graphQLSchemaTransform.js

const fs = require('fs').promises;

const ALLOWED_MUTATIONS = [
    'manage_splash',
    'create_public_api_credential',
    'delete_public_api_credential'
];

const loadSchema = async (file) => {
    try {
        const data = await fs.readFile(file);
        return JSON.parse(data);
    } catch (error) {
        console.error(error);
        throw error;
    }
};

const sanitizeSchema = async (schema) => {
    const { mutationType, types } = schema;
    const replace = (array, index, ...items) => [...array.slice(0, index), ...items, ...array.slice(index + 1)];
    const mutations =  types.find(type => type.name === mutationType.name);
    const index = types.findIndex(type => type.name === mutationType.name);

    if (mutations && index !== -1) {
        const { fields } = mutations;
        const result = fields.filter(field => ALLOWED_MUTATIONS.includes(field.name));
        const patchedMutations = {...mutations, fields: result};
        const patchedTypes = replace(types, index, patchedMutations);

        return {
            data: {
                __schema: {
                    ...schema, 
                    types: patchedTypes
                }
            }
        };
    }
    return schema;
};

const saveSchema = (file) => {
    return async (schema) => {
        try {
            const data = JSON.stringify(schema, null, 4);
            return await fs.writeFile(file, data, 'utf8');
        } catch (error) {
            console.error(error);
            throw error;
        }
    };
};

loadSchema('schema.json').then(sanitizeSchema).then(saveSchema('output.json'));