Simple parser for `adb shell dumpsys batterystats` output

process.js

#!/usr/bin/env node

// usage:
//
//   $ adb shell dumpsys batterystats | ./process.js
//   1706369159690,2024-01-27 15:25:59,86
//   1706372879649,2024-01-27 16:27:59,85
//   1706378519690,2024-01-27 18:01:59,84
//   1706381668555,2024-01-27 18:54:28,82
//   1706386019511,2024-01-27 20:06:59,81
//   [ ... ]

const fs = require("fs");
const readline = require("readline");

const BATTERY_HISTORY_ENTRY_REGEX = new RegExp(
  "^\\s*(?:(?:\\+(?:(\\d+)d)?(?:(\\d+)h)?(?:(\\d+)m)?" +
    "(?:(\\d+)s)?(?:(\\d+)ms)?)|0) \\(\\d+\\) (.+)$"
);

const TIME_MESSAGE_REGEX =
  /^(?:RESET:)?TIME: (\d{4})-(\d{2})-(\d{2})-(\d{2})-(\d{2})-(\d{2})$/;

const BATTERY_PERCENT_REGEX = /^\s*(\d{3})/;

function timeOffsetFromHistoryEntryMatch(result) {
  // Parse the components of the relative timestamp
  const [d, h, m, s, ms] = result
    .slice(1, 6)
    .map((v) => (v ? Number(v) || 0 : 0));
  return ms + 1000 * (s + 60 * (m + 60 * (h + d * 24)));
}

function utcTimestampFromTimeMessageMatch(timeResult) {
  return Date.UTC(
    Number(timeResult[1]),
    Number(timeResult[2]) - 1,
    Number(timeResult[3]),
    Number(timeResult[4]),
    Number(timeResult[5]),
    Number(timeResult[6]),
    0
  );
}

function utcTimestampToTimeString(t) {
  const date = new Date(t); // Convert to milliseconds
  const year = date.getFullYear();
  const month = String(date.getMonth() + 1).padStart(2, "0"); // Month starts from 0
  const day = String(date.getDate()).padStart(2, "0");
  const hours = String(date.getHours()).padStart(2, "0");
  const minutes = String(date.getMinutes()).padStart(2, "0");
  const seconds = String(date.getSeconds()).padStart(2, "0");

  return `${year}-${month}-${day} ${hours}:${minutes}:${seconds}`;
}

let inputSource;

// Check if a file name is passed
if (process.argv.length >= 3) {
  const filePath = process.argv[2];
  // Create a readable stream
  inputSource = fs.createReadStream(filePath);

  // Handle file not found error
  inputSource.on("error", (err) => {
    console.error(`Could not open file: ${err.message}`);
    process.exit(1);
  });
} else {
  // If no file name is provided, read from stdin
  inputSource = process.stdin;
}

const rl = readline.createInterface({
  input: inputSource,
  output: process.stdout,
  terminal: false,
});

let lastExplicitUtcTimestamp;
let lastExplicitOffset;
let lastPercent;

rl.on("line", (line) => {
  if (line.match(/^Per-PID Stats/)) {
    process.exit(0);
  }

  const result = line.match(BATTERY_HISTORY_ENTRY_REGEX);

  let utcTimestamp = null;

  if (result) {
    const offset = timeOffsetFromHistoryEntryMatch(result);
    message = result[6];
    // Check if the message contains an absolute timestamp
    const timeResult = message.match(TIME_MESSAGE_REGEX);
    if (timeResult) {
      utcTimestamp = utcTimestampFromTimeMessageMatch(timeResult);
      lastExplicitUtcTimestamp = utcTimestamp;
      lastExplicitOffset = offset;
    } else if (lastExplicitUtcTimestamp) {
      utcTimestamp = lastExplicitUtcTimestamp - lastExplicitOffset + offset;
    }
  } else {
    // continuation of the previous line, reuse the previous timestamp
    message = line;
  }

  let percent;
  const resultMessage = message.match(BATTERY_PERCENT_REGEX);
  if (resultMessage) {
    percent = parseInt(resultMessage[0], 10);
  } else {
    return;
  }

  if (lastPercent == percent) {
    return;
  } else {
    lastPercent = percent;
  }

  if (utcTimestamp && percent) {
    //console.log({ utcTimestamp, timestamp, percent, message, line });
    console.log(
      [utcTimestamp, utcTimestampToTimeString(utcTimestamp), percent].join(",")
    );
  }
});