index.js

#!/usr/bin/env node
'use strict'

const cp = require('child_process')
const fs = require('fs')
const mkdirp = require('mkdirp')
const path = require('path')
const yargs = require('yargs')

if (require.main === module) {
  parseArgs()
}

function parseArgs () {
  return yargs
    .command(
      'install',
      'Set up the merge driver in the current git repository.',
    {
      legacy: {
        type: 'boolean',
        default: true,
        description:
            'when the merge driver errors, it will retry the command after resolving the merge conflict with --theirs'
      },
      global: {
        type: 'boolean',
        default: false,
        description: 'install to your user-level git configuration'
      },
      driver: {
        type: 'string',
        default: 'npx npm-merge-driver merge %A %O %B %P',
        description:
            'string to install as the driver in the git configuration'
      },
      'driver-name': {
        type: 'string',
        default: 'npm-merge-driver',
        description:
            'String to use as the merge driver name in your configuration.'
      },
      files: {
        description: 'Filenames that will trigger this driver.',
        type: 'array',
        default: ['npm-shrinkwrap.json', 'package-lock.json']
      }
    },
      install
    )
    .command(
      'uninstall',
      'Remove a previously configured driver',
    {
      global: {
        type: 'boolean',
        default: false,
        description: 'install to your user-level git configuration'
      },
      'driver-name': {
        type: 'string',
        default: 'npm-merge-driver',
        description:
            'String to use as the merge driver name in your configuration.'
      }
    },
      uninstall
    )
    .command(
      'merge <%A> <%O> <%B> <%P>',
      'Check for lockfile conflicts and correct them if necessary.',
    {
      command: {
        alias: 'c',
        description: 'Command to execute to resolve conflicts.',
        type: 'string',
        default: 'npm install --package-lock-only'
      },
      legacy: {
        type: 'boolean',
        default: true,
        description:
            'If <command> errors, it will be re-run after checking out the --theirs version of the file, with no granular merging.'
      }
    },
      merge
    )
    .version(require('./package.json').version)
    .alias('version', 'v')
    .help()
    .alias('help', 'h')
    .epilogue('For the full documentation, see npm-merge-driver(1)')
    .demandCommand().argv
}

function install (argv) {
  const attrFile = findAttributes(argv)
  const opts = argv.global ? '--global' : '--local'
  cp.execSync(
    `git config ${opts} merge."${argv.driverName}".name "automatically merge npm lockfiles"`
  )
  cp.execSync(
    `git config ${opts} merge."${argv.driverName}".driver "${argv.driver}${!argv.legacy
      ? ' --no-legacy'
      : ''}"`
  )
  mkdirp.sync(path.dirname(attrFile))
  fs.appendFileSync(
    attrFile,
    '\n' +
      argv.files.map(f => `${f} merge=${argv.driverName}`).join('\n') +
      '\n'
  )
  console.error(
    'npm-merge-driver:',
    argv.driverName,
    'installed to `git config',
    opts + '`',
    'and',
    attrFile
  )
}

function uninstall (argv) {
  const attrFile = findAttributes(argv)
  const opts = argv.global ? '--global' : '--local'
  try {
    cp.execSync(
      `git config ${opts} --remove-section merge."${argv.driverName}"`
    )
  } catch (e) {
    if (!e.message.match(/no such section/gi)) {
      throw e
    }
  }
  let currAttrs
  try {
    currAttrs = fs.readFileSync(attrFile, 'utf8').split('\n')
  } catch (e) {}
  if (currAttrs) {
    let newAttrs = ''
    currAttrs.forEach(attr => {
      const match = attr.match(/ merge=(.*)$/i)
      if (!match || match[1].trim() !== argv.driverName) {
        newAttrs += attr + '\n'
      }
    })
    fs.writeFileSync(attrFile, newAttrs)
  }
}

function findAttributes (argv) {
  let attrFile
  if (argv.global) {
    try {
      attrFile = cp
        .execSync(`git config --global core.attributesfile`)
        .toString('utf8')
        .trim()
    } catch (e) {}
    if (!attrFile) {
      if (process.env.XDG_CONFIG_HOME) {
        attrFile = path.join(process.env.XDG_CONFIG_HOME, 'git', 'attributes')
      } else {
        attrFile = path.join(process.env.HOME, '.config', 'git', 'attributes')
      }
    }
  } else {
    const gitDir = cp
      .execSync(`git rev-parse --git-dir`, {
        encoding: 'utf8'
      })
      .trim()
    attrFile = path.join(gitDir, 'info', 'attributes')
  }
  return attrFile
}

function merge (argv) {
  console.error('npm-merge-driver: merging', argv['%P'])
  const ret = cp.spawnSync(
    'git',
    ['merge-file', '-p', argv['%A'], argv['%O'], argv['%B']],
    {
      stdio: [0, 'pipe', 2]
    }
  )
  fs.writeFileSync(argv['%P'], ret.stdout)
  try {
    cp.execSync(argv.command, {
      stdio: 'inherit',
      cwd: path.dirname(argv['%P'])
    })
  } catch (e) {
    if (!argv.legacy) {
      throw e
    }
    fs.writeFileSync(argv['%P'], fs.readFileSync(argv['%B']))
    console.error(
      'npm-merge-driver: --legacy enabled. Checking out --theirs and retrying merge.'
    )
    console.error('npm-merge-driver: !!!SOME CHANGES MAY BE LOST!!!')
    cp.execSync(argv.command, {
      stdio: 'inherit',
      cwd: path.dirname(argv['%P'])
    })
  }
  fs.writeFileSync(argv['%A'], fs.readFileSync(argv['%P']))
  console.error('npm-merge-driver:', argv['%P'], 'successfully merged.')
}