require 'active_support/core_ext/string/filters'

module ActiveRecord
  module Tasks # :nodoc:
    class DatabaseAlreadyExists < StandardError; end # :nodoc:
    class DatabaseNotSupported < StandardError; end # :nodoc:

    # <tt>ActiveRecord::Tasks::DatabaseTasks</tt> is a utility class, which encapsulates
    # logic behind common tasks used to manage database and migrations.
    #
    # The tasks defined here are used with Rake tasks provided by Active Record.
    #
    # In order to use DatabaseTasks, a few config values need to be set. All the needed
    # config values are set by Rails already, so it's necessary to do it only if you
    # want to change the defaults or when you want to use Active Record outside of Rails
    # (in such case after configuring the database tasks, you can also use the rake tasks
    # defined in Active Record).
    #
    # The possible config values are:
    #
    #   * +env+: current environment (like Rails.env).
    #   * +database_configuration+: configuration of your databases (as in +config/database.yml+).
    #   * +db_dir+: your +db+ directory.
    #   * +fixtures_path+: a path to fixtures directory.
    #   * +migrations_paths+: a list of paths to directories with migrations.
    #   * +seed_loader+: an object which will load seeds, it needs to respond to the +load_seed+ method.
    #   * +root+: a path to the root of the application.
    #
    # Example usage of +DatabaseTasks+ outside Rails could look as such:
    #
    #   include ActiveRecord::Tasks
    #   DatabaseTasks.database_configuration = YAML.load_file('my_database_config.yml')
    #   DatabaseTasks.db_dir = 'db'
    #   # other settings...
    #
    #   DatabaseTasks.create_current('production')
    module DatabaseTasks
      extend self

      attr_writer :current_config, :db_dir, :migrations_paths, :fixtures_path, :root, :env, :seed_loader
      attr_accessor :database_configuration

      LOCAL_HOSTS    = ['127.0.0.1', 'localhost']

      def register_task(pattern, task)
        @tasks ||= {}
        @tasks[pattern] = task
      end

      register_task(/mysql/,        ActiveRecord::Tasks::MySQLDatabaseTasks)
      register_task(/postgresql/,   ActiveRecord::Tasks::PostgreSQLDatabaseTasks)
      register_task(/sqlite/,       ActiveRecord::Tasks::SQLiteDatabaseTasks)

      def db_dir
        @db_dir ||= Rails.application.config.paths["db"].first
      end

      def migrations_paths
        @migrations_paths ||= Rails.application.paths['db/migrate'].to_a
      end

      def fixtures_path
        @fixtures_path ||= if ENV['FIXTURES_PATH']
                             File.join(root, ENV['FIXTURES_PATH'])
                           else
                             File.join(root, 'test', 'fixtures')
                           end
      end

      def root
        @root ||= Rails.root
      end

      def env
        @env ||= Rails.env
      end

      def seed_loader
        @seed_loader ||= Rails.application
      end

      def current_config(options = {})
        options.reverse_merge! :env => env
        if options.has_key?(:config)
          @current_config = options[:config]
        else
          @current_config ||= ActiveRecord::Base.configurations[options[:env]]
        end
      end

      def create(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).create
      rescue DatabaseAlreadyExists
        $stderr.puts "#{configuration['database']} already exists"
      rescue Exception => error
        $stderr.puts error, *(error.backtrace)
        $stderr.puts "Couldn't create database for #{configuration.inspect}"
      end

      def create_all
        each_local_configuration { |configuration| create configuration }
      end

      def create_current(environment = env)
        each_current_configuration(environment) { |configuration|
          create configuration
        }
        ActiveRecord::Base.establish_connection(environment.to_sym)
      end

      def drop(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).drop
      rescue ActiveRecord::NoDatabaseError
        $stderr.puts "Database '#{configuration['database']}' does not exist"
      rescue Exception => error
        $stderr.puts error, *(error.backtrace)
        $stderr.puts "Couldn't drop #{configuration['database']}"
      end

      def drop_all
        each_local_configuration { |configuration| drop configuration }
      end

      def drop_current(environment = env)
        each_current_configuration(environment) { |configuration|
          drop configuration
        }
      end

      def migrate
        verbose = ENV["VERBOSE"] ? ENV["VERBOSE"] == "true" : true
        version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
        scope   = ENV['SCOPE']
        verbose_was, Migration.verbose = Migration.verbose, verbose
        Migrator.migrate(migrations_paths, version) do |migration|
          scope.blank? || scope == migration.scope
        end
      ensure
        Migration.verbose = verbose_was
      end

      def charset_current(environment = env)
        charset ActiveRecord::Base.configurations[environment]
      end

      def charset(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).charset
      end

      def collation_current(environment = env)
        collation ActiveRecord::Base.configurations[environment]
      end

      def collation(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).collation
      end

      def purge(configuration)
        class_for_adapter(configuration['adapter']).new(configuration).purge
      end

      def purge_all
        each_local_configuration { |configuration|
          purge configuration
        }
      end

      def purge_current(environment = env)
        each_current_configuration(environment) { |configuration|
          purge configuration
        }
        ActiveRecord::Base.establish_connection(environment.to_sym)
      end

      def structure_dump(*arguments)
        configuration = arguments.first
        filename = arguments.delete_at 1
        class_for_adapter(configuration['adapter']).new(*arguments).structure_dump(filename)
      end

      def structure_load(*arguments)
        configuration = arguments.first
        filename = arguments.delete_at 1
        class_for_adapter(configuration['adapter']).new(*arguments).structure_load(filename)
      end

      def load_schema(format = ActiveRecord::Base.schema_format, file = nil)
        ActiveSupport::Deprecation.warn(<<-MSG.squish)
          This method will act on a specific connection in the future.
          To act on the current connection, use `load_schema_current` instead.
        MSG

        load_schema_current(format, file)
      end

      def schema_file(format = ActiveRecord::Base.schema_format)
        case format
        when :ruby
          File.join(db_dir, "schema.rb")
        when :sql
          File.join(db_dir, "structure.sql")
        end
      end

      # This method is the successor of +load_schema+. We should rename it
      # after +load_schema+ went through a deprecation cycle. (Rails > 4.2)
      def load_schema_for(configuration, format = ActiveRecord::Base.schema_format, file = nil) # :nodoc:
        file ||= schema_file(format)

        case format
        when :ruby
          check_schema_file(file)
          ActiveRecord::Base.establish_connection(configuration)
          load(file)
        when :sql
          check_schema_file(file)
          structure_load(configuration, file)
        else
          raise ArgumentError, "unknown format #{format.inspect}"
        end
      end

      def load_schema_current_if_exists(format = ActiveRecord::Base.schema_format, file = nil, environment = env)
        if File.exist?(file || schema_file(format))
          load_schema_current(format, file, environment)
        end
      end

      def load_schema_current(format = ActiveRecord::Base.schema_format, file = nil, environment = env)
        each_current_configuration(environment) { |configuration|
          load_schema_for configuration, format, file
        }
        ActiveRecord::Base.establish_connection(environment.to_sym)
      end

      def check_schema_file(filename)
        unless File.exist?(filename)
          message = %{#{filename} doesn't exist yet. Run `rake db:migrate` to create it, then try again.}
          message << %{ If you do not intend to use a database, you should instead alter #{Rails.root}/config/application.rb to limit the frameworks that will be loaded.} if defined?(::Rails)
          Kernel.abort message
        end
      end

      def load_seed
        if seed_loader
          seed_loader.load_seed
        else
          raise "You tried to load seed data, but no seed loader is specified. Please specify seed " +
                "loader with ActiveRecord::Tasks::DatabaseTasks.seed_loader = your_seed_loader\n" +
                "Seed loader should respond to load_seed method"
        end
      end

      private

      def class_for_adapter(adapter)
        key = @tasks.keys.detect { |pattern| adapter[pattern] }
        unless key
          raise DatabaseNotSupported, "Rake tasks not supported by '#{adapter}' adapter"
        end
        @tasks[key]
      end

      def each_current_configuration(environment)
        environments = [environment]
        # add test environment only if no RAILS_ENV was specified.
        environments << 'test' if environment == 'development' && ENV['RAILS_ENV'].nil?

        configurations = ActiveRecord::Base.configurations.values_at(*environments)
        configurations.compact.each do |configuration|
          yield configuration unless configuration['database'].blank?
        end
      end

      def each_local_configuration
        ActiveRecord::Base.configurations.each_value do |configuration|
          next unless configuration['database']

          if local_database?(configuration)
            yield configuration
          else
            $stderr.puts "This task only modifies local databases. #{configuration['database']} is on a remote host."
          end
        end
      end

      def local_database?(configuration)
        configuration['host'].blank? || LOCAL_HOSTS.include?(configuration['host'])
      end
    end
  end
end
