move shim to new package

packages/shim/src/crypto/create-hash.js

@@ -0,0 +1,88 @@
+import { sha256, sha512 } from "@noble/hashes/sha2.js";
+import { sha1, md5 } from "@noble/hashes/legacy.js";
+
+const HASHERS = {
+  SHA1: sha1,
+  SHA256: sha256,
+  SHA512: sha512,
+  MD5: md5,
+};
+
+const SUBTLE_ALG = {
+  SHA1: "SHA-1",
+  SHA256: "SHA-256",
+  SHA512: "SHA-512",
+};
+
+function normalizeAlgorithm(algorithm) {
+  return algorithm.toUpperCase().replace(/-/g, "");
+}
+
+function encode(bytes, encoding) {
+  if (!encoding) {
+    return bytes;
+  }
+
+  if (encoding === "hex") {
+    let hex = "";
+
+    for (let i = 0; i < bytes.length; i++) {
+      hex += bytes[i].toString(16).padStart(2, "0");
+    }
+
+    return hex;
+  }
+
+  if (encoding === "base64") {
+    let binary = "";
+
+    for (let i = 0; i < bytes.length; i++) {
+      binary += String.fromCharCode(bytes[i]);
+    }
+
+    return btoa(binary);
+  }
+
+  throw new Error(`Unsupported digest encoding: ${encoding}`);
+}
+
+export function createHash(algorithm) {
+  const alg = normalizeAlgorithm(algorithm);
+  const hasher = HASHERS[alg];
+
+  if (!hasher) {
+    throw new Error(`Unsupported hash algorithm: ${algorithm}`);
+  }
+
+  let inputData = new Uint8Array(0);
+
+  return {
+    update(data) {
+      const bytes =
+        typeof data === "string" ? new TextEncoder().encode(data) : data;
+      const merged = new Uint8Array(inputData.length + bytes.length);
+
+      merged.set(inputData);
+      merged.set(bytes, inputData.length);
+      inputData = merged;
+
+      return this;
+    },
+
+    digest(encoding) {
+      return encode(hasher(inputData), encoding);
+    },
+
+    async digestAsync(encoding) {
+      const subtleAlg = SUBTLE_ALG[alg];
+
+      if (!subtleAlg) {
+        // SubtleCrypto doesn't cover MD5; fall back to the sync hasher.
+        return encode(hasher(inputData), encoding);
+      }
+
+      const buf = await crypto.subtle.digest(subtleAlg, inputData);
+      return encode(new Uint8Array(buf), encoding);
+    },
+  };
+}