feat(view): add Prism, ViewHelpers and PaginationHelpers

lib/prism/view/helpers.rb

@@ -0,0 +1,26 @@
+require_relative 'tag_builder'
+require_relative 'form_builder'
+require_relative 'form_helpers'
+require_relative 'url_helpers'
+require_relative 'content_for_helpers'
+require_relative 'cache_helpers'
+require_relative 'pagination_helpers'
+require_relative 'asset_helpers'
+
+module Prism
+  module ViewHelpers
+    include TagBuilder
+    include FormHelpers
+    include UrlHelpers
+    include ContentForHelpers
+    include CacheHelpers
+    include PaginationHelpers
+    include AssetHelpers
+  end
+
+  module Template
+    class Context
+      include ViewHelpers
+    end
+  end
+end

lib/prism/view/pagination_helpers.rb

@@ -0,0 +1,47 @@
+module Prism
+  # Renders page links for an `Orm::Relation` that has been through
+  # `.page(n)`. Deliberately decoupled from the router/request: the caller
+  # supplies `path` (a Proc mapping a page number to a URL string), so the
+  # helper works for `/posts?page=n`, `/blog/:id/comments?page=n`, or
+  # anything else without knowing about routes itself.
+  module PaginationHelpers
+    def paginate(relation, path:, window: 2)
+      return '' if relation.total_pages <= 1
+
+      links = +''
+      links << pagination_nav_link('Previous', relation.prev_page, path)
+      pagination_page_numbers(relation, window).each do |page|
+        links << if page == :gap
+                   content_tag(:span, '...', class: 'page-gap')
+                 else
+                   pagination_page_link(page, relation.current_page, path)
+                 end
+      end
+      links << pagination_nav_link('Next', relation.next_page, path)
+      "#{tag(:nav, class: 'pagination')}#{links}</nav>"
+    end
+
+    private
+
+    def pagination_page_numbers(relation, window)
+      total = relation.total_pages
+      current = relation.current_page
+      visible = (1..total).select { |page| page == 1 || page == total || (page - current).abs <= window }
+
+      visible.each_with_object([]) do |page, result|
+        result << :gap if result.any? && result.last != :gap && page - result.last != 1
+        result << page
+      end
+    end
+
+    def pagination_page_link(page, current_page, path)
+      classes = page == current_page ? 'page-link current' : 'page-link'
+      content_tag(:a, page.to_s, href: path.call(page), class: classes)
+    end
+
+    def pagination_nav_link(text, target_page, path)
+      return content_tag(:span, text, class: 'page-link disabled') unless target_page
+      content_tag(:a, text, href: path.call(target_page), class: 'page-link')
+    end
+  end
+end

lib/prism/view/tag_builder.rb

@@ -0,0 +1,38 @@
+module Prism
+  # HTML tag construction shared by every other view helper. `tag` and the
+  # content-returning form of `content_tag` are meant to be used from a
+  # `<%== %>` template tag (they hand back an already-escaped string);
+  # the block form of `content_tag` is meant to be used from a plain
+  # `<% %>` tag and appends itself to the template's output buffer, same
+  # as `form_for` (see Prism::Template::Context#capture).
+  module TagBuilder
+    def tag(name, attributes = {})
+      "<#{name}#{html_attributes(attributes)}>"
+    end
+
+    def content_tag(name, content = nil, attributes = {})
+      if block_given?
+        attributes = content if content.is_a?(Hash)
+        inner = capture { yield }
+        @__out << "<#{name}#{html_attributes(attributes)}>#{inner}</#{name}>"
+        nil
+      else
+        "<#{name}#{html_attributes(attributes)}>#{escape_html(content.to_s)}</#{name}>"
+      end
+    end
+
+    def html_attributes(attributes)
+      return '' if attributes.nil? || attributes.empty?
+      attributes.filter_map { |key, value| html_attribute(key, value) }.join
+    end
+
+    private
+
+    def html_attribute(key, value)
+      return nil if value.nil? || value == false
+      name = key.to_s.tr('_', '-')
+      return %( #{name}="#{name}") if value == true
+      %( #{name}="#{escape_html(value.to_s)}")
+    end
+  end
+end

lib/prism/view/url_helpers.rb

@@ -0,0 +1,17 @@
+module Prism
+  module UrlHelpers
+    def link_to(text, url, attributes = {})
+      content_tag(:a, text, attributes.merge(href: url))
+    end
+
+    def button_to(text, url, method: :post, form: {}, **button_attrs)
+      verb = method.to_s.upcase
+      markup = +"<form action=\"#{escape_html(url)}\" method=\"post\"#{html_attributes(form.merge(class: [form[:class], 'button-to'].compact.join(' ')))}>"
+      markup << hidden_method_field(verb) unless verb == 'POST'
+      markup << csrf_hidden_field
+      markup << content_tag(:button, text, { type: 'submit' }.merge(button_attrs))
+      markup << '</form>'
+      markup
+    end
+  end
+end