require "sequel"
require "sequel/connection_pool/threaded"
require "yaml"
require "pact_broker/logging"
require "erb"
require "pact_broker/project_root"
require "fileutils"

module DB
  include PactBroker::Logging
  ##
  # Sequel by default does not test connections in its connection pool before
  # handing them to a client. To enable connection testing you need to load the
  # "connection_validator" extension like below. The connection validator
  # extension is configurable, by default it only checks connections once per
  # hour:
  #
  # http://sequel.rubyforge.org/rdoc-plugins/files/lib/sequel/extensions/connection_validator_rb.html
  #
  # Because most of our applications so far are accessed infrequently, there is
  # very little overhead in checking each connection when it is requested. This
  # takes care of stale connections.
  #
  # A gotcha here is that it is not enough to enable the "connection_validator"
  # extension, we also need to specify that we want to use the threaded connection
  # pool, as noted in the documentation for the extension.
  #
  def self.connect db_credentials
    # Keep this conifiguration in sync with lib/pact_broker/app.rb#configure_database_connection
    Sequel.datetime_class = DateTime
    if ENV["DEBUG"] == "true" && ENV["PACT_BROKER_SQL_LOG_LEVEL"] != "none"
      logger = Logger.new($stdout)
    end
    if db_credentials.fetch("adapter") == "sqlite"
      FileUtils.mkdir_p(File.dirname(db_credentials.fetch("database")))
    end
    con = Sequel.connect(db_credentials.merge(:logger => logger, :pool_class => Sequel::ThreadedConnectionPool, :encoding => "utf8"))
    con.extension(:connection_validator)
    con.extension(:pagination)
    con.extension(:statement_timeout)
    #con.extension(:caller_logging)
    con.extend_datasets do
      # rubocop: disable Lint/NestedMethodDefinition
      def any?
        !empty?
      end
      # rubocop: enable Lint/NestedMethodDefinition
    end
    con.timezone = :utc
    con.run("SET sql_mode='STRICT_TRANS_TABLES';") if db_credentials[:adapter].to_s =~ /mysql/
    con
  end

  def self.connection_for_env env
    config = configuration_for_env(env)
    logger.info "Connecting to #{env} #{config['adapter']} database #{config['database']}."
    connect config
  end

  def self.configuration_for_env env
    database_yml = PactBroker.project_root.join("config","database.yml")
    config = YAML.load(ERB.new(File.read(database_yml)).result)
    config.fetch(env).fetch(ENV.fetch("DATABASE_ADAPTER","default"))
  end

  def self.sqlite?
    !!(PACT_BROKER_DB.adapter_scheme.to_s =~ /sqlite/)
  end

  def self.mysql?
    !!(PACT_BROKER_DB.adapter_scheme.to_s =~ /mysql/)
  end

  def self.postgres?
    !!(PACT_BROKER_DB.adapter_scheme.to_s =~ /postgres/)
  end

  PACT_BROKER_DB ||= connection_for_env ENV.fetch("RACK_ENV")

  def self.health_check
    PACT_BROKER_DB.synchronize do |c|
      PACT_BROKER_DB.valid_connection? c
    end
  end
end