require 'geoff'
require 'geoff/node_dsl'
require 'geoff/container'
require 'geoff/dsl_exception_handling'
require 'active_support/core_ext/string'

class ChildrenDsl
  include DslExceptionHandling

  attr_reader :node_dsls
  attr_writer :parent_node_dsl

  def initialize options, &block
    @parent_node_dsl  = options[:parent_node_dsl]
    @parent_rel_type  = options[:type]
    @target           = options[:target]
    @outer_geoff      = options[:geoff]

    @write_mode = false

    @node_dsls = {}
    @container = options[:container] || Container.new

    eval_with_exceptions(&block)
  end

  # Node dsls of children dsl defined inside other children dsl
  # are merged into outer children dsl.
  def children &block
    options = {
      parent_node_dsl: @parent_node_dsl,
      parent_rel_type: @type,
      target:          @target,
      outer_geoff:     @geoff,
      container:       @container
    }

    children_dsl = ChildrenDsl.new(options, &block) if block_given?
    @node_dsls.merge children_dsl.node_dsls

    children_dsl
  end

  def to_geoff
    "#{@outer_geoff}\n#{geoff_lines.join("\n")}".strip
  end

  def geoff_lines
    lines = []

    @node_dsls.each do |node_dsl, properties|
      lines += node_dsl.geoff_lines
      lines << rel_geoff(node_dsl, properties) unless top_level_node?
    end

    lines
  end

  def rel_geoff node_dsl, properties
    properties = properties.dup
    type       = properties.delete :type

    "(#{parent_node_name})-[:#{type}]->(#{node_dsl.node_name})".tap do |r|
      r << " #{properties.to_json}" if properties.any?
    end
  end

  def b
    @container.set_recipient_of_node_dsl self
    @container
  end

  def add_node_dsl node_dsl, rel_properties
    rel_properties ||= {}
    rel_properties[:type] ||= @parent_rel_type
    @node_dsls[node_dsl] = rel_properties
  end

  def clone
    c = self.class.new(
      parent_node_dsl: @parent_node_dsl,
      parent_rel_type: @type,
      target:          @target,
      outer_geoff:     @geoff,
      container:       @container
    ) {}

    node_dsls = {}
    @node_dsls.each do |node_dsl, rel_properties|
      node_dsls[node_dsl.clone] = rel_properties.dup
    end

    # sort it out, instance_variable_set is probably not the best way to clone object
    c.instance_variable_set('@node_dsls', node_dsls)

    c
  end

  private

  # e.g.
  #company "ACME" do
  #  children "works_at" do
  #    employee 'Bob'
  #    employee 'Lenny'
  #    employee 'Tom'
  #  end
  #end
  #
  def method_missing m, *args, &blk
    return super unless @write_mode
    relationship, options = parse_method_missing m, *args

    options.merge!(target: @target)
    NodeDsl.new(options, &blk).tap do |n|
      @node_dsls[n] = relationship
    end
  end

  def parse_method_missing m, *args
    node_name = args.first
    relationship = args[1] || {}
    relationship[:type] ||= @parent_rel_type

    if type_missing? relationship
      raise ArgumentError, "Missing relationship type for node #{node_name}"
    end

    return [
      relationship,

      {
        node_name:  node_name,
        klass_name: m.to_s.camelize,
        rel_type:   relationship[:type],
        container:  @container
      }
    ]

  end

  def type_missing? r
    !top_level_node? and !r[:type]
  end

  def top_level_node?
    @parent_node_dsl.nil?
  end

  def parent_node_name
    top_level_node? ? 'ROOT' : @parent_node_dsl.node_name
  end
end