feat: Initial clean release of CHM

packages/lib/mime-utils.ts

@@ -0,0 +1,46 @@
+import mimeTypes from './mime-utils-types';
+
+export const fromFileExtension = (ext: string) => {
+	ext = ext.toLowerCase();
+	for (let i = 0; i < mimeTypes.length; i++) {
+		const t = mimeTypes[i];
+		if (t.e.indexOf(ext) >= 0) {
+			return t.t;
+		}
+	}
+	return null;
+};
+
+export const fromFilename = (name: string) => {
+	if (!name) return null;
+	const splitted = name.trim().split('.');
+	if (splitted.length <= 1) return null;
+	return fromFileExtension(splitted[splitted.length - 1]);
+};
+
+export const toFileExtension = (mimeType: string) => {
+	mimeType = mimeType.toLowerCase();
+	for (let i = 0; i < mimeTypes.length; i++) {
+		const t = mimeTypes[i];
+		if (mimeType === t.t) {
+			// Return the first file extension that is 3 characters long
+			// If none exist return the first one in the list.
+			for (let j = 0; j < t.e.length; j++) {
+				if (t.e[j].length === 3) return t.e[j];
+			}
+			return t.e[0];
+		}
+	}
+	return null;
+};
+
+export const fromDataUrl = (dataUrl: string) => {
+	// Example: data:image/jpeg;base64,/9j/4AAQSkZJR.....
+	const defaultMime = 'text/plain';
+	const p = dataUrl.substr(0, dataUrl.indexOf(',')).split(';');
+	let s = p[0];
+	const result = s.split(':');
+	if (result.length <= 1) return defaultMime;
+	s = result[1];
+	return s.indexOf('/') >= 0 ? s : defaultMime; // https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
+};