import deepmerge from "deepmerge";
import isPlainObject from "is-plain-object";
import { lowercaseKeys } from "./util/lowercase-keys";
export function merge(defaults, route, options) {
    if (typeof route === "string") {
        let [method, url] = route.split(" ");
        options = Object.assign(url ? { method, url } : { url: method }, options);
    }
    else {
        options = route || {};
    }
    // lowercase header names before merging with defaults to avoid duplicates
    options.headers = lowercaseKeys(options.headers);
    const mergedOptions = deepmerge.all([defaults, options].filter(Boolean), {
        isMergeableObject: isPlainObject
    });
    // mediaType.previews arrays are merged, instead of overwritten
    if (defaults && defaults.mediaType.previews.length) {
        mergedOptions.mediaType.previews = defaults.mediaType.previews
            .filter(preview => !mergedOptions.mediaType.previews.includes(preview))
            .concat(mergedOptions.mediaType.previews);
    }
    mergedOptions.mediaType.previews = mergedOptions.mediaType.previews.map((preview) => preview.replace(/-preview/, ""));
    return mergedOptions;
}