From 663b410b0b04477912d03ccdf02fbfec30e30b4d Mon Sep 17 00:00:00 2001
From: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Date: Wed, 2 Nov 2016 18:59:04 -0400
Subject: [PATCH] scripts: new attempt-backport script for PRs

---
 lib/node-repo.js            |   1 +
 scripts/attempt-backport.js | 205 ++++++++++++++++++++++++++++++++++++
 server.js                   |  15 +++
 3 files changed, 221 insertions(+)
 create mode 100644 scripts/attempt-backport.js

diff --git a/lib/node-repo.js b/lib/node-repo.js
index 762f0df7..97bb83c5 100644
--- a/lib/node-repo.js
+++ b/lib/node-repo.js
@@ -45,4 +45,5 @@ function updatePrWithLabels (options, labels) {
   })
 }
 
+exports.updatePrWithLabels = updatePrWithLabels
 exports.resolveLabelsThenUpdatePr = deferredResolveLabelsThenUpdatePr
diff --git a/scripts/attempt-backport.js b/scripts/attempt-backport.js
new file mode 100644
index 00000000..32fe2f8c
--- /dev/null
+++ b/scripts/attempt-backport.js
@@ -0,0 +1,205 @@
+'use strict'
+
+const child_process = require('child_process')
+const debug = require('debug')('attempt-backport')
+const request = require('request')
+const updatePrWithLabels = require('../lib/node-repo').updatePrWithLabels
+
+const enabledRepos = ['node']
+const queue = []
+let inProgress = false
+
+module.exports = function (app) {
+  if (!global._node_repo_dir) return
+
+  app.on('pull_request.opened', handlePrUpdate)
+  // Pull Request updates
+  app.on('pull_request.synchronize', handlePrUpdate)
+
+  function handlePrUpdate (event, owner, repo) {
+    if (!~enabledRepos.indexOf(repo)) return
+
+    const prId = event.number
+    const options = { owner, repo, prId, logger: event.logger }
+
+    debug(`/${owner}/${repo}/pull/${prId} sync`)
+    queueAttemptBackport(options, 7, false)
+    queueAttemptBackport(options, 6, true)
+    queueAttemptBackport(options, 4, true)
+
+    if (!inProgress) processNextBackport()
+  }
+
+  // to trigger polling manually
+  app.get('/pr/:owner/:repo/:id', (req, res) => {
+    const owner = req.params.owner
+    const repo = req.params.repo
+    const prId = parseInt(req.params.id, 10)
+    const options = { owner, repo, prId, logger: req.log }
+
+    if (~enabledRepos.indexOf(repo)) {
+      queueAttemptBackport(options, 7, false)
+      queueAttemptBackport(options, 6, true)
+      queueAttemptBackport(options, 4, true)
+    }
+
+    if (!inProgress) processNextBackport()
+
+    res.end()
+  })
+}
+
+function processNextBackport() {
+  const item = queue.shift()
+  if (!item) return
+
+  if (typeof item !== 'function') {
+    debug(`item was not a function! - queue size: ${queue.length}`)
+    return
+  } else if (inProgress) {
+    debug(`was still in progress! - queue size: ${queue.length}`)
+    return
+  }
+  item()
+}
+
+function queueAttemptBackport(options, version, isLTS) {
+  queue.push(function() {
+    debug(`processing a new backport to v${version}`)
+    attemptBackport(options, version, isLTS, processNextBackport)
+  })
+}
+
+function attemptBackport(options, version, isLTS, cb) {
+  // Start
+  gitAmAbort()
+
+  function wrapCP(cmd, args, opts, callback) {
+    let exited = false
+
+    if (arguments.length === 3) {
+      callback = opts
+      opts = {}
+    }
+
+    opts.cwd = global._node_repo_dir
+
+    const cp = child_process.spawn(cmd, args, opts)
+    const argsString = [cmd, ...args].join(' ')
+
+    cp.on('error', function(err) {
+      debug(`child_process err: ${err}`)
+      if (!exited) onError()
+    })
+    cp.on('exit', function(code) {
+      exited = true
+      if (!cb) {
+        debug(`error before exit, code: ${code}, on '${argsString}'`)
+        return
+      } else if (code > 0) {
+        debug(`exit code > 0: ${code}, on '${argsString}'`)
+        onError()
+        return
+      }
+      callback()
+    })
+    // Useful when debugging.
+    //
+    // cp.stdout.on('data', (data) => {
+    //   console.log(data.toString())
+    // })
+    // cp.stderr.on('data', (data) => {
+    //   console.log(data.toString())
+    // })
+
+    return cp
+  }
+
+  function onError() {
+    if (!cb) return
+    const _cb = cb
+    setImmediate(() => {
+      debug(`backport to ${version} failed`)
+      if (!isLTS) updatePrWithLabels(options, [`dont-land-on-v${version}.x`])
+      setImmediate(() => {
+        inProgress = false
+        _cb()
+      })
+    })
+    cb = null
+  }
+
+  function gitAmAbort() {
+    // TODO(Fishrock123): this should probably just merge into wrapCP
+    let exited = false
+    debug(`aborting any previous backport attempt...`)
+
+    const cp = child_process.spawn('git', ['am', '--abort'], { cwd: global._node_repo_dir })
+    const argsString = 'git am --abort'
+
+    cp.on('error', function(err) {
+      debug(`child_process err: ${err}`)
+      if (!exited) onError()
+    })
+    cp.on('exit', function() {
+      exited = true
+      if (!cb) {
+        debug(`error before exit, code: ${code}, on '${argsString}'`)
+        return
+      }
+      gitRemoteUpdate()
+    })
+  }
+
+  function gitRemoteUpdate() {
+    debug(`updating git remotes...`)
+    wrapCP('git', ['remote', 'update', '-p'], gitCheckout)
+  }
+
+  function gitCheckout() {
+    debug(`checking out upstream/v${version}.x-staging...`)
+    wrapCP('git', ['checkout', `upstream/v${version}.x-staging`], gitReset)
+  }
+
+  function gitReset() {
+    debug(`resetting upstream/v${version}.x-staging...`)
+    wrapCP('git', ['reset', `upstream/v${version}.x-staging`, '--hard'], fetchDiff)
+  }
+
+  function fetchDiff() {
+    debug(`fetching diff from pr ${options.prId}...`)
+
+    const url = `https://patch-diff.githubusercontent.com/raw/${options.owner}/${options.repo}/pull/${options.prId}.patch`
+
+    const req = request(url)
+
+    req.on('error', function(err) {
+      debug(`request err: ${err}`)
+      return onError()
+    })
+    req.on('response', function(response) {
+      if (response.statusCode !== 200) {
+        debug(`request non-200 status: ${response.statusCode}`)
+        return onError()
+      }
+    })
+
+    gitAttemptBackport(req)
+  }
+
+  function gitAttemptBackport(req) {
+    debug(`attempting a backport to v${version}...`)
+    const cp = wrapCP('git', ['am'], { stdio: 'pipe' }, function done() {
+      // Success!
+      if (isLTS) updatePrWithLabels(options, [`lts-watch-v${version}.x`])
+
+      setImmediate(() => {
+        debug(`backport to v${version} successful`)
+        inProgress = false
+        cb()
+      })
+    })
+
+    req.pipe(cp.stdin)
+  }
+}
diff --git a/server.js b/server.js
index f7676129..1790f35d 100644
--- a/server.js
+++ b/server.js
@@ -1,5 +1,20 @@
 'use strict'
 
+const child_process = require('child_process')
+
+if (process.env.NODE_REPO_DIR) {
+  const fs = require('fs')
+  global._node_repo_dir = fs.realpathSync(process.env.NODE_REPO_DIR)
+  const out = child_process.spawnSync('git', ['status'], { cwd: global._node_repo_dir })
+
+  if (out.status !== 0) {
+    logger.info(out.stdout)
+    logger.error(out.stderr)
+    logger.error('Bad NODE_REPO_DIR. Backport patch testing disabled.')
+    global._node_repo_dir = false
+  }
+}
+
 const app = require('./app')
 const logger = require('./lib/logger')