chromium/third_party/blink/web_tests/wpt_internal/fenced_frame/resources/fledge-decision-logic.py

# These functions are used by FLEDGE to determine the logic for the ad seller.
# For our testing purposes, we only need the minimal amount of boilerplate
# code in place to allow them to be invoked properly and move the FLEDGE
# process along. The tests do not deal with reporting results, so we leave
# `reportResult` empty. See `generateURNFromFledge` in "utils.js" to see how
# this file is used.

from wptserve.utils import isomorphic_decode


def main(request, response):
    # Set up response headers.
    headers = [('Content-Type', 'Application/Javascript'),
               ('Ad-Auction-Allowed', 'true')]

    # Parse URL params.
    requested_size = request.GET.first(b"requested-size", None)

    # Use URL params to modify Javascript.
    requested_size_check = ''
    if requested_size is not None:
        # request.GET stores URL keys and values in iso-8859-1 binary encoding. We
        # have to decode the values back to a string to parse width/height. Don't
        # bother sanitizing the size, because it is sanitized before auction logic
        # runs already.
        width, height = isomorphic_decode(requested_size).split('-')

        requested_size_check = (f'''
        if (!(auctionConfig.requestedSize.width === '{width}') &&
            (auctionConfig.requestedSize.height === '{height}')) {{
          throw new Error('requestedSize missing/incorrect in auctionConfig');
        }}
      ''')

    # Generate Javascript.
    # Note: Python fstrings use double-brackets ( {{, }} ) to insert bracket
    # literals instead of substitution sequences.
    score_ad = (f'''function scoreAd(
      adMetadata,
      bid,
      auctionConfig,
      trustedScoringSignals,
      browserSignals) {{
        {requested_size_check}
        return 2*bid;
      }}
    ''')

    report_result = (f'''function reportResult(
    auctionConfig,
      browserSignals) {{
        {requested_size_check}
        return;
      }}
    ''')

    content = f'{score_ad}\n{report_result}'

    return (headers, content)