const express = require('express');
const bodyParser = require('body-parser');
const vptree = require('vptree'); // Assuming you have the vptree library available
const fs = require('fs');
const path = require('path');

const app = express();
const port = 3000;

app.use(bodyParser.json());


var dataset = [
    'culture',
    'democracy',
    'metaphor',
    'irony',
    'hypothesis',
    'science',
    'fastuous',
    'integrity',
    'synonym',
    'empathy'     // and on and on...
];

// Example Levenshtein distance function
function levenshteinDistance(a, b) {
    // Implement or use an existing Levenshtein distance function
    // Here's a simple implementation:
    const d = [];
    const alen = a.length;
    const blen = b.length;
    
    for (let i = 0; i <= alen; i++) d[i] = [i];
    for (let j = 0; j <= blen; j++) d[0][j] = j;
  
    for (let i = 1; i <= alen; i++) {
      for (let j = 1; j <= blen; j++) {
        const cost = a[i - 1] === b[j - 1] ? 0 : 1;
        d[i][j] = Math.min(
          d[i - 1][j] + 1,
          d[i][j - 1] + 1,
          d[i - 1][j - 1] + cost
        );
      }
    }
    
    return d[alen][blen];
}

let tree

loadVPTree()

// Load tree endpoint
app.post('/search/:word', (req, res) => {

    const searchWord = req.params.word;

    if (!searchWord) {
        return res.status(400).send({ success: false, message: 'No word provided' });
    }

    let idx = queryVPTree("democratic")

    res.send({idx});
});

function queryVPTree(value){
    let nearest = tree.search(value)
    let index = nearest[0].i
    return index
}

function buildVPTree(){
    // building the tree
    tree = vptree.build(stringList, levenshteinDistance)
}

function saveVPTree(fileName){

    const treeString = tree.stringify();

    const filePath = path.join(__dirname, `${fileName}.txt`);

    fs.writeFile(filePath, treeString, 'utf8', (err) => {
        if (err) {
            console.log("Tree did not save to file.")
            return
        }
        
        console.log("Tree saved successfully.")
    });
}

function loadVPTree(){
    loadTreeFromDisk("vp-tree-new", (err, treeData) => {
        if (err) {
            console.error('Failed to load tree from disk:', err);
            return;
        }

        // Rebuild the VP-tree using the saved structure
        try {
            tree = vptree.load(dataset, levenshteinDistance, treeData);
            console.log('Tree loaded successfully.');

        } catch (loadError) {
            console.error('Error loading the VP-tree:', loadError);
        }
    });
}

function loadTreeFromDisk(fileName, callback){
    const filePath = path.join(__dirname, `${fileName}.txt`);

    fs.readFile(filePath, 'utf8', (err, data) => {
        if (err) {
            console.error('Error reading the file:', err);
            return callback(err, null);
        }

        // Parse the data as a JavaScript object
        try {
            const treeData = eval(`(${data})`); // Using eval to convert to object
            callback(null, treeData);
        } catch (parseError) {
            console.error('Error parsing the tree data:', parseError);
            callback(parseError, null);
        }
    });
}

app.listen(port, () => {
  console.log(`Server listening at http://localhost:${port}`);
});