Example #1
0
        /// <summary>
        /// Implements the Early Url Localization logic.
        /// <see href="https://docs.google.com/drawings/d/1cH3_PRAFHDz7N41l8Uz7hOIRGpmgaIlJe0fYSIOSZ_Y/edit?usp=sharing"/>
        /// </summary>
        public void ProcessIncoming(
            HttpContextBase context)
        {
            // Is URL explicitly excluded from localization?
            if (!m_urlLocalizer.FilterIncoming(context.Request.Url)) {
                return; } // YES. Continue handling request.

            bool allowRedirect =
                   context.Request.HttpMethod.Equals("GET", StringComparison.OrdinalIgnoreCase)
                || context.Request.HttpMethod.Equals("HEAD", StringComparison.OrdinalIgnoreCase);

            // NO. Is request URL localized?
            string urlNonlocalized;
            string langtag = m_urlLocalizer.ExtractLangTagFromUrl(context, context.Request.RawUrl, UriKind.Relative, true, out urlNonlocalized);
            if (langtag == null)
            {
                // NO.
                // langtag = best match between
                // 1. Inferred user languages (cookie and Accept-Language header)
                // 2. App Languages.
                LanguageTag lt = context.GetInferredLanguage();

                // If redirection allowed...redirect user agent (browser) to localized URL.
                // The principle purpose of this redirection is to ensure the browser is showing the correct URL
                // in its address field.
                if (allowRedirect) {
                    RedirectWithLanguage(context, lt.ToString(), m_urlLocalizer);
                    return;
                }

                // Otherwise, handle the request under the language infered above but without doing the redirect.
                // NB: this will mean that the user agent (browser) won't have the correct URL displayed;
                // however, this typically won't be an issue because we are talking about POST, PUT and DELETE methods
                // here which are typically not shown to the user.
                else {
                    context.SetPrincipalAppLanguageForRequest(lt);
                    return; // Continue handling request.
                }
            }

            // YES. Does langtag EXACTLY match an App Language?
            LanguageTag appLangTag = LanguageHelpers.GetMatchingAppLanguage(langtag);
            if (appLangTag.IsValid()
                && appLangTag.Equals(langtag))
            {
                // YES. Establish langtag as the PAL for the request.
                context.SetPrincipalAppLanguageForRequest(appLangTag);

                // Rewrite URL for this request.
                context.RewritePath(urlNonlocalized);

                // Continue handling request.
                return;
            }

            // NO. Does langtag LOOSELY match an App Language?
            else if (appLangTag.IsValid()
                && !appLangTag.Equals(langtag))
            {
                // YES. Localize URL with matching App Language.
                // Conditionally redirect user agent to localized URL.
                if (allowRedirect) {
                    RedirectWithLanguage(context, appLangTag.ToString(), m_urlLocalizer);
                    return;
                }
            }
            // NO. Do nothing to URL; expect a 404 which corresponds to language not supported.
            // Continue handling request.
        }