// require the whatwg compatible URL library (same behaviour in node and browser)
const {URL} = require('url');
const stripSubdirectoryFromPath = require('./strip-subdirectory-from-path');

/**
 * Convert an absolute URL to a root-relative path if it matches the supplied root domain.
 *
 * @param {string} url Absolute URL to convert to relative if possible
 * @param {string} rootUrl Absolute URL to which the returned relative URL will match the domain root
 * @param {Object} [options] Options that affect the conversion
 * @param {boolean} [options.ignoreProtocol=true] Ignore protocol when matching url to root
 * @param {boolean} [options.withoutSubdirectory=false] Strip the root subdirectory from the returned path
 * @returns {string} The passed-in url or a relative path
 */
const absoluteToRelative = function absoluteToRelative(url, rootUrl, _options = {}) {
    const defaultOptions = {
        ignoreProtocol: true,
        withoutSubdirectory: false,
        assetsOnly: false,
        staticImageUrlPrefix: 'content/images'
    };
    const options = Object.assign({}, defaultOptions, _options);

    if (options.assetsOnly) {
        const staticImageUrlPrefixRegex = new RegExp(options.staticImageUrlPrefix);
        if (!url.match(staticImageUrlPrefixRegex)) {
            return url;
        }
    }

    let parsedUrl;
    let parsedRoot;

    try {
        parsedUrl = new URL(url, 'http://relative');
        parsedRoot = parsedUrl.origin === 'null' ? undefined : new URL(rootUrl || parsedUrl.origin);

        // return the url as-is if it was relative or non-http
        if (parsedUrl.origin === 'null' || parsedUrl.origin === 'http://relative') {
            return url;
        }
    } catch (e) {
        return url;
    }

    const matchesHost = parsedUrl.host === parsedRoot.host;
    const matchesProtocol = parsedUrl.protocol === parsedRoot.protocol;
    const matchesPath = parsedUrl.pathname.indexOf(parsedRoot.pathname) === 0;

    if (matchesHost && (options.ignoreProtocol || matchesProtocol) && matchesPath) {
        let path = parsedUrl.href.replace(parsedUrl.origin, '');

        if (options.withoutSubdirectory) {
            path = stripSubdirectoryFromPath(path, rootUrl);
        }

        return path;
    }

    return url;
};

module.exports = absoluteToRelative;