'use strict';

// `fetch` will be available for node and browsers as a global
//var fetch = window.fetch;

// https://developer.mozilla.org/en-US/docs/Web/API/fetch
// https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch
let _fetchDefaults = {
    method: 'GET', // *GET, POST, PATCH, PUT, DELETE, etc
    headers: {},
    body: undefined, // String, ArrayBuffer, FormData, etc
    mode: 'cors', // no-cors, *cors, same-origin
    credentials: 'same-origin', // omit, *same-origin, include
    cache: 'default', // *default, no-store, reload, no-cache, force-cache, only-if-cached
    redirect: 'follow', // *follow, error, manual,
    referrer: undefined,
    referrerPolicy: 'no-referrer-when-downgrade', // no-referrer, *no-referrer-when-downgrade, same-origin, origin, strict-origin, origin-when-cross-origin, strict-origin-when-cross-origin, unsafe-url
    integrity: '',
    keepalive: false,
    signal: null //
};

let _optionKeys = Object.keys(_fetchDefaults).concat([
    //'encoding', // N/A
    //'stream', // TODO via getReader
    //'json' // handled manually
    //'form', // TODO
    //'auth' // handled manually
    //'formData', // TODO
    //'FormData', // TODO
    //'userAgent' // not allowed, non-standard for request.js
]);

function setDefaults(_defs) {
    return async function request(opts) {
        if ('string' === typeof opts) {
            opts = { url: opts };
        }
        let reqOpts = { headers: {} };

        if (
            opts.body ||
            (opts.json && true !== opts.json) ||
            opts.form ||
            opts.formData
        ) {
            // TODO this is probably a deviation from request's API
            // need to check and probably eliminate it
            reqOpts.method = (reqOpts.method || 'POST').toUpperCase();
        } else {
            reqOpts.method = (reqOpts.method || 'GET').toUpperCase();
        }

        _optionKeys.forEach(function (key) {
            if (key in opts) {
                if ('undefined' !== typeof opts[key]) {
                    reqOpts[key] = opts[key];
                }
            } else if (key in _defs) {
                reqOpts[key] = _defs[key];
            }
        });

        if (opts.auth) {
            // if opts.uri specifies auth it will be parsed by url.parse and passed directly to the http module
            if ('string' !== typeof opts.auth) {
                let u = opts.auth.user || opts.auth.username || '';
                let p = opts.auth.pass || opts.auth.password || '';
                reqOpts.headers.Authorization = encodeBasicAuth(`${u}:${p}`);
            } else if ('string' === typeof opts.auth) {
                reqOpts.headers.Authorization = encodeBasicAuth(`${opts.auth}`);
            }

            // [request-compat]
            if (opts.auth.bearer) {
                // having a shortcut for base64 encoding makes sense,
                // but this? Eh, whatevs...
                reqOpts.header.Authorization = `Bearer ${opts.auth.bearer}`;
            }
        }

        let body;
        if (opts.json && true !== opts.json) {
            if (!opts.headers['content-type']) {
                opts.headers['content-type'] = 'application/json';
            }
            body = JSON.stringify(opts.json);
            if (!opts.method) {
                opts.method = 'POST';
            }
        }

        // The node version will send HTTP Auth by default, but not Cookies.
        // We don't have an equivalent option for `fetch`. Furthermore,
        // `fetch` caches HTTP Auth Basic across browser refreshes,
        // which is not analogous to the node behavior.
        //
        // "In the face of ambiguity, refuse the temptation to guess"
        //
        //if (!('credentials' in opts)) {
        //    opts.credentials = 'include';
        //}

        if (!('mode' in opts)) {
            reqOpts.mode = 'cors';
        }
        if (!('body' in opts)) {
            if (body) {
                reqOpts.body = body;
            }
        }

        let resp = await fetch(opts.url, reqOpts);

        let result = {
            ok: resp.ok,
            headers: headersToObj(resp.headers),
            body: undefined,
            // swapped to match request.js
            statusCode: resp.status,
            status: resp.statusText,
            request: reqOpts,
            response: resp
        };
        result.toJSON = function () {
            return {
                ok: result.ok,
                headers: result.headers,
                body: result.body,
                statusCode: result.statusCode,
                status: result.status
            };
        };

        // return early if there's no body
        if (!result.headers['content-type']) {
            return result;
        }

        // TODO blob, formData ?
        if (null === opts.encoding) {
            return await resp.arrayBuffer();
        }

        if (!opts.json) {
            result.body = await resp.text();
        } else {
            result.body = await resp.json().catch(async function () {
                return await resp.text();
            });
        }
        return result;
    };
}

/**
 * @param {Iterable.<*>} rheaders
 * @returns {Object.<String, String>}
 */
function headersToObj(rheaders) {
    /*
    Array.from(resp.headers.entries()).forEach(function (h) {
        headers[h[0]] = h[1];
    });
    */
    let headerNames = Array.from(rheaders.keys());
    let resHeaders = {};
    headerNames.forEach(function (k) {
        resHeaders[k] = rheaders.get(k);
    });
    return resHeaders;
}

/**
 * @param {String} utf8
 * @returns {String}
 */
function encodeBasicAuth(utf8) {
    let b64 = unicodeToBase64(utf8);
    return `Basic ${b64}`;
}

/**
 * @param {String} utf8
 * @returns {String}
 */
function unicodeToBase64(utf8) {
    let str = '';
    let uint8 = new TextEncoder().encode(utf8);
    uint8.forEach(function (b) {
        str += String.fromCharCode(b);
    });
    let b64 = btoa(str);
    return b64;
}

let defaultRequest = setDefaults({ mode: 'cors' });
exports.request = defaultRequest;
exports.defaults = setDefaults;
module.exports = defaultRequest;
module.exports.defaults = setDefaults;