/**
 * @fileoverview Rule to flag octal escape sequences in string literals.
 * @author Ian Christian Myers
 */

'use strict';

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

/** @type {import('../types').Rule.RuleModule} */
module.exports = {
  meta: {
    type: 'suggestion',

    docs: {
      description: 'Disallow octal escape sequences in string literals',
      recommended: false,
      url: 'https://eslint.org/docs/latest/rules/no-octal-escape',
    },

    schema: [],

    messages: {
      octalEscapeSequence:
        "Don't use octal: '\\{{sequence}}'. Use '\\u....' instead.",
    },
  },

  create(context) {
    return {
      Literal(node) {
        if (typeof node.value !== 'string') {
          return;
        }

        // \0 represents a valid NULL character if it isn't followed by a digit.
        const match = node.raw.match(
          /^(?:[^\\]|\\.)*?\\([0-3][0-7]{1,2}|[4-7][0-7]|0(?=[89])|[1-7])/su
        );

        if (match) {
          context.report({
            node,
            messageId: 'octalEscapeSequence',
            data: { sequence: match[1] },
          });
        }
      },
    };
  },
};