/**
 * @author gsmith
 */

// When the user changes a textarea, update the result
function update() {

    // input
	var regex = document.getElementById("regex").value;
	var text = document.getElementById("text").value;
	
	// regex arguments
	var args = "";
	if (document.getElementById("m").checked) {
		args += "m";
	}
	if (document.getElementById("i").checked) {
		args += "i";
	}
	if (document.getElementById("g").checked) {
		args += "g";
    }
			
    // create and show the result
	var result;
	var resultArea = document.getElementsByName("matchArea")[0];
	try {
		if (document.getElementById("replace").checked) {
			result = text.replace(new RegExp(regex, args), document.getElementById("replacement").value);
		}
		else { // replace
			result = text.match(new RegExp(regex, args));
		}
		resultArea.style.color = "black";
	}
	// if regex impl provides a useful error on exception, display it
	catch(e) {
		result = e.message;
		resultArea.style.color = "red";
	}
	// message for no matches to valid regex
	if (result === null) {
		result = "No matches";
		resultArea.style.color = "#8B23BF";
	}
	resultArea.value = result;
}

// resizing textareas based on window size. it's a pain since percents don't work right
function resize() {
	var screenHeight;
	var regex, text, replacement, match; // heights for text areas
	
	var extraHeightForDocument = 10 + 5; // body margin
	var extraHeightPerTextarea = 22 + 5 + 1 + 1; // header, margin, padding
	
	// get screenHeight based on browser details
	if (window.innerHeight) {
		screenHeight = window.innerHeight;
	}
	else {
		screenHeight = document.documentElement.clientHeight;
	}
	
	// replace mode resize
	if (document.getElementById("replace").checked) {
		regex = Math.round(screenHeight / 5) - extraHeightPerTextarea;
		text = Math.round(screenHeight / 2.5) - extraHeightPerTextarea;
		replacement = Math.round(screenHeight / 5) - extraHeightPerTextarea;
		match = screenHeight - regex - text - replacement - extraHeightForDocument - (extraHeightPerTextarea * 4);
		document.getElementById("regex").style.height = regex + "px";
		document.getElementById("text").style.height = text + "px";
		document.getElementById("replacement").style.height = replacement + "px";
		document.getElementsByName("matchArea")[0].style.height = match + "px";
	}
	// match mode resize
	else {
		regex = Math.round(screenHeight / 4) - extraHeightPerTextarea;
		text = Math.round(screenHeight / 2) - extraHeightPerTextarea;
		match = screenHeight - regex - text - extraHeightForDocument - (extraHeightPerTextarea * 3);
		document.getElementById("regex").style.height = regex + "px";
		document.getElementById("text").style.height = text + "px";
		document.getElementsByName("matchArea")[0].style.height = match + "px";
	}
}

// switch between replace and match modes
function typeChange() {
	var replacementContainer = document.getElementById("replacementContainer");
	if (document.getElementById("replace").checked) {
		replacementContainer.style.display = "block";
	}
	else {
		replacementContainer.style.display = "none";
	}
	resize();
}