add examples

app.rb

@@ -1,7 +1,6 @@
 require 'rack'
 require 'sqlite3'
 require 'erb'
-require 'json'
 
 # Rack application
 #

examples/001.ru

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require 'bundler/inline'
+
+gemfile do
+  source 'https://rubygems.org'
+  gem 'rack'
+end
+
+require 'rack'
+
+app =
+  proc do |_env|
+    [200, { 'content-type' => 'text/html' }, ['Hello, World!']]
+  end
+
+run app
+
+# curl -i "http://localhost:9292"

examples/002.ru

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require 'bundler/inline'
+
+gemfile do
+  source 'https://rubygems.org'
+  gem 'rack'
+end
+
+require 'rack'
+
+class MyApp
+  def call(env)
+    request = Rack::Request.new(env)
+
+    case [request.request_method, request.path]
+    in ['GET', '/']
+      [200, { 'content-type' => 'text/plain' }, ['Home page']]
+    in ['POST', '/books']
+      [201, { 'content-type' => 'text/plain' }, ['The book was created']]
+    else [404, { 'content-type' => 'text/html' }, ['Not Found']]
+    end
+  end
+end
+
+run MyApp.new
+
+# curl -i -X POST http://localhost:9292/books

examples/003.ru

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+require 'bundler/inline'
+
+gemfile do
+  source 'https://rubygems.org'
+  gem 'rack'
+end
+
+require 'rack'
+
+class MyApp
+  def call(env)
+    request   = Rack::Request.new(env)
+    @response = Rack::Response.new
+
+    case [request.request_method, request.path]
+    in ['GET', '/']
+      @response.status = 200
+      @response['content-type'] = 'text/plain'
+      @response.write('Home page')
+
+      response.finish
+    in ['POST', '/books']
+      @response.status = 201
+      @response['content-type'] = 'text/plain'
+      @response.write('The book was created')
+
+      @response.finish
+    else not_found
+    end
+  end
+
+  def not_found
+    @response.status = 404
+    @response['content-type'] = 'text/plain'
+    @response.write('Not Found')
+
+    @response.finish
+  end
+end
+
+run MyApp.new
+
+# curl -i http://localhost:9292/
+# curl -i -X POST http://localhost:9292/books

examples/004.ru

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require 'bundler/inline'
+
+gemfile do
+  source 'https://rubygems.org'
+  gem 'rack'
+end
+
+require 'rack'
+require_relative 'gurupi_middleware'
+
+class MyApp
+  def call(env)
+    request   = Rack::Request.new(env)
+    @response = Rack::Response.new
+
+    case [request.request_method, request.path]
+    in ['GET', '/']
+      @response.status = 200
+      @response['content-type'] = 'text/plain'
+      @response.write('Home page')
+
+      response.finish
+    in ['POST', '/books']
+      @response.status = 201
+      @response['content-type'] = 'text/plain'
+      @response.write('The book was created')
+
+      @response.finish
+    else not_found
+    end
+  end
+
+  def not_found
+    @response.status = 404
+    @response['content-type'] = 'text/plain'
+    @response.write('Not Found')
+
+    @response.finish
+  end
+end
+
+use GurupiMiddleware
+
+run MyApp.new
+
+

examples/gurupi_middleware.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class GurupiMiddleware
+  def initialize(app)
+    @app = app
+  end
+
+  def call(env)
+    status, headers, body = @app.call(env)
+
+    headers['x-gurupi'] = 'Gurupi'
+
+    [status, headers, body]
+  end
+end