/**
 * @fileoverview Rule to flag references to undeclared variables.
 * @author Mark Macdonald
 */
'use strict';

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

/**
 * Checks if the given node is the argument of a typeof operator.
 * @param {ASTNode} node The AST node being checked.
 * @returns {boolean} Whether or not the node is the argument of a typeof operator.
 */
function hasTypeOfOperator(node) {
  const parent = node.parent;

  return parent.type === 'UnaryExpression' && parent.operator === 'typeof';
}

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

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

    defaultOptions: [
      {
        typeof: false,
      },
    ],

    docs: {
      description:
        'Disallow the use of undeclared variables unless mentioned in `/*global */` comments',
      recommended: true,
      url: 'https://eslint.org/docs/latest/rules/no-undef',
    },

    schema: [
      {
        type: 'object',
        properties: {
          typeof: {
            type: 'boolean',
          },
        },
        additionalProperties: false,
      },
    ],
    messages: {
      undef: "'{{name}}' is not defined.",
    },
  },

  create(context) {
    const [{ typeof: considerTypeOf }] = context.options;
    const sourceCode = context.sourceCode;

    return {
      'Program:exit'(node) {
        const globalScope = sourceCode.getScope(node);

        globalScope.through.forEach((ref) => {
          const identifier = ref.identifier;

          if (!considerTypeOf && hasTypeOfOperator(identifier)) {
            return;
          }

          context.report({
            node: identifier,
            messageId: 'undef',
            data: identifier,
          });
        });
      },
    };
  },
};