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SkillRack Math Captcha Solver

Solves Math Captcha on the SkillRack website using Tesseract.js.

当前为 2024-11-21 提交的版本，查看 最新版本。

// ==UserScript==
// @name         SkillRack Math Captcha Solver
// @namespace    http://tampermonkey.net/
// @version      0.4
// @description  Solves Math Captcha on the SkillRack website using Tesseract.js.
// @author       Bit-Blazer
// @license      GNU GPLv3
// @match        https://www.skillrack.com/faces/candidate/codeprogram.xhtml
// @match        https://www.skillrack.com/faces/candidate/tutorprogram.xhtml
// @icon         https://envs.sh/GiG.png
// @require      https://cdn.jsdelivr.net/npm/tesseract.js@5/dist/tesseract.min.js
// @grant        none
// ==/UserScript==

(function () {
  "use strict";

  // Define the IDs of the captcha image, input field, and proceed button
  const CAPTCHA_INPUT = "capval";
  const PROCEED_BTN = "proceedbtn";

  /**
   * Inverts the colors of the Captcha Image for better OCR results.
   * This is useful for enhancing the text recognition capability of Tesseract.js.
   * @param {HTMLImageElement} image - The image to be inverted.
   * @returns {string} - Base64 encoded data URL of the inverted image.
   */
  function invertColors(image) {
    const canvas = document.createElement("canvas");
    const ctx = canvas.getContext("2d");
    canvas.width = image.width;
    canvas.height = image.height;
    ctx.drawImage(image, 0, 0);
    ctx.globalCompositeOperation = "difference"; // Invert colors
    ctx.fillStyle = "white"; // Set background to white
    ctx.fillRect(0, 0, canvas.width, canvas.height); // Fill the canvas
    return canvas.toDataURL(); // Return the inverted image as a data URL
  }

  /**
   * Extracts the username from the span element.
   * This function looks for the username pattern in the badge label.
   * @returns {string} - The extracted username or an empty string if not found.
   */
  function getUsername() {
    const usernameElement = document.querySelector(".ui-badge-label"); // Select the username element
    const match = usernameElement
      ? usernameElement.textContent.match(/(\d{12}@\w{3})/)
      : null; // Match the username pattern
    return match ? match[0] : ""; // Return the matched username or empty string
  }

  /**
   * Solves the captcha by extracting numbers and performing the calculation.
   * @param {string} text - The OCR result from the captcha image.
   * @param {string} username - The username to be removed from the OCR text.
   * @returns {number|null} - The result of the addition or null if not found.
   */
  function solveCaptcha(text, username) {
    // Remove the username from the OCR text and trim whitespace
    const cleanedText = text.replace(new RegExp(username, "gi"), "").trim();
    // Match the addition pattern in the cleaned text
    const match = cleanedText.match(/(\d+)\s*\+\s*(\d+)/);
    // Return the sum of the two numbers if a match is found
    return match ? parseInt(match[1], 10) + parseInt(match[2], 10) : null;
  }

  /**
   * Handles the captcha-solving process.
   * This function orchestrates the overall captcha solving by coordinating image processing and user interactions.
   */
  async function handleCaptcha() {
    // Get the captcha elements from the DOM
    const captchaImage = document.querySelector("img[src*='data:image']");
    const captchaInput = document.getElementById(CAPTCHA_INPUT);
    const proceedBtn = document.getElementById(PROCEED_BTN);

    // Log an error and exit if any elements are not found
    if (!captchaImage || !captchaInput || !proceedBtn) {
      console.log("Captcha or input elements not found.");
      return; // Stop execution
    }

    // Get the username from the UI
    const username = getUsername();
    // Invert the colors of the captcha image for better OCR processing
    const invertedImg = invertColors(captchaImage);

    try {
      // Process the inverted image using Tesseract.js for OCR
      const {
        data: { text },
      } = await Tesseract.recognize(invertedImg, "eng", {
        whitelist:
          "1234567890+=abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ@ ", // Allowed characters
        psm: 6, // Page segmentation mode
      });

      // Solve the Captcha using the OCR text and username
      const result = solveCaptcha(text, username);
      // Notify if the captcha could not be solved
      if (result === null) {
        console.log("Unable to solve Captcha. Please try again.");
        return; // Stop execution
      }
      // Fill the captcha input with the calculated result
      captchaInput.value = result;
      // Click the submit button to proceed
      proceedBtn.click();
    } catch (error) {
      // Log any errors encountered during the OCR process
      console.error("Error processing captcha:", error);
      alert(
        "An error occurred while processing the captcha. Please try again."
      ); // Notify user
    }
  }

  // Wait for the window to fully load before handling the captcha
  window.addEventListener("load", handleCaptcha);
})();