// Must be called directly in a "short interaction event handler" 
// like `click` or `mousedown`/`touchstart`. Cannot be triggered from 
// an <a> anchor element, even if `e.preventDefault()` is called on the
// event. passed `input` must be an <input> of any type or a <textarea>.
export function copyToClipboard(input = null) {
	
	if (! input || (['INPUT', 'TEXTAREA'].indexOf(input.tagName) === -1)) {
		throw new Error('A Valid <input> or <textarea> HTML element must be passed as the first parameter.');
	}
	
	// check if device is iOS.
	const isIos = /iPhone|iphone|iPod|ipod|iPad|ipad/.test(window.navigator.userAgent);
	
	if (isIos) {
		
		// if is iOS, do all of this ridiculousness.
		const oldContentEditable = input.getAttribute('contenteditable');
		const oldReadOnly = input.getAttribute('readonly');
		input.setAttribute('contenteditable', true);
		input.setAttribute('readonly', false);
		const range = document.createRange();
		range.selectNodeContents(input);
		const selection = window.getSelection();
		selection.removeAllRanges();
		selection.addRange(range);
		input.setSelectionRange(0, input.value.length); 
		input.setAttribute('contenteditable', oldContentEditable);
		input.setAttribute('readonly', oldReadOnly);
		
	} else {
		
		// else just select the input :)
		input.select();
		
	}
	
	// copy the selected text.
	document.execCommand('copy');
	
	// blur immediately so that the keyboard never shows.
	input.blur();
	
}