class ActiveRecord::ConnectionAdapters::ConnectionSpecification::Resolver

def connection_url_to_hash(url) # :nodoc:
  config = URI.parse url
  adapter = config.scheme
  adapter = "postgresql" if adapter == "postgres"
  spec = { :adapter  => adapter,
           :username => config.user,
           :password => config.password,
           :port     => config.port,
           :database => config.path.sub(%r{^/},""),
           :host     => config.host }
  spec.reject!{ |_,value| value.blank? }
  uri_parser = URI::Parser.new
  spec.map { |key,value| spec[key] = uri_parser.unescape(value) if value.is_a?(String) }
  if config.query
    options = Hash[config.query.split("&").map{ |pair| pair.split("=") }].symbolize_keys
    spec.merge!(options)
  end
  spec
end

def initialize(config, configurations)
  @config         = config
  @configurations = configurations
end

def resolve_hash_connection(spec) # :nodoc:
  spec = spec.symbolize_keys
  raise(AdapterNotSpecified, "database configuration does not specify adapter") unless spec.key?(:adapter)
  path_to_adapter = "active_record/connection_adapters/#{spec[:adapter]}_adapter"
  begin
    require path_to_adapter
  rescue Gem::LoadError => e
    raise Gem::LoadError, "Specified '#{spec[:adapter]}' for database adapter, but the gem is not loaded. Add `gem '#{e.name}'` to your Gemfile."
  rescue LoadError => e
    raise LoadError, "Could not load '#{path_to_adapter}'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql', 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile.", e.backtrace
  end
  adapter_method = "#{spec[:adapter]}_connection"
  ConnectionSpecification.new(spec, adapter_method)
end

def resolve_string_connection(spec) # :nodoc:
  hash = configurations.fetch(spec) do |k|
    connection_url_to_hash(k)
  end
  raise(AdapterNotSpecified, "#{spec} database is not configured") unless hash
  resolve_hash_connection hash
end

def spec
  case config
  when nil
    raise AdapterNotSpecified unless defined?(Rails.env)
    resolve_string_connection Rails.env
  when Symbol, String
    resolve_string_connection config.to_s
  when Hash
    resolve_hash_connection config
  end
end