diff --git a/02-filter-a-log-file/chains_parser_incremental.js b/02-filter-a-log-file/chains_parser_incremental.js
new file mode 100644
index 0000000..af12192
--- /dev/null
+++ b/02-filter-a-log-file/chains_parser_incremental.js
@@ -0,0 +1,347 @@
+import fs from "fs";
+import assert from "assert";
+import UAParser from "ua-parser-js";
+import readline from "readline";
+import { program } from "commander";
+import glob from "fast-glob";
+import format from "date-fns/format/index.js";
+
+program
+  .option("--min <Number>", "The lowest count to print. Stop at this.", 1)
+  .option("--errors", "Show the errors so you can fix them.", false)
+  .option("--format <String>", "Output format, text or json. Ignores min for raw output.")
+  .option("--outfile <String>", "Save to file rather than stdout.")
+  .option("--results <file>", "Save/load incremental results here.")
+  .requiredOption("--domain <String>", "Domain for the log. Gets removed as a refer.")
+  .requiredOption("--input <String>", "Input file glob.")
+  .description("Processes different web server logs to determine request chain frequency.")
+  .version(0.1);
+
+program.parse();
+const OPTS = program.opts();
+OPTS.min = parseInt(OPTS.min);
+assert(!isNaN(OPTS.min), `min must be a number, you have ${OPTS.min}`);
+
+
+class Parser {
+  constructor() {
+    this.text = "";
+    this.next = "";
+  }
+
+  match(reg, consume=true) {
+    const n = this.next.match(reg);
+
+    if(n === null) {
+      return undefined;
+    } else {
+      const element = n.length > 1 ? n.slice(1) : n[0];
+
+      if(consume) {
+        this.next = this.next.slice(n[0].length);
+      }
+
+      return element;
+    }
+  }
+
+  start(line) {
+    this.text = line;
+    this.next = line;
+  }
+
+  ws(consume=true) {
+    return this.match(/ +/, consume);
+  }
+
+  parse_new_log(ip) {
+    const [port, conn_id, conn_count] = this.match(/^([0-9]+):([0-9]+):([0-9]+)/);
+
+    this.ws();
+
+    const [ time ] = this.match(/\[(.*)\]/);
+
+    this.ws();
+
+    const [ full_url ] = this.match(/"(.+?)"/);
+
+    const [url, params] = full_url.split("?");
+
+    this.ws();
+
+    const code = this.match(/\-|[0-9]+/);
+
+    this.ws();
+
+    const bytes = this.match(/\-|[0-9]+/);
+
+    this.ws();
+
+    const [refer] = this.match(/"(.+?)"/);
+
+    this.ws();
+
+    const [ua] = this.match(/"(.+?)"/);
+
+    return {
+      ip,
+      conn_id: parseInt(conn_id),
+      conn_count: parseInt(conn_count),
+      time: new Date(time),
+      url, params,
+      code: parseInt(code),
+      size: parseInt(bytes),
+      refer: refer === '-' ? undefined : refer,
+      ua: UAParser(ua)
+    };
+  }
+
+  parse_old_log(ip) {
+    this.match(/- -/);
+
+    this.ws();
+
+    // FORMAT: 29/Mar/2022:22:40:52 +0200
+    const [ day, month, year, hour, minute, seconds, tz_offset ] = this.match(/\[([0-9]+)\/([A-Za-z]+)\/([0-9]+):([0-9]+):([0-9]+):([0-9]+) (.+?)\]/);
+
+    this.ws();
+
+    const [ method, full_url, http_version ] = this.match(/"([A-Z]+) (.+) HTTP\/([0-9].[0-9])"/);
+
+    const [ url, params ] = full_url.split("?");
+
+    this.ws();
+
+    const code = this.match(/\-|[0-9]+/);
+
+    this.ws();
+
+    const bytes = this.match(/\-|[0-9]+/);
+
+    this.ws();
+
+    const [refer] = this.match(/"(.+?)"/);
+
+    this.ws();
+
+    const [ua] = this.match(/"(.+?)"/);
+
+    // this is another IP address sometimes in another log format that I'll ignore
+    const unknown = this.match(/".+?"$/);
+
+    return {
+      ip,
+      method,
+      http_version,
+      time: new Date(`${day} ${month} ${year} ${hour}:${minute}:${seconds} ${tz_offset}`),
+      url, params,
+      code: parseInt(code),
+      size: parseInt(bytes),
+      refer: refer === '-' ? undefined : refer,
+      ua: UAParser(ua)
+    };
+  }
+
+  parse() {
+    const ip = this.match(/^[0-9\.]+/);
+    const test = this.match(/(:| )/);
+
+    // BUG: uhh for some reason it needs == here? === says : doesn't equal :
+    if(test == ":") {
+      return this.parse_new_log(ip);
+    } else if(test == " ") {
+      return this.parse_old_log(ip);
+    } else {
+      // console.log(`PARSE ERROR, expected : or ' ' but got ${test}`);
+      return {};
+    }
+  }
+}
+
+const parse_log_file = async (results, stats, file_name, errors) => {
+  const read_stream = fs.createReadStream(file_name);
+
+  const rl = readline.createInterface({
+    input: read_stream,
+    crlfDelay: Infinity
+  });
+
+  const parser = new Parser();
+
+  const skip = /(authcheck|.*\.svg|.*\.webmanifest|.*\.js|.*\.css|.*php|socket\.io|\.env|.*\.png|.*\.txt|.*\.woff|.*\.jpg|.*\.mp4|.*\.torrent|\-|.*\.ico|\/api\/.*\?.*|.*\.html|.*\.map|.*.php)/
+
+  for await (let line of rl) {
+    try {
+      stats.lines += 1;
+      parser.start(line);
+
+      const data = parser.parse();
+
+      // skip lines that have content we don't care about
+      if(data.url.match(skip)) continue;
+
+      // convert the date to a only day length
+      const date_key = format(data.time, "yyyy-MM-dd");
+
+      // get the date entry or a new one
+      const date_entry = results[date_key] || {};
+
+      // store or update the chain in the by_ip chain
+      const ip_chain = date_entry[data.ip] || [];
+      ip_chain.push(data);
+      date_entry[data.ip] = ip_chain;
+
+      // and update this date entry
+      results[date_key] = date_entry;
+
+    } catch(error) {
+      if(errors) console.error(error);
+
+      stats.errors += 1;
+    }
+  }
+}
+
+const parse_logs_glob = async (file_glob, errors) => {
+  const file_list = glob.sync(file_glob);
+  const results = {};
+  const stats = {
+    lines: 0,
+    chains: 0,
+    excluded: 0,
+    errors: 0,
+    roots: 0,
+    firsts: 0
+  };
+
+  for(let file_name of file_list) {
+    await parse_log_file(results, stats, file_name, errors);
+  }
+
+  return [results, stats];
+}
+
+const chain_to_set = (requests) => {
+  const path = new Set();
+
+  for(let r of requests) {
+    path.add(r.url);
+  }
+
+  return path.values();
+}
+
+const construct_url_set = (domain, ref, full_chain) => {
+  // this tags the chains with refer using [ref]
+  if(ref && !ref.includes(domain)) {
+    return [`[${ref}]`, ...full_chain.slice(1)].join(" ");
+  } else {
+    return full_chain.join(" ");
+  }
+}
+
+const construct_request_chains = (ip_chains, by_ip, domain) => {
+  for(let [ip, requests] of Object.entries(by_ip)) {
+    const chain = chain_to_set(requests);
+
+    // record the initial refer to track entry to the site
+    const ref = requests[0].refer;
+    const full_chain = [...chain];
+    const url_set = construct_url_set(domain, ref, full_chain);
+
+    // using url as key to count,full_chain
+    if(url_set in ip_chains) {
+      ip_chains[url_set].count += 1;
+    } else {
+      ip_chains[url_set] = { count: 1, comes_from: ref, full_chain};
+    }
+  }
+
+  return ip_chains;
+}
+
+const sort_request_chains = (chains) => {
+  const converted = [];
+
+  for(let [url, stats] of Object.entries(chains)) {
+    if(stats.comes_from) {
+      converted.push([stats.count, `[${stats.comes_from}] ${stats.full_chain.join(' ')}`]);
+    } else {
+      converted.push([stats.count, `${stats.full_chain.join(' ')}`]);
+    }
+  }
+
+  return converted.sort((a, b) => b[0] - a[0]);
+}
+
+const output_report = async (stats, data, min) => {
+  for(let key in data) {
+    console.log(`--- ${key} ---`);
+    const chains_sorted = data[key];
+
+    for(let [count, url] of chains_sorted) {
+      if(count < min) continue; // skip below min
+
+      console.log(count, url);
+    }
+  }
+}
+
+const output_json = async (stats, result, min, outfile) => {
+  if(outfile) {
+    const fd = fs.openSync(outfile, "w+");
+    const data = {stats, result, generated_on: new Date()};
+    const bytes = fs.writeSync(fd, Buffer.from(JSON.stringify(data, null, 4)), 0);
+    fs.closeSync(fd);
+  } else {
+    console.log({stats, result});
+  }
+}
+
+const construct_chains = (result, by_date, domain, min) => {
+  // first go through the new entries and get chains
+  for(let key in by_date) {
+    const ip_chains = result[key] || {}; // get the chains to update
+    const chains = construct_request_chains(ip_chains, by_date[key], domain);
+
+    result[key] = ip_chains; // store them for later
+  }
+
+  const sorted = {};
+
+  // now result has the previous and current results, sort them
+  for(let key in result) {
+    sorted[key] = sort_request_chains(result[key], min);
+  }
+
+  return sorted;
+}
+
+const load_result = (results_file) => {
+  if(OPTS.results && fs.existsSync(results_file)) {
+    return JSON.parse(fs.readFileSync(results_file));
+  } else {
+    return {};
+  }
+}
+
+const save_result = (results, results_file) => {
+  fs.writeFileSync(results_file, JSON.stringify(results, null, 4));
+}
+
+
+const [by_date, stats] = await parse_logs_glob(OPTS.input, OPTS.errors);
+
+const results = load_result(OPTS.results);
+
+const chains_by_date = construct_chains(results, by_date, OPTS.domain, OPTS.min);
+
+if(OPTS.format === "json") {
+  output_json(stats, chains_by_date, OPTS.outfile);
+} else {
+  output_report(stats, chains_by_date, OPTS.min);
+}
+
+if(OPTS.results) save_result(results, OPTS.results);
+
+console.log(stats);