# frozen_string_literal: false

# @!method ActiveRecord::Migration#drop_view(name, **options, &block)
# Drop a view
#
# @param [#to_s] name (nil) The qualified name of the view
# @option [Boolean] :replace_existing (false) If the view should overwrite an existing one
# @option [Boolean] :if_exists (false) Suppress the error when the view is absent
# @option [Symbol] :force (:restrict) How to process dependent objects (`:cascade` or `:restrict`)
# @option [#to_s] :sql_definition (nil) The snippet containing the query
# @option [#to_i] :revert_to_version (nil)
#   The alternative way to set sql_definition by referencing to a file containing the snippet
# @option [#to_s] :check (nil) Controls the behavior of automatically updatable views
#   Supported values: :local, :cascaded
# @option [#to_s] :comment (nil) The comment describing the view
# @yield [Proc] the block with the view's definition
# @yieldparam The receiver of methods specifying the view
#
# The operation drops the existing view identified by its
# qualified name (it can include a schema).
#
#   drop_view "views.admin_users"
#
# To make the operation invertible, use the same options
# as in the `create_view` operation.
#
#   drop_view "views.admin_users" do |v|
#     v.sql_definition "SELECT name, email FROM users WHERE admin;"
#     v.check :local
#     v.comment "Admin users only"
#   end
#
# You can also use a version-base SQL definition like:
#
#    drop_view "views.admin_users", revert_to_version: 1
#
# With the `force: :cascade` option the operation would remove
# all the objects which depend on the view.
#
#   drop_view "views.admin_users", force: :cascade
#
# With the `if_exists: true` option the operation won't fail
# even when the view was absent in the database.
#
#   drop_view "views.admin_users", if_exists: true
#
# Both options make an operation irreversible due to uncertainty
# of the previous state of the database.

module PGTrunk::Operations::Views
  # @private
  class DropView < Base
    validates :replace_existing, :new_name, absence: true

    def to_sql(_version)
      sql = "DROP VIEW"
      sql << " IF EXISTS" if if_exists
      sql << " #{name.to_sql}"
      sql << " CASCADE" if force == :cascade
      sql << ";"
    end

    def invert
      irreversible!("if_exists: true") if if_exists
      irreversible!("force: :cascade") if force == :cascade
      CreateView.new(**to_h.except(:force))
    end
  end
end