@graphql-mesh/serve-runtime/esm/plugins/usePropagateHeaders.js

import { mapMaybePromise } from '@envelop/core';
import { subgraphNameByExecutionRequest } from '@graphql-mesh/fusion-runtime';
export function usePropagateHeaders(opts) {
    const resHeadersByRequest = new WeakMap();
    return {
        onFetch({ executionRequest, context, options, setOptions }) {
            const request = context?.request || executionRequest?.context?.request;
            if (request) {
                const subgraphName = executionRequest && subgraphNameByExecutionRequest.get(executionRequest);
                let job;
                if (opts.fromClientToSubgraphs) {
                    job = mapMaybePromise(opts.fromClientToSubgraphs({
                        request,
                        subgraphName,
                    }), headers => setOptions({
                        ...options,
                        headers: {
                            ...headers,
                            ...options.headers,
                        },
                    }));
                }
                return mapMaybePromise(job, () => {
                    if (opts.fromSubgraphsToClient) {
                        return function onFetchDone({ response }) {
                            return mapMaybePromise(opts.fromSubgraphsToClient({
                                response,
                                subgraphName,
                            }), headers => {
                                if (headers && request) {
                                    resHeadersByRequest.set(request, headers);
                                }
                            });
                        };
                    }
                });
            }
        },
        onResponse({ response, request }) {
            const headers = resHeadersByRequest.get(request);
            if (headers) {
                for (const key in headers) {
                    const value = headers[key];
                    if (value) {
                        response.headers.set(key, value);
                    }
                }
            }
        },
    };
}