Provide a configuration file for the Redirector extension

Instead of providing long detailed instructions for how to configure
the Redirector extension, this provides a single json file that users
can import. I started by making a single file stored in the
`public/assets` directory, but then realized this was a regression since
the instructions were customized to each domain. Instead I can use
Lucky's [data] response to dynamically build the JSON config.

[data]:
https://luckyframework.org/guides/http-and-routing/request-and-response#
handling-responses

CHANGELOG

@@ -4,6 +4,7 @@
 * Upgrade to Lucky 0.30.1
 * Upgrade to Crystal 1.5.0
 * Add scrollbar to long code blocks
+* Add a downloadable config file for Redirector extension
 
 2022-05-21
 

src/actions/redirection_config/index.cr

@@ -0,0 +1,55 @@
+class RedirectionConfig::Index < Lucky::Action
+  include Lucky::ProtectFromForgery
+  include Lucky::EnforceUnderscoredRoute
+  include Lucky::SecureHeaders::DisableFLoC
+
+  default_format :json
+
+  get "/redirection_config" do
+    data(
+      data: config_json,
+      content_type: "application/json",
+      disposition: "attachment",
+      filename: "redirector-config.json"
+    )
+  end
+
+  private def config_json
+    <<-JSON
+      {
+        "createdBy": "Redirector v3.5.3",
+        "createdAt": "2022-07-17T00:00:00.000Z",
+        "redirects": [
+          {
+            "description": "Medium -> Scribe",
+            "exampleUrl": "https://medium.com/@user/post-123456abcdef",
+            "exampleResult": "https://#{app_domain}/@user/post-123456abcdef",
+            "error": null,
+            "includePattern": "^https?://(?:.*\\.)*(?<!(link\\.|cdn\\-images\\-\\d+\\.))medium\\.com(/.*)?$",
+            "excludePattern": "",
+            "patternDesc": "",
+            "redirectUrl": "https://#{app_domain}$2",
+            "patternType": "R",
+            "processMatches": "noProcessing",
+            "disabled": false,
+            "grouped": false,
+            "appliesTo": [
+              "main_frame",
+              "sub_frame",
+              "xmlhttprequest",
+              "history",
+              "other"
+            ]
+          }
+        ]
+      }
+    JSON
+  end
+
+  private def app_domain
+    URI.parse(Home::Index.url).normalize
+      .to_s
+      .sub(/\/$/, "")
+      .sub(/^https?:\/\//, "")
+  end
+end

src/pages/faq/index_page.cr

@@ -22,58 +22,16 @@ class Faq::IndexPage < MainLayout
         a "This extension", href: "https://einaregilsson.com/redirector/"
         text " works well across most browsers."
       end
-      para "Once installed, create a new redirect with the following settings:"
-      ul do
-        li do
-          strong "Description: "
-          code "Medium -> Scribe"
+      para do
+        text "Once installed download a configuration file by "
+        link "clicking here", to: RedirectionConfig::Index
+        text "."
       end
-        li do
-          strong "Example URL: "
-          code "https://medium.com/@user/post-123456abcdef"
+      para do
+        text "Install it by opening the extension preferences, editing redirects, clicking "
+        code "Import"
+        text " and selecting the downloaded file. This will add a new redirection and not overwrite any existing ones. Now visiting any medium.com site (including user.medium.com subdomains) should redirect to Scribe instead!"
       end
-        li do
-          strong "Include pattern: "
-          code "^https?://(?:.*\\.)*(?<!(link\\.|cdn\\-images\\-\\d+\\.))medium\\.com(/.*)?$"
-        end
-        li do
-          strong "Redirect to: "
-          code "https://"
-          code app_domain
-          code "$2"
-        end
-        li do
-          strong "Pattern type: "
-          code "( ) Wildcard   (•) Regular Expression"
-        end
-      end
-      h3 "Advanced options"
-      ul do
-        li do
-          strong "Exclude pattern: "
-          text "(leave blank)"
-        end
-        li do
-          strong "Process matches: "
-          code "No Processing"
-        end
-        li do
-          strong "Apply to: "
-          ul do
-            li { code "[x] Main window (address bar)" }
-            li { code "[x] IFrames" }
-            li { code "[ ] Stylesheets" }
-            li { code "[ ] Scripts" }
-            li { code "[ ] Images" }
-            li { code "[ ] Responsive images" }
-            li { code "[ ] Objects" }
-            li { code "[x] XMLHttpRequests" }
-            li { code "[x] History State" }
-            li { code "[x] Other" }
-          end
-        end
-      end
-      para "Visiting any medium.com site (including user.medium.com subdomains) should now redirect to Scribe instead!"
     end
   end