require 'lotus/helpers/html_helper/html_builder'

module Lotus
  module Helpers
    # HTML builder
    #
    # By including <tt>Lotus::Helpers::HtmlHelper</tt> it will inject one private method: <tt>html</tt>.
    # This is a HTML5 markup builder.
    #
    # Features:
    #   * Support for complex markup without the need of concatenation
    #   * Auto closing HTML5 tags
    #   * Custom tags
    #   * Content tag auto escape (XSS protection)
    #   * Support for view local variables
    #
    # Usage:
    #
    #   * It knows how to close tags according to HTML5 spec (1)
    #   * It accepts content as first argument (2)
    #   * It accepts another builder as first argument (3)
    #   * It accepts content as block which returns a string (4)
    #   * It accepts content as a block with nested markup builders (5)
    #   * It builds attributes from given hash (6)
    #   * It combines attributes and block (7)
    #
    # @since 0.1.0
    #
    # @see Lotus::Helpers::HtmlHelper#html
    #
    # @example Usage
    #   # 1
    #   html.div # => <div></div>
    #   html.img # => <img>
    #
    #   # 2
    #   html.div('hello') # => <div>hello</div>
    #
    #   # 3
    #   html.div(html.p('hello')) # => <div><p>hello</p></div>
    #
    #   # 4
    #   html.div { 'hello' }
    #   # =>
    #   #<div>
    #   #  hello
    #   #</div>
    #
    #   # 5
    #   html.div do
    #     p 'hello'
    #   end
    #   # =>
    #   #<div>
    #   #  <p>hello</p>
    #   #</div>
    #
    #   # 6
    #   html.div('hello', id: 'el', 'data-x': 'y') # => <div id="el" data-x="y">hello</div>
    #
    #   # 7
    #   html.div(id: 'yay') { 'hello' }
    #   # =>
    #   #<div id="yay">
    #   #  hello
    #   #</div>
    #
    #   # 8
    #   html do
    #     li 'Hello'
    #     li 'Lotus'
    #   end
    #   # =>
    #   #<li>Hello</li>
    #   #<li>Lotus</li>
    #
    #
    #
    # @example Complex markup
    #   #
    #   # NOTICE THE LACK OF CONCATENATION BETWEEN div AND input BLOCKS <3
    #   #
    #
    #   html.form(action: '/users', method: 'POST') do
    #     div do
    #       label 'First name', for: 'user-first-name'
    #       input type: 'text', id: 'user-first-name', name: 'user[first_name]', value: 'L'
    #     end
    #
    #     input type: 'submit', value: 'Save changes'
    #   end
    #   # =>
    #   #<form action="/users" method="POST" accept-charset="utf-8">
    #   #  <div>
    #   #    <label for="user-first-name">First name</label>
    #   #    <input type="text" id="user-first-name" name="user[first_name]" value="L">
    #   #  </div>
    #   #  <input type="submit" value="Save changes">
    #   #</form>
    #
    #
    #
    # @example Custom tags
    #   html.tag(:custom, 'Foo', id: 'next') # => <custom id="next">Foo</custom>
    #   html.empty_tag(:xr, id: 'next')      # => <xr id="next">
    #
    #
    #
    # @example Auto escape
    #  html.div('hello')         # => <div>hello</hello>
    #  html.div { 'hello' }      # => <div>hello</hello>
    #  html.div(html.p('hello')) # => <div><p>hello</p></hello>
    #  html.div do
    #    p 'hello'
    #  end # => <div><p>hello</p></hello>
    #
    #
    #
    #  html.div("<script>alert('xss')</script>")
    #    # =>  "<div>&lt;script&gt;alert(&apos;xss&apos;)&lt;&#x2F;script&gt;</div>"
    #
    #  html.div { "<script>alert('xss')</script>" }
    #    # =>  "<div>&lt;script&gt;alert(&apos;xss&apos;)&lt;&#x2F;script&gt;</div>"
    #
    #  html.div(html.p("<script>alert('xss')</script>"))
    #    # => "<div><p>&lt;script&gt;alert(&apos;xss&apos;)&lt;&#x2F;script&gt;</p></div>"
    #
    #  html.div do
    #    p "<script>alert('xss')</script>"
    #  end
    #    # => "<div><p>&lt;script&gt;alert(&apos;xss&apos;)&lt;&#x2F;script&gt;</p></div>"
    #
    #
    # @example Basic usage
    #   #
    #   # THE VIEW CAN BE A SIMPLE RUBY OBJECT
    #   #
    #
    #   require 'lotus/helpers'
    #
    #   class MyView
    #     include Lotus::Helpers::HtmlHelper
    #
    #     # Generates
    #     # <aside id="sidebar">
    #     #    <div>hello</hello>
    #     #  </aside>
    #     def sidebar
    #       html.aside(id: 'sidebar') do
    #         div 'hello'
    #       end
    #     end
    #   end
    #
    #
    # @example View context
    #   #
    #   # LOCAL VARIABLES FROM VIEWS ARE AVAILABLE INSIDE THE NESTED BLOCKS OF HTML BUILDER
    #   #
    #
    #   require 'lotus/view'
    #   require 'lotus/helpers'
    #
    #   Book = Struct.new(:title)
    #
    #   module Books
    #     class Show
    #       include Lotus::View
    #       include Lotus::Helpers::HtmlHelper
    #
    #       def title_widget
    #         html.div do
    #           h1 book.title
    #         end
    #       end
    #     end
    #   end
    #
    #   book     = Book.new('The Work of Art in the Age of Mechanical Reproduction')
    #   rendered = Books::Show.render(format: :html, book: book)
    #
    #   rendered
    #     # => <div>
    #     #      <h1>The Work of Art in the Age of Mechanical Reproduction</h1>
    #     #    </div>
    module HtmlHelper
      private
      # Instantiate an HTML builder
      #
      # @param blk [Proc,Lotus::Helpers::HtmlHelper::HtmlBuilder,NilClass] the optional content block
      #
      # @return [Lotus::Helpers::HtmlHelper::HtmlBuilder] the HTML builder
      #
      # @since 0.1.0
      #
      # @see Lotus::Helpers::HtmlHelper
      # @see Lotus::Helpers::HtmlHelper::HtmlBuilder
      def html(&blk)
        if block_given?
          HtmlBuilder.new.fragment(&blk)
        else
          HtmlBuilder.new
        end
      end
    end
  end
end