zkoss/zk

import { AST_NODE_TYPES } from '@typescript-eslint/utils';
import { createRule } from '../util';

export const noTopLevelScopingIIFE = createRule({
    name: 'noTopLevelScopingIIFE',
    meta: {
        type: 'problem',
        docs: {
            description: 'Avoid top-level IIFE for scoping in Typescript modules.',
            recommended: 'error',
        },
        fixable: 'code',
        messages: {
            removeTopLevelScopingIIFE: 'Remove top-level IIFE for scoping.',
        },
        schema: []
    },
    defaultOptions: [],
    create(context) {
        return {
            CallExpression(node) {
                const { parent, callee } = node;

                if (callee.type !== AST_NODE_TYPES.ArrowFunctionExpression &&
                    callee.type !== AST_NODE_TYPES.FunctionExpression
                ) {
                    return; // not iife
                }

                if (parent?.type !== AST_NODE_TYPES.ExpressionStatement ||
                    parent.parent?.type !== AST_NODE_TYPES.Program
                ) {
                    return; // not top-level
                }

                if (callee.params.length !== 0 ||
                    callee.body.type !== AST_NODE_TYPES.BlockStatement ||
                    callee.async ||
                    callee.generator ||
                    callee.expression
                ) {
                    return; // not for scoping
                }

                const { body } = callee.body;
                context.report({
                    node,
                    messageId: 'removeTopLevelScopingIIFE',
                    fix(fixer) {
                        // Remove the whole statement if the body is empty.
                        if (body.length === 0) {
                            return fixer.remove(parent);
                        }
                        // `body` is guaranteed to contain something from this point on.
                        return [
                            // (function () {
                            // ^^^^^^^^^^^^^^ -> remove until reaching the first enclosing statement
                            fixer.removeRange([
                                parent.range[0],
                                // One character after the left parenthesis of the body statement
                                callee.body.range[0] + 1
                            ]),
                            // })();
                            // ^^^^^ -> remove the trailing semicolon as well
                            fixer.removeRange([
                                // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
                                body.at(-1)!.range[1],
                                // The end of the statement includes the trailing semicolon.
                                parent.range[1]
                            ]),
                        ];
                    }
                });
            }
        };
    }
});