feat: custom static error pages (#2)

* feat: ✨ Detect custom error pages

Closes #1

* more descriptive comment

* feat: use IO.copy instead of reading the file

* chore: avoid building string twice

* feat: spec

* chore: format

---------

Co-authored-by: Evangelos Paterakis <evan@geopjr.dev>

README.md

@@ -61,7 +61,7 @@ They are built & published by our lovely [actions](https://github.com/GeopJr/sab
 ## Usage
 
 ```
-sabo-tabby v1.0.0
+sabo-tabby v1.1.0
 
 Usage: sabo-tabby [arguments]
 

shard.yml

@@ -1,5 +1,5 @@
 name: sabo-tabby
-version: 1.0.0
+version: 1.1.0
 
 authors:
  - Evangelos Paterakis <evan@geopjr.dev>

spec/static_file_handler_spec.cr

@@ -95,6 +95,28 @@ describe Sabo::Tabby::StaticFileHandler do
  response.headers["Content-Encoding"]?.should be_nil
  end
 
+ it "should serve custom static error pages" do
+ page_content = "🫖"
+
+ # Create custom static error page
+ current_public_folder = Sabo::Tabby.config.public_folder
+ folder = Path[Dir.tempdir, Random::Secure.hex(5)]
+ Dir.mkdir(folder)
+ Sabo::Tabby.config.public_folder = folder.to_s
+
+ custom_page_path = Path[folder, "404.html"]
+ File.write(custom_page_path, page_content)
+
+ response = handle_request HTTP::Request.new("GET", "/I_DO_NOT_EXIST")
+ response.status_code.should eq(404)
+ response.body.should eq(page_content)
+
+ # Cleanup
+ Sabo::Tabby.config.public_folder = current_public_folder
+ File.delete(custom_page_path)
+ Dir.delete(folder)
+ end
+
  it "should not serve a not found file" do
  response = handle_request HTTP::Request.new("GET", "/not_found_file.txt")
  response.status_code.should eq(404)

src/sabo-tabby/error_handler.cr

@@ -34,8 +34,14 @@ module Sabo::Tabby
  @status_message = message ||= @status.description
  self.headers.add "Server", Sabo::Tabby::SERVER_HEADER if Sabo::Tabby.config.server_header
 
- # If HTML pages are enabled, call `error_page` else return a basic text/plain one.
- if Sabo::Tabby.config.error_page
+ # If it exists, use file in the public dir matching error_code.html (eg 404.html).
+ static_error_page = Path[Sabo::Tabby.config.public_folder, "#{status_code}.html"]
+ if File.exists?(static_error_page)
+ self.content_type = "text/html; charset=UTF-8"
+ IO.copy File.open(static_error_page), self
+
+ # If HTML pages are enabled, call `error_page` else return a basic text/plain one.
+ elsif Sabo::Tabby.config.error_page
  self.content_type = "text/html; charset=UTF-8"
  self << error_page(@status.code, @status_message.to_s) << '\n'
  else