def redirect()

in kitsune/inproduct/views.py [0:0]

• 62 lines of code
• 26 McCabe index (conditional complexity)

def redirect(request, product, version, platform, locale, topic=None):
    """Redirect in-product URLs to the right place."""
    redirects = Redirect.objects.all()

    # In order from least to most important.
    parts = ("locale", "product", "version", "platform", "topic")

    # First we remove any redirects that explicitly don't match. Do this in
    # Python to avoid an explosion of cache use.
    t = topic if topic else ""

    def f(redirect):
        matches = (
            redirect.product.lower() in (product.lower(), ""),
            redirect.version.lower() in (version.lower(), ""),
            redirect.platform.lower() in (platform.lower(), ""),
            redirect.locale.lower() in (locale.lower(), ""),
            redirect.topic.lower() == t.lower(),
        )
        return all(matches)

    redirects = list(filter(f, redirects))

    # Assign a ordinal (score) to each redirect based on how specific it is,
    # then order by score descending.
    #
    # Scores are weighted by powers of 2 so that specifying the most important
    # field (i.e. topic) outweighs specifying all 4 other fields. This means
    # we should find the correct match faster in most common cases.
    # For example, if you have two redirects that have topic='foo', and one
    # of them also has platform='mac', and one with platform='win', they'll
    # sort like:
    #   24, Redirect(topic='foo', platform='mac')
    #   16, Redirect(topic='foo')
    #   8,  Redirect(platform='win')
    # Macs going to 'foo' will will hit the first redirect. Everyone else
    # going to 'foo' will hit the second. (Windows users going to 'foo' would
    # never match Redirect(platform='win') but if it sorted higher, it would
    # take longer to get there.)
    def ordinal(redirect):
        score = 0
        for i, part in enumerate(parts):
            if getattr(redirect, part) != "":
                score += 1 << i
        return score, redirect

    ordered = list(map(ordinal, redirects))
    ordered.sort(key=lambda x: x[0], reverse=True)

    # A redirect matches if all its fields match. A field matches if it is
    # blank or matches the input.
    def matches(redirect, **kw):
        for part in parts:
            attr = getattr(redirect, part)
            if attr != "":
                v = kw[part] if kw[part] else ""
                if attr.lower() != v.lower():
                    return False
        return True

    # As soon as we've found a match, that's the best one.
    destination = None
    for score, redirect in ordered:
        if matches(
            redirect,
            product=product,
            version=version,
            platform=platform,
            locale=locale,
            topic=topic,
        ):
            destination = redirect
            break

    # Oh noes! We didn't find a target.
    if not destination:
        raise Http404

    # If the target starts with HTTP, we don't add a locale or query string
    # params.
    if destination.target.startswith("http"):
        # Preserve all incoming query parameters when redirecting to the target.
        target = urlparams(destination.target, query_dict=request.GET)
    else:
        # Preserve all incoming query parameters except for "as" and "eu".
        params = {"as": "u"}
        if (
            ("utm_source" not in request.GET)
            and ("?utm_source=" not in destination.target)
            and ("&utm_source=" not in destination.target)
        ):
            params["utm_source"] = "inproduct"
        if hasattr(request, "eu_build"):
            params["eu"] = 1
        target = "/%s/%s" % (locale, destination.target.lstrip("/"))
        target = urlparams(target, query_dict=request.GET, **params)

        # Switch over to HTTPS if we DEBUG=False and sample is active.
        if not settings.DEBUG and waffle.sample_is_active("inproduct-https"):
            domain = Site.objects.get_current().domain
            target = "https://%s%s" % (domain, target)

    # 302 because these can change over time.
    return HttpResponseRedirect(target)