From 6f1f5cba0fdf80045b2f5dd295ecfd305fcca7c4 Mon Sep 17 00:00:00 2001
From: Igor Kasyanchuk <igorkasyanchuk@gmail.com>
Date: Thu, 10 Feb 2022 10:18:16 -0800
Subject: [PATCH] with dumper and loader

---
 Gemfile                                       |  1 -
 Gemfile.lock                                  |  1 -
 lib/generators/sql_view/view/USAGE            | 20 ++--
 .../view/templates/db/migrate/create_view.erb |  5 -
 .../sql_view/view/view_generator.rb           | 83 +++++++++-------
 lib/sql_view.rb                               | 14 ++-
 lib/sql_view/railtie.rb                       |  6 ++
 lib/sql_view/schema_dumper.rb                 | 94 +++++++++++++++++++
 lib/sql_view/statements.rb                    |  7 ++
 sql_view.gemspec                              |  1 -
 10 files changed, 175 insertions(+), 57 deletions(-)
 delete mode 100755 lib/generators/sql_view/view/templates/db/migrate/create_view.erb
 mode change 100644 => 100755 lib/sql_view/railtie.rb
 create mode 100755 lib/sql_view/schema_dumper.rb
 create mode 100755 lib/sql_view/statements.rb

diff --git a/Gemfile b/Gemfile
index 8ff8b35..1330cde 100755
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,6 @@ gemspec
 gem "pg"
 gem "pry"
 gem "wrapped_print"
-gem "scenic"
 
 # Start debugger with binding.b [https://github.com/ruby/debug]
 # gem "debug", ">= 1.0.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index 445a22a..ad60900 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,7 +3,6 @@ PATH
   specs:
     sql_view (0.1.0)
       rails
-      scenic
 
 GEM
   remote: https://rubygems.org/
diff --git a/lib/generators/sql_view/view/USAGE b/lib/generators/sql_view/view/USAGE
index 6811fba..61d1f78 100755
--- a/lib/generators/sql_view/view/USAGE
+++ b/lib/generators/sql_view/view/USAGE
@@ -1,20 +1,16 @@
 Description:
-  Create a new database view for your application. This will create a new
-  view definition file and the accompanying migration.
-
-  If a view of the given name already exists, create a new version of the view
-  and a migration to replace the old version with the new.
+  Create a new database view in your application.
 
   To create a materialized view, pass the '--materialized' option.
-  To create a materialized view with NO DATA, pass '--no-data' option.
 
 Examples:
-    rails generate scenic:view searches
+    rails generate sql_view:view ActiveUser 'User.where(active: true)'
 
-      create: db/views/searches_v01.sql
-      create: db/migrate/20140803191158_create_searches.rb
+      create: app/sql_views/search_view.rb
+      create: db/migrate/20140803191158_create_active_users_views.rb
 
-    rails generate scenic:view searches
+Examples:
+    rails generate sql_view:view ArchivedAccount Account.archived --materialized --view-name=inactive_accounts
 
-      create: db/views/searches_v02.sql
-      create: db/migrate/20140804191158_update_searches_to_version_2.rb
+      create: app/sql_views/search_view.rb
+      create: db/migrate/20140803191158_create_search_views.rb
diff --git a/lib/generators/sql_view/view/templates/db/migrate/create_view.erb b/lib/generators/sql_view/view/templates/db/migrate/create_view.erb
deleted file mode 100755
index 75b5160..0000000
--- a/lib/generators/sql_view/view/templates/db/migrate/create_view.erb
+++ /dev/null
@@ -1,5 +0,0 @@
-class <%= migration_class_name %> < <%= activerecord_migration_class %>
-  def change
-    create_view <%= formatted_plural_name %><%= create_view_options %>
-  end
-end
diff --git a/lib/generators/sql_view/view/view_generator.rb b/lib/generators/sql_view/view/view_generator.rb
index 3138ddc..5bfacd4 100755
--- a/lib/generators/sql_view/view/view_generator.rb
+++ b/lib/generators/sql_view/view/view_generator.rb
@@ -3,26 +3,42 @@
 
 module SqlView
   module Generators
-    # @api private
     class ViewGenerator < Rails::Generators::NamedBase
       include Rails::Generators::Migration
-      source_root File.expand_path("templates", __dir__)
 
-      def create_views_directory
-        unless views_directory_path.exist?
-          empty_directory(views_directory_path)
-        end
-      end
+      class_option :"view-name", type: :string, default: nil
+      class_option :materialized, type: :boolean, default: false
 
-      def create_view_definition
-        create_file definition.path
-      end
+      def create_everything
+        create_file "app/sql_views/#{file_name}_view.rb", <<-FILE
+class #{class_name}View < SqlView::Model
+#{top_code}
+
+  schema -> {#{schema_code} }
+
+  extend_model_with do
+    # sample how you can extend it, similar to regular AR model
+    #
+    # belongs_to :user
+    # has_many :posts
+    #
+    # scope :ordered, -> { order(:created_at) }
+    # scope :by_role, ->(role) { where(role: role) }
+  end
+end
+FILE
 
-      def create_migration_file
-        migration_template(
-          "db/migrate/create_view.erb",
-          "db/migrate/create_#{plural_file_name}.rb",
-        )
+        create_file "db/migrate/#{self.class.next_migration_number("db/migrate")}_create_#{file_name}s_view.rb", <<-FILE
+class #{migration_class_name} < #{activerecord_migration_class}
+  def up
+    #{class_name}View.sql_view.up
+  end
+
+  def down
+    #{class_name}View.sql_view.down
+  end
+end
+FILE
       end
 
       def self.next_migration_number(dir)
@@ -30,8 +46,24 @@ def self.next_migration_number(dir)
       end
 
       no_tasks do
+        def top_code
+          [view_name_code, materialized_code].compact.join("\n\n")
+        end
+
+        def view_name_code
+          options["view-name"] ? "  self.view_name = '#{options["view-name"]}'" : nil
+        end
+
+        def materialized_code
+          options[:materialized] ? "  materialized" : nil
+        end
+
+        def schema_code
+          " #{args[0].presence || "\n    # ActiveRecord::Relation or SQL\n    # for example: User.where(active: true)\n " }"
+        end
+
         def migration_class_name
-          "Create#{class_name.tr('.', '').pluralize}"
+          "Create#{class_name.tr('.', '').pluralize}View"
         end
 
         def activerecord_migration_class
@@ -51,25 +83,6 @@ def file_name
         super.tr(".", "_")
       end
 
-      def views_directory_path
-        @views_directory_path ||= Rails.root.join("db", "views")
-      end
-
-      def formatted_plural_name
-        if plural_name.include?(".")
-          "\"#{plural_name}\""
-        else
-          ":#{plural_name}"
-        end
-      end
-
-      def create_view_options
-        if materialized?
-          ", materialized: #{no_data? ? '{ no_data: true }' : true}"
-        else
-          ""
-        end
-      end
     end
   end
 end
diff --git a/lib/sql_view.rb b/lib/sql_view.rb
index be15f4e..7dcbd33 100755
--- a/lib/sql_view.rb
+++ b/lib/sql_view.rb
@@ -1,13 +1,24 @@
-require 'singleton'
+require "singleton"
+require_relative "./sql_view/schema_dumper.rb"
+require_relative "./sql_view/statements.rb"
 require "sql_view/version"
 require "sql_view/railtie"
 
 module SqlView
+  # mattr_accessor :klasses
+  # @@klasses = {}
+
   class Model
     class_attribute :view, :sql_view_options
 
+    class << self
+      delegate_missing_to :model
+    end
+
     def self.inherited(subclass)
+      # puts subclass
       subclass.sql_view_options = {}
+      # SqlView.klasses[subclass] = subclass.sql_view
     end
 
     def self.view_name=(name)
@@ -39,7 +50,6 @@ def self.extend_model_with(&block)
     end
   end
 
-
   class Migration
     attr_reader :parent
 
diff --git a/lib/sql_view/railtie.rb b/lib/sql_view/railtie.rb
old mode 100644
new mode 100755
index 6bf2c3e..2b447b4
--- a/lib/sql_view/railtie.rb
+++ b/lib/sql_view/railtie.rb
@@ -1,4 +1,10 @@
 module SqlView
   class Railtie < ::Rails::Railtie
+    initializer "sql_view.load" do
+      ActiveSupport.on_load :active_record do
+        ActiveRecord::ConnectionAdapters::AbstractAdapter.include SqlView::Statements
+        ActiveRecord::SchemaDumper.prepend SqlView::SchemaDumper
+      end
+    end
   end
 end
diff --git a/lib/sql_view/schema_dumper.rb b/lib/sql_view/schema_dumper.rb
new file mode 100755
index 0000000..36b883b
--- /dev/null
+++ b/lib/sql_view/schema_dumper.rb
@@ -0,0 +1,94 @@
+require "rails"
+
+# Copy-pasted from scenic game. Scenic is a very nice gem
+
+module SqlView
+  # @api private
+  module SchemaDumper
+    class DBView < OpenStruct
+
+      def materialized?
+        self.kind == "m"
+      end
+
+      def materialized_or_not
+        materialized? ? " MATERIALIZED " : nil
+      end
+
+      def to_schema
+        <<-DEFINITION
+    create_sql_view "#{self.viewname}", sql: <<-\SQL
+      CREATE #{materialized_or_not} VIEW "#{self.viewname}" AS
+      #{escaped_definition.indent(2)}
+    SQL
+        DEFINITION
+      end
+
+      def escaped_definition
+        definition.gsub("\\", "\\\\\\")
+      end
+    end
+
+    def tables(stream)
+      super
+      views(stream)
+    end
+
+    def views(stream)
+      if dumpable_views_in_database.any?
+        stream.puts
+      end
+
+      dumpable_views_in_database.each do |viewname|
+        view = DBView.new(get_view_info(viewname))
+        #puts view.to_schema
+        stream.puts(view.to_schema)
+        #indexes(view.name, stream)
+      end
+    end
+
+    private
+
+    def dumpable_views_in_database
+      @dumpable_views_in_database ||= ActiveRecord::Base.connection.views.reject do |viewname|
+        ignored?(viewname)
+      end
+    end
+
+    def get_view_info(viewname)
+      views_schema.detect{|e| e['viewname'] == viewname}
+    end
+
+    def views_schema
+      @views_schema ||= ActiveRecord::Base.connection.execute(<<-SQL)
+        SELECT
+          c.relname as viewname,
+          pg_get_viewdef(c.oid) AS definition,
+          c.relkind AS kind,
+          n.nspname AS namespace
+        FROM pg_class c
+          LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
+        WHERE
+          c.relkind IN ('m', 'v')
+          AND c.relname NOT IN (SELECT extname FROM pg_extension)
+          AND n.nspname = ANY (current_schemas(false))
+        ORDER BY c.oid
+      SQL
+    .to_a
+    end
+
+    unless ActiveRecord::SchemaDumper.private_instance_methods(false).include?(:ignored?)
+      # This method will be present in Rails 4.2.0 and can be removed then.
+      def ignored?(table_name)
+        ["schema_migrations", ignore_tables].flatten.any? do |ignored|
+          case ignored
+          when String then remove_prefix_and_suffix(table_name) == ignored
+          when Regexp then remove_prefix_and_suffix(table_name) =~ ignored
+          else
+            raise StandardError, "ActiveRecord::SchemaDumper.ignore_tables accepts an array of String and / or Regexp values."
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/sql_view/statements.rb b/lib/sql_view/statements.rb
new file mode 100755
index 0000000..1a2e716
--- /dev/null
+++ b/lib/sql_view/statements.rb
@@ -0,0 +1,7 @@
+module SqlView
+  module Statements
+    def create_sql_view(viewname, sql:)
+      ActiveRecord::Base.connection.execute(sql)
+    end
+  end
+end
diff --git a/sql_view.gemspec b/sql_view.gemspec
index 5af92fa..4e80423 100755
--- a/sql_view.gemspec
+++ b/sql_view.gemspec
@@ -17,7 +17,6 @@ Gem::Specification.new do |spec|
   end
 
   spec.add_dependency "rails"
-  spec.add_dependency "scenic"
 
   spec.add_development_dependency "pg"
   spec.add_development_dependency "pry"