document.addEventListener("DOMContentLoaded", function () {
    var searchBar = document.getElementById("search-bar");
    var degreeFilter = document.getElementById("degree-filter");
    var graduationDateFilter = document.getElementById("graduation-date-filter");
    var filterButton = document.getElementById("filter-button");
    var alumniResults = document.getElementById("alumni-results");


    var alumniBlocks = Array.from(document.querySelectorAll(".alumni-block"));


    // 학위 추출 (새 양식: .alumni-degree-badge, 기존 양식: .details)
    function getDegree(block) {
        var badge = block.querySelector(".alumni-degree-badge");
        if (badge) return badge.textContent.trim();
        var details = block.querySelector(".details");
        if (details) {
            if (details.textContent.indexOf("PhD") !== -1) return "PhD";
            if (details.textContent.indexOf("M.S.") !== -1) return "M.S.";
        }
        return "";
    }


    // 졸업년도 추출
    function getYear(block) {
        var el = block.querySelector(".graduation-year");
        if (!el) return "";
        var match = el.textContent.match(/(\d{4})/);
        return match ? match[1] : "";
    }


    // 학위 카운트 업데이트
    function updateDegreeCounts() {
        var degreeCounts = { PhD: 0, "M.S.": 0 };
        var total = 0;


        alumniBlocks.forEach(function (block) {
            total++;
            var deg = getDegree(block);
            if (deg === "PhD") degreeCounts.PhD++;
            else if (deg === "M.S.") degreeCounts["M.S."]++;
        });


        degreeFilter.innerHTML =
            '<option value="">All Degrees (' + total + '명)</option>' +
            '<option value="PhD">PhD (' + degreeCounts.PhD + '명)</option>' +
            '<option value="M.S.">M.S. (' + degreeCounts["M.S."] + '명)</option>';
    }


    // 연도별 그룹핑 + 렌더링
    function renderAlumniWithDividers(filteredBlocks) {
        if (!filteredBlocks) filteredBlocks = alumniBlocks;


        var grouped = {};
        filteredBlocks.forEach(function (block) {
            var year = getYear(block) || "Unknown";
            if (!grouped[year]) grouped[year] = [];
            grouped[year].push(block);
        });


        var sortedYears = Object.keys(grouped).sort(function (a, b) { return b - a; });


        alumniResults.innerHTML = "";
        sortedYears.forEach(function (year) {
            var divider = document.createElement("div");
            divider.className = "year-divider";
            divider.textContent = "Graduation Year: " + year;
            alumniResults.appendChild(divider);


            grouped[year].forEach(function (block) {
                alumniResults.appendChild(block);
            });
        });
    }


    // 필터 적용
    function applyFilters() {
        var searchValue = searchBar.value.toLowerCase();
        var degreeValue = degreeFilter.value;
        var yearValue = graduationDateFilter.value.trim();


        var filtered = alumniBlocks.filter(function (block) {
            // 이름
            var nameEl = block.querySelector(".alumni-name");
            var name = nameEl ? nameEl.textContent.toLowerCase() : "";


            // 학위
            var degree = getDegree(block);


            // 졸업년도
            var gradYear = getYear(block);


            // 전체 텍스트 (검색용)
            var fullText = block.textContent.toLowerCase();


            var matchName = !searchValue || name.indexOf(searchValue) !== -1 || fullText.indexOf(searchValue) !== -1;
            var matchDegree = !degreeValue || degree === degreeValue;
            var matchYear = !yearValue || gradYear === yearValue;


            return matchName && matchDegree && matchYear;
        });


        renderAlumniWithDividers(filtered);


        // 카운트 업데이트
        var allOption = degreeFilter.querySelector('option[value=""]');
        if (allOption) {
            allOption.textContent = "All Degrees (" + filtered.length + "명)";
        }
    }


    // 이벤트 바인딩
    filterButton.addEventListener("click", applyFilters);
    searchBar.addEventListener("input", applyFilters);
    degreeFilter.addEventListener("change", applyFilters);
    graduationDateFilter.addEventListener("input", applyFilters);


    // 초기화
    updateDegreeCounts();
    renderAlumniWithDividers();
});