123 lines
3.8 KiB
JavaScript
123 lines
3.8 KiB
JavaScript
class Extractor {
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constructor(options) {
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this._tasks = [];
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this._running = false;
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this._options = options;
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}
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/**
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* Add a task to Extractor. \n
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* One Extractor could has multiple tasks, which orgnized in a task chian.
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* If url arguments not given within later tasks, they will use previous task result as input (target url list).
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* @param {...any} args itemsSelector, fieldSelectors, and more args to specify target urls.
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*/
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task(...args) {
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this._tasks.push(new Task(this._options, ...args));
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return this;
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}
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/**
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* Clear tasks and task caches.
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*/
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clear() {
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this._tasks = [];
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return this;
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}
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/**
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* Start the task chain.
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*/
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async start() {
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return this._startTasks(0);
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}
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/**
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* restart from specified task, but don't restart the previous tasks.
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* @param {number} from where to restart the tasks, begins with 0
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*/
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async restart(from = 0) {
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let id = this._checkTaskId(from, 0);
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if (id < 0) return;
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for (let i = id; i < this._tasks.length; i++) {
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this._tasks[i].clean();
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}
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return this._startTasks(0);
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}
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async _startTasks(from) {
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if (this._running) {
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console.log('The Extractor is running. Please wait..');
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return;
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}
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if (!this._tasks.length) {
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console.log('No task to run.');
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return;
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}
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let tab;
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let task = this._tasks[0];
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if (task.urls.length) {
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// task specifies target urls, create new tab with first url for it
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tab = await createTab(task.urls[0], false);
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} else {
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tab = await getActiveTab(true) || await getActiveTab(false);
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let succ = await ping(tab);
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if (!succ) {
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console.log('Cannot contact with active tab.');
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return;
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}
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}
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this._running = true;
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return this._tasks.reduce((pms, task, i) => {
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return pms.then(
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() => {
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if (i < from) return;
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if (i > 0) {
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let prevTask = this._tasks[i - 1];
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return task.execute(tab, new ExtractResult(prevTask.results));
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}
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return task.execute(tab, undefined);
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});
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}, Promise.resolve(undefined)).then(
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() => {
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this._running = false;
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this.save();
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}
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).catch(err => {
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this._running = false;
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console.log(err);
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});
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}
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/**
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* Save result of a task
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* @param {number} taskid which task id to save, begins with 0
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*/
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save(taskid) {
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let id = this._checkTaskId(taskid, this._tasks.length - 1);
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if (id < 0) return;
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let results = this._tasks[id].results
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results.unshift(this._tasks[id].fieldSelectors);
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let exResults = new ExtractResult(results);
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if (!results.length) {
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console.log(`No result for task #${id}. Forget to call ".start()"?`);
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return;
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}
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let msg = `
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Please confirm to download (${results.length - 1} items)：
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${exResults.toString(50) || "- Empty -"}
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`.trim();
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if (confirm(msg)) {
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saveFile(exResults, "text/csv");
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}
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}
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_checkTaskId(id, defaultId) {
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if (!this._tasks.length) {
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console.log("No task found.");
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return -1;
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}
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if (!isNaN(defaultId) && id === undefined) id = defaultId;
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if (isNaN(id) || id < 0 || id >= this._tasks.length) {
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console.log(`Invalid task id. Rang(0-${this._tasks.length - 1})`);
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return -1;
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}
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return id
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}
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} |