/**
 * @fileoverview Rule to flag comparisons to null without a type-checking
 * operator.
 * @author Ian Christian Myers
 */

'use strict';

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

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

    docs: {
      description:
        'Disallow `null` comparisons without type-checking operators',
      recommended: false,
      url: 'https://eslint.org/docs/latest/rules/no-eq-null',
    },

    schema: [],

    messages: {
      unexpected: "Use '===' to compare with null.",
    },
  },

  create(context) {
    return {
      BinaryExpression(node) {
        const badOperator = node.operator === '==' || node.operator === '!=';

        if (
          (node.right.type === 'Literal' &&
            node.right.raw === 'null' &&
            badOperator) ||
          (node.left.type === 'Literal' &&
            node.left.raw === 'null' &&
            badOperator)
        ) {
          context.report({ node, messageId: 'unexpected' });
        }
      },
    };
  },
};