import {Repl} from './repl.js';

let buffer = '';
const input = document.querySelector('#hidden-input');
const history = document.querySelector('#history');
const text = document.querySelector('#text');
const prefix = document.querySelector('#prefix');

const canvas = document.querySelector('#canvas');
const canvasSwitch = document.querySelector('#canvas-switch');
let showCanvas = false;

const ctx = canvas.getContext('2d');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
const clearScreen = () => {
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
    ctx.clearRect(0, 0, canvas.width, canvas.height);
};
const fillRect = (color, x, y, w, h) => {
    ctx.fillStyle = color;
    ctx.fillRect(x, y, w, h);
};

canvasSwitch.addEventListener('click', () => {
    showCanvas = !showCanvas;
    if (showCanvas) {
	canvas.style.display = 'block';
	canvasSwitch.textContent = 'REPL';
    } else {
	canvas.style.display = 'none';
	canvasSwitch.textContent = 'CANVAS';
    }
})

const repl = new Repl(loadFromFile, loadTest, async () => {
    const onwrite = repl.stdout.onwrite;
    prefix.innerHTML = '<br>';
    const text = await read('<br>');

    repl.stdout.onwrite = result => {
	history.innerHTML += `${result.replaceAll('\n', '<br>')}`;
	repl.stdout.onwrite = onwrite;
    };
    prefix.textContent = '';
    repl.stdin.pushData(text);
});

function evalp(text) {
    if (!text.trim()) {
	return false;
    }
    return Array.from(text).reduce((op, c) => {
	if (c === '(') {
	    return op + 1;
	}
	if (c === ')' && op > 0) {
	    return op - 1;
	}
	return op;
    }, 0) === 0;
}

function read(prefix = '') {
    return new Promise(resolve => {
	const controller = new AbortController();
	input.addEventListener(
	    'keypress',
	    (e) => {
		switch(e.key) {
		case 'Enter':
		    if (evalp(input.value) &&
			(input.selectionStart == input.value.length || e.shiftKey)) {
			let text = input.value;
			history.innerHTML += `${prefix}${text}`;
			input.value = '';
			updateText();
			resolve(text);
			e.preventDefault();
			controller.abort();
		    }
		    break;
		}
	    },
	    { signal: controller.signal })
    });
}

function loadFromFile() {
    return new Promise((resolve) => {
	const input = document.createElement('input');
	input.setAttribute('type', 'file');
	input.setAttribute('accept', '.ptlisp');
	input.setAttribute('class', 'hidden');
	document.body.appendChild(input);
	input.addEventListener('change', e => {
	    const reader = new FileReader();
	    reader.addEventListener('load', e => {
		resolve(e.target.result)
		document.body.removeChild(input);
	    });
	    reader.readAsText(e.target.files[0]);
	});
	input.click();
    });
}

async function loadTest() {
    let response = await fetch("test.ptlisp");

    if (response.status != 200) {
	throw new Error("Server Error");
    }

    return await response.text();
}

function readInput() {
    prefix.textContent = 'USER > ';
    read(prefix.textContent).then(text => {
	prefix.textContent = '';

	repl.stdout.onwrite = result => {
	    history.innerHTML += `${result.replaceAll('\n', '<br>')}`;
	    readInput();
	};

	repl.stdin.pushData(text);
    });
}

readInput();

function getNextBracket (chars, searched, alternate) {
    let alternates = 0;
    let i = 0;
    for (let c of chars) {
	if (alternates == 0 && c == searched) {
	    return i;
	} else if (c == alternate) {
	    alternates++;
	} else if (c == searched) {
	    alternates--;
	}
	i++;
    }
}

function getNextClosingBracket(text, index) {
    return getNextBracket(Array.from(text.substr(index)), ')', '(') + index;
}

function getPreviousOpenBracket(text, index) {
    return index - getNextBracket(Array.from(text.substr(0, index)).reverse(), '(', ')') - 1;
}

function updateText(selectionStart, selectionEnd) {
    while(text.firstChild) {
	text.removeChild(text.lastChild);
    }

    selectionEnd += selectionEnd - selectionStart ? 0 : 1;
    let cursorText = input.value.substr(selectionStart, selectionEnd - selectionStart) || '&nbsp;';

    let secondCursorIdx = -1;
    switch (cursorText) {
    case '(': secondCursorIdx = getNextClosingBracket(input.value, selectionEnd); break;
    case ')': secondCursorIdx = getPreviousOpenBracket(input.value, selectionStart); break;
    }

    if (secondCursorIdx >= 0 && selectionStart > secondCursorIdx) {
	text.appendChild(document.createTextNode(input.value.substr(0, secondCursorIdx)));
	const secondCursor = document.createElement('SPAN');
	secondCursor.classList.add('second-cursor');
	secondCursor.appendChild(document.createTextNode(input.value.substr(secondCursorIdx, 1)));
	text.appendChild(secondCursor);
	if (secondCursorIdx + 1 != selectionStart) {
	    text.appendChild(
		document.createTextNode(
		    input.value.substr(secondCursorIdx + 1, selectionStart - (secondCursorIdx + 1))));
	}
    } else if (selectionStart > 0) {
	text.appendChild(document.createTextNode(input.value.substr(0, selectionStart)));
    }

    let cursor = document.createElement('SPAN');
    cursor.classList.add('cursor');
    // cursor.appendChild(document.createTextNode(cursorText));
    cursor.innerHTML = cursorText;
    if (cursorText == '\n') {
	cursor.classList.add('end-of-line');
    }
    text.appendChild(cursor);

    if (secondCursorIdx >= selectionEnd) {
	text.appendChild(
	    document.createTextNode(
		input.value.substr(selectionEnd, secondCursorIdx - selectionEnd)));
	const secondCursor = document.createElement('SPAN');
	secondCursor.classList.add('second-cursor');
	secondCursor.appendChild(document.createTextNode(input.value.substr(secondCursorIdx, 1)));
	text.appendChild(secondCursor);
	text.appendChild(
	    document.createTextNode(
		input.value.substr(secondCursorIdx + 1)));
    } else if (selectionEnd < input.value.length) {
	text.appendChild(document.createTextNode(input.value.substr(selectionEnd)));
    }
}

input.addEventListener('input', (e) => {
    var selection = input.selectionStart;
    if (e.data == '(') {
	input.value = input.value.slice(0, selection) + ')' + input.value.slice(selection);
	input.setSelectionRange(selection, selection);
    }

    updateText(input.selectionStart, input.selectionEnd);
    buffer = input.value;
})

input.addEventListener('keydown', (e) => {
    if (e.key == 'Backspace' &&
	input.selectionEnd == input.selectionStart) { 
	if (input.value.substr(input.selectionStart - 1, 1) == '(' &&
	    input.value.substr(input.selectionStart, 1) == ')') {
	    input.value = input.value.substr(0, input.selectionStart - 1) + input.value.substr(input.selectionStart + 1);
	    input.selectionStart = input.selectionEnd = input.selectionStart - 1;
	    e.preventDefault();
	} else if (input.value.substr(input.selectionStart - 1, 1) == ')'){
	    input.selectionStart = input.selectionEnd = input.selectionStart - 1;
	    e.preventDefault();
	}
    } else if (e.key == ')' &&
	       input.selectionStart - input.selectionEnd == 0 &&
	       input.value.substr(input.selectionStart, 1) == ')') {
	input.selectionEnd = ++input.selectionStart;
	e.preventDefault();
    }
    setTimeout(() => {
	updateText(input.selectionStart, input.selectionEnd);
    });
})

document.addEventListener('mouseup', (e) => {
    const selection = document.getSelection();
    if (!(selection.anchorNode.parentNode == text ||
	  selection.anchorNode.parentNode.parentNode == text)) {
	return;
    }

    let textNodes = [], node, walk = document.createTreeWalker(text, NodeFilter.SHOW_TEXT, null, false);
    while (node = walk.nextNode()) {
	textNodes.push(node);
    }
    let startNodeIdx = textNodes.indexOf(selection.anchorNode);
    let endNodeIdx = textNodes.indexOf(selection.focusNode);
    let startNodeOffset = selection.anchorOffset;
    let endNodeOffset = selection.focusOffset;
    for (let i = 0; i < startNodeIdx; i++) {
	startNodeOffset += textNodes[i].textContent.length;
    }

    for (let i = 0; i < endNodeIdx; i++) {
	endNodeOffset += textNodes[i].textContent.length;
    }

    input.setSelectionRange(Math.min(startNodeOffset, endNodeOffset),
     			    Math.max(startNodeOffset, endNodeOffset));
    updateText(input.selectionStart, input.selectionEnd);
});



function focusInput() {
    input.focus();
}

window.addEventListener('focus', focusInput);

window.addEventListener('click', focusInput);

focusInput();





// WASM
const response = await fetch('./lisp.wasm');
const bytes = await response.arrayBuffer();
const results = await WebAssembly.instantiate(bytes, {
    env: {
	jsprint: (byteOffset) => {
	    let s = '';
	    const a = new Uint8Array(memory.buffer);
	    for (var i = byteOffset; a[i]; i++) {
		s += String.fromCharCode(a[i]);
	    }

	    console.log(s);
	}
    }
});
const instance = results.instance;
const memory = instance.exports.pagememory;
instance.exports.helloworld();