RegularExpression.ts

import { GraphQLScalarType, Kind } from 'graphql';
import { createGraphQLError } from './error.js';

export type RegularExpressionErrorMessageFn = (r: RegExp, v: any) => string;

export interface RegularExpressionOptions {
  errorMessage?: RegularExpressionErrorMessageFn;
  description?: string;
  stringOnly?: boolean;
}

export class RegularExpression extends GraphQLScalarType {
  constructor(name: string, regex: RegExp, options: RegularExpressionOptions = {}) {
    const errorMessage: RegularExpressionErrorMessageFn = options.errorMessage
      ? options.errorMessage
      : (r, v) => `Value does not match ${r}: ${v}`;
    super({
      name,

      description: options.description || `A field whose value matches ${regex}.`,

      serialize(value) {
        if (value != null && !regex.test(value.toString())) {
          throw createGraphQLError(errorMessage(regex, value));
        }

        return value;
      },

      parseValue(value) {
        if (value != null && !regex.test(value?.toString())) {
          throw createGraphQLError(errorMessage(regex, value));
        }

        return value;
      },

      parseLiteral(ast) {
        if (ast.kind === Kind.NULL) {
          return null;
        }

        if (options.stringOnly && ast.kind !== Kind.STRING) {
          throw createGraphQLError(`Can only validate strings as ${name} but got a: ${ast.kind}`);
        }

        if (!('value' in ast) || ast.kind === Kind.ENUM) {
          throw createGraphQLError(
            `Can only validate primitive values as ${name} but got a: ${ast.kind}`,
            {
              nodes: [ast],
            },
          );
        }

        if (ast.value != null && !regex.test(ast.value.toString())) {
          throw createGraphQLError(errorMessage(regex, ast.value), { nodes: ast });
        }

        return ast.value;
      },
      extensions: {
        codegenScalarType: options.stringOnly ? 'string' : 'string | number | boolean',
      },
    });
  }
}