import { GraphQLError } from '../../error'; /**
                                             * Copyright (c) 2015-present, Facebook, Inc.
                                             *
                                             * This source code is licensed under the MIT license found in the
                                             * LICENSE file in the root directory of this source tree.
                                             *
                                             *  strict
                                             */

export function unusedVariableMessage(varName, opName) {
  return opName ? 'Variable "$' + varName + '" is never used in operation "' + opName + '".' : 'Variable "$' + varName + '" is never used.';
}

/**
 * No unused variables
 *
 * A GraphQL operation is only valid if all variables defined by an operation
 * are used, either directly or within a spread fragment.
 */
export function NoUnusedVariables(context) {
  var variableDefs = [];

  return {
    OperationDefinition: {
      enter: function enter() {
        variableDefs = [];
      },
      leave: function leave(operation) {
        var variableNameUsed = Object.create(null);
        var usages = context.getRecursiveVariableUsages(operation);
        var opName = operation.name ? operation.name.value : null;

        usages.forEach(function (_ref) {
          var node = _ref.node;

          variableNameUsed[node.name.value] = true;
        });

        variableDefs.forEach(function (variableDef) {
          var variableName = variableDef.variable.name.value;
          if (variableNameUsed[variableName] !== true) {
            context.reportError(new GraphQLError(unusedVariableMessage(variableName, opName), [variableDef]));
          }
        });
      }
    },
    VariableDefinition: function VariableDefinition(def) {
      variableDefs.push(def);
    }
  };
}