import { app } from "../../../scripts/app.js";
import { $el } from "../../../scripts/ui.js";
import { getValue, setValue, addJNodesSetting, clamp, getKeyList } from "./common/utils.js"

// localStorage accessors
const getVal = (n, d) => {
	return getValue("MultilineText.BatchComment." + n, d);
}

const saveVal = (n, v) => {
	setValue("MultilineText.BatchComment." + n, v);
}

function getModifierKeyCombos() {
	return [
		'ctrl/meta + shift +',
		'ctrl/meta + alt +',
	];
}

function getLineStartIndex(textarea, cursorPosition) {
	const text = textarea.value;

	// Iterate backward from the cursor position to find the beginning of the line
	let startIndex = cursorPosition;
	while (startIndex > 0 && text[startIndex - 1] !== '\n') {
		startIndex--;
	}

	return startIndex;
}

function getLineEndIndex(textarea, cursorPosition) {
	const text = textarea.value;

	// Iterate backward from the cursor position to find the beginning of the line
	let endIndex = cursorPosition;
	while (endIndex < text.length && text[endIndex] !== '\n') {
		endIndex++;
	}

	return endIndex;
}

// Insert Text Or Remove Existing Text 
// At the Beginning Of Each Line In Selected Text In Text Area
function toggleTextAtTheBeginningOfEachSelectedLine(text, textarea) {

	if (textarea.readOnly) {
		return;
	}

	if (textarea.tagName === 'TEXTAREA' || (textarea.tagName === 'INPUT' && textarea.type === 'text')) {
		const originalSelectionStart = textarea.selectionStart;
		const selectionStart = getLineStartIndex(textarea, originalSelectionStart);
		const bOriginalSelectionStartIsLineStart = selectionStart == originalSelectionStart;

		const originalSelectionEnd = textarea.selectionEnd;
		const selectionEnd = getLineEndIndex(textarea, originalSelectionEnd);

		const scrollPosition = textarea.scrollTop;

		let selectionStartOffset = 0;
		let selectionEndOffset = 0;

		// Resize selection temporarily
		textarea.selectionStart = selectionStart;
		textarea.selectionEnd = selectionEnd;

		const selectedText = textarea.value.substring(selectionStart, selectionEnd);
		const lines = selectedText.split('\n');

		// Our goal is to remove the comment text from all lines if all lines have it.
		// If any lines do not have the comment text, we want to add it to those 
		// and leave the rest alone.

		// Assume that all lines are currently commented
		// Iterate over lines in the selection until we find one that is not commented
		// If we do, set bShouldToggleOff to false and add the comment text before the line.
		let bShouldToggleOff = true;
		for (let index = 0; index < lines.length; index++) {
			if (lines[index].startsWith(text)) { continue; } // Skip lines that are already commented
			if (lines[index].trim() == "") { continue; } // Skip empty lines

			bShouldToggleOff = false;
			lines[index] = text + lines[index];

			if (!bOriginalSelectionStartIsLineStart) {
				if (index == 0) {
					selectionStartOffset += text.length;
				}
				selectionEndOffset += text.length;
			}
		}

		// Skip second loop if we don't need to toggle the comment off
		if (bShouldToggleOff) {
			for (let index = 0; index < lines.length; index++) {
				if (lines[index].startsWith(text + text)) { continue; } // Skip always-on comments ('##')
				if (lines[index].trim() == "") { continue; } // Skip empty lines

				// Guaranteed removal on each line
				lines[index] = lines[index].substring(text.length);

				if (index == 0 && !bOriginalSelectionStartIsLineStart) {
					selectionStartOffset -= text.length;
				}
				selectionEndOffset -= text.length;
			}
		}
		const modifiedText = lines.join('\n');

		// Using execCommand to support undo, but since it's officially 
		// 'deprecated' we need a backup solution, but it won't support undo :(
		let pasted = true;
		try {
			if (!document.execCommand("insertText", false, modifiedText)) {
				pasted = false;
			}
		} catch (e) {
			console.error("Error caught during batch commenting:", e);
			pasted = false;
		}

		if (!pasted) {
			console.error(
				"execCommand unsuccessful; not supported. Batch commenting manually, no undo support.");
			textarea.setRangeText(modifiedText, selectionStart, selectionEnd, 'end');
		}

		// Restore original selection + offsets from adding/removing comment text
		textarea.selectionStart = clamp(originalSelectionStart + selectionStartOffset, 0, textarea.value.length);
		textarea.selectionEnd = clamp(originalSelectionEnd + selectionEndOffset, textarea.selectionStart, textarea.value.length);

		// Restore scroll position, as it can change when commenting or uncommenting a lot of lines
		textarea.scrollTop = scrollPosition;
	}
}

app.registerExtension({
	name: "JNodes.BatchCommenting",
	async setup() {

		const labelWidget = $el("label", {
			textContent: "Batch-commenting Hotkey:",
		});

		const modifierKeysWidget = $el(
			"select",
			{
				oninput: (e) => {
					saveVal("ModifierKeyCombo", e.target.value);
					setFontOnAllTextAreas();
				},
			},
			getModifierKeyCombos().map((m) =>
				$el("option", {
					value: m,
					textContent: m,
					selected: getVal("ModifierKeyCombo", getModifierKeyCombos()[0]) === m,
				})
			)
		);

		const keyCodeWidget = $el(
			"select",
			{
				oninput: (e) => {
					saveVal("KeyCode", e.target.value);
					setFontOnAllTextAreas();
				},
			},
			getKeyList().map((m) =>
				$el("option", {
					value: m,
					textContent: m,
					selected: getVal("KeyCode", 'Slash') === m,
				})
			)
		);

		const settingWidget = $el("div", {}, [modifierKeysWidget, keyCodeWidget]);

		const tooltip =
			"A key combo that, when pressed, will insert text at the beginning of the selected " +
			"lines in a multiline textarea, assuming it is the active element. If no text is " +
			"selected, the text will be inserted at the beginning of the line where the cursor " +
			"currently sits. This text will not automatically dummy out any lines, you will need " +
			"to pass the resulting text into a custom node that removes lines marked as 'commented'.";
		addJNodesSetting(labelWidget, settingWidget, tooltip);

		window.addEventListener("keydown", function(event) {
			const { ctrlKey, metaKey, shiftKey, altKey, code } = event;
			const bUseShiftInCombo = getVal("ModifierKeyCombo", getModifierKeyCombos()[0]) === getModifierKeyCombos()[0];
			const bModifiersPressed =
				(metaKey || ctrlKey) &&
				((bUseShiftInCombo && shiftKey) || (!bUseShiftInCombo && altKey));

			if (bModifiersPressed &&
				event.code == getVal("KeyCode", 'Slash')) {
				const textarea = document.activeElement;

				if (textarea.tagName === 'TEXTAREA') {
					toggleTextAtTheBeginningOfEachSelectedLine('#', textarea);
				}
			}
		}, true);
	}
});