require 'flydata/source'
require 'flydata/source/component'
require 'flydata/source/errors'

module Flydata
module Source

class SyncGenerateTableDdl < Component
  def self.inherited(child_class)
    Source.register(child_class, self)
  end

  def initialize(source, dp, options = {})
    super(source, options)
    @dp = dp
  end
  attr_reader :dp

  # Public Interface: Run compatibility check
  #
  # Run whatever check (compatibility, connectivity, privilege, etc) to ensure
  # that the 'sync:generate_table_ddl' command can run without an issue.
  #
  # Raises exception when check fails
  def run_compatibility_check
    raise UnsupportedSourceError,  "subclass must implement"
  end

  def generate_flydata_tabledef(tables, options)
    prefs = data_entry_prefs
    reset_uk_as_pk_override(tables, prefs)
    options = options.merge(prefs)
    flydata_tabledefs = []
    error_list = []
    uk_as_pk_override = {}

    missing_tables = each_source_tabledef(tables, options) do |source_tabledef, error|
      if error
        error_list << error.err_hash
        next
      end

      if source_tabledef.converting_uk_to_pk?
        new_pk_override = source_tabledef.get_pk_override_as_hash
        uk_as_pk_override.merge!(new_pk_override)
      end
      flydata_tabledefs << source_tabledef.to_flydata_tabledef
    end

    if missing_tables
      missing_tables.each {|missing_table| error_list << { error: "Table does not exist in the #{data_source_type_display_name}", table: missing_table } }
    end

    [flydata_tabledefs, error_list, uk_as_pk_override]
  end

  private

  # Returns the namne of the data source type.  The name will be used in an error message.
  def data_source_type_display_name
    raise UnsupportedSourceError,  "subclass must implement"
  end

  # Returns a data entry preference hash
  def data_entry_prefs
    raise UnsupportedSourceError,  "subclass must implement"
  end

  # Calls `block` with the source tabledef or error for each table.
  #
  #   tables:  An array of table names
  #
  #   options: A hash including options.  It includes the contents of
  #   `data_entry_prefs` and :skip_primary_key_check.  When the option is true,
  #   the method must call the `block` for a table which is missing the primary
  #   key.  Otherwise, it should call the `block` with an error.
  #
  #   block: A callback block called for each table with the following
  #   arguments:
  #     source_tabledef: A TableDef object of the source (e.g. MysqlTableDef)
  #     The value will be nil if it failed to create the object.
  #     error: A FlydataCore::TableDefError object.  If no error ocurred,
  #     this will be nil.
  #
  # Returns an array of tables which do not exist in the source
  def each_source_tabledef(tables, options, &block)
    raise UnsupportedSourceError,  "subclass must implement"
  end

  def reset_uk_as_pk_override(target_tables, prefs)
    # Reset uk_as_pk_override for target tables.
    prefs['uk_as_pk_override'].delete_if do |table_name, val|
      target_tables.include?(table_name)
    end
    update_pk_override_pref(prefs)
  end

  def update_pk_override_pref(prefs)
    # pk_override = user_pk_override + uk_as_pk_override
    # (`user_pk_override` takes precedence)
    prefs['pk_override'] = prefs['uk_as_pk_override'].merge( prefs['user_pk_override'] )
    $log.info "primary key override: #{prefs['pk_override']}"
  end
end

end
end