// ==UserScript==
// @name         EME Logger
// @namespace    http://greasyfork.org/
// @version      0.2
// @description  Inject EME interface and log its function calls.
// @author       cramer
// @match        *://*/*
// @run-at       document-start
// @grant        none
// @downloadURL none
// ==/UserScript==

(async () => {
    const indent = (s,n=4) => s.split('\n').map(l=>Array(n).fill(' ').join('')+l).join('\n');

    const b64 = {
        decode: s => Uint8Array.from(atob(s), c => c.charCodeAt(0)),
        encode: b => btoa(String.fromCharCode(...new Uint8Array(b)))
    };

    const fnproxy = (object, func) => new Proxy(object, { apply: func });

    const proxy = (object, key, func) => Object.defineProperty(object, key, {
        value: fnproxy(object[key], func)
    });

    proxy(Navigator.prototype, 'requestMediaKeySystemAccess', async (_target, _this, _args) => {
        const [keySystem, supportedConfigurations] = _args;
        console.log(
            `[EME] Navigator::requestMediaKeySystemAccess\n` +
            `    Key System: ${keySystem}\n` +
            `    Supported Configurations:\n` +
            indent(JSON.stringify(supportedConfigurations, null, '    '))
        );
        console.trace();
        return _target.apply(_this, _args);
    });

    proxy(MediaKeySystemAccess.prototype, 'createMediaKeys', async (_target, _this, _args) => {
        console.log(
            `[EME] MediaKeySystemAccess::createMediaKeys\n` +
            `    Key System: ${_this.keySystem}\n` +
            `    Configurations:\n` +
            indent(JSON.stringify(_this.getConfiguration(), null, '    '))
        );
        console.trace();
        return _target.apply(_this, _args);
    });

    proxy(MediaKeys.prototype, 'setServerCertificate', async (_target, _this, _args) => {
        const [serverCertificate] = _args;
        console.log(
            `[EME] MediaKeys::setServerCertificate\n` +
            `    Server Certificate: ${b64.encode(serverCertificate)}`
        );
        console.trace();
        return _target.apply(_this, _args);
    });

    proxy(MediaKeys.prototype, 'createSession', (_target, _this, _args) => {
        const [sessionType] = _args;
        console.log(
            `[EME] MediaKeys::createSession\n` +
            `    Session Type: ${sessionType || 'temporary (default)'}`
        );
        console.trace();
        return _target.apply(_this, _args);
    });

    proxy(EventTarget.prototype, 'addEventListener', async (_target, _this, _args) => {
        const [type, listener] = _args;
        if (_this instanceof MediaKeySession) {
            switch(type) {
                case 'keystatuseschange': {
                    _args[1] = fnproxy(listener, (_target, _this, _args) => {
                        const [event] = _args;
                        const keySession = event.target;
                        const {sessionId} = keySession;
                        console.log(
                            `[EME] MediaKeySession::keystatuseschange\n` +
                            `    Session ID: ${sessionId || '(not available)'}\n` +
                            Array.from(keySession.keyStatuses).map(([keyId, status]) =>
                                `    [${status.toUpperCase()}] ${b64.encode(keyId)}`
                            ).join('\n')
                        );
                        console.trace();
                        return _target.apply(_this, _args);;
                    });
                    break;
                }
                case 'message': {
                    _args[1] = fnproxy(listener, (_target, _this, _args) => {
                        const [event] = _args;
                        const keySession = event.target;
                        const {sessionId} = keySession;
                        const {message} = event;
                        console.log(
                            `[EME] MediaKeySession::message\n` +
                            `    Session ID: ${sessionId || '(not available)'}\n` +
                            `    Message: ${b64.encode(message)}`
                        );
                        console.trace();
                        return _target.apply(_this, _args);;
                    });
                    break;
                }
            }
        }
        return _target.apply(_this, _args);
    });

    proxy(MediaKeySession.prototype, 'generateRequest', async (_target, _this, _args) => {
        const [initDataType, initData] = _args;
        console.log(
            `[EME] MediaKeySession::generateRequest\n` +
            `    Session ID: ${_this.sessionId || '(not available)'}\n` +
            `    Init Data Type: ${initDataType}\n` +
            `    Init Data: ${b64.encode(initData)}`
        );
        console.trace();
        return _target.apply(_this, _args);
    });

    proxy(MediaKeySession.prototype, 'load', async (_target, _this, _args) => {
        const [sessionId] = _args;
        console.log(
            `[EME] MediaKeySession::load\n` +
            `    Session ID: ${sessionId || '(not available)'}`
        );
        console.trace();
        return _target.apply(_this, _args);
    });

    proxy(MediaKeySession.prototype, 'update', async (_target, _this, _args) => {
        const [response] = _args;
        console.log(
            `[EME] MediaKeySession::update\n` +
            `    Session ID: ${_this.sessionId || '(not available)'}\n` +
            `    Response: ${b64.encode(response)}`
        );
        console.trace();
        return _target.apply(_this, _args);
    });

    proxy(MediaKeySession.prototype, 'close', async (_target, _this, _args) => {
        console.log(
            `[EME] MediaKeySession::close\n` +
            `    Session ID: ${_this.sessionId || '(not available)'}`
        );
        console.trace();
        return _target.apply(_this, _args);
    });

    proxy(MediaKeySession.prototype, 'remove', async (_target, _this, _args) => {
        console.log(
            `[EME] MediaKeySession::remove\n` +
            `    Session ID: ${_this.sessionId || '(not available)'}`
        );
        console.trace();
        return _target.apply(_this, _args);
    });
})();