feat(auth): prepare MSAL browser integration

eme-frontend/web/auth/msal_bridge.js

@@ -0,0 +1,105 @@
+import {
+  InteractionRequiredAuthError,
+  PublicClientApplication,
+} from "@azure/msal-browser";
+
+let msalInstance = null;
+let apiScope = "";
+
+function requireInstance() {
+  if (!msalInstance) {
+    throw new Error("MSAL n'est pas initialise.");
+  }
+
+  return msalInstance;
+}
+
+function activeAccount() {
+  const instance = requireInstance();
+  return instance.getActiveAccount() ?? instance.getAllAccounts()[0] ?? null;
+}
+
+async function initialize(tenantId, clientId, scope, redirectUri) {
+  if (msalInstance) {
+    return;
+  }
+
+  if (!tenantId || !clientId || !scope || !redirectUri) {
+    throw new Error("La configuration Azure du frontend est incomplete.");
+  }
+
+  apiScope = scope;
+  msalInstance = await PublicClientApplication.createPublicClientApplication({
+    auth: {
+      clientId,
+      authority: `https://login.microsoftonline.com/${tenantId}`,
+      redirectUri,
+      postLogoutRedirectUri: redirectUri,
+    },
+    cache: {
+      cacheLocation: "sessionStorage",
+    },
+  });
+
+  const account = activeAccount();
+  if (account) {
+    msalInstance.setActiveAccount(account);
+  }
+}
+
+async function signIn() {
+  const instance = requireInstance();
+  const result = await instance.loginPopup({
+    scopes: ["openid", "profile", "email", apiScope],
+  });
+
+  instance.setActiveAccount(result.account);
+}
+
+async function getAccessToken() {
+  const instance = requireInstance();
+  const account = activeAccount();
+  if (!account) {
+    throw new Error("Aucun compte Microsoft connecte.");
+  }
+
+  try {
+    const result = await instance.acquireTokenSilent({
+      account,
+      scopes: [apiScope],
+    });
+    return result.accessToken;
+  } catch (error) {
+    if (!(error instanceof InteractionRequiredAuthError)) {
+      throw error;
+    }
+
+    const result = await instance.acquireTokenPopup({
+      account,
+      scopes: [apiScope],
+    });
+    return result.accessToken;
+  }
+}
+
+function hasAccount() {
+  return activeAccount() !== null;
+}
+
+async function signOut() {
+  const instance = requireInstance();
+  const account = activeAccount();
+  if (!account) {
+    return;
+  }
+
+  await instance.logoutPopup({ account });
+}
+
+globalThis.emeMsal = {
+  getAccessToken,
+  hasAccount,
+  initialize,
+  signIn,
+  signOut,
+};