Add a position field to books (#1593)

* Add a `position` field to books

backfill script:

This script isn't that important as we can always manually fiddle with
the positions in production

```ruby
BOOK_SLUGS_IN_ORDER = %w[no-wall-they-can-build
                         from-democracy-to-freedom
                         contradictionary
                         work
                         expect-resistance
                         recipes-for-disaster
                         days-of-war-nights-of-love
                         off-the-map
                         no-habra-muro-que-nos-pare
                         da-democracia-a-liberdade
                         trabalho-edicao-resumida-de-emergencia
                         espere-resistencia
                         receitas-para-o-desastre
                         dias-de-guerra-noites-de-amor].freeze

BOOK_SLUGS_IN_ORDER.each_with_index do |slug, index|
  Book.find_by(slug: slug)&.update!(position: index)
end
```

resolves #1446

app/controllers/admin/books_controller.rb

@@ -59,7 +59,7 @@ def book_params
                                    :print_black_and_white_a4_download_present, :print_color_a4_download_present,
                                    :print_color_download_present, :print_black_and_white_download_present,
                                    :screen_single_page_view_download_present, :screen_two_page_view_download_present,
-                                   :featured_status, :featured_at, :canonical_id)
+                                   :featured_status, :featured_at, :canonical_id, :position, :hide_from_index)
     end
   end
 end

app/controllers/books_controller.rb

@@ -1,43 +1,18 @@
 class BooksController < ApplicationController
   before_action :set_book, only: %i[show extras]
 
-  INDEX_BOOK_SLUGS = %w[
-    no-wall-they-can-build
-    from-democracy-to-freedom
-    contradictionary
-    work
-    expect-resistance
-    recipes-for-disaster
-    days-of-war-nights-of-love
-    off-the-map
-    no-habra-muro-que-nos-pare
-    da-democracia-a-liberdade
-    trabalho-edicao-resumida-de-emergencia
-    espere-resistencia
-    receitas-para-o-desastre
-    dias-de-guerra-noites-de-amor
-  ].map(&:freeze).freeze
-
-  NON_INDEX_BOOK_SLUGS = %w[
-    days-of-war-nights-of-love-ne-plus-ultra-edition
-  ].map(&:freeze).freeze
-
-  BOOK_SLUGS = INDEX_BOOK_SLUGS + NON_INDEX_BOOK_SLUGS
-
   def index
     @html_id = 'page'
     @body_id = 'tools'
     @type    = 'books'
     @title   = PageTitle.new title_for(:books)
 
-    @books = INDEX_BOOK_SLUGS.map { |slug| Book.find_by(slug: slug) }
+    @books = Book.english.for_index
 
     render "#{Theme.name}/books/index"
   end
 
   def show
-    return redirect_to [:books] unless BOOK_SLUGS.include?(@book.slug)
-
     @html_id  = 'page'
     @body_id  = 'tools'
     @type     = 'books'

app/models/book.rb

@@ -2,6 +2,8 @@ class Book < ApplicationRecord
   include MultiPageTool
   include Featureable
 
+  scope :for_index, -> { where.not(hide_from_index: true).reorder(position: :asc).order(title: :asc) }
+
   def ask_for_donation?
     downloads_available?
   end

app/views/admin/books/_form.html.erb

@@ -61,6 +61,21 @@
 
   <%= render "admin/books/categories_form", form: form %>
 
+  <div class="row">
+    <div class="col-6">
+      <%= render "admin/books/form/position", form: form %>
+      <p class="form-text text-muted">This will set the order that
+      this book shows up on <a href="/books">crimethinc.com/books</a>.</p>
+    </div>
+
+    <div class="col-6">
+      <%= form.check_box :hide_from_index %>
+      <%= form.label :has_index, "Hide this book from the index page?" %><br>
+      <p class="form-text text-muted">This will prevent the book from
+      showing up on <a href="/books">crimethinc.com/books</a>.</p>
+    </div>
+  </div>
+
   <%= render "admin/books/downloads_form", form: form, resource: resource %>
 
   <%= render "admin/form_actions", cancel_url: [:admin, resource.namespace] %>

app/views/admin/books/form/_position.html.erb

@@ -0,0 +1,4 @@
+<div id="position" class="form-group">
+  <%= form.label :position, "Position this book on the index page" %>
+  <%= number_field :book, :position, step: 1, class: 'form-control' %>
+</div><!-- #position -->

db/migrate/20200511024239_add_position_to_books.rb

@@ -0,0 +1,11 @@
+class AddPositionToBooks < ActiveRecord::Migration[6.0]
+  def up
+    add_column :books, :position, :integer
+    add_column :books, :hide_from_index, :boolean, default: false
+  end
+
+  def down
+    remove_column :books, :position, :integer
+    remove_column :books, :hide_from_index, :boolean, default: false
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_04_05_003649) do
+ActiveRecord::Schema.define(version: 2020_05_11_024239) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_stat_statements"
@@ -98,6 +98,8 @@
     t.integer "canonical_id"
     t.boolean "featured_status", default: false
     t.datetime "featured_at"
+    t.integer "position"
+    t.boolean "hide_from_index", default: false
     t.index ["canonical_id"], name: "index_books_on_canonical_id"
   end