/**
 *  Explain fetching here...
 *
 *  @_section api/utils/fetching:Fetching Web Content  [about-fetch]
 */
import { decodeBase64, encodeBase64 } from "./base64.js";
import { hexlify } from "./data.js";
import { assert, assertArgument } from "./errors.js";
import { defineProperties } from "./properties.js";
import { toUtf8Bytes, toUtf8String } from "./utf8.js";
import { getUrl } from "./geturl.js";
const MAX_ATTEMPTS = 12;
const SLOT_INTERVAL = 250;
// The global FetchGetUrlFunc implementation.
let getUrlFunc = getUrl;
const reData = new RegExp("^data:([^;:]*)?(;base64)?,(.*)$", "i");
const reIpfs = new RegExp("^ipfs:/\/(ipfs/)?(.*)$", "i");
// If locked, new Gateways cannot be added
let locked = false;
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URLs
async function dataGatewayFunc(url, signal) {
    try {
        const match = url.match(reData);
        if (!match) {
            throw new Error("invalid data");
        }
        return new FetchResponse(200, "OK", {
            "content-type": (match[1] || "text/plain"),
        }, (match[2] ? decodeBase64(match[3]) : unpercent(match[3])));
    }
    catch (error) {
        return new FetchResponse(599, "BAD REQUEST (invalid data: URI)", {}, null, new FetchRequest(url));
    }
}
/**
 *  Returns a [[FetchGatewayFunc]] for fetching content from a standard
 *  IPFS gateway hosted at %%baseUrl%%.
 */
function getIpfsGatewayFunc(baseUrl) {
    async function gatewayIpfs(url, signal) {
        try {
            const match = url.match(reIpfs);
            if (!match) {
                throw new Error("invalid link");
            }
            return new FetchRequest(`${baseUrl}${match[2]}`);
        }
        catch (error) {
            return new FetchResponse(599, "BAD REQUEST (invalid IPFS URI)", {}, null, new FetchRequest(url));
        }
    }
    return gatewayIpfs;
}
const Gateways = {
    "data": dataGatewayFunc,
    "ipfs": getIpfsGatewayFunc("https:/\/gateway.ipfs.io/ipfs/")
};
const fetchSignals = new WeakMap();
/**
 *  @_ignore
 */
export class FetchCancelSignal {
    #listeners;
    #cancelled;
    constructor(request) {
        this.#listeners = [];
        this.#cancelled = false;
        fetchSignals.set(request, () => {
            if (this.#cancelled) {
                return;
            }
            this.#cancelled = true;
            for (const listener of this.#listeners) {
                setTimeout(() => { listener(); }, 0);
            }
            this.#listeners = [];
        });
    }
    addListener(listener) {
        assert(this.#cancelled, "singal already cancelled", "UNSUPPORTED_OPERATION", {
            operation: "fetchCancelSignal.addCancelListener"
        });
        this.#listeners.push(listener);
    }
    get cancelled() { return this.#cancelled; }
    checkSignal() {
        if (!this.cancelled) {
            return;
        }
        assert(false, "cancelled", "CANCELLED", {});
    }
}
// Check the signal, throwing if it is cancelled
function checkSignal(signal) {
    if (signal == null) {
        throw new Error("missing signal; should not happen");
    }
    signal.checkSignal();
    return signal;
}
/**
 *  Represents a request for a resource using a URI.
 *
 *  By default, the supported schemes are ``HTTP``, ``HTTPS``, ``data:``,
 *  and ``IPFS:``.
 *
 *  Additional schemes can be added globally using [[registerGateway]].
 *
 *  @example:
 *    req = new FetchRequest("https://www.ricmoo.com")
 *    resp = await req.send()
 *    resp.body.length
 *    //_result:
 */
export class FetchRequest {
    #allowInsecure;
    #gzip;
    #headers;
    #method;
    #timeout;
    #url;
    #body;
    #bodyType;
    #creds;
    // Hooks
    #preflight;
    #process;
    #retry;
    #signal;
    #throttle;
    /**
     *  The fetch URI to requrest.
     */
    get url() { return this.#url; }
    set url(url) {
        this.#url = String(url);
    }
    /**
     *  The fetch body, if any, to send as the request body. //(default: null)//
     *
     *  When setting a body, the intrinsic ``Content-Type`` is automatically
     *  set and will be used if **not overridden** by setting a custom
     *  header.
     *
     *  If %%body%% is null, the body is cleared (along with the
     *  intrinsic ``Content-Type``) and the .
     *
     *  If %%body%% is a string, the intrincis ``Content-Type`` is set to
     *  ``text/plain``.
     *
     *  If %%body%% is a Uint8Array, the intrincis ``Content-Type`` is set to
     *  ``application/octet-stream``.
     *
     *  If %%body%% is any other object, the intrincis ``Content-Type`` is
     *  set to ``application/json``.
     */
    get body() {
        if (this.#body == null) {
            return null;
        }
        return new Uint8Array(this.#body);
    }
    set body(body) {
        if (body == null) {
            this.#body = undefined;
            this.#bodyType = undefined;
        }
        else if (typeof (body) === "string") {
            this.#body = toUtf8Bytes(body);
            this.#bodyType = "text/plain";
        }
        else if (body instanceof Uint8Array) {
            this.#body = body;
            this.#bodyType = "application/octet-stream";
        }
        else if (typeof (body) === "object") {
            this.#body = toUtf8Bytes(JSON.stringify(body));
            this.#bodyType = "application/json";
        }
        else {
            throw new Error("invalid body");
        }
    }
    /**
     *  Returns true if the request has a body.
     */
    hasBody() {
        return (this.#body != null);
    }
    /**
     *  The HTTP method to use when requesting the URI. If no method
     *  has been explicitly set, then ``GET`` is used if the body is
     *  null and ``POST`` otherwise.
     */
    get method() {
        if (this.#method) {
            return this.#method;
        }
        if (this.hasBody()) {
            return "POST";
        }
        return "GET";
    }
    set method(method) {
        if (method == null) {
            method = "";
        }
        this.#method = String(method).toUpperCase();
    }
    /**
     *  The headers that will be used when requesting the URI. All
     *  keys are lower-case.
     *
     *  This object is a copy, so any chnages will **NOT** be reflected
     *  in the ``FetchRequest``.
     *
     *  To set a header entry, use the ``setHeader`` method.
     */
    get headers() {
        const headers = Object.assign({}, this.#headers);
        if (this.#creds) {
            headers["authorization"] = `Basic ${encodeBase64(toUtf8Bytes(this.#creds))}`;
        }
        ;
        if (this.allowGzip) {
            headers["accept-encoding"] = "gzip";
        }
        if (headers["content-type"] == null && this.#bodyType) {
            headers["content-type"] = this.#bodyType;
        }
        if (this.body) {
            headers["content-length"] = String(this.body.length);
        }
        return headers;
    }
    /**
     *  Get the header for %%key%%, ignoring case.
     */
    getHeader(key) {
        return this.headers[key.toLowerCase()];
    }
    /**
     *  Set the header for %%key%% to %%value%%. All values are coerced
     *  to a string.
     */
    setHeader(key, value) {
        this.#headers[String(key).toLowerCase()] = String(value);
    }
    /**
     *  Clear all headers, resetting all intrinsic headers.
     */
    clearHeaders() {
        this.#headers = {};
    }
    [Symbol.iterator]() {
        const headers = this.headers;
        const keys = Object.keys(headers);
        let index = 0;
        return {
            next: () => {
                if (index < keys.length) {
                    const key = keys[index++];
                    return {
                        value: [key, headers[key]], done: false
                    };
                }
                return { value: undefined, done: true };
            }
        };
    }
    /**
     *  The value that will be sent for the ``Authorization`` header.
     *
     *  To set the credentials, use the ``setCredentials`` method.
     */
    get credentials() {
        return this.#creds || null;
    }
    /**
     *  Sets an ``Authorization`` for %%username%% with %%password%%.
     */
    setCredentials(username, password) {
        assertArgument(!username.match(/:/), "invalid basic authentication username", "username", "[REDACTED]");
        this.#creds = `${username}:${password}`;
    }
    /**
     *  Enable and request gzip-encoded responses. The response will
     *  automatically be decompressed. //(default: true)//
     */
    get allowGzip() {
        return this.#gzip;
    }
    set allowGzip(value) {
        this.#gzip = !!value;
    }
    /**
     *  Allow ``Authentication`` credentials to be sent over insecure
     *  channels. //(default: false)//
     */
    get allowInsecureAuthentication() {
        return !!this.#allowInsecure;
    }
    set allowInsecureAuthentication(value) {
        this.#allowInsecure = !!value;
    }
    /**
     *  The timeout (in milliseconds) to wait for a complere response.
     *  //(default: 5 minutes)//
     */
    get timeout() { return this.#timeout; }
    set timeout(timeout) {
        assertArgument(timeout >= 0, "timeout must be non-zero", "timeout", timeout);
        this.#timeout = timeout;
    }
    /**
     *  This function is called prior to each request, for example
     *  during a redirection or retry in case of server throttling.
     *
     *  This offers an opportunity to populate headers or update
     *  content before sending a request.
     */
    get preflightFunc() {
        return this.#preflight || null;
    }
    set preflightFunc(preflight) {
        this.#preflight = preflight;
    }
    /**
     *  This function is called after each response, offering an
     *  opportunity to provide client-level throttling or updating
     *  response data.
     *
     *  Any error thrown in this causes the ``send()`` to throw.
     *
     *  To schedule a retry attempt (assuming the maximum retry limit
     *  has not been reached), use [[response.throwThrottleError]].
     */
    get processFunc() {
        return this.#process || null;
    }
    set processFunc(process) {
        this.#process = process;
    }
    /**
     *  This function is called on each retry attempt.
     */
    get retryFunc() {
        return this.#retry || null;
    }
    set retryFunc(retry) {
        this.#retry = retry;
    }
    /**
     *  Create a new FetchRequest instance with default values.
     *
     *  Once created, each property may be set before issuing a
     *  ``.send()`` to make teh request.
     */
    constructor(url) {
        this.#url = String(url);
        this.#allowInsecure = false;
        this.#gzip = true;
        this.#headers = {};
        this.#method = "";
        this.#timeout = 300000;
        this.#throttle = {
            slotInterval: SLOT_INTERVAL,
            maxAttempts: MAX_ATTEMPTS
        };
    }
    /**
     *  Update the throttle parameters used to determine maximum
     *  attempts and exponential-backoff properties.
     */
    setThrottleParams(params) {
        if (params.slotInterval != null) {
            this.#throttle.slotInterval = params.slotInterval;
        }
        if (params.maxAttempts != null) {
            this.#throttle.maxAttempts = params.maxAttempts;
        }
    }
    async #send(attempt, expires, delay, _request, _response) {
        if (attempt >= this.#throttle.maxAttempts) {
            return _response.makeServerError("exceeded maximum retry limit");
        }
        assert(getTime() <= expires, "timeout", "TIMEOUT", {
            operation: "request.send", reason: "timeout", request: _request
        });
        if (delay > 0) {
            await wait(delay);
        }
        let req = this.clone();
        const scheme = (req.url.split(":")[0] || "").toLowerCase();
        // Process any Gateways
        if (scheme in Gateways) {
            const result = await Gateways[scheme](req.url, checkSignal(_request.#signal));
            if (result instanceof FetchResponse) {
                let response = result;
                if (this.processFunc) {
                    checkSignal(_request.#signal);
                    try {
                        response = await this.processFunc(req, response);
                    }
                    catch (error) {
                        // Something went wrong during processing; throw a 5xx server error
                        if (error.throttle == null || typeof (error.stall) !== "number") {
                            response.makeServerError("error in post-processing function", error).assertOk();
                        }
                        // Ignore throttling
                    }
                }
                return response;
            }
            req = result;
        }
        // We have a preflight function; update the request
        if (this.preflightFunc) {
            req = await this.preflightFunc(req);
        }
        const resp = await getUrlFunc(req, checkSignal(_request.#signal));
        let response = new FetchResponse(resp.statusCode, resp.statusMessage, resp.headers, resp.body, _request);
        if (response.statusCode === 301 || response.statusCode === 302) {
            // Redirect
            try {
                const location = response.headers.location || "";
                return req.redirect(location).#send(attempt + 1, expires, 0, _request, response);
            }
            catch (error) { }
            // Things won't get any better on another attempt; abort
            return response;
        }
        else if (response.statusCode === 429) {
            // Throttle
            if (this.retryFunc == null || (await this.retryFunc(req, response, attempt))) {
                const retryAfter = response.headers["retry-after"];
                let delay = this.#throttle.slotInterval * Math.trunc(Math.random() * Math.pow(2, attempt));
                if (typeof (retryAfter) === "string" && retryAfter.match(/^[1-9][0-9]*$/)) {
                    delay = parseInt(retryAfter);
                }
                return req.clone().#send(attempt + 1, expires, delay, _request, response);
            }
        }
        if (this.processFunc) {
            checkSignal(_request.#signal);
            try {
                response = await this.processFunc(req, response);
            }
            catch (error) {
                // Something went wrong during processing; throw a 5xx server error
                if (error.throttle == null || typeof (error.stall) !== "number") {
                    response.makeServerError("error in post-processing function", error).assertOk();
                }
                // Throttle
                let delay = this.#throttle.slotInterval * Math.trunc(Math.random() * Math.pow(2, attempt));
                ;
                if (error.stall >= 0) {
                    delay = error.stall;
                }
                return req.clone().#send(attempt + 1, expires, delay, _request, response);
            }
        }
        return response;
    }
    /**
     *  Resolves to the response by sending the request.
     */
    send() {
        assert(this.#signal == null, "request already sent", "UNSUPPORTED_OPERATION", { operation: "fetchRequest.send" });
        this.#signal = new FetchCancelSignal(this);
        return this.#send(0, getTime() + this.timeout, 0, this, new FetchResponse(0, "", {}, null, this));
    }
    /**
     *  Cancels the inflight response, causing a ``CANCELLED``
     *  error to be rejected from the [[send]].
     */
    cancel() {
        assert(this.#signal != null, "request has not been sent", "UNSUPPORTED_OPERATION", { operation: "fetchRequest.cancel" });
        const signal = fetchSignals.get(this);
        if (!signal) {
            throw new Error("missing signal; should not happen");
        }
        signal();
    }
    /**
     *  Returns a new [[FetchRequest]] that represents the redirection
     *  to %%location%%.
     */
    redirect(location) {
        // Redirection; for now we only support absolute locataions
        const current = this.url.split(":")[0].toLowerCase();
        const target = location.split(":")[0].toLowerCase();
        // Don't allow redirecting:
        // - non-GET requests
        // - downgrading the security (e.g. https => http)
        // - to non-HTTP (or non-HTTPS) protocols [this could be relaxed?]
        assert(this.method === "GET" && (current !== "https" || target !== "http") && location.match(/^https?:/), `unsupported redirect`, "UNSUPPORTED_OPERATION", {
            operation: `redirect(${this.method} ${JSON.stringify(this.url)} => ${JSON.stringify(location)})`
        });
        // Create a copy of this request, with a new URL
        const req = new FetchRequest(location);
        req.method = "GET";
        req.allowGzip = this.allowGzip;
        req.timeout = this.timeout;
        req.#headers = Object.assign({}, this.#headers);
        if (this.#body) {
            req.#body = new Uint8Array(this.#body);
        }
        req.#bodyType = this.#bodyType;
        // Do not forward credentials unless on the same domain; only absolute
        //req.allowInsecure = false;
        // paths are currently supported; may want a way to specify to forward?
        //setStore(req.#props, "creds", getStore(this.#pros, "creds"));
        return req;
    }
    /**
     *  Create a new copy of this request.
     */
    clone() {
        const clone = new FetchRequest(this.url);
        // Preserve "default method" (i.e. null)
        clone.#method = this.#method;
        // Preserve "default body" with type, copying the Uint8Array is present
        if (this.#body) {
            clone.#body = this.#body;
        }
        clone.#bodyType = this.#bodyType;
        // Preserve "default headers"
        clone.#headers = Object.assign({}, this.#headers);
        // Credentials is readonly, so we copy internally
        clone.#creds = this.#creds;
        if (this.allowGzip) {
            clone.allowGzip = true;
        }
        clone.timeout = this.timeout;
        if (this.allowInsecureAuthentication) {
            clone.allowInsecureAuthentication = true;
        }
        clone.#preflight = this.#preflight;
        clone.#process = this.#process;
        clone.#retry = this.#retry;
        return clone;
    }
    /**
     *  Locks all static configuration for gateways and FetchGetUrlFunc
     *  registration.
     */
    static lockConfig() {
        locked = true;
    }
    /**
     *  Get the current Gateway function for %%scheme%%.
     */
    static getGateway(scheme) {
        return Gateways[scheme.toLowerCase()] || null;
    }
    /**
     *  Use the %%func%% when fetching URIs using %%scheme%%.
     *
     *  This method affects all requests globally.
     *
     *  If [[lockConfig]] has been called, no change is made and this
     *  throws.
     */
    static registerGateway(scheme, func) {
        scheme = scheme.toLowerCase();
        if (scheme === "http" || scheme === "https") {
            throw new Error(`cannot intercept ${scheme}; use registerGetUrl`);
        }
        if (locked) {
            throw new Error("gateways locked");
        }
        Gateways[scheme] = func;
    }
    /**
     *  Use %%getUrl%% when fetching URIs over HTTP and HTTPS requests.
     *
     *  This method affects all requests globally.
     *
     *  If [[lockConfig]] has been called, no change is made and this
     *  throws.
     */
    static registerGetUrl(getUrl) {
        if (locked) {
            throw new Error("gateways locked");
        }
        getUrlFunc = getUrl;
    }
    /**
     *  Creates a function that can "fetch" data URIs.
     *
     *  Note that this is automatically done internally to support
     *  data URIs, so it is not necessary to register it.
     *
     *  This is not generally something that is needed, but may
     *  be useful in a wrapper to perfom custom data URI functionality.
     */
    static createDataGateway() {
        return dataGatewayFunc;
    }
    /**
     *  Creates a function that will fetch IPFS (unvalidated) from
     *  a custom gateway baseUrl.
     *
     *  The default IPFS gateway used internally is
     *  ``"https:/\/gateway.ipfs.io/ipfs/"``.
     */
    static createIpfsGatewayFunc(baseUrl) {
        return getIpfsGatewayFunc(baseUrl);
    }
}
;
/**
 *  The response for a FetchREquest.
 */
export class FetchResponse {
    #statusCode;
    #statusMessage;
    #headers;
    #body;
    #request;
    #error;
    toString() {
        return `<Response status=${this.statusCode} body=${this.#body ? hexlify(this.#body) : "null"}>`;
    }
    /**
     *  The response status code.
     */
    get statusCode() { return this.#statusCode; }
    /**
     *  The response status message.
     */
    get statusMessage() { return this.#statusMessage; }
    /**
     *  The response headers. All keys are lower-case.
     */
    get headers() { return Object.assign({}, this.#headers); }
    /**
     *  The response body, or ``null`` if there was no body.
     */
    get body() {
        return (this.#body == null) ? null : new Uint8Array(this.#body);
    }
    /**
     *  The response body as a UTF-8 encoded string, or the empty
     *  string (i.e. ``""``) if there was no body.
     *
     *  An error is thrown if the body is invalid UTF-8 data.
     */
    get bodyText() {
        try {
            return (this.#body == null) ? "" : toUtf8String(this.#body);
        }
        catch (error) {
            assert(false, "response body is not valid UTF-8 data", "UNSUPPORTED_OPERATION", {
                operation: "bodyText", info: { response: this }
            });
        }
    }
    /**
     *  The response body, decoded as JSON.
     *
     *  An error is thrown if the body is invalid JSON-encoded data
     *  or if there was no body.
     */
    get bodyJson() {
        try {
            return JSON.parse(this.bodyText);
        }
        catch (error) {
            assert(false, "response body is not valid JSON", "UNSUPPORTED_OPERATION", {
                operation: "bodyJson", info: { response: this }
            });
        }
    }
    [Symbol.iterator]() {
        const headers = this.headers;
        const keys = Object.keys(headers);
        let index = 0;
        return {
            next: () => {
                if (index < keys.length) {
                    const key = keys[index++];
                    return {
                        value: [key, headers[key]], done: false
                    };
                }
                return { value: undefined, done: true };
            }
        };
    }
    constructor(statusCode, statusMessage, headers, body, request) {
        this.#statusCode = statusCode;
        this.#statusMessage = statusMessage;
        this.#headers = Object.keys(headers).reduce((accum, k) => {
            accum[k.toLowerCase()] = String(headers[k]);
            return accum;
        }, {});
        this.#body = ((body == null) ? null : new Uint8Array(body));
        this.#request = (request || null);
        this.#error = { message: "" };
    }
    /**
     *  Return a Response with matching headers and body, but with
     *  an error status code (i.e. 599) and %%message%% with an
     *  optional %%error%%.
     */
    makeServerError(message, error) {
        let statusMessage;
        if (!message) {
            message = `${this.statusCode} ${this.statusMessage}`;
            statusMessage = `CLIENT ESCALATED SERVER ERROR (${message})`;
        }
        else {
            statusMessage = `CLIENT ESCALATED SERVER ERROR (${this.statusCode} ${this.statusMessage}; ${message})`;
        }
        const response = new FetchResponse(599, statusMessage, this.headers, this.body, this.#request || undefined);
        response.#error = { message, error };
        return response;
    }
    /**
     *  If called within a [request.processFunc](FetchRequest-processFunc)
     *  call, causes the request to retry as if throttled for %%stall%%
     *  milliseconds.
     */
    throwThrottleError(message, stall) {
        if (stall == null) {
            stall = -1;
        }
        else {
            assertArgument(Number.isInteger(stall) && stall >= 0, "invalid stall timeout", "stall", stall);
        }
        const error = new Error(message || "throttling requests");
        defineProperties(error, { stall, throttle: true });
        throw error;
    }
    /**
     *  Get the header value for %%key%%, ignoring case.
     */
    getHeader(key) {
        return this.headers[key.toLowerCase()];
    }
    /**
     *  Returns true of the response has a body.
     */
    hasBody() {
        return (this.#body != null);
    }
    /**
     *  The request made for this response.
     */
    get request() { return this.#request; }
    /**
     *  Returns true if this response was a success statusCode.
     */
    ok() {
        return (this.#error.message === "" && this.statusCode >= 200 && this.statusCode < 300);
    }
    /**
     *  Throws a ``SERVER_ERROR`` if this response is not ok.
     */
    assertOk() {
        if (this.ok()) {
            return;
        }
        let { message, error } = this.#error;
        if (message === "") {
            message = `server response ${this.statusCode} ${this.statusMessage}`;
        }
        assert(false, message, "SERVER_ERROR", {
            request: (this.request || "unknown request"), response: this, error
        });
    }
}
function getTime() { return (new Date()).getTime(); }
function unpercent(value) {
    return toUtf8Bytes(value.replace(/%([0-9a-f][0-9a-f])/gi, (all, code) => {
        return String.fromCharCode(parseInt(code, 16));
    }));
}
function wait(delay) {
    return new Promise((resolve) => setTimeout(resolve, delay));
}
//# sourceMappingURL=fetch.js.map