iota-reader/.read.js

Command line utility to download mam streams that contain json data to a json file.

const Mam=require('@iota/mam')
const { asciiToTrytes, trytesToAscii } = require('@iota/converter')
const mode='public'
const provider='https://dyn.tangle-nodes.com'
//const root = 'HNWCIUCQGMMNGORVVVUTL9SSXDELAUASOJIEAWQOUJHLYLDGNWFIPKVERG9RKQDDWHGGPZGSQ9MEZPNIY'
//const root='HI9FKCXRDNFWHCICCFADORCECRXKLQ9CUGYIDGANCKBUXDKSCBFKIAKYOQNWFRQOJDKNPHRHBLJEMYPNC'
const root = 'YBLXOSGIETIJHYEIXREDROOLKZDWIDFIUWVVYUGURWQZOJXK9QZXKXGDUSQFBZP9ADELMHMUPN9ZKEWMI'
let mamState=Mam.init(provider)
const log = data=>console.log(JSON.parse(trytesToAscii(data)),'\n')
var fs = require('fs')

function parseMsg(msg){
    try{
	return JSON.parse(JSON.parse(trytesToAscii(msg)))
    }catch(error){
	return undefined
    }
}

async function init(thisRoot,write=null,filename=null){
    console.log("initialized on",thisRoot)
    latestRoot=thisRoot
    try{
	await Mam.fetch(thisRoot,mode,null,m=>{
	    if (m != undefined){
		try{
		    msg=parseMsg(m)
		    if (msg != undefined){
			console.log("Recieved message",msg)
			if(write!=null){
			    write(msg,filename)
			}
		    }else{
			console.log("Problem with message",msg)
		    }
		}catch(error){
		    console.log("Failed to parse.")
		}
	    }else{
		console.log("Message Undefined")
	    }
	})
	    .then(response=>{
		if (response.messages != undefined && response.messages.length != 0){
		    latestRoot=response.nextRoot
		    init(response.nextRoot,write,filename)
		}else{
		    console.log("Failed to retrieve. Retrying...")
		    init(latestRoot,write,filename)
		}
	    })
	    .catch(err=>{
		console.log("MAM broke, retry.")
		init(latestRoot,write,filename)
	    })
    }catch(error){
	console.log("Message Broken.")
    }
}
function append(data,filename){
    if(fs.existsSync(filename)){
	fs.readFile(filename,{encoding: 'utf-8'},function(err,d){
	    if (!err){
		myFile=JSON.parse(d)
		myFile.push(data)
		fs.writeFile(filename,JSON.stringify(myFile),console.log)
	    }
	})
    }
    else{
	fs.writeFile(filename,JSON.stringify([data]),console.log)
    }
}
if (process.argv.length >= 3){
    init(root,append,process.argv[2])
}else{
    init(root)
}