// We'll only fetch the `ListIteratee` type from the `@types/lodash`, but get
// `sortBy` from the modularized version of the package to avoid bringing in
// all of `lodash`.
import {
  visit,
  DocumentNode,
  OperationDefinitionNode,
  DirectiveNode,
  FragmentDefinitionNode,
  InlineFragmentNode,
  FragmentSpreadNode,
  FieldNode,
  SelectionSetNode,
  ArgumentNode,
  VariableDefinitionNode,
} from "graphql";
import sortBy from "lodash.sortby";

// sortAST sorts most multi-child nodes alphabetically. Using this as part of
// your signature calculation function may make it easier to tell the difference
// between queries that are similar to each other, and if for some reason your
// GraphQL client generates query strings with elements in nondeterministic
// order, it can make sure the queries are treated as identical.
export function sortAST(ast: DocumentNode): DocumentNode {
  return visit(ast, {
    Document(node: DocumentNode) {
      return {
        ...node,
        // The sort on "kind" places fragments before operations within the document
        definitions: sortBy(node.definitions, "kind", "name.value"),
      };
    },
    OperationDefinition(
      node: OperationDefinitionNode,
    ): OperationDefinitionNode {
      return sortVariableDefinitions(node);
    },
    SelectionSet(node): SelectionSetNode {
      return {
        ...node,
        // Define an ordering for field names in a SelectionSet.  Field first,
        // then FragmentSpread, then InlineFragment.  By a lovely coincidence,
        // the order we want them to appear in is alphabetical by node.kind.
        // Use sortBy instead of sorted because 'selections' is not optional.
        selections: sortBy(node.selections, "kind", "name.value"),
      };
    },
    Field(node): FieldNode {
      return sortArguments(node);
    },
    FragmentSpread(node): FragmentSpreadNode {
      return sortDirectives(node);
    },
    InlineFragment(node): InlineFragmentNode {
      return sortDirectives(node);
    },
    FragmentDefinition(node): FragmentDefinitionNode {
      return sortDirectives(sortVariableDefinitions(node));
    },
    Directive(node): DirectiveNode {
      return sortArguments(node);
    },
  });
}

function sortDirectives<T extends { directives?: readonly DirectiveNode[] }>(
  node: T,
): T {
  return "directives" in node
    ? { ...node, directives: sortBy(node.directives, "name.value") }
    : node;
}

function sortArguments<T extends { arguments?: readonly ArgumentNode[] }>(
  node: T,
): T {
  return "arguments" in node
    ? { ...node, arguments: sortBy(node.arguments, "name.value") }
    : node;
}

function sortVariableDefinitions<
  T extends { variableDefinitions?: readonly VariableDefinitionNode[] },
>(node: T): T {
  return "variableDefinitions" in node
    ? {
        ...node,
        variableDefinitions: sortBy(
          node.variableDefinitions,
          "variable.name.value",
        ),
      }
    : node;
}