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Amazon Enhancements: Ratings Display and Filtering

Display rating scores and add filtering capabilities on Amazon search results.

// ==UserScript==
// @name Amazon Enhancements: Ratings Display and Filtering
// @namespace http://tampermonkey.net/
// @version 2.3
// @description Display rating scores and add filtering capabilities on Amazon search results.
// @author Dave w/ Claudi.ai & ChatGPT
// @match https://*.amazon.com/s?*
// @grant none
// @license MIT
// ==/UserScript==

(function() {
    'use strict';

    let currentFilter = 0;

    // Function to enhance rating display
    const enhanceRatingDisplay = (result) => {
        const ratingElement = result.querySelector('i.a-icon-star-small span.a-icon-alt');
        if (ratingElement && !result.classList.contains('enhanced-rating')) {
            const ratingText = ratingElement.textContent.trim();
            const ratingValue = parseFloat(ratingText.split(' ')[0]);
            const newRatingElement = document.createElement('span');
            newRatingElement.textContent = ratingValue + ' ';
            newRatingElement.style.fontWeight = 'bold';
            newRatingElement.style.color = '#007600'; // Change color if needed
            newRatingElement.style.marginRight = '5px'; // Add some spacing between the ratings
            ratingElement.parentElement.parentElement.insertBefore(newRatingElement, ratingElement.parentElement);
            result.dataset.ratingValue = ratingValue;
            result.classList.add('enhanced-rating');
        }
    };

    // Function to add filter dropdown and refresh icon
    const addFilterDropdown = () => {
        const filterBar = document.createElement('div');
        filterBar.id = 'rating-filter-bar';

        const filterLabel = document.createElement('span');
        filterLabel.textContent = 'Filter by star rating: ';
        filterLabel.style.marginRight = '5px';
        filterBar.appendChild(filterLabel);

        const filterDropdown = document.createElement('select');
        filterDropdown.style.marginRight = '10px';

        // Define dropdown options and their actions
        const filters = [
            { text: 'All', score: 0 },
            { text: '4.9+', score: 4.9 },
            { text: '4.8+', score: 4.8 },
            { text: '4.7+', score: 4.7 },
            { text: '4.6+', score: 4.6 },
            { text: '4.5+', score: 4.5 },
            { text: '4.4+', score: 4.4 },
            { text: '4.3+', score: 4.3 },
            { text: '4.2+', score: 4.2 },
            { text: '4.1+', score: 4.1 }
        ];

        filters.forEach(filter => {
            const option = document.createElement('option');
            option.value = filter.score;
            option.textContent = filter.text;
            filterDropdown.appendChild(option);
        });

        filterDropdown.addEventListener('change', (event) => {
            currentFilter = parseFloat(event.target.value);
            filterResults(currentFilter);
        });

        filterBar.appendChild(filterDropdown);

        const refreshIcon = document.createElement('span');
        refreshIcon.innerHTML = '↻'; // HTML entity for refresh icon
        refreshIcon.style.cursor = 'pointer';
        refreshIcon.style.marginLeft = '5px';
        refreshIcon.addEventListener('click', () => {
            filterResults(currentFilter);
        });

        filterBar.appendChild(refreshIcon);

        // Insert the filter bar at the top of the search results
        const searchResults = document.querySelector('div.s-main-slot.s-result-list.s-search-results.sg-row');
        if (searchResults) {
            searchResults.insertBefore(filterBar, searchResults.firstChild);
        }
    };

    // Function to filter results based on rating score
    const filterResults = (minScore) => {
        const results = document.querySelectorAll('div[data-asin]:not(.s-pagination-container)');
        results.forEach(result => {
            if (!result.querySelector('.s-pagination-container')) {
                const ratingValue = parseFloat(result.dataset.ratingValue);
                result.style.display = ratingValue >= minScore ? '' : 'none';
            }
        });
    };

    // Function to process search results
    const processSearchResults = () => {
        const searchResults = document.querySelectorAll('div[data-asin]:not(.s-pagination-container)');
        searchResults.forEach(result => {
            enhanceRatingDisplay(result);
        });
        filterResults(currentFilter);
    };

    // Throttle function to limit the rate of execution
    const throttle = (func, delay) => {
        let timeoutId = null;
        return (...args) => {
            if (timeoutId === null) {
                func(...args);
                timeoutId = setTimeout(() => {
                    timeoutId = null;
                }, delay);
            }
        };
    };

    // Throttled version of processSearchResults
    const throttledProcessSearchResults = throttle(processSearchResults, 500);

    // Observe changes in the search results
    const observeSearchResults = () => {
        const searchResultsContainer = document.querySelector('div.s-main-slot.s-result-list.s-search-results.sg-row');
        if (searchResultsContainer) {
            const observer = new MutationObserver(throttledProcessSearchResults);
            observer.observe(searchResultsContainer, {
                childList: true,
                subtree: true
            });
        }
    };

    // Initialize the script
    const init = () => {
        addFilterDropdown();
        processSearchResults();
        observeSearchResults();
    };

    // Run the script when the page has loaded
    window.addEventListener('load', init);
})();