(function (global, factory) {
    typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
    typeof define === 'function' && define.amd ? define(['exports'], factory) :
    (global = typeof globalThis !== 'undefined' ? globalThis : global || self, factory(global.Comlink = {}));
})(this, (function (exports) { 'use strict';

    /**
     * @license
     * Copyright 2019 Google LLC
     * SPDX-License-Identifier: Apache-2.0
     */
    const proxyMarker = Symbol("Comlink.proxy");
    const createEndpoint = Symbol("Comlink.endpoint");
    const releaseProxy = Symbol("Comlink.releaseProxy");
    const finalizer = Symbol("Comlink.finalizer");
    const throwMarker = Symbol("Comlink.thrown");
    const isObject = (val) => (typeof val === "object" && val !== null) || typeof val === "function";
    /**
     * Internal transfer handle to handle objects marked to proxy.
     */
    const proxyTransferHandler = {
        canHandle: (val) => isObject(val) && val[proxyMarker],
        serialize(obj) {
            const { port1, port2 } = new MessageChannel();
            expose(obj, port1);
            return [port2, [port2]];
        },
        deserialize(port) {
            port.start();
            return wrap(port);
        },
    };
    /**
     * Internal transfer handler to handle thrown exceptions.
     */
    const throwTransferHandler = {
        canHandle: (value) => isObject(value) && throwMarker in value,
        serialize({ value }) {
            let serialized;
            if (value instanceof Error) {
                serialized = {
                    isError: true,
                    value: {
                        message: value.message,
                        name: value.name,
                        stack: value.stack,
                    },
                };
            }
            else {
                serialized = { isError: false, value };
            }
            return [serialized, []];
        },
        deserialize(serialized) {
            if (serialized.isError) {
                throw Object.assign(new Error(serialized.value.message), serialized.value);
            }
            throw serialized.value;
        },
    };
    /**
     * Allows customizing the serialization of certain values.
     */
    const transferHandlers = new Map([
        ["proxy", proxyTransferHandler],
        ["throw", throwTransferHandler],
    ]);
    function isAllowedOrigin(allowedOrigins, origin) {
        for (const allowedOrigin of allowedOrigins) {
            if (origin === allowedOrigin || allowedOrigin === "*") {
                return true;
            }
            if (allowedOrigin instanceof RegExp && allowedOrigin.test(origin)) {
                return true;
            }
        }
        return false;
    }
    function expose(obj, ep = globalThis, allowedOrigins = ["*"]) {
        ep.addEventListener("message", function callback(ev) {
            if (!ev || !ev.data) {
                return;
            }
            if (!isAllowedOrigin(allowedOrigins, ev.origin)) {
                console.warn(`Invalid origin '${ev.origin}' for comlink proxy`);
                return;
            }
            const { id, type, path } = Object.assign({ path: [] }, ev.data);
            const argumentList = (ev.data.argumentList || []).map(fromWireValue);
            let returnValue;
            try {
                const parent = path.slice(0, -1).reduce((obj, prop) => obj[prop], obj);
                const rawValue = path.reduce((obj, prop) => obj[prop], obj);
                switch (type) {
                    case "GET" /* MessageType.GET */:
                        {
                            returnValue = rawValue;
                        }
                        break;
                    case "SET" /* MessageType.SET */:
                        {
                            parent[path.slice(-1)[0]] = fromWireValue(ev.data.value);
                            returnValue = true;
                        }
                        break;
                    case "APPLY" /* MessageType.APPLY */:
                        {
                            returnValue = rawValue.apply(parent, argumentList);
                        }
                        break;
                    case "CONSTRUCT" /* MessageType.CONSTRUCT */:
                        {
                            const value = new rawValue(...argumentList);
                            returnValue = proxy(value);
                        }
                        break;
                    case "ENDPOINT" /* MessageType.ENDPOINT */:
                        {
                            const { port1, port2 } = new MessageChannel();
                            expose(obj, port2);
                            returnValue = transfer(port1, [port1]);
                        }
                        break;
                    case "RELEASE" /* MessageType.RELEASE */:
                        {
                            returnValue = undefined;
                        }
                        break;
                    default:
                        return;
                }
            }
            catch (value) {
                returnValue = { value, [throwMarker]: 0 };
            }
            Promise.resolve(returnValue)
                .catch((value) => {
                return { value, [throwMarker]: 0 };
            })
                .then((returnValue) => {
                const [wireValue, transferables] = toWireValue(returnValue);
                ep.postMessage(Object.assign(Object.assign({}, wireValue), { id }), transferables);
                if (type === "RELEASE" /* MessageType.RELEASE */) {
                    // detach and deactive after sending release response above.
                    ep.removeEventListener("message", callback);
                    closeEndPoint(ep);
                    if (finalizer in obj && typeof obj[finalizer] === "function") {
                        obj[finalizer]();
                    }
                }
            })
                .catch((error) => {
                // Send Serialization Error To Caller
                const [wireValue, transferables] = toWireValue({
                    value: new TypeError("Unserializable return value"),
                    [throwMarker]: 0,
                });
                ep.postMessage(Object.assign(Object.assign({}, wireValue), { id }), transferables);
            });
        });
        if (ep.start) {
            ep.start();
        }
    }
    function isMessagePort(endpoint) {
        return endpoint.constructor.name === "MessagePort";
    }
    function closeEndPoint(endpoint) {
        if (isMessagePort(endpoint))
            endpoint.close();
    }
    function wrap(ep, target) {
        return createProxy(ep, [], target);
    }
    function throwIfProxyReleased(isReleased) {
        if (isReleased) {
            throw new Error("Proxy has been released and is not useable");
        }
    }
    function releaseEndpoint(ep) {
        return requestResponseMessage(ep, {
            type: "RELEASE" /* MessageType.RELEASE */,
        }).then(() => {
            closeEndPoint(ep);
        });
    }
    const proxyCounter = new WeakMap();
    const proxyFinalizers = "FinalizationRegistry" in globalThis &&
        new FinalizationRegistry((ep) => {
            const newCount = (proxyCounter.get(ep) || 0) - 1;
            proxyCounter.set(ep, newCount);
            if (newCount === 0) {
                releaseEndpoint(ep);
            }
        });
    function registerProxy(proxy, ep) {
        const newCount = (proxyCounter.get(ep) || 0) + 1;
        proxyCounter.set(ep, newCount);
        if (proxyFinalizers) {
            proxyFinalizers.register(proxy, ep, proxy);
        }
    }
    function unregisterProxy(proxy) {
        if (proxyFinalizers) {
            proxyFinalizers.unregister(proxy);
        }
    }
    function createProxy(ep, path = [], target = function () { }) {
        let isProxyReleased = false;
        const proxy = new Proxy(target, {
            get(_target, prop) {
                throwIfProxyReleased(isProxyReleased);
                if (prop === releaseProxy) {
                    return () => {
                        unregisterProxy(proxy);
                        releaseEndpoint(ep);
                        isProxyReleased = true;
                    };
                }
                if (prop === "then") {
                    if (path.length === 0) {
                        return { then: () => proxy };
                    }
                    const r = requestResponseMessage(ep, {
                        type: "GET" /* MessageType.GET */,
                        path: path.map((p) => p.toString()),
                    }).then(fromWireValue);
                    return r.then.bind(r);
                }
                return createProxy(ep, [...path, prop]);
            },
            set(_target, prop, rawValue) {
                throwIfProxyReleased(isProxyReleased);
                // FIXME: ES6 Proxy Handler `set` methods are supposed to return a
                // boolean. To show good will, we return true asynchronously ¯\_(ツ)_/¯
                const [value, transferables] = toWireValue(rawValue);
                return requestResponseMessage(ep, {
                    type: "SET" /* MessageType.SET */,
                    path: [...path, prop].map((p) => p.toString()),
                    value,
                }, transferables).then(fromWireValue);
            },
            apply(_target, _thisArg, rawArgumentList) {
                throwIfProxyReleased(isProxyReleased);
                const last = path[path.length - 1];
                if (last === createEndpoint) {
                    return requestResponseMessage(ep, {
                        type: "ENDPOINT" /* MessageType.ENDPOINT */,
                    }).then(fromWireValue);
                }
                // We just pretend that `bind()` didn’t happen.
                if (last === "bind") {
                    return createProxy(ep, path.slice(0, -1));
                }
                const [argumentList, transferables] = processArguments(rawArgumentList);
                return requestResponseMessage(ep, {
                    type: "APPLY" /* MessageType.APPLY */,
                    path: path.map((p) => p.toString()),
                    argumentList,
                }, transferables).then(fromWireValue);
            },
            construct(_target, rawArgumentList) {
                throwIfProxyReleased(isProxyReleased);
                const [argumentList, transferables] = processArguments(rawArgumentList);
                return requestResponseMessage(ep, {
                    type: "CONSTRUCT" /* MessageType.CONSTRUCT */,
                    path: path.map((p) => p.toString()),
                    argumentList,
                }, transferables).then(fromWireValue);
            },
        });
        registerProxy(proxy, ep);
        return proxy;
    }
    function myFlat(arr) {
        return Array.prototype.concat.apply([], arr);
    }
    function processArguments(argumentList) {
        const processed = argumentList.map(toWireValue);
        return [processed.map((v) => v[0]), myFlat(processed.map((v) => v[1]))];
    }
    const transferCache = new WeakMap();
    function transfer(obj, transfers) {
        transferCache.set(obj, transfers);
        return obj;
    }
    function proxy(obj) {
        return Object.assign(obj, { [proxyMarker]: true });
    }
    function windowEndpoint(w, context = globalThis, targetOrigin = "*") {
        return {
            postMessage: (msg, transferables) => w.postMessage(msg, targetOrigin, transferables),
            addEventListener: context.addEventListener.bind(context),
            removeEventListener: context.removeEventListener.bind(context),
        };
    }
    function toWireValue(value) {
        for (const [name, handler] of transferHandlers) {
            if (handler.canHandle(value)) {
                const [serializedValue, transferables] = handler.serialize(value);
                return [
                    {
                        type: "HANDLER" /* WireValueType.HANDLER */,
                        name,
                        value: serializedValue,
                    },
                    transferables,
                ];
            }
        }
        return [
            {
                type: "RAW" /* WireValueType.RAW */,
                value,
            },
            transferCache.get(value) || [],
        ];
    }
    function fromWireValue(value) {
        switch (value.type) {
            case "HANDLER" /* WireValueType.HANDLER */:
                return transferHandlers.get(value.name).deserialize(value.value);
            case "RAW" /* WireValueType.RAW */:
                return value.value;
        }
    }
    function requestResponseMessage(ep, msg, transfers) {
        return new Promise((resolve) => {
            const id = generateUUID();
            ep.addEventListener("message", function l(ev) {
                if (!ev.data || !ev.data.id || ev.data.id !== id) {
                    return;
                }
                ep.removeEventListener("message", l);
                resolve(ev.data);
            });
            if (ep.start) {
                ep.start();
            }
            ep.postMessage(Object.assign({ id }, msg), transfers);
        });
    }
    function generateUUID() {
        return new Array(4)
            .fill(0)
            .map(() => Math.floor(Math.random() * Number.MAX_SAFE_INTEGER).toString(16))
            .join("-");
    }

    exports.createEndpoint = createEndpoint;
    exports.expose = expose;
    exports.finalizer = finalizer;
    exports.proxy = proxy;
    exports.proxyMarker = proxyMarker;
    exports.releaseProxy = releaseProxy;
    exports.transfer = transfer;
    exports.transferHandlers = transferHandlers;
    exports.windowEndpoint = windowEndpoint;
    exports.wrap = wrap;

}));
//# sourceMappingURL=comlink.js.map