Add Book model as PORO

Author: yasulab

app/models/book.rb

@@ -0,0 +1,33 @@
+class Book
+  attr_reader :title, :filename
+  DIR_PATH = 'app/views/books'
+
+  def initialize(title, filename)
+    @title    = title
+    @filename = filename
+  end
+
+  class << self
+    def all
+      Dir.glob("#{DIR_PATH}/*").sort
+    end
+
+    def find(title)
+      Dir.glob("#{DIR_PATH}/#{title}/*.html.erb").sort.map do |filename|
+        self.new(title, File.basename(filename, '.*'))
+      end
+    end
+
+    def exist?(title, filename)
+      self.find(title).map(&:filename).include?(filename)
+    end
+  end
+
+  def path
+    "#{DIR_PATH}/#{self.title}/#{self.filename}"
+  end
+
+  def exist?
+    Book.find(self.title).map(&:filename).include?(self.filename)
+  end
+end