var SubtitlesOctopus = function (options) {
    var supportsWebAssembly = false;
    try {
        if (typeof WebAssembly === "object"
            && typeof WebAssembly.instantiate === "function") {
            const module = new WebAssembly.Module(Uint8Array.of(0x0, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00));
            if (module instanceof WebAssembly.Module)
                supportsWebAssembly = (new WebAssembly.Instance(module) instanceof WebAssembly.Instance);
        }
    } catch (e) {
    }
    console.log("WebAssembly support detected: " + (supportsWebAssembly ? "yes" : "no"));

    var self = this;
    self.canvas = options.canvas; // HTML canvas element (optional if video specified)
    self.renderMode = options.renderMode || (options.lossyRender ? 'fast' : (options.blendRender ? 'blend' : 'normal'));

    // play with those when you need some speed, e.g. for slow devices
    self.dropAllAnimations = options.dropAllAnimations || false;
    self.libassMemoryLimit = options.libassMemoryLimit || 0; // set libass bitmap cache memory limit in MiB (approximate)
    self.libassGlyphLimit = options.libassGlyphLimit || 0; // set libass glyph cache memory limit in MiB (approximate)
    self.targetFps = options.targetFps || 60;
    self.prescaleTradeoff = options.prescaleTradeoff || null; // render subtitles less than viewport when less than 1.0 to improve speed, render to more than 1.0 to improve quality; set to null to disable scaling
    self.softHeightLimit = options.softHeightLimit || 1080; // don't apply prescaleTradeoff < 1 when viewport height is less that this limit
    self.hardHeightLimit = options.hardHeightLimit || 2160; // don't ever go above this limit
    self.resizeVariation = options.resizeVariation || 0.2; // by how many a size can vary before it would cause clearance of prerendered buffer

    self.renderAhead = options.renderAhead || 0; // how many MiB to render ahead and store; 0 to disable (approximate)
    self.isOurCanvas = false; // (internal) we created canvas and manage it
    self.video = options.video; // HTML video element (optional if canvas specified)
    self.canvasParent = null; // (internal) HTML canvas parent element
    self.fonts = options.fonts || []; // Array with links to fonts used in sub (optional)
    self.availableFonts = options.availableFonts || []; // Object with all available fonts (optional). Key is font name in lower case, value is link: {"arial": "/font1.ttf"}
    self.onReadyEvent = options.onReady; // Function called when SubtitlesOctopus is ready (optional)
    if (supportsWebAssembly) {
        self.workerUrl = options.workerUrl || 'subtitles-octopus-worker.js'; // Link to WebAssembly worker
    } else {
        self.workerUrl = options.legacyWorkerUrl || 'subtitles-octopus-worker-legacy.js'; // Link to legacy worker
    }
    self.subUrl = options.subUrl; // Link to sub file (optional if subContent specified)
    self.subContent = options.subContent || null; // Sub content (optional if subUrl specified)
    self.onErrorEvent = options.onError; // Function called in case of critical error meaning sub wouldn't be shown and you should use alternative method (for instance it occurs if browser doesn't support web workers).
    self.debug = options.debug || false; // When debug enabled, some performance info printed in console.
    self.lastRenderTime = 0; // (internal) Last time we got some frame from worker
    self.pixelRatio = window.devicePixelRatio || 1; // (internal) Device pixel ratio (for high dpi devices)

    self.timeOffset = options.timeOffset || 0; // Time offset would be applied to currentTime from video (option)

    self.renderedItems = []; // used to store items rendered ahead when renderAhead > 0
    self.renderAhead = self.renderAhead * 1024 * 1024 * 0.9 /* try to eat less than requested */;
    self.oneshotState = {
        eventStart: null,
        eventOver: false,
        iteration: 0,
        renderRequested: false,
        requestNextTimestamp: -1,
        prevWidth: null,
        prevHeight: null
    }

    self.hasAlphaBug = false;

    (function() {
        if (typeof ImageData.prototype.constructor === 'function') {
            try {
                // try actually calling ImageData, as on some browsers it's reported
                // as existing but calling it errors out as "TypeError: Illegal constructor"
                new window.ImageData(new Uint8ClampedArray([0, 0, 0, 0]), 1, 1);
                return;
            } catch (e) {
                console.log("detected that ImageData is not constructable despite browser saying so");
            }
        }

        var canvas = document.createElement('canvas');
        var ctx = canvas.getContext('2d');

        window.ImageData = function () {
            var i = 0;
            if (arguments[0] instanceof Uint8ClampedArray) {
                var data = arguments[i++];
            }
            var width = arguments[i++];
            var height = arguments[i];

            var imageData = ctx.createImageData(width, height);
            if (data) imageData.data.set(data);
            return imageData;
        }
    })();

    self.workerError = function (error) {
        console.error('Worker error: ', error);
        if (self.onErrorEvent) {
            self.onErrorEvent(error);
        }
        if (!self.debug) {
            self.dispose();
            throw new Error('Worker error: ' + error);
        }
    };

    // Not tested for repeated usage yet
    self.init = function () {
        if (!window.Worker) {
            self.workerError('worker not supported');
            return;
        }
        // Worker
        if (!self.worker) {
            self.worker = new Worker(self.workerUrl);
            self.worker.onmessage = self.onWorkerMessage;
            self.worker.onerror = self.workerError;
        }
        self.workerActive = false;
        self.createCanvas();
        self.setVideo(options.video);
        self.setSubUrl(options.subUrl);
        self.worker.postMessage({
            target: 'worker-init',
            width: self.canvas.width,
            height: self.canvas.height,
            URL: document.URL,
            currentScript: self.workerUrl,
            preMain: true,
            renderMode: self.renderMode,
            subUrl: self.subUrl,
            subContent: self.subContent,
            fonts: self.fonts,
            availableFonts: self.availableFonts,
            debug: self.debug,
            targetFps: self.targetFps,
            libassMemoryLimit: self.libassMemoryLimit,
            libassGlyphLimit: self.libassGlyphLimit,
            renderOnDemand: self.renderAhead > 0,
            dropAllAnimations: self.dropAllAnimations
        });
    };

    self.createCanvas = function () {
        if (!self.canvas) {
            if (self.video) {
                self.isOurCanvas = true;
                self.canvas = document.createElement('canvas');
                self.canvas.className = 'libassjs-canvas';
                self.canvas.style.display = 'none';

                self.canvasParent = document.createElement('div');
                self.canvasParent.className = 'libassjs-canvas-parent';
                self.canvasParent.appendChild(self.canvas);

                if (self.video.nextSibling) {
                    self.video.parentNode.insertBefore(self.canvasParent, self.video.nextSibling);
                }
                else {
                    self.video.parentNode.appendChild(self.canvasParent);
                }
            }
            else {
                if (!self.canvas) {
                    self.workerError('Don\'t know where to render: you should give video or canvas in options.');
                }
            }
        }
        self.ctx = self.canvas.getContext('2d');
        self.bufferCanvas = document.createElement('canvas');
        self.bufferCanvasCtx = self.bufferCanvas.getContext('2d');

        // test for alpha bug, where e.g. WebKit can render a transparent pixel
        // (with alpha == 0) as non-black which then leads to visual artifacts
        self.bufferCanvas.width = 1;
        self.bufferCanvas.height = 1;
        var testBuf = new Uint8ClampedArray([0, 255, 0, 0]);
        var testImage = new ImageData(testBuf, 1, 1);
        self.bufferCanvasCtx.clearRect(0, 0, 1, 1);
        self.ctx.clearRect(0, 0, 1, 1);
        var prePut = self.ctx.getImageData(0, 0, 1, 1).data;
        self.bufferCanvasCtx.putImageData(testImage, 0, 0);
        self.ctx.drawImage(self.bufferCanvas, 0, 0);
        var postPut = self.ctx.getImageData(0, 0, 1, 1).data;
        self.hasAlphaBug = prePut[1] != postPut[1];
        if (self.hasAlphaBug) {
            console.log("Detected a browser having issue with transparent pixels, applying workaround");
        }
    };

    self.setVideo = function (video) {
        self.video = video;
        if (self.video) {
            var timeupdate = function () {
                self.setCurrentTime(video.currentTime + self.timeOffset);
            }
            self.video.addEventListener("timeupdate", timeupdate, false);
            self.video.addEventListener("playing", function () {
                self.setIsPaused(false, video.currentTime + self.timeOffset);
            }, false);
            self.video.addEventListener("pause", function () {
                self.setIsPaused(true, video.currentTime + self.timeOffset);
            }, false);
            self.video.addEventListener("seeking", function () {
                self.video.removeEventListener("timeupdate", timeupdate);
            }, false);
            self.video.addEventListener("seeked", function () {
                self.video.addEventListener("timeupdate", timeupdate, false);
                self.setCurrentTime(video.currentTime + self.timeOffset);
                if (self.renderAhead > 0) {
                    _cleanPastRendered(video.currentTime + self.timeOffset, true);
                }
            }, false);
            self.video.addEventListener("ratechange", function () {
                self.setRate(video.playbackRate);
            }, false);
            self.video.addEventListener("timeupdate", function () {
                self.setCurrentTime(video.currentTime + self.timeOffset);
            }, false);
            self.video.addEventListener("waiting", function () {
                self.setIsPaused(true, video.currentTime + self.timeOffset);
            }, false);

            document.addEventListener("fullscreenchange", self.resizeWithTimeout, false);
            document.addEventListener("mozfullscreenchange", self.resizeWithTimeout, false);
            document.addEventListener("webkitfullscreenchange", self.resizeWithTimeout, false);
            document.addEventListener("msfullscreenchange", self.resizeWithTimeout, false);
            window.addEventListener("resize", self.resizeWithTimeout, false);

            // Support Element Resize Observer
            if (typeof ResizeObserver !== "undefined") {
                self.ro = new ResizeObserver(self.resizeWithTimeout);
                self.ro.observe(self.video);
            }

            if (self.video.videoWidth > 0) {
                self.resize();
            }
            else {
                self.video.addEventListener("loadedmetadata", function (e) {
                    e.target.removeEventListener(e.type, arguments.callee);
                    self.resize();
                }, false);
            }
        }
    };

    self.getVideoPosition = function () {
        var videoRatio = self.video.videoWidth / self.video.videoHeight;
        var width = self.video.offsetWidth, height = self.video.offsetHeight;
        var elementRatio = width / height;
        var realWidth = width, realHeight = height;
        if (elementRatio > videoRatio) realWidth = Math.floor(height * videoRatio);
        else realHeight = Math.floor(width / videoRatio);

        var x = (width - realWidth) / 2;
        var y = (height - realHeight) / 2;

        return {
            width: realWidth,
            height: realHeight,
            x: x,
            y: y
        };
    };

    self.setSubUrl = function (subUrl) {
        self.subUrl = subUrl;
    };

    function _cleanPastRendered(currentTime, seekClean) {
        var retainedItems = [];
        for (var i = 0, len = self.renderedItems.length; i < len; i++) {
            var item = self.renderedItems[i];
            if (item.emptyFinish < 0 || item.emptyFinish >= currentTime) {
                // item is not yet finished, retain it
                retainedItems.push(item);
            }
        }

        if (seekClean && retainedItems.length > 0) {
            // items are ordered by event start time when we push to self.renderedItems,
            // so first item is the earliest
            if (currentTime < retainedItems[0].eventStart) {
                if (retainedItems[0].eventStart - currentTime > 60) {
                    console.info("seeked back too far, cleaning prerender buffer");
                    retainedItems = [];
                } else {
                    console.info("seeked backwards, need to free up some buffer");
                    var size = 0, limit = self.renderAhead * 0.3 /* try to take no more than 1/3 of buffer */;
                    var retain = [];
                    for (var i = 0, len = retainedItems.length; i < len; i++) {
                        var item = retainedItems[i];
                        size += item.size;
                        if (size >= limit) break;
                        retain.push(item);
                    }
                    retainedItems = retain;
                }
            }
        }

        var removed = retainedItems.length < self.renderedItems;
        self.renderedItems = retainedItems;
        return removed;
    }

    function tryRequestOneshot(currentTime, renderNow) {
        if (!self.renderAhead || self.renderAhead <= 0) return;
        if (self.oneshotState.renderRequested && !renderNow) return;

        if (typeof currentTime === 'undefined') {
            if (!self.video) return;
            currentTime = self.video.currentTime + self.timeOffset;
        }

        var size = 0;
        for (var i = 0, len = self.renderedItems.length; i < len; i++) {
            var item = self.renderedItems[i];
            if (item.emptyFinish < 0) {
                console.info('oneshot already reached end-of-events');
                return;
            }
            if (currentTime >= item.eventStart && currentTime < item.emptyFinish) {
                // an event for requested time already exists
                console.debug('not requesting a render for ' + currentTime +
                    ' as event already covering it exists (start=' +
                    item.eventStart + ', empty=' + item.emptyFinish + ')');
                return;
            }
            size += item.size;
        }

        if (size <= self.renderAhead) {
            lastRendered = currentTime - (renderNow ? 0 : 0.001);
            if (!self.oneshotState.renderRequested) {
                self.oneshotState.renderRequested = true;
                self.worker.postMessage({
                    target: 'oneshot-render',
                    lastRendered: lastRendered,
                    renderNow: renderNow,
                    iteration: self.oneshotState.iteration
                });
            } else {
                if (self.workerActive) {
                    console.info('worker busy, requesting to seek');
                }
                self.oneshotState.requestNextTimestamp = lastRendered;
            }
        }
    }

    function _renderSubtitleEvent(event, currentTime) {
        var eventOver = event.eventFinish < currentTime;
        if (self.oneshotState.eventStart == event.eventStart && self.oneshotState.eventOver == eventOver) return;
        self.oneshotState.eventStart = event.eventStart;
        self.oneshotState.eventOver = eventOver;

        var beforeDrawTime = performance.now();
        if (event.viewport.width != self.canvas.width || event.viewport.height != self.canvas.height) {
            self.canvas.width = event.viewport.width;
            self.canvas.height = event.viewport.height;
        }
        self.ctx.clearRect(0, 0, self.canvas.width, self.canvas.height);
        if (!eventOver) {
            for (var i = 0; i < event.items.length; i++) {
                var image = event.items[i];
                self.bufferCanvas.width = image.w;
                self.bufferCanvas.height = image.h;
                self.bufferCanvasCtx.putImageData(image.image, 0, 0);
                self.ctx.drawImage(self.bufferCanvas, image.x, image.y);
            }
        }
        if (self.debug) {
            var drawTime = Math.round(performance.now() - beforeDrawTime);
            console.log('render: ' + Math.round(event.spentTime - event.blendTime) + ' ms, blend: ' + Math.round(event.blendTime) + ' ms, draw: ' + drawTime + ' ms');
        }
    }

    function oneshotRender() {
        window.requestAnimationFrame(oneshotRender);
        if (!self.video) return;

        var currentTime = self.video.currentTime + self.timeOffset;
        var finishTime = -1, eventShown = false, animated = false;
        for (var i = 0, len = self.renderedItems.length; i < len; i++) {
            var item = self.renderedItems[i];
            if (!eventShown && item.eventStart <= currentTime && (item.emptyFinish < 0 || item.emptyFinish > currentTime)) {
                _renderSubtitleEvent(item, currentTime);
                eventShown = true;
                finishTime = item.emptyFinish;
            } else if (finishTime >= 0) {
                // we've already found a known event, now find
                // the farthest point of consequent events
                // NOTE: self.renderedItems may have gaps due to seeking
                if (item.eventStart - finishTime < 0.01) {
                    finishTime = item.emptyFinish;
                    animated = item.animated;
                } else {
                    break;
                }
            }
        }

        if (!eventShown) {
            if (Math.abs(self.oneshotState.requestNextTimestamp - currentTime) > 0.01) {
                _cleanPastRendered(currentTime);
                tryRequestOneshot(currentTime, true);
            }
        } else if (_cleanPastRendered(currentTime) && finishTime >= 0) {
            tryRequestOneshot(finishTime, animated);
        }
    }

    self.resetRenderAheadCache = function (isResizing) {
        if (self.renderAhead > 0) {
            var newCache = [];
            if (isResizing && self.oneshotState.prevHeight && self.oneshotState.prevWidth) {
                if (self.oneshotState.prevHeight == self.canvas.height &&
                    self.oneshotState.prevWidth == self.canvas.width) return;
                var timeLimit = 10, sizeLimit = self.renderAhead * 0.3;
                if (self.canvas.height >= self.oneshotState.prevHeight * (1.0 - self.resizeVariation) &&
                    self.canvas.height <= self.oneshotState.prevHeight * (1.0 + self.resizeVariation) &&
                    self.canvas.width >= self.oneshotState.prevWidth * (1.0 - self.resizeVariation) &&
                    self.canvas.width <= self.oneshotState.prevWidth * (1.0 + self.resizeVariation)) {
                    console.debug('viewport changes are small, leaving more of prerendered buffer');
                    timeLimit = 30;
                    sizeLimit = self.renderAhead * 0.5;
                }
                var stopTime = self.video.currentTime + self.timeOffset + timeLimit;
                var size = 0;
                for (var i = 0; i < self.renderedItems.length; i++) {
                    var item = self.renderedItems[i];
                    if (item.emptyFinish < 0 || item.emptyFinish >= stopTime) break;
                    size += item.size;
                    if (size >= sizeLimit) break;
                    newCache.push(item);
                }
            }

            console.info('resetting prerender cache');
            self.renderedItems = newCache;
            self.oneshotState.eventStart = null;
            self.oneshotState.iteration++;
            self.oneshotState.renderRequested = false;
            self.oneshotState.prevHeight = self.canvas.height;
            self.oneshotState.prevWidth = self.canvas.width;

            window.requestAnimationFrame(oneshotRender);
            tryRequestOneshot(undefined, true);
        }
    }

    self.renderFrameData = null;
    function renderFrames() {
        var data = self.renderFramesData;
        var beforeDrawTime = performance.now();
        self.ctx.clearRect(0, 0, self.canvas.width, self.canvas.height);
        for (var i = 0; i < data.canvases.length; i++) {
            var image = data.canvases[i];
            self.bufferCanvas.width = image.w;
            self.bufferCanvas.height = image.h;
            var imageBuffer = new Uint8ClampedArray(image.buffer);
            if (self.hasAlphaBug) {
                for (var j = 3; j < imageBuffer.length; j = j + 4) {
                    imageBuffer[j] = (imageBuffer[j] >= 1) ? imageBuffer[j] : 1;
                }
            }
            var imageData = new ImageData(imageBuffer, image.w, image.h);
            self.bufferCanvasCtx.putImageData(imageData, 0, 0);
            self.ctx.drawImage(self.bufferCanvas, image.x, image.y);
        }
        if (self.debug) {
            var drawTime = Math.round(performance.now() - beforeDrawTime);
            var blendTime = data.blendTime;
            if (typeof blendTime !== 'undefined') {
                console.log('render: ' + Math.round(data.spentTime - blendTime) + ' ms, blend: ' + Math.round(blendTime) + ' ms, draw: ' + drawTime + ' ms; TOTAL=' + Math.round(data.spentTime + drawTime) + ' ms');
            } else {
                console.log(Math.round(data.spentTime) + ' ms (+ ' + drawTime + ' ms draw)');
            }
            self.renderStart = performance.now();
        }
    }

    /**
     * Lossy Render Mode
     *
     */
    function renderFastFrames() {
        var data = self.renderFramesData;
        var beforeDrawTime = performance.now();
        self.ctx.clearRect(0, 0, self.canvas.width, self.canvas.height);
        for (var i = 0; i < data.bitmaps.length; i++) {
            var image = data.bitmaps[i];
            self.ctx.drawImage(image.bitmap, image.x, image.y);
        }
        if (self.debug) {
            var drawTime = Math.round(performance.now() - beforeDrawTime);
            console.log(data.bitmaps.length + ' bitmaps, libass: ' + Math.round(data.libassTime) + 'ms, decode: ' + Math.round(data.decodeTime) + 'ms, draw: ' + drawTime + 'ms');
            self.renderStart = performance.now();
        }
    }

    self.workerActive = false;
    self.frameId = 0;
    self.onWorkerMessage = function (event) {
        //dump('\nclient got ' + JSON.stringify(event.data).substr(0, 150) + '\n');
        if (!self.workerActive) {
            self.workerActive = true;
            if (self.onReadyEvent) {
                self.onReadyEvent();
            }
        }
        var data = event.data;
        switch (data.target) {
            case 'stdout': {
                console.log(data.content);
                break;
            }
            case 'console-log': {
                console.log.apply(console, JSON.parse(data.content));
                break;
            }
            case 'console-debug': {
                console.debug.apply(console, JSON.parse(data.content));
                break;
            }
            case 'console-info': {
                console.info.apply(console, JSON.parse(data.content));
                break;
            }
            case 'console-warn': {
                console.warn.apply(console, JSON.parse(data.content));
                break;
            }
            case 'console-error': {
                console.error.apply(console, JSON.parse(data.content));
                break;
            }
            case 'stderr': {
                console.error(data.content);
                break;
            }
            case 'window': {
                window[data.method]();
                break;
            }
            case 'canvas': {
                switch (data.op) {
                    case 'getContext': {
                        self.ctx = self.canvas.getContext(data.type, data.attributes);
                        break;
                    }
                    case 'resize': {
                        self.resize(data.width, data.height);
                        break;
                    }
                    case 'renderCanvas': {
                        if (self.lastRenderTime < data.time) {
                            self.lastRenderTime = data.time;
                            self.renderFramesData = data;
                            window.requestAnimationFrame(renderFrames);
                        }
                        break;
                    }
                    case 'renderFastCanvas': {
                        if (self.lastRenderTime < data.time) {
                            self.lastRenderTime = data.time;
                            self.renderFramesData = data;
                            window.requestAnimationFrame(renderFastFrames);
                        }
                        break;
                    }
                    case 'setObjectProperty': {
                        self.canvas[data.object][data.property] = data.value;
                        break;
                    }
                    case 'oneshot-result': {
                        if (data.iteration != self.oneshotState.iteration) {
                            console.debug('received stale prerender, ignoring');
                            return;
                        }

                        if (self.debug) {
                            console.info('oneshot received (start=' +
                                    data.eventStart + ', empty=' + data.emptyFinish +
                                    '), render: ' + Math.round(data.spentTime) + ' ms');
                        }
                        self.oneshotState.renderRequested = false;
                        if (Math.abs(data.lastRenderedTime - self.oneshotState.requestNextTimestamp) < 0.01) {
                            self.oneshotState.requestNextTimestamp = -1;
                        }
                        if (data.eventStart - data.lastRenderedTime > 0.01) {
                            // generate bogus empty element, so all timeline is covered anyway
                            self.renderedItems.push({
                                eventStart: data.lastRenderedTime,
                                eventFinish: data.lastRenderedTime - 0.001,
                                emptyFinish: data.eventStart,
                                viewport: data.viewport,
                                spentTime: 0,
                                blendTime: 0,
                                items: [],
                                animated: false,
                                size: 0
                            });
                        }

                        var items = [];
                        var size = 0;
                        for (var i = 0, len = data.canvases.length; i < len; i++) {
                            var item = data.canvases[i];
                            items.push({
                                w: item.w,
                                h: item.h,
                                x: item.x,
                                y: item.y,
                                image: new ImageData(new Uint8ClampedArray(item.buffer), item.w, item.h)
                            });
                            size += item.buffer.byteLength;
                        }

                        var eventSplitted = false;
                        if ((data.emptyFinish > 0 && data.emptyFinish - data.eventStart < 1.0 / self.targetFps) || data.animated) {
                            var newFinish = data.eventStart + 1.0 / self.targetFps;
                            data.emptyFinish = newFinish;
                            data.eventFinish = newFinish;
                            eventSplitted = true;
                        }
                        self.renderedItems.push({
                            eventStart: data.eventStart,
                            eventFinish: data.eventFinish,
                            emptyFinish: data.emptyFinish,
                            spentTime: data.spentTime,
                            blendTime: data.blendTime,
                            viewport: data.viewport,
                            items: items,
                            animated: data.animated,
                            size: size
                        });

                        self.renderedItems.sort(function (a, b) {
                            return a.eventStart - b.eventStart;
                        });

                        if (self.oneshotState.requestNextTimestamp >= 0) {
                            // requesting an out of order event render
                            tryRequestOneshot(self.oneshotState.requestNextTimestamp, true);
                        } else if (data.eventStart < 0) {
                            console.info('oneshot received "end of frames" event');
                        } else if (data.emptyFinish >= 0) {
                            // there's some more event to render, try requesting next event
                            tryRequestOneshot(data.emptyFinish, eventSplitted);
                        } else {
                            console.info('there are no more events to prerender');
                        }
                        break;
                    }
                    default:
                        throw 'eh?';
                }
                break;
            }
            case 'tick': {
                self.frameId = data.id;
                self.worker.postMessage({
                    target: 'tock',
                    id: self.frameId
                });
                break;
            }
            case 'custom': {
                if (self['onCustomMessage']) {
                    self['onCustomMessage'](event);
                } else {
                    throw 'Custom message received but client onCustomMessage not implemented.';
                }
                break;
            }
            case 'setimmediate': {
                self.worker.postMessage({
                    target: 'setimmediate'
                });
                break;
            }
            case 'get-events': {
                console.log(data.target);
                console.log(data.events);
                break;
            }
            case 'get-styles': {
                console.log(data.target);
                console.log(data.styles);
                break;
            }
            default:
                throw 'what? ' + data.target;
        }
    };

    function _computeCanvasSize(width, height) {
        if (self.prescaleTradeoff === null) {
            if (height > self.hardHeightLimit) {
                width = width * self.hardHeightLimit / height;
                height = self.hardHeightLimit;
            }
        } else if (self.prescaleTradeoff > 1) {
            if (height * self.prescaleTradeoff <= self.softHeightLimit) {
                width *= self.prescaleTradeoff;
                height *= self.prescaleTradeoff;
            } else if (height < self.softHeightLimit) {
                width = width * self.softHeightLimit / height;
                height = self.softHeightLimit;
            } else if (height >= self.hardHeightLimit) {
                width = width * self.hardHeightLimit / height;
                height = self.hardHeightLimit;
            }
        } else if (height >= self.softHeightLimit) {
            if (height * self.prescaleTradeoff <= self.softHeightLimit) {
                width = width * self.softHeightLimit / height;
                height = self.softHeightLimit;
            } else if (height * self.prescaleTradeoff <= self.hardHeightLimit) {
                width *= self.prescaleTradeoff;
                height *= self.prescaleTradeoff;
            } else {
                width = width * self.hardHeightLimit / height;
                height = self.hardHeightLimit;
            }
        }

        return {'width': width, 'height': height};
    }

    self.resize = function (width, height, top, left) {
        var videoSize = null;
        top = top || 0;
        left = left || 0;
        if ((!width || !height) && self.video) {
            videoSize = self.getVideoPosition();
            var newsize = _computeCanvasSize(videoSize.width * self.pixelRatio, videoSize.height * self.pixelRatio);
            width = newsize.width;
            height = newsize.height;
            var offset = self.canvasParent.getBoundingClientRect().top - self.video.getBoundingClientRect().top;
            top = videoSize.y - offset;
            left = videoSize.x;
        }
        if (!width || !height) {
            if (!self.video) {
                console.error('width or height is 0. You should specify width & height for resize.');
            }
            return;
        }


        if (
          self.canvas.width != width ||
          self.canvas.height != height ||
          self.canvas.style.top != top ||
          self.canvas.style.left != left
        ) {
            self.canvas.width = width;
            self.canvas.height = height;

            if (videoSize != null) {
                self.canvasParent.style.position = 'relative';
                self.canvas.style.display = 'block';
                self.canvas.style.position = 'absolute';
                self.canvas.style.width = videoSize.width + 'px';
                self.canvas.style.height = videoSize.height + 'px';
                self.canvas.style.top = top + 'px';
                self.canvas.style.left = left + 'px';
                self.canvas.style.pointerEvents = 'none';
            }

            self.worker.postMessage({
                target: 'canvas',
                width: self.canvas.width,
                height: self.canvas.height
            });
            self.resetRenderAheadCache(true);
        }
    };

    self.resizeWithTimeout = function () {
        self.resize();
    };

    self.runBenchmark = function () {
        self.worker.postMessage({
            target: 'runBenchmark'
        });
    };

    self.customMessage = function (data, options) {
        options = options || {};
        self.worker.postMessage({
            target: 'custom',
            userData: data,
            preMain: options.preMain
        });
    };

    self.setCurrentTime = function (currentTime) {
        self.worker.postMessage({
            target: 'video',
            currentTime: currentTime
        });
    };

    self.setTrackByUrl = function (url) {
        self.worker.postMessage({
            target: 'set-track-by-url',
            url: url
        });
        self.resetRenderAheadCache(false);
    };

    self.setTrack = function (content) {
        self.worker.postMessage({
            target: 'set-track',
            content: content
        });
        self.resetRenderAheadCache(false);
    };

    self.freeTrack = function (content) {
        self.worker.postMessage({
            target: 'free-track'
        });
        self.resetRenderAheadCache(false);
    };


    self.render = self.setCurrentTime;

    self.setIsPaused = function (isPaused, currentTime) {
        self.worker.postMessage({
            target: 'video',
            isPaused: isPaused,
            currentTime: currentTime
        });
    };

    self.setRate = function (rate) {
        self.worker.postMessage({
            target: 'video',
            rate: rate
        });
    };

    self.dispose = function () {
        self.worker.postMessage({
            target: 'destroy'
        });

        self.worker.terminate();
        self.workerActive = false;
        // Remove the canvas element to remove residual subtitles rendered on player
        if (self.video) {
            self.video.parentNode.removeChild(self.canvasParent);
        }
    };

    self.createEvent = function (event) {
        self.worker.postMessage({
            target: 'create-event',
            event: event
        });
    };

    self.getEvents = function () {
        self.worker.postMessage({
            target: 'get-events'
        });
    };

    self.setEvent = function (event, index) {
        self.worker.postMessage({
            target: 'set-event',
            event: event,
            index: index
        });
    };

    self.removeEvent = function (index) {
        self.worker.postMessage({
            target: 'remove-event',
            index: index
        });
    };

    self.createStyle = function (style) {
        self.worker.postMessage({
            target: 'create-style',
            style: style
        });
    };

    self.getStyles = function () {
        self.worker.postMessage({
            target: 'get-styles'
        });
    };

    self.setStyle = function (style, index) {
        self.worker.postMessage({
            target: 'set-style',
            style: style,
            index: index
        });
    };

    self.removeStyle = function (index) {
        self.worker.postMessage({
            target: 'remove-style',
            index: index
        });
    };

    self.init();
};

if (typeof SubtitlesOctopusOnLoad == 'function') {
    SubtitlesOctopusOnLoad();
}

if (typeof exports !== 'undefined') {
    if (typeof module !== 'undefined' && module.exports) {
        exports = module.exports = SubtitlesOctopus
    }
}