import {MultiProgressHandler} from '../utils/progress';
import {loaderList} from './loaderList';
// file content types
export const fileContentTypes = {
Text: 0,
ArrayBuffer: 1,
DataURL: 2
};
/**
* Files loader.
*/
export class FilesLoader {
/**
* Input data.
*
* @type {Array}
*/
#inputData = null;
/**
* Array of launched file readers.
*
* @type {Array}
*/
#readers = [];
/**
* Data loader.
*
* @type {object}
*/
#runningLoader = null;
/**
* Number of loaded data.
*
* @type {number}
*/
#nLoad = 0;
/**
* Number of load end events.
*
* @type {number}
*/
#nLoadend = 0;
/**
* The default character set (optional).
*
* @type {string}
*/
#defaultCharacterSet;
/**
* Get the default character set.
*
* @returns {string} The default character set.
*/
getDefaultCharacterSet() {
return this.#defaultCharacterSet;
}
/**
* Set the default character set.
*
* @param {string} characterSet The character set.
*/
setDefaultCharacterSet(characterSet) {
this.#defaultCharacterSet = characterSet;
}
/**
* Store the current input.
*
* @param {object} data The input data.
*/
#storeInputData(data) {
this.#inputData = data;
// reset counters
this.#nLoad = 0;
this.#nLoadend = 0;
// clear storage
this.#clearStoredReaders();
this.#clearStoredLoader();
}
/**
* Store a launched reader.
*
* @param {object} reader The launched reader.
*/
#storeReader(reader) {
this.#readers.push(reader);
}
/**
* Clear the stored readers.
*
*/
#clearStoredReaders() {
this.#readers = [];
}
/**
* Store the launched loader.
*
* @param {object} loader The launched loader.
*/
#storeLoader(loader) {
this.#runningLoader = loader;
}
/**
* Clear the stored loader.
*
*/
#clearStoredLoader() {
this.#runningLoader = null;
}
/**
* Increment the number of loaded data
* and call onload if loaded all data.
*
* @param {object} _event The load data event.
*/
#addLoad = (_event) => {
this.#nLoad++;
// call onload when all is loaded
// (not using the input event since it is not the
// general load)
if (this.#nLoad === this.#inputData.length) {
this.onload({
source: this.#inputData
});
}
};
/**
* Increment the counter of load end events
* and run callbacks when all done, erroneus or not.
*
* @param {object} _event The load end event.
*/
#addLoadend = (_event) => {
this.#nLoadend++;
// call onloadend when all is run
// (not using the input event since it is not the
// general load end)
// x2 to count for reader + load
if (this.#nLoadend === 2 * this.#inputData.length) {
this.onloadend({
source: this.#inputData
});
}
};
/**
* @callback eventFn
* @param {object} event The event.
*/
/**
* Augment a callback event with a srouce.
*
* @param {object} callback The callback to augment its event.
* @param {object} source The source to add to the event.
* @returns {eventFn} The augmented callback.
*/
#augmentCallbackEvent(callback, source) {
return (event) => {
event.source = source;
callback(event);
};
}
/**
* Get a load handler for a data element.
*
* @param {object} loader The associated loader.
* @param {object} dataElement The data element.
* @param {number} i The index of the element.
* @returns {eventFn} A load handler.
*/
#getLoadHandler(loader, dataElement, i) {
return (event) => {
loader.load(event.target.result, dataElement, i);
};
}
/**
* Load a list of files.
*
* @param {Array} data The list of files to load.
*/
load(data) {
// check input
if (typeof data === 'undefined' || data.length === 0) {
return;
}
this.#storeInputData(data);
// send start event
this.onloadstart({
source: data
});
// create prgress handler
const mproghandler = new MultiProgressHandler(this.onprogress);
mproghandler.setNToLoad(data.length);
// create loaders
const loaders = [];
for (let m = 0; m < loaderList.length; ++m) {
loaders.push(new loaderList[m]());
}
// find an appropriate loader
let dataElement = data[0];
let loader = null;
let foundLoader = false;
for (let l = 0; l < loaders.length; ++l) {
loader = loaders[l];
if (loader.canLoadFile(dataElement)) {
foundLoader = true;
// load options
loader.setOptions({
numberOfFiles: data.length,
defaultCharacterSet: this.getDefaultCharacterSet()
});
// set loader callbacks
// loader.onloadstart: nothing to do
loader.onprogress = mproghandler.getUndefinedMonoProgressHandler(1);
loader.onloaditem = this.onloaditem;
loader.onload = this.#addLoad;
loader.onloadend = this.#addLoadend;
loader.onerror = this.onerror;
loader.onabort = this.onabort;
// store loader
this.#storeLoader(loader);
// exit
break;
}
}
if (!foundLoader) {
throw new Error('No loader found for file: ' + dataElement.name);
}
// loop on I/O elements
for (let i = 0; i < data.length; ++i) {
dataElement = data[i];
// check loader
if (!loader.canLoadFile(dataElement)) {
throw new Error('Input file of different type: ' + dataElement);
}
/**
* The file reader.
*
* @external FileReader
* @see https://developer.mozilla.org/en-US/docs/Web/API/FileReader
*/
const reader = new FileReader();
// store reader
this.#storeReader(reader);
// set reader callbacks
// reader.onloadstart: nothing to do
reader.onprogress = this.#augmentCallbackEvent(
mproghandler.getMonoProgressHandler(i, 0), dataElement);
reader.onload = this.#getLoadHandler(loader, dataElement, i);
reader.onloadend = this.#addLoadend;
reader.onerror = this.#augmentCallbackEvent(this.onerror, dataElement);
reader.onabort = this.#augmentCallbackEvent(this.onabort, dataElement);
// read
if (loader.loadFileAs() === fileContentTypes.Text) {
reader.readAsText(dataElement);
} else if (loader.loadFileAs() === fileContentTypes.DataURL) {
reader.readAsDataURL(dataElement);
} else if (loader.loadFileAs() === fileContentTypes.ArrayBuffer) {
reader.readAsArrayBuffer(dataElement);
}
}
}
/**
* Abort a load.
*/
abort() {
// abort readers
for (let i = 0; i < this.#readers.length; ++i) {
// 0: EMPTY, 1: LOADING, 2: DONE
if (this.#readers[i].readyState === 1) {
this.#readers[i].abort();
}
}
// abort loader
if (this.#runningLoader && this.#runningLoader.isLoading()) {
this.#runningLoader.abort();
}
}
/**
* Handle a load start event.
* Default does nothing.
*
* @param {object} _event The load start event.
*/
onloadstart(_event) {}
/**
* Handle a load progress event.
* Default does nothing.
*
* @param {object} _event The progress event.
*/
onprogress(_event) {}
/**
* Handle a load item event.
* Default does nothing.
*
* @param {object} _event The load item event fired
* when a file item has been loaded successfully.
*/
onloaditem(_event) {}
/**
* Handle a load event.
* Default does nothing.
*
* @param {object} _event The load event fired
* when a file has been loaded successfully.
*/
onload(_event) {}
/**
* Handle a load end event.
* Default does nothing.
*
* @param {object} _event The load end event fired
* when a file load has completed, successfully or not.
*/
onloadend(_event) {}
/**
* Handle an error event.
* Default does nothing.
*
* @param {object} _event The error event.
*/
onerror(_event) {}
/**
* Handle an abort event.
* Default does nothing.
*
* @param {object} _event The abort event.
*/
onabort(_event) {}
} // class FilesLoader