hpcore/examples/nodejs_contract/file_contract.js

const HotPocket = require("hotpocket-nodejs-contract");
const fs = require('fs');
const bson = require('bson');

const fileContract = async (ctx) => {

    for (const user of ctx.users.list()) {

        for (const input of user.inputs) {
            const buf = await ctx.users.read(input);
            const msg = bson.deserialize(buf);

            if (msg.type == "upload") {
                if (fs.existsSync(msg.fileName)) {
                    await user.send(bson.serialize({
                        type: "uploadResult",
                        status: "already_exists",
                        fileName: msg.fileName
                    }));
                }
                else if (msg.content.length > 10 * 1024 * 1024) { // 10MB
                    await user.send(bson.serialize({
                        type: "uploadResult",
                        status: "too_large",
                        fileName: msg.fileName
                    }));
                }
                else {

                    // Save the file.
                    fs.writeFileSync(msg.fileName, msg.content.buffer);

                    await user.send(bson.serialize({
                        type: "uploadResult",
                        status: "ok",
                        fileName: msg.fileName
                    }));
                }
            }
            else if (msg.type == "delete") {
                if (fs.existsSync(msg.fileName)) {
                    fs.unlinkSync(msg.fileName);
                    await user.send(bson.serialize({
                        type: "deleteResult",
                        status: "ok",
                        fileName: msg.fileName
                    }));
                }
                else {
                    await user.send(bson.serialize({
                        type: "deleteResult",
                        status: "not_found",
                        fileName: msg.fileName
                    }));
                }
            }
            else if (msg.type == "download") {
                if (fs.existsSync(msg.fileName)) {
                    const fileContent = fs.readFileSync(msg.fileName);
                    await user.send(bson.serialize({
                        type: "downloadResult",
                        status: "ok",
                        fileName: msg.fileName,
                        content: fileContent
                    }));
                }
                else {
                    await user.send(bson.serialize({
                        type: "downloadResult",
                        status: "not_found",
                        fileName: msg.fileName
                    }));
                }
            }
        }
    }
};

const hpc = new HotPocket.Contract();
hpc.init(fileContract, HotPocket.clientProtocols.bson);