require_relative "../node"

module VagrantPlugins
  module Compose
    module Programmatic

      # This class defines a group of nodes, representig a set of vagrant machines with similar characteristics.
      # Nodes will be composed by NodeGroup.compose method, according with the configuration of values/value_generator
      # of the group of node itself.
      class NodeGroup

        # A number identifying the group of nodes withing the cluster.
        attr_reader :index

        # The name of the group of nodes
        attr_reader :name

        # The number of nodes/instances to be created in the group of nodes.
        attr_reader :instances

        # The value/value generator to be used for assigning to each node in this group a vagrant base box to be used for creating vagrant machines implementing nodes in this group.
        attr_accessor :box

        # The value/value generator to be used for assigning to each node in this group a box name a.k.a. the name for the machine in VirtualBox/VMware console.
        attr_accessor :boxname

        # The value/value generator to be used for assigning to each node in this group a unique hostname
        attr_accessor :hostname

        # The value/value generator to be used for assigning to each node in this group a unique list of aliases a.k.a. alternative host names
        attr_accessor :aliases

        # The value/value generator to be used for assigning to each node in this groupa unique ip
        attr_accessor :ip

        # The value/value generator to be used for assigning to each node in this group cpus
        attr_accessor :cpus

        # The value/value generator to be used for assigning to each node in this group memory
        attr_accessor :memory

        # The value/value generator to be used for assigning each node in this group to a list of ansible groups
        attr_accessor :ansible_groups

        # The value/value generator to be used for assigning a dictionary with custom attributes - Hash(String, obj) - to each node in this group.
        attr_accessor :attributes

        def initialize(index, instances, name)
          @index  = index
          @name = name
          @instances = instances
        end

        # Composes the group of nodes, by creating the required number of nodes
        # in accordance with values/value_generators.
        # Additionally, some "embedded" trasformation will be applied to attributes (boxname, hostname) and
        # some "autogenerated" node properties will be computed (fqdn).
        def compose(cluster_name, cluster_domain, cluster_offset)
          node_index = 0
          while node_index < @instances
            box            = generate(:box, @box, node_index)
            boxname        = maybe_prefix(cluster_name,
                                          "#{generate(:boxname, @boxname, node_index)}")
            hostname       = maybe_prefix(cluster_name,
                                          "#{generate(:hostname, @hostname, node_index)}")
            aliases        = generate(:aliases, @aliases, node_index).join(',')
            fqdn           = cluster_domain.empty? ? "#{hostname}" : "#{hostname}.#{cluster_domain}"
            ip             = generate(:ip, @ip, node_index)
            cpus           = generate(:cpus, @cpus, node_index)
            memory         = generate(:memory, @memory, node_index)
            ansible_groups = generate(:ansible_groups, @ansible_groups, node_index)
            attributes     = generate(:attributes, @attributes, node_index)
            yield VagrantPlugins::Compose::Node.new(box, boxname, hostname, fqdn, aliases, ip, cpus, memory, ansible_groups, attributes, cluster_offset + node_index, node_index)

            node_index += 1
          end
        end

        # utility function for concatenating cluster name (if present) to boxname/hostname
        def maybe_prefix(cluster_name, name)
          if cluster_name && cluster_name.length > 0
            "#{cluster_name}-" + name
          else
            name
          end
        end

        # utility function for resolving value/value generators
        def generate(var, generator, node_index)
          unless generator.respond_to? :call
            return generator
          else
            begin
              return generator.call(@index, @name, node_index)
            rescue Exception => e
              raise VagrantPlugins::Compose::Errors::AttributeExpressionError, :message => e.message, :attribute => var, :node_index => node_index, :node_group_name => name
            end
          end
        end
      end

    end
  end
end