vp-tree-node/server.js

const express = require('express');
const bodyParser = require('body-parser');
const vptree = require('vptree'); 
const similarity = require('compute-cosine-similarity');
const fs = require('fs');
const path = require('path');
const app = express();
const port = 2000;

app.use(bodyParser.json());

// Function to load JSON data
function loadJSON(filePath) {
    return new Promise((resolve, reject) => {
        fs.readFile(filePath, 'utf8', (err, data) => {
            if (err) {
                return reject(err);
            }
            try {
                const jsonData = JSON.parse(data);
                resolve(jsonData);
            } catch (parseError) {
                reject(parseError);
            }
        });
    });
}

function cosineDistanceMatching(vector1, vector2) {
    let cosineSimilarity = similarity(vector1, vector2);
    let distance = 2 * (1 - cosineSimilarity);
    return Math.sqrt(distance);
}

let tree, vectors, jsonEmbeddings, filteredEmbeddings;

async function buildVPTree() {
    // Load JSON data from embeddings.json
    const jsonFilePath = path.join(__dirname, 'embeddings.json');
    try {
        jsonEmbeddings = await loadJSON(jsonFilePath);

        // Filter embeddings
        filteredEmbeddings = jsonEmbeddings.filter(item => item.lost !== 1);
        vectors = filteredEmbeddings.map(item => item.vector);

        tree = vptree.build(vectors, cosineDistanceMatching);
        const treeString = tree.stringify();
        const fileName = "sv-tree";
        const filePath = path.join(__dirname, `${fileName}.txt`);

        await fs.promises.writeFile(filePath, treeString, 'utf8');
        console.log("Tree saved successfully.");
    } catch (err) {
        console.error('Error building VP-tree:', err);
    }
}

async function loadVPTree() {
    try {
        const treeData = await loadTreeFromDisk("sv-tree");
        // Rebuild the VP-tree using the saved structure
        const jsonFilePath = path.join(__dirname, 'embeddings.json');
        try {
            jsonEmbeddings = await loadJSON(jsonFilePath);
            filteredEmbeddings = jsonEmbeddings.filter(item => item.lost !== 1); // Filter again after loading
            vectors = filteredEmbeddings.map(item => item.vector);

            console.log(vectors.length);
            tree = vptree.load(vectors, cosineDistanceMatching, treeData);
            console.log('Tree loaded successfully.');
        } catch (loadError) {
            console.error('Error loading the VP-tree:', loadError);
        }
    } catch (err) {
        console.error('Failed to load tree from disk:', err);
    }
}

function loadTreeFromDisk(fileName) {
    const filePath = path.join(__dirname, `${fileName}.txt`);
    return new Promise((resolve, reject) => {
        fs.readFile(filePath, 'utf8', (err, data) => {
            if (err) {
                console.error('Error reading the file:', err);
                return reject(err);
            }

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

async function initialize() {
    await buildVPTree();
    await loadVPTree();
}

// Initialize the VP-tree building and loading process
initialize();

app.post('/search/', (req, res) => {
    const { vector } = req.body;

    if (!Array.isArray(vector) || vector.length !== 7 || !vector.every(num => typeof num === 'number')) {
        return res.status(400).send({ success: false, message: 'Invalid vector provided. It must be an array of 7 floating-point numbers.' });
    }

    let idx = queryVPTree(vector);
    if (idx !== undefined && idx < filteredEmbeddings.length) {
        res.send({ 
            folder: filteredEmbeddings[idx].folder, 
            image: filteredEmbeddings[idx].image, 
            video: filteredEmbeddings[idx].video, 
            frame: filteredEmbeddings[idx].frame, 
            lost: filteredEmbeddings[idx].lost 
        });
    } else {
        res.status(404).send({ success: false, message: 'No matching entry found.' });
    }
});

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

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