1 files changed, 122 insertions, 0 deletions
diff --git a/site/static/js/404.js b/site/static/js/404.js
new file mode 100644
index 0000000..cecf83f
--- /dev/null
+++ b/site/static/js/404.js
@@ -0,0 +1,122 @@
+(function () {
+
+    // regexes as strings
+    // NOTE:
+    //      these patterns should NOT contain capturing groups (parentheses)
+    //      because they might be combined with other regexes
+    var DOCS_VERSION_PATTERN      = "(?:[\\d\\.]+x?|dev|latest)";
+    var DOCS_LANGUAGE_PATTERN     = "\\w\\w(?:-\\w\\w)?";
+    var DOCS_VERSION_PATH_PATTERN = "docs\\/" + DOCS_LANGUAGE_PATTERN + "\\/" + DOCS_VERSION_PATTERN;
+
+    function splitDocsURL(url) {
+        var splitPattern = new RegExp("(" + DOCS_VERSION_PATH_PATTERN + ")");
+        return url.split(splitPattern);
+    }
+
+    function transformOldURL(oldURL) {
+        var splitURL = splitDocsURL(oldURL);
+
+        var baseURL       = splitURL[0];
+        var versionString = splitURL[1];
+        var pageExtension = splitURL.slice(2).join("");
+
+        // get rid of the fragment and replace underscores with slashes
+        // also remove the ".md" extension
+        pageExtension = pageExtension.split("#")[0];
+        pageExtension = pageExtension.replace(".md", "");
+        pageExtension = pageExtension.replace(/_/g, "/");
+
+        // undo special cases of paths that really do contain underscores
+        // NOTE:
+        //      this list is complete; in the pre-migration docs, no other
+        //      directories or files contained underscores
+        pageExtension = pageExtension.replace("config/ref", "config_ref");
+        pageExtension = pageExtension.replace("plugin/ref", "plugin_ref");
+        pageExtension = pageExtension.replace("display/name", "display_name");
+        pageExtension = pageExtension.replace("platform/plugin/versioning/ref", "platform_plugin_versioning_ref");
+
+        return baseURL + versionString + pageExtension;
+    }
+
+    function getDevURL(url) {
+        var replaceWhat = new RegExp("docs\\/(" + DOCS_LANGUAGE_PATTERN + ")\\/" + DOCS_VERSION_PATTERN);
+        var replaceWith = "docs/$1/dev";
+        return url.replace(replaceWhat, replaceWith);
+    }
+
+    function getRootURL(url) {
+        var splitURL      = splitDocsURL(url);
+        var baseURL       = splitURL[0];
+        var versionString = splitURL[1];
+
+        return baseURL + versionString + "/";
+    }
+
+    function isDocsURL(url) {
+        var testPattern = new RegExp(DOCS_VERSION_PATH_PATTERN);
+        return testPattern.test(url);
+    }
+
+    function showNewRedirect(url) {
+        $("#new-redirect-link").attr("href", url);
+        $("#not-found-redirect-alert").css("display", "block");
+    }
+
+    function showDevRedirect(url) {
+        $("#dev-redirect-link").attr("href", url);
+        $("#no-version-redirect-alert").css("display", "block");
+    }
+
+    function showRootRedirect(url) {
+        $("#root-redirect-link").attr("href", url);
+        $("#no-page-redirect-alert").css("display", "block");
+    }
+
+    function main() {
+
+        var url = window.location.href;
+
+        if (!isDocsURL(url)) {
+            return;
+        }
+
+        // get related URLs
+        var rootURL = getRootURL(url);
+        var devURL = getDevURL(url);
+        var newURL  = transformOldURL(url);
+
+        // try the root URL
+        $.ajax({
+            url: rootURL,
+            statusCode: {
+
+                // if the root exists, check if the new URL exists
+                200: function () {
+                    $.ajax({
+                        url: newURL,
+                        statusCode: {
+
+                            // redirect to the new URL if it exists
+                            200: function () {
+                                showNewRedirect(newURL)
+                            },
+
+                            // if the new URL doesn't exist, redirect to root
+                            404: function() {
+                                showRootRedirect(rootURL)
+                            }
+                        }
+                    });
+                },
+
+                // if root doesn't exist, assume that the version
+                // is invalid and redirect to dev
+                404: function () {
+                    showDevRedirect(devURL)
+                }
+            }
+        });
+    }
+
+    main();
+}());