@putout/plugin-remove-useless-types/lib/remove-useless-types.js

putout plugin adds ability to find and remove useless

'use strict';

module.exports.report = () => `Avoid useless type declaration`;

module.exports.fix = ({name, path, nodes}) => {
    for (const node of nodes) {
        node.name = name;
    }
    
    path.remove();
};

module.exports.traverse = ({push, store}) => ({
    TSTypeAliasDeclaration(path) {
        const typePath = path.get('typeAnnotation');
        const isGeneric = typePath.get('typeParameters').node;
        
        if (isGeneric)
            return;
        
        if (path.parentPath.isExportNamedDeclaration())
            return;
        
        if (typePath.get('typeName').isTSQualifiedName())
            return;
        
        if (typePath.isTSTypeReference()) {
            const newName = path.node.id.name;
            const {name} = typePath.node.typeName;
            
            store(newName, {
                name,
                path,
                nodes: [],
            });
        }
    },
    
    TSTypeAnnotation(path) {
        const typePath = path.get('typeAnnotation');
        
        if (!typePath.isTSTypeReference())
            return;
        
        const {typeName} = typePath.node;
        const {name} = typeName;
        const current = store(name);
        
        if (!current)
            return;
        
        current.nodes.push(typeName);
    },
    
    TSTypeReference(path) {
        const {typeName} = path.node;
        const {name} = typeName;
        const current = store(name);
        
        if (!current)
            return;
        
        current.nodes.push(typeName);
    },
    
    Program: {
        exit() {
            for (const [newName, {name, path, nodes}] of store.entries()) {
                push({
                    name,
                    newName,
                    path,
                    nodes,
                });
            }
        },
    },
});