and accessibility features.

lib/admin-auth.ts

@@ -0,0 +1,98 @@
+import { createHmac, timingSafeEqual } from "crypto";
+import { cookies } from "next/headers";
+
+const COOKIE_NAME = "admin_session";
+const SESSION_TTL_SECONDS = 60 * 60 * 12;
+
+type SessionPayload = {
+  sub: string;
+  exp: number;
+};
+
+function getSecret() {
+  const secret = process.env.ADMIN_SESSION_SECRET;
+  if (!secret) {
+    throw new Error("ADMIN_SESSION_SECRET is missing.");
+  }
+  return secret;
+}
+
+function encodeBase64Url(value: string) {
+  return Buffer.from(value).toString("base64url");
+}
+
+function decodeBase64Url(value: string) {
+  return Buffer.from(value, "base64url").toString();
+}
+
+function sign(value: string) {
+  return createHmac("sha256", getSecret()).update(value).digest("base64url");
+}
+
+function safeEqual(a: string, b: string) {
+  const aBuffer = Buffer.from(a);
+  const bBuffer = Buffer.from(b);
+  if (aBuffer.length !== bBuffer.length) {
+    return false;
+  }
+  return timingSafeEqual(aBuffer, bBuffer);
+}
+
+export function createAdminToken(username: string) {
+  const payload: SessionPayload = {
+    sub: username,
+    exp: Math.floor(Date.now() / 1000) + SESSION_TTL_SECONDS,
+  };
+
+  const encodedPayload = encodeBase64Url(JSON.stringify(payload));
+  const signature = sign(encodedPayload);
+  return `${encodedPayload}.${signature}`;
+}
+
+function verifyToken(token: string): SessionPayload | null {
+  const [payloadPart, signaturePart] = token.split(".");
+  if (!payloadPart || !signaturePart) {
+    return null;
+  }
+
+  const expectedSignature = sign(payloadPart);
+  if (!safeEqual(signaturePart, expectedSignature)) {
+    return null;
+  }
+
+  try {
+    const payload = JSON.parse(decodeBase64Url(payloadPart)) as SessionPayload;
+    if (!payload?.sub || !payload?.exp) {
+      return null;
+    }
+
+    if (payload.exp < Math.floor(Date.now() / 1000)) {
+      return null;
+    }
+
+    return payload;
+  } catch {
+    return null;
+  }
+}
+
+export async function isAdminAuthenticated() {
+  const cookieStore = await cookies();
+  const token = cookieStore.get(COOKIE_NAME)?.value;
+  if (!token) {
+    return false;
+  }
+
+  return Boolean(verifyToken(token));
+}
+
+export function getAdminCredentials() {
+  return {
+    username: process.env.ADMIN_USERNAME || "admin",
+    password: process.env.ADMIN_PASSWORD || "change-me",
+  };
+}
+
+export function getAdminCookieName() {
+  return COOKIE_NAME;
+}