eslint-plugin-i18n-json/src/valid-message-syntax.js

Fully extendable eslint plugin for JSON i18n translation files.

const { set, isPlainObject } = require('lodash');
const diff = require('jest-diff');
const prettyFormat = require('pretty-format');
const icuValidator = require('./message-validators/icu');
const notEmpty = require('./message-validators/not-empty');
const isString = require('./message-validators/is-string');
const deepForOwn = require('./util/deep-for-own');
const requireNoCache = require('./util/require-no-cache');
const getTranslationFileSource = require('./util/get-translation-file-source');

/* Error tokens */
const EMPTY_OBJECT = Symbol.for('EMPTY_OBJECT');
const ARRAY = Symbol.for('ARRAY');

/* Formatting */
const ALL_BACKSLASHES = /[\\]/g;
const ALL_DOUBLE_QUOTES = /["]/g;

const prettyFormatTypePlugin = {
  test(val) {
    return typeof val === 'number' || typeof val === 'string';
  },
  serialize(val) {
    return (
      (typeof val === 'string' && `String(${`'${val}'`})`) || `Number(${val})`
    );
  }
};

const formatExpectedValue = ({ value }) => {
  switch (value) {
    case EMPTY_OBJECT:
    case ARRAY:
      return 'ObjectContaining<ValidMessages> | ValidMessage<String>';
    default:
      return 'ValidMessage<String>';
  }
};

const formatReceivedValue = ({ value, error }) => {
  const errorMessage = error.message
    .replace(ALL_BACKSLASHES, '')
    .replace(ALL_DOUBLE_QUOTES, "'");
  switch (value) {
    case EMPTY_OBJECT:
      return `${prettyFormat({})} ===> ${error}`;
    case ARRAY:
      return `${prettyFormat([])} ===> ${error}`;
    default:
      return `${prettyFormat(value, {
        plugins: [prettyFormatTypePlugin]
      })} ===> ${errorMessage}`;
  }
};

const createValidator = (syntax) => {
  // each syntax type defined here must have a case!
  if (['icu', 'non-empty-string'].includes(syntax)) {
    return (value) => {
      switch (syntax) {
        case 'icu':
          notEmpty(value);
          isString(value);
          icuValidator(value);
          break;
        default:
          notEmpty(value);
          isString(value);
      }
    };
  }
  // custom validator
  const customValidator = requireNoCache(syntax);
  return (value, key) => {
    customValidator(value, key);
  };
};

const validMessageSyntax = (context, source) => {
  const { options, settings = {} } = context;

  let { syntax } = options[0] || {};

  syntax = syntax && syntax.trim();

  let translations = null;
  const invalidMessages = [];

  if (!syntax) {
    return [
      {
        message: '"syntax" not specified in rule option.',
        loc: {
          start: {
            line: 0,
            col: 0
          }
        }
      }
    ];
  }

  try {
    translations = JSON.parse(source);
  } catch (e) {
    return [];
  }

  let validate;

  try {
    validate = createValidator(syntax);
  } catch (e) {
    return [
      {
        message: `Error configuring syntax validator. Rule option specified: ${syntax}. ${e}`,
        loc: {
          start: {
            line: 0,
            col: 0
          }
        }
      }
    ];
  }

  const ignorePaths = settings['i18n-json/ignore-keys'] || [];

  deepForOwn(
    translations,
    (value, key, path) => {
      // empty object itself is an error
      if (isPlainObject(value)) {
        if (Object.keys(value).length === 0) {
          invalidMessages.push({
            value: EMPTY_OBJECT,
            key,
            path,
            error: new SyntaxError('Empty object.')
          });
        }
      } else if (Array.isArray(value)) {
        invalidMessages.push({
          value: ARRAY,
          key,
          path,
          error: new TypeError('An Array cannot be a translation value.')
        });
      } else {
        try {
          validate(value, key);
        } catch (validationError) {
          invalidMessages.push({
            value,
            key,
            path,
            error: validationError
          });
        }
      }
    },
    {
      ignorePaths
    }
  );

  if (invalidMessages.length > 0) {
    const expected = {};
    const received = {};
    invalidMessages.forEach((invalidMessage) => {
      set(expected, invalidMessage.path, formatExpectedValue(invalidMessage));
      set(received, invalidMessage.path, formatReceivedValue(invalidMessage));
    });

    return [
      {
        message: `\n${diff(expected, received)}`,
        loc: {
          start: {
            line: 0,
            col: 0
          }
        }
      }
    ];
  }
  // no errors
  return [];
};

module.exports = {
  meta: {
    docs: {
      category: 'Validation',
      description:
        'Validates message syntax for each translation key in the file.',
      recommended: true
    },
    schema: [
      {
        properties: {
          syntax: {
            type: ['string']
          }
        },
        type: 'object',
        additionalProperties: false
      }
    ]
  },
  create(context) {
    return {
      Program(node) {
        const { valid, source } = getTranslationFileSource({
          context,
          node
        });
        if (!valid) {
          return;
        }
        const errors = validMessageSyntax(context, source);
        errors.forEach((error) => {
          context.report(error);
        });
      }
    };
  }
};