Superview link helper

links.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'rspec'
end

require 'rspec/autorun'

class Scope
  include Enumerable

  def initialize(*segments)
    @segments = segments
  end

  def each(&)
    @segments.each(&)
  end

  def models
    select { |segment| segment.respond_to? :to_model }
  end

  def path
    map do |segment|
      if segment.respond_to? :to_param
        segment.to_param
      else
        segment.to_s
      end
    end.join("/").prepend("/")
  end

  def a(**attributes, &content)
    "<a #{attributes.map { |k, v| "#{k}=\"#{v}\"" }.join(" ")}>#{content&.call}</a>"
  end

  def show(*,**,&)
    path, content = segment(*,&)
    a(href: path, data_turbo_method: :get, **, &content)
  end

  def scope(*segments)
    Scope.new(*@segments, *segments)
  end

  def parent
    *segments, _ = @segments
    Scope.new(*segments)
  end

  protected

  def segment(*segments, &block)
    if segments.any?
      scope(*segments).segment(&block)
    else
      content = content(&block) || Proc.new { path }
      [ path, content ]
    end
  end

  def content(&block)
    Proc.new {
      if block.lambda?
        block.call models.last
      elsif block
        block.call *models
      end
    } if block
  end
end

def scope(*)
  Scope.new(*)
end

def show(*, **, &) = scope(*, **).show(&)

class Blog < Struct.new(:id, :name)
  def to_param = id
  def to_model = self
end

class Post < Struct.new(:id, :title, :blog)
  def to_param = id
  def to_model = self
end

RSpec.describe "Links" do
  let(:blog) { Blog.new(1, "Bob Law's Law Blog") }
  let(:post) { Post.new(1, "Post", blog) }
  let(:posts) { scope(:blogs, blog, :posts) }
  let(:post_scope) { scope(:blogs, blog, :posts, post) }

  describe "post title link" do
    subject { posts.show(post, &:title) }
    it { is_expected.to eq %(<a href="/blogs/1/posts/1" data_turbo_method="get">Post</a>) }
  end

  describe "edit link with block content" do
    subject do
      posts.show(post, :edit) { |blog, post| "Open #{blog.name} - #{post.title}" }
    end
    it { is_expected.to eq %(<a href="/blogs/1/posts/1/edit" data_turbo_method="get">Open Bob Law's Law Blog - Post</a>) }
  end

  describe "preview link with block content" do
    subject do
      posts.show(post, :preview) { |blog, post| "Preview #{blog.name} - #{post.title}" }
    end
    it { is_expected.to eq %(<a href="/blogs/1/posts/1/preview" data_turbo_method="get">Preview Bob Law's Law Blog - Post</a>) }
  end

  describe "default show link with block content" do
    subject do
      post_scope.show { |blog, post| "#{blog.name} - #{post.title}" }
    end
    it { is_expected.to eq %(<a href="/blogs/1/posts/1" data_turbo_method="get">Bob Law's Law Blog - Post</a>) }
  end

  describe "link using title lambda" do
    subject { post_scope.show(class: "btn btn-primary", &:title) }
    it { is_expected.to eq %(<a href="/blogs/1/posts/1" data_turbo_method="get" class="btn btn-primary">Post</a>) }
  end

  describe "preview link using title lambda" do
    subject { post_scope.show(:preview, &:title) }
    it { is_expected.to eq %(<a href="/blogs/1/posts/1/preview" data_turbo_method="get">Post</a>) }
  end

  describe "parent link with custom block content" do
    subject { post_scope.parent.show { "#{_1.name} Posts" } }
    it { is_expected.to eq %(<a href="/blogs/1/posts" data_turbo_method="get">Bob Law's Law Blog Posts</a>) }
  end

  describe "parent link with no block" do
    subject { post_scope.parent.show }
    it { is_expected.to eq %(<a href="/blogs/1/posts" data_turbo_method="get">/blogs/1/posts</a>) }
  end
end