Feat/embedded fonts (#2174)

* #239 Embedded fonts

* Add boilerplate for font table

* Fix linting

* Fix linting

* Fix odttf naming

* Correct writing of fonts to relationships and font table

new uuid function

* Add font to run

* Add demo

Fix tests

* Add character set support

* Add tests

* Write tests

src/file/fonts/obfuscate-ttf-to-odttf.ts

@@ -0,0 +1,22 @@
+const obfuscatedStartOffset = 0;
+const obfuscatedEndOffset = 32;
+const guidSize = 32;
+
+export const obfuscate = (buf: Buffer, fontKey: string): Buffer => {
+    const guid = fontKey.replace(/-/g, "");
+    if (guid.length !== guidSize) {
+        throw new Error(`Error: Cannot extract GUID from font filename: ${fontKey}`);
+    }
+
+    const hexStrings = guid.replace(/(..)/g, "$1 ").trim().split(" ");
+    const hexNumbers = hexStrings.map((hexString) => parseInt(hexString, 16));
+    // eslint-disable-next-line functional/immutable-data
+    hexNumbers.reverse();
+
+    const bytesToObfuscate = buf.slice(obfuscatedStartOffset, obfuscatedEndOffset);
+    // eslint-disable-next-line no-bitwise
+    const obfuscatedBytes = bytesToObfuscate.map((byte, i) => byte ^ hexNumbers[i % hexNumbers.length]);
+
+    const out = Buffer.concat([buf.slice(0, obfuscatedStartOffset), obfuscatedBytes, buf.slice(obfuscatedEndOffset)]);
+    return out;
+};