require 'active_support'
require 'flydata'

module Flydata

module Source
  def self.create(de)
    MasterContext.new(de)
  end

  def self.register(component_class, type_class)
    @component_classes ||= {}
    source_sym = underscored_source_module_sym(component_class)
    unless source_sym
      raise "Class must must be under a 'SourceXxxx' module"
    end
    component_sym = underscored_class_name_sym(type_class)
    @component_classes[component_key(source_sym, component_sym)] = component_class
  end

  DATA_ENTRY_TYPE_MAP = {
    "RedshiftMysqlDataEntry" => :source_mysql,
    "RedshiftFileDataEntry" => :source_file,
    "FileDataEntry" => :source_file,
    "RedshiftPostgresqlDataEntry" => :source_postgresql,
    "RedshiftZendeskDataEntry" => :source_zendesk,
    "RedshiftOracleDataEntry" => :source_oracle,
  }
  def self.component_class_for(component_sym, de)
    source_sym = DATA_ENTRY_TYPE_MAP[de['type']]
    unless source_sym
      raise "No source components are available for this data entry"
    end
    @component_classes ||= {}
    component_key = component_key(source_sym, component_sym)
    unless @component_classes.has_key?(component_key)
      require_component(source_sym, component_sym)
      unless @component_classes.has_key?(component_key)
        @component_classes[component_key] = nil
      end
    end
    klass = @component_classes[component_key]
    unless klass
      raise "Component '#{component_sym}' is not defined in source '#{source_sym}'"
    end
    klass
  end

  COMMAND_SUBDIR = "command"
  # Returns require-friendly paths to the source specific command directory.
  #  ex) ["flydata/source_mysql/command", "flydata/source_postgres/command"]
  def self.command_dir_paths
    result = []
    DATA_ENTRY_TYPE_MAP.values.each do |source_key|
      path = File.join(source_dir_path(source_key), COMMAND_SUBDIR)
      if File.exists?(path)
        result << File.join("flydata", source_key.to_s, COMMAND_SUBDIR)
      end
    end
    result
  end

  private

  def self.underscored_source_module_sym(klass)
    source_module = klass.name.split("::").detect{|m| m.start_with?("Source")}
    source_module ? underscore_sym(source_module) : nil
  end

  def self.underscored_class_name_sym(klass)
    underscore_sym(klass.name.split("::").last)
  end

  def self.underscore_sym(name)
    ActiveSupport::Inflector.underscore(name).to_sym
  end

  def self.component_key(source_key, component_key)
    "#{source_key}:#{component_key}"
  end

  def self.require_component(source_key, component_key)
    path = source_dir_path(source_key)
    path = File.join(path, "**", "#{component_key}.rb")
    paths = Dir.glob(path)
    paths.each {|pth| require pth}
  end

  def self.source_dir_path(source_key)
    File.absolute_path(File.join(__FILE__, "..", source_key.to_s))
  end

  class MasterContext
    def initialize(de)
      @de = de
    end
    attr_reader :de

    def method_missing(method_sym, *args)
      source_class = Source.component_class_for method_sym, de
      source_class.new(self, *args)
    end
  end
end

end