feat: add core contracts

packages/core/src/hash.ts

@@ -0,0 +1,74 @@
+import { createHash } from "node:crypto";
+
+type JsonValue = null | boolean | number | string | JsonValue[] | { [key: string]: JsonValue };
+
+export function canonicalize(value: unknown): string {
+  return renderCanonical(assertJsonValue(value));
+}
+
+export function hash(value: unknown): string {
+  return createHash("sha256").update(canonicalize(value)).digest("hex");
+}
+
+function renderCanonical(value: JsonValue): string {
+  if (value === null || typeof value === "boolean" || typeof value === "string") {
+    return JSON.stringify(value);
+  }
+
+  if (typeof value === "number") {
+    return JSON.stringify(value);
+  }
+
+  if (Array.isArray(value)) {
+    return `[${value.map((item) => renderCanonical(item)).join(",")}]`;
+  }
+
+  return `{${Object.keys(value)
+    .sort()
+    .map((key) => `${JSON.stringify(key)}:${renderCanonical(value[key] as JsonValue)}`)
+    .join(",")}}`;
+}
+
+function assertJsonValue(value: unknown): JsonValue {
+  if (
+    value === null ||
+    typeof value === "boolean" ||
+    typeof value === "string" ||
+    Array.isArray(value)
+  ) {
+    if (Array.isArray(value)) {
+      return value.map((item) => assertJsonValue(item));
+    }
+
+    return value;
+  }
+
+  if (typeof value === "number") {
+    if (!Number.isFinite(value)) {
+      throw new TypeError("Cannot canonicalize non-finite numbers");
+    }
+
+    return value;
+  }
+
+  if (typeof value === "object") {
+    const prototype = Object.getPrototypeOf(value);
+    if (prototype !== Object.prototype && prototype !== null) {
+      throw new TypeError("Cannot canonicalize non-plain object");
+    }
+
+    const objectValue: Record<string, JsonValue> = {};
+
+    for (const [key, childValue] of Object.entries(value as Record<string, unknown>)) {
+      if (childValue === undefined) {
+        throw new TypeError(`Cannot canonicalize undefined at key ${key}`);
+      }
+
+      objectValue[key] = assertJsonValue(childValue);
+    }
+
+    return objectValue;
+  }
+
+  throw new TypeError(`Cannot canonicalize ${typeof value}`);
+}