# Okay so maybe everyone else already knows all this, but it took some time
# for Michael and I [Han] to really see how everything fits together.
#
# Basically, what we're doing here is automated browser testing, so CircleCI
# handles the automation, and Sauce Labs handles the browser testing.
# Specifically, Sauce Labs offers a REST API to run tests in browsers in VMs,
# and CircleCI can be configured to listen for git pushes and run local
# servers and call out to REST APIs to test against these local servers.
#
# The flow goes like this:
#   - CircleCI notices/is notified of a git push
#   - they pull and checkout and magically know to install dependencies and shit
#       + https://circleci.com/docs/manually/
#   - their magic works fine for MathQuill's dependencies but to run the tests,
#     it foolishly runs `make test`, what an inconceivable mistake
#   - that's where we come in: `circle.yml` lets us override the test script.
#       + https://circleci.com/docs/configuration/
#   - our `circle.yml` first installs and runs a tunnel to Sauce Labs
#   - and runs `make server`
#   - then it calls out to Sauce Labs' REST API to open browsers that reach
#     back through the tunnel to access test pages on the local server
#       + > Sauce Connect allows you to run a test server within the CircleCI
#         > build container and expose it it (using a URL like `localhost:8080`)
#         > to Sauce Labs’ browsers.
#
#         https://circleci.com/docs/browser-testing-with-sauce-labs/
#
#   - boom testing boom


# this file is based on https://github.com/circleci/sauce-connect/blob/a65e41c91e02550ce56c75740a422bebc4acbf6f/circle.yml
# via https://circleci.com/docs/browser-testing-with-sauce-labs/

machine:
  environment:
    json: node_modules/.bin/json

dependencies:
  cache_directories:
    - ~/sauce-connect
  pre:
    - "test $SAUCE_USERNAME && test $SAUCE_ACCESS_KEY
       # Sauce Labs credentials required. Sign up here: https://saucelabs.com/opensauce/"
    - ? |-
        {
          mkdir -p ~/sauce-connect
          cd ~/sauce-connect
          if [ -x sc-*-linux/bin/sc ]; then
            echo Using cached sc-*-linux/bin/sc
          else
            time wget https://saucelabs.com/downloads/sc-latest-linux.tar.gz
            time tar -xzf sc-latest-linux.tar.gz
          fi
          # Sauce Connect randomly fails so try twice https://git.io/vPN8v
          time sc-*-linux/bin/sc --user $SAUCE_USERNAME --api-key $SAUCE_ACCESS_KEY \
            --readyfile ~/sauce_is_ready
          test -e ~/sauce_is_ready && exit
          time sc-*-linux/bin/sc --user $SAUCE_USERNAME --api-key $SAUCE_ACCESS_KEY \
            --readyfile ~/sauce_is_ready
          test -e ~/sauce_is_ready && exit
          echo 'ERROR: Exited twice without creating readyfile' \
            | tee /dev/stderr > ~/sauce_is_ready
          exit 1
        } >$CIRCLE_ARTIFACTS/sauce-connect.log 2>&1
      :
        background: true
    - test -x $json || npm install json

test:
  override:
    # Safari on Sauce can only connect to port 3000, 4000, 7000, or 8000. Edge needs port 7000 or 8000.
    # https://david263a.wordpress.com/2015/04/18/fixing-safari-cant-connect-to-localhost-issue-when-using-sauce-labs-connect-tunnel/
    # https://support.saucelabs.com/customer/portal/questions/14368823-requests-to-localhost-on-microsoft-edge-are-failing-over-sauce-connect
    - PORT=8000 make server >$CIRCLE_ARTIFACTS/make_server.log 2>&1:
        background: true

    # CircleCI expects test results to be reported in an JUnit/xUnit-style XML file:
    #   https://circleci.com/docs/test-metadata/
    # Our unit tests are in a browser, so they can't write to a file, and Sauce
    # apparently truncates custom data in their test result reports, so instead we
    # POST to this trivial Node server on localhost:9000 that writes the body of
    # any POST request to $CIRCLE_TEST_REPORTS/mocha/xunit.xml
    - mkdir -p $CIRCLE_TEST_REPORTS/mocha
    - ? |-
        node << 'EOF' >$CIRCLE_TEST_REPORTS/mocha/xunit.xml \
                      2>$CIRCLE_ARTIFACTS/mocha-test-report.log
          require('http').createServer(function(req, res) {
            res.setHeader('Access-Control-Allow-Origin', '*');
            req.pipe(process.stdout);
            req.on('end', res.end.bind(res));
          })
          .listen(9000);
          console.error('listening on http://0.0.0.0:9000/');
        EOF
      :
        background: true

    # Wait for tunnel to be ready (`make server` and the trivial Node server
    # are much faster, no need to wait for them)
    - while [ ! -e ~/sauce_is_ready ]; do sleep 1; done; test -z "$(<~/sauce_is_ready)"

    # Start taking screenshots in the background while the unit tests are running
    - ? |-
        {
          build_name="CircleCI build #$CIRCLE_BUILD_NUM"
          if [ $CIRCLE_PR_NUMBER ]; then
            build_name="$build_name: PR #$CIRCLE_PR_NUMBER"
            [ "$CIRCLE_BRANCH" ] && build_name="$build_name ($CIRCLE_BRANCH)"
          else
            build_name="$build_name: $CIRCLE_BRANCH"
          fi
          build_name="$build_name @ ${CIRCLE_SHA1:0:7}"
          export MQ_CI_BUILD_NAME="$build_name"

          time { test -d node_modules/wd || npm install wd; }
          time node script/screenshots.js http://localhost:8000/test/visual.html \
            && touch ~/screenshots_are_ready || echo EXIT STATUS $? | tee /dev/stderr > ~/screenshots_are_ready:
        } >$CIRCLE_ARTIFACTS/screenshots.log 2>&1
      :
        background: true

    # Run in-browser unit tests, based on:
    #   https://wiki.saucelabs.com/display/DOCS/JavaScript+Unit+Testing+Methods
    # "build" and "customData" parameters from:
    #   https://wiki.saucelabs.com/display/DOCS/Test+Configuration+Options#TestConfigurationOptions-TestAnnotation
    # CircleCI environment variables from:
    #   https://circleci.com/docs/environment-variables/
    - |-
      build_name="CircleCI build #$CIRCLE_BUILD_NUM"
      if [ $CIRCLE_PR_NUMBER ]; then
        build_name="$build_name: PR #$CIRCLE_PR_NUMBER"
        [ "$CIRCLE_BRANCH" ] && build_name="$build_name ($CIRCLE_BRANCH)"
      else
        build_name="$build_name: $CIRCLE_BRANCH"
      fi
      build_name="$build_name @ ${CIRCLE_SHA1:0:7}"

      set -o pipefail
      curl -i -X POST https://saucelabs.com/rest/v1/$SAUCE_USERNAME/js-tests \
           -u $SAUCE_USERNAME:$SAUCE_ACCESS_KEY \
           -H 'Content-Type: application/json' \
           -d '{
                 "build": "'"$build_name"'",
                 "customData": {"build_url": "'"$CIRCLE_BUILD_URL"'"},
                 "framework": "mocha",
                 "url": "http://localhost:8000/test/unit.html?post_xunit_to=http://localhost:9000",
                 "platforms": [["", "Chrome", ""]]
      }' | tee /dev/stderr | tail -1 > js-tests.json

    # Wait for tests to finish:
    #
    #   > Make the request multiple times as the tests run until the response
    #   > contains `completed: true` to the get the final results.
    #
    #   https://wiki.saucelabs.com/display/DOCS/JavaScript+Unit+Testing+Methods
    - |-
      while true  # Bash has no do...while >:(
      do
        sleep 5
        curl -i -X POST https://saucelabs.com/rest/v1/$SAUCE_USERNAME/js-tests/status \
             -u $SAUCE_USERNAME:$SAUCE_ACCESS_KEY \
             -H 'Content-Type: application/json' \
             -d @js-tests.json \
        | tee /dev/stderr | tail -1 > status.json

        # deliberately do `... != false` rather than `... == true`
        # because unexpected values should break rather than infinite loop
        [ "$($json completed <status.json)" != false ] && break
      done

    # Complain to Circle CI if any unit tests failed
    - test "$($json 'js tests'.0.result.failures <status.json)" = 0

    # Wait for screenshots to be ready
    - while [ ! -e ~/screenshots_are_ready ]; do sleep 1; done; test -z "$(<~/screenshots_are_ready)":
        timeout: 300

    # Stitch together images
    - |-
      for img in $(ls $CIRCLE_ARTIFACTS/imgs/pieces/); do
        convert $(ls -1 $CIRCLE_ARTIFACTS/imgs/pieces/$img/*.png | sort -n) -append $CIRCLE_ARTIFACTS/imgs/$img.png
      done

    # Download the latest mathquill artifacts from master.
    - |-
      artifacts_json="$(curl https://circleci.com/api/v1/project/mathquill/mathquill/latest/artifacts?branch=master)"
      echo
      echo '/latest/artifacts?branch=master:'
      echo
      echo "$artifacts_json"
      echo

      prev_imgs="$(echo "$artifacts_json" \
                    | $json -a url pretty_path -d '\n\t' \
                    | grep '\.png$' \
                    | grep -v '/PREV_' \
                    | grep -v '/DIFF_' \
                    | grep -v '/pieces/' \
                    | sed "s:\$CIRCLE_ARTIFACTS/imgs/:-o $CIRCLE_ARTIFACTS/imgs/PREV_:")"
      echo 'Previous image URLs and files:'
      echo
      echo "$prev_imgs"
      echo

      test -z "$prev_imgs" || curl $prev_imgs

    # Generate image diffs.
    - |-
      cd $CIRCLE_ARTIFACTS/imgs/
      for file in $(ls PINNED*); do
        prev=PREV_$file
        metric_diff=$(compare -metric AE -compose src $prev $file raw_diff.png)
        composite -alpha on raw_diff.png $prev DIFF_$file
      done

    - |-
      cd $CIRCLE_ARTIFACTS/imgs/
      for file in $(ls EVERGREEN*); do
        prev=$(ls PREV_$file*)
        metric_diff=$(compare -metric AE -compose src $prev $file raw_diff.png)
        composite -alpha on raw_diff.png $prev DIFF_$file
      done

    - rm $CIRCLE_ARTIFACTS/imgs/raw_diff.png
  post:
    - killall --wait sc; true  # wait for Sauce Connect to close the tunnel; ignore errors since it's just cleanup