1 files changed, 45 insertions, 0 deletions
diff --git a/src/Auth.js b/src/Auth.js
new file mode 100644
index 0000000..7254c40
--- /dev/null
+++ b/src/Auth.js
@@ -0,0 +1,45 @@
+function generateNonce() {
+    var arr = new Uint8Array(20);
+    window.crypto.getRandomValues(arr);
+    return Array.from(arr, b => b.toString(16).padStart(2, "0")).join("");
+}
+
+export const _startTwitchAuth = (clientID) => (redirectURL) => () => {
+    const nonce = generateNonce();
+    document.cookie = `authnonce=${nonce}; path=/; max-age=3000`;
+    window.location.href =
+        `https://id.twitch.tv/oauth2/authorize?response_type=id_token`
+        + `&client_id=${clientID}`
+        + `&redirect_uri=${redirectURL}`
+        + `&scope=openid`
+        + `&nonce=${nonce}`
+        + `&claims=${JSON.stringify({id_token: {preferred_username: null}})}`
+    ;
+};
+
+function getFragmentQuery() {
+    let query = new Map();
+    const hashQuery = document.location.hash.slice(1).split("&");
+    for (let equals of hashQuery) {
+        const pair = equals.split("=");
+        query.set(decodeURIComponent(pair[0]), decodeURIComponent(pair[1]));
+    }
+    return query;
+}
+
+export const _getToken = (Just) => (Nothing) => (pair) => () => {
+    const frag = getFragmentQuery();
+    const token = frag.get("id_token");
+    if (token) {
+        document.cookie = `id_token=${token}; path=/; SameSite=Strict`;
+    }
+    let id_token = null;
+    let authnonce = null;
+    for (let c of document.cookie.split("; ")) {
+        const [k, v] = c.split("=");
+        if (k === "id_token") id_token = v;
+        else if (k === "authnonce") authnonce = v;
+    }
+    if (id_token && authnonce) return Just(pair(id_token)(authnonce));
+    return Nothing;
+};