module GromNative

# File lib/grom_native.rb, line 38
def self.build_nodes(data_struct, filter, decorators)
  nodes = []
  nodes_by_subject = {}
  filtered_nodes = Array.new(filter.size) { [] }

  data_struct.fetch('statementsBySubject', []).each do |subject, statements|
    node = GromNative::Node.new(statements, decorators)

    nodes << node
    nodes_by_subject[subject] = node

    if !filter.empty? && node.respond_to?(:type)
      node_types = node.blank? ? Array(::Grom::Node::BLANK) : Array(node.type)
      indexes = node_types.reduce([]) do |memo, type|
        index = filter.index(type)
        memo << index if index

        memo
      end

      indexes.each { |index| filtered_nodes[index] << node }
    end
  end

  link_nodes(nodes_by_subject, data_struct)

  return filtered_nodes.first if filter && filter.size == 1
  return filtered_nodes       if filter

  nodes
end

# File lib/grom_native.rb, line 13
def self.fetch(uri:, headers: {}, filter: [], decorators: nil)
  input = { uri: uri, headers: headers, filter: filter }
  data_struct = JSON.parse(get(uri))

  handle_errors(data_struct)

  build_nodes(data_struct, filter, decorators)
end

# File lib/grom_native.rb, line 22
def self.handle_errors(data_struct)
  error = nil
  status_code = data_struct.fetch('status_code', 0)

  if status_code >= 500
    error = "Server error: #{data_struct['error']}"
  elsif status_code >= 300 && status_code < 500
    error = "Client error: #{data_struct['error']}"
  end

  # require 'irb'; binding.irb
  error ||= data_struct['error']

  raise StandardError, error if error != "" && error != nil
end

# File lib/grom_native.rb, line 70
def self.link_nodes(nodes_by_subject, data_struct)
  data_struct.fetch('edgesBySubject', {}).each do |subject, predicates|
    predicates.each do |predicate, object_uris|
      raise NamingError if predicate == 'type'

      current_node = nodes_by_subject[subject]
      next if current_node.nil?

      object_uris.each do |object_uri|
        predicate_name_symbol = "@#{predicate}".to_sym

        # Get the current value (if there is one)
        current_value = current_node.instance_variable_get(predicate_name_symbol)

        object = current_value

        # If we have stored a string, and there are objects to link, create an empty array
        current_value_is_string    = current_value.is_a?(String)
        object_is_array_of_strings = object.all? { |entry| entry.is_a?(String) } if object.is_a?(Array)
        object_by_uri              = nodes_by_subject[object_uri]

        object = [] if (current_value_is_string || object_is_array_of_strings) && object_by_uri

        # If the above is correct, and we have an array
        if object.is_a?(Array)
          # Insert the current value (only if this is a new array (prevents possible duplication),
          # the current value is a string, and there are no linked objects to insert)
          object << current_value if object.empty? && current_value_is_string && object_by_uri.nil?

          # Insert linked objects, if there are any
          object << object_by_uri if object_by_uri
        end

        current_node.instance_variable_set(predicate_name_symbol, object)
      end
    end
  end

  self
end