#!/usr/bin/env node

/*
npm init -y
npm install @lezer/html
*/

import { parser as lezerParserHtml } from '@lezer/html';

const inputHtml = `
<div>

  aaa

  bbb

</div>
`;

const htmlParser = lezerParserHtml.configure({
    strict: true, // throw on parse error
    //dialect: "selfClosing",
});

const htmlTree = htmlParser.parse(inputHtml);

const rootNode = htmlTree.topNode;

// based on nix-eval-js/src/lezer-parser-nix/src/nix-format.js
/** @param {Tree | TreeNode} tree */
function walkHtmlTree(tree, func) {
    const cursor = tree.cursor();
    //if (!cursor) return '';
    if (!cursor) return;
    let depth = 0;
    while (true) {
        // NLR: Node, Left, Right
        // Node
        // NOTE InvalidEntity breaks the parser
        // <a t="a&amp;b&c">a&amp;b&c</a>
        // -> require valid input, throw on parse error
        const cursorTypeId = cursor.type.id;
        if (
            //true || // debug: dont filter
            !(
                cursorTypeId == 15 || // Document
                cursorTypeId == 20 || // Element
                cursorTypeId == 23 || // Attribute
                cursorTypeId == 21 || // OpenTag <script>
                cursorTypeId == 30 || // OpenTag <style>
                cursorTypeId == 36 || // OpenTag
                cursorTypeId == 32 || // CloseTag </style>
                cursorTypeId == 29 || // CloseTag </script>
                cursorTypeId == 37 || // CloseTag
                cursorTypeId == 38 || // SelfClosingTag
                // note: this is inconsistent in the parser
                // InvalidEntity is child node
                // EntityReference is separate node (sibling of other text nodes)
                cursorTypeId == 19 || // InvalidEntity: <a href="?a=1&b=2" -> "&" is parsed as InvalidEntity
                //cursorTypeId == 17 || // EntityReference: "&amp;" or "&mdash;" is parsed as EntityReference
                false
            )
        ) {
            func(cursor)
        }
        // Left
        if (cursor.firstChild()) {
            // moved down
            depth++;
            continue;
        }
        // Right
        if (depth > 0 && cursor.nextSibling()) {
            // moved right
            continue;
        }
        let continueMainLoop = false;
        let firstUp = true;
        while (cursor.parent()) {
            // moved up
            depth--;
            if (depth <= 0) {
                // when tree is a node, stop at the end of node
                // == dont visit sibling or parent nodes
                return;
            }
            if (cursor.nextSibling()) {
                // moved up + right
                continueMainLoop = true;
                break;
            }
            firstUp = false;
        }
        if (continueMainLoop) continue;
        break;
    }
}

let lastNodeTo = 0;
const maxLen = 30;
walkHtmlTree(rootNode, (node) => {
    let nodeSource = JSON.stringify(inputHtml.slice(node.from, node.to));
    let spaceNodeSource = JSON.stringify(inputHtml.slice(lastNodeTo, node.to));
    if (nodeSource.length > maxLen) {
        nodeSource = nodeSource.slice(0, maxLen);
    }
    if (spaceNodeSource.length > maxLen) {
        spaceNodeSource = spaceNodeSource.slice(0, maxLen);
    }
    console.log(`node ${String(node.type.id).padStart(2)} = ${node.type.name.padEnd(15)} : ${nodeSource.padEnd(maxLen)} : ${spaceNodeSource}`);
    lastNodeTo = node.to;
});