#!/bin/bash
#
# Copyright (c) 2016, Facebook. All rights reserved.
#
# Overall wrapper script for RocksDB continuous builds. The implementation is a
# trivial pulling scheme. We loop infinitely, check if any new changes have been
# committed, if yes then trigger a Sandcastle run, and finally go to sleep again
# for a certain interval.
#

function log {
  DATE=`date +%Y-%m-%d:%H:%M:%S`
  echo $DATE $@
}

function log_err {
  log "ERROR: $@ Error code: $?."
}

#
# Execution starts here.
#

# Path to the determinator from the root of the RocksDB repo.
CONTRUN_DETERMINATOR=./arcanist_util/config/RocksDBCommonHelper.php

# Value of the previous commit.
PREV_COMMIT=

log "Starting to monitor for new RocksDB changes ..."
log "Running under `pwd` as `whoami`."

git remote -v
git status

# Paranoia. Make sure that we're using the right branch.
git checkout master

if [ ! $? -eq 0 ]; then
  log_err "This is not good. Can't checkout master. Bye-bye!"
  exit 1
fi

# We'll run forever and let the execution environment terminate us if we'll
# exceed whatever timeout is set for the job.
while true;
do
  # Get the latest changes committed.
  git pull --rebase

  if [  $? -eq 0 ]; then
    LAST_COMMIT=`git log -1 | head -1 | grep commit | awk '{ print $2; }'`

    log "Last commit is '$LAST_COMMIT', previous commit is '$PREV_COMMIT'."

    if [ "$PREV_COMMIT" == "$LAST_COMMIT" ]; then
      log "There were no changes since the last time I checked. Going to sleep."
    else
      if [ ! -z "$LAST_COMMIT" ]; then
        log "New code has been committed or previous commit not known. " \
            "Will trigger the tests."

        PREV_COMMIT=$LAST_COMMIT
        log "Updated previous commit to '$PREV_COMMIT'."

        #
        # This is where we'll trigger the Sandcastle run. The values for
        # HTTPS_APP_VALUE and HTTPS_APP_VALUE will be set in the container we're
        # running in.
        #
        POST_RECEIVE_HOOK=1 php $CONTRUN_DETERMINATOR

        if [ $? -eq 0 ]; then
          log "Sandcastle run successfully triggered."
        else
          log_err "Failed to trigger Sandcastle run."
        fi
      else
        log_err "Previous commit not updated. Don't know what the last one is."
      fi
    fi
  else
    log_err "git pull --rebase failed. Will skip running tests for now."
  fi

  # Always sleep, even if errors happens while trying to determine the latest
  # commit. This will prevent us terminating in case of transient errors.
  log "Will go to sleep for 5 minutes."
  sleep 5m
done