LoRaWAN-Signal-Mapping/server/process-data/DataProcessor.mjs

"use strict";

import fs from 'fs';
import readline from 'readline';

/**
 * Folds data from the microSD card into the SQLite database.
 */
class DataProcessor {
	constructor({ settings, log, ReadingRepo }) {
		this.settings = settings;
		this.l = log;
		this.repo_reading = ReadingRepo;
	}
	
	/**
	 * Given a filename, reads it and folds the data into the SQLite database.
	 * @param	{string}	filename	The path tot he file to read in.
	 * @return	{Promise}	A promise that resolves when the folding is complete.
	 */
	process(filename) {
		return new Promise((resolve, reject) => { // Arrow functions keep the scope of their parent functions
			if(!fs.existsSync(filename)) {
				this.l.log(`Error: ${filename} doesn't exist.`);
				reject();
			}
			
			let reader = readline.createInterface({
				input: fs.createReadStream(filename)
			});
			
			reader.on("line", this.process_line.bind(this));
			reader.on("close", resolve);
		})
		
	}
	
	process_line(line_text) {
		let parts = line_text.split(/\s+/),
			reading = {
				id: parseInt(parts[0]),
				latitude: parseFloat(parts[1]),
				longitude: parseFloat(parts[2]),
				
				// For inserting into the database
				data_rate: null, code_rate: null, rssis: []
			};
		
		let log_message = `Processing reading with id ${reading.id}`;
		
		if(!this.repo_reading.exists(reading.id)) {
			// Since the reading doesn't exist in the database already, we should insert it now.
			// We can deduce that it doesn't exist because no gateways picked up the message when it was transmitted - hence the IoT device was in a dead sopt at the time of transmission.
			this.repo_reading.add(reading);
			log_message += " no database entry detected, inserted new record";
		}
		
		this.l.log(log_message);
	}
}

export default DataProcessor;