.. عنوان: لوڈ بیلنسر پول ڈسٹری بیوشن اینالائزر
.. slug: load-balancer-pool-distribution-analyzer
.. تاریخ: 2026-03-26 12:00:00 UTC
.. ٹیگز: نیٹ ورکنگ، لوڈ بیلنسر، ٹول، کیلکولیٹر
.. زمرہ: اوزار
.. لنک:
.. تفصیل: تصور کریں کہ کس طرح لوڈ بیلنسر الگورتھم پول ممبروں میں ٹریفک کو تقسیم کرتے ہیں۔ راؤنڈ رابن، سورس آئی پی ہیش، وزنی، اور عام اور ناکامی کے حالات میں مسلسل ہیشنگ کی تقلید کریں۔
.. قسم: متن
<style>
    .calc-container {
        max-width: 900px;
        margin: 20px auto;
        padding: 20px;
    }

    .calc-header {
        margin-bottom: 30px;
        padding: 25px;
        background: linear-gradient(135deg, #FF6B6B 0%, #C92A2A 100%);
        border-radius: 12px;
        box-shadow: 0 4px 6px rgba(0,0,0,0.1);
        color: white;
    }

    .calc-header h2 {
        margin-top: 0;
        color: white;
        font-size: 28px;
        margin-bottom: 10px;
    }

    .calc-header p {
        margin: 10px 0 20px 0;
        opacity: 0.95;
        font-size: 15px;
    }

    .form-grid {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 15px;
        margin-top: 20px;
    }

    .form-grid-3 {
        display: grid;
        grid-template-columns: 1fr 1fr 1fr;
        gap: 15px;
        margin-top: 15px;
    }

    .form-group {
        display: flex;
        flex-direction: column;
        gap: 8px;
    }

    .form-group label {
        font-weight: 600;
        font-size: 14px;
        color: white;
    }

    .form-group input,
    .form-group select {
        padding: 12px;
        font-size: 15px;
        border: 2px solid rgba(255,255,255,0.3);
        border-radius: 6px;
        background: rgba(255,255,255,0.95);
        transition: all 0.3s ease;
        font-family: 'Courier New', monospace;
    }

    .form-group input:focus,
    .form-group select:focus {
        outline: none;
        border-color: #4CAF50;
        background: white;
        box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.15);
    }

    .form-group select {
        cursor: pointer;
        font-family: inherit;
    }

    .submit-btn {
        padding: 14px 35px;
        font-size: 16px;
        background: #4CAF50;
        color: white;
        border: none;
        border-radius: 6px;
        cursor: pointer;
        font-weight: bold;
        transition: all 0.3s ease;
        box-shadow: 0 2px 4px rgba(0,0,0,0.2);
        margin-top: 15px;
        width: 100%;
    }

    .submit-btn:hover {
        background: #45a049;
        transform: translateY(-1px);
        box-shadow: 0 4px 8px rgba(0,0,0,0.3);
    }

    .submit-btn:active {
        background: #3d8b40;
        transform: translateY(0);
    }

    .secondary-btn {
        padding: 10px 20px;
        font-size: 14px;
        background: rgba(255,255,255,0.2);
        color: white;
        border: 2px solid rgba(255,255,255,0.5);
        border-radius: 6px;
        cursor: pointer;
        font-weight: bold;
        transition: all 0.3s ease;
    }

    .secondary-btn:hover {
        background: rgba(255,255,255,0.35);
        border-color: white;
    }

    .danger-btn {
        padding: 8px 14px;
        font-size: 13px;
        background: #e53935;
        color: white;
        border: none;
        border-radius: 4px;
        cursor: pointer;
        font-weight: bold;
        transition: all 0.2s ease;
    }

    .danger-btn:hover {
        background: #c62828;
    }

    .result-section {
        background: white;
        border: 1px solid #e0e0e0;
        border-radius: 8px;
        margin-top: 20px;
        overflow: hidden;
        box-shadow: 0 2px 4px rgba(0,0,0,0.05);
        transition: all 0.3s ease;
        display: none;
    }

    .result-section.show {
        display: block;
    }

    .result-section:hover {
        box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    }

    .section-header {
        background: linear-gradient(135deg, #4CAF50 0%, #45a049 100%);
        color: white;
        padding: 15px 20px;
    }

    .section-header h3 {
        margin: 0;
        font-size: 18px;
        display: flex;
        align-items: center;
        gap: 10px;
    }

    .section-content {
        padding: 20px;
        background: #fafafa;
    }

    .data-row {
        display: flex;
        margin: 12px 0;
        padding: 10px;
        background: white;
        border-radius: 4px;
        border-left: 3px solid #4CAF50;
        align-items: center;
    }

    .data-label {
        font-weight: bold;
        color: #555;
        min-width: 220px;
        flex-shrink: 0;
        font-size: 14px;
    }

    .data-value {
        color: #333;
        font-family: 'Courier New', monospace;
        word-break: break-word;
        font-size: 18px;
    }

    .data-value.highlight {
        color: #4CAF50;
        font-weight: bold;
        font-size: 22px;
    }

    .data-value.warning {
        color: #FF6B6B;
        font-weight: bold;
        font-size: 22px;
    }

    .help-text {
        margin-top: 15px;
        font-size: 14px;
        color: rgba(255,255,255,0.9);
        background: rgba(0,0,0,0.1);
        padding: 10px 15px;
        border-radius: 4px;
    }

    .help-text strong {
        color: white;
    }

    /* Member list table */
    .member-table {
        width: 100%;
        border-collapse: collapse;
        margin-top: 10px;
        font-size: 14px;
    }

    .member-table th {
        background: #f0f0f0;
        padding: 10px 12px;
        text-align: left;
        font-weight: 600;
        color: #444;
        border-bottom: 2px solid #ddd;
    }

    .member-table td {
        padding: 10px 12px;
        border-bottom: 1px solid #eee;
        vertical-align: middle;
    }

    .member-table tr:last-child td {
        border-bottom: none;
    }

    .member-table tr:hover td {
        background: #f9f9f9;
    }

    /* Status badge */
    .status-badge {
        display: inline-block;
        padding: 3px 10px;
        border-radius: 12px;
        font-size: 12px;
        font-weight: bold;
        text-transform: uppercase;
        letter-spacing: 0.5px;
    }

    .status-badge.up {
        background: #e8f5e9;
        color: #2e7d32;
        border: 1px solid #a5d6a7;
    }

    .status-badge.down {
        background: #ffebee;
        color: #c62828;
        border: 1px solid #ef9a9a;
    }

    /* Balance score ring */
    .balance-score-container {
        display: flex;
        align-items: center;
        gap: 20px;
        padding: 15px;
        background: white;
        border-radius: 8px;
        border: 1px solid #e0e0e0;
        margin-bottom: 15px;
    }

    .balance-score-ring {
        width: 80px;
        height: 80px;
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 22px;
        font-weight: bold;
        color: white;
        flex-shrink: 0;
        box-shadow: 0 2px 8px rgba(0,0,0,0.2);
    }

    .balance-score-ring.excellent {
        background: linear-gradient(135deg, #43a047, #1b5e20);
    }

    .balance-score-ring.good {
        background: linear-gradient(135deg, #7cb342, #558b2f);
    }

    .balance-score-ring.fair {
        background: linear-gradient(135deg, #fb8c00, #e65100);
    }

    .balance-score-ring.poor {
        background: linear-gradient(135deg, #e53935, #b71c1c);
    }

    .balance-score-info {
        flex: 1;
    }

    .balance-score-info h4 {
        margin: 0 0 5px 0;
        font-size: 18px;
        color: #333;
    }

    .balance-score-info p {
        margin: 0;
        font-size: 13px;
        color: #666;
        line-height: 1.5;
    }

    /* Metrics grid */
    .metrics-grid {
        display: grid;
        grid-template-columns: repeat(4, 1fr);
        gap: 12px;
        margin-bottom: 20px;
    }

    .metric-card {
        background: white;
        border: 1px solid #e0e0e0;
        border-radius: 8px;
        padding: 15px;
        text-align: center;
        border-top: 3px solid #4CAF50;
    }

    .metric-card .metric-value {
        font-size: 22px;
        font-weight: bold;
        color: #333;
        font-family: 'Courier New', monospace;
    }

    .metric-card .metric-label {
        font-size: 12px;
        color: #888;
        margin-top: 4px;
    }

    /* Chart container */
    .chart-wrapper {
        background: white;
        border: 1px solid #e0e0e0;
        border-radius: 8px;
        padding: 20px;
        margin-bottom: 20px;
    }

    .chart-wrapper h4 {
        margin: 0 0 15px 0;
        color: #444;
        font-size: 15px;
        font-weight: 600;
    }

    /* Algorithm explanation */
    .algo-explanation {
        background: #fff8e1;
        border: 1px solid #ffe082;
        border-radius: 6px;
        padding: 12px 15px;
        font-size: 13px;
        color: #5d4037;
        line-height: 1.6;
        margin-top: 10px;
    }

    .algo-explanation strong {
        color: #3e2723;
    }

    /* Hash ring visualization */
    .ring-wrapper {
        display: flex;
        align-items: flex-start;
        gap: 20px;
    }

    #hashRingCanvas {
        border: 1px solid #e0e0e0;
        border-radius: 50%;
        display: block;
        flex-shrink: 0;
    }

    .ring-legend {
        flex: 1;
    }

    .ring-legend-item {
        display: flex;
        align-items: center;
        gap: 10px;
        padding: 6px 0;
        font-size: 13px;
        border-bottom: 1px solid #f0f0f0;
    }

    .ring-legend-dot {
        width: 14px;
        height: 14px;
        border-radius: 50%;
        flex-shrink: 0;
    }

    /* Redistribution info */
    .redistribution-row {
        display: flex;
        align-items: center;
        gap: 10px;
        padding: 8px 12px;
        background: white;
        border-radius: 4px;
        border-left: 3px solid #FF6B6B;
        margin-bottom: 6px;
        font-size: 14px;
    }

    .redistribution-row .arrow {
        color: #FF6B6B;
        font-size: 18px;
        flex-shrink: 0;
    }

    .redistribution-row .move-label {
        color: #555;
        flex: 1;
    }

    .redistribution-row .move-count {
        font-family: 'Courier New', monospace;
        font-weight: bold;
        color: #333;
    }

    /* Slider styling */
    .slider-group {
        display: flex;
        flex-direction: column;
        gap: 8px;
        margin-top: 5px;
    }

    .slider-group label {
        font-weight: 600;
        font-size: 14px;
        color: white;
        display: flex;
        justify-content: space-between;
    }

    .slider-group label span {
        font-family: 'Courier New', monospace;
        background: rgba(0,0,0,0.2);
        padding: 2px 8px;
        border-radius: 4px;
        font-size: 13px;
    }

    input[type="range"] {
        width: 100%;
        accent-color: #4CAF50;
        height: 6px;
        cursor: pointer;
    }

    /* Controls area inside header */
    .header-controls {
        margin-top: 20px;
    }

    .control-group-label {
        font-weight: 600;
        font-size: 13px;
        color: rgba(255,255,255,0.8);
        text-transform: uppercase;
        letter-spacing: 0.5px;
        margin-bottom: 8px;
        margin-top: 18px;
    }

    .add-member-row {
        display: flex;
        gap: 8px;
        align-items: flex-end;
        flex-wrap: wrap;
    }

    .add-member-row .form-group {
        flex: 1;
        min-width: 120px;
    }

    /* Failure simulation section */
    .failure-section {
        background: rgba(0,0,0,0.1);
        border-radius: 8px;
        padding: 15px;
        margin-top: 18px;
    }

    .failure-section .control-group-label {
        margin-top: 0;
    }

    .failure-row {
        display: flex;
        gap: 10px;
        align-items: flex-end;
        flex-wrap: wrap;
    }

    .failure-row .form-group {
        flex: 1;
        min-width: 140px;
    }

    .failure-btn-group {
        display: flex;
        gap: 8px;
    }

    /* Responsive design */
    @media (max-width: 768px) {
        .form-grid,
        .form-grid-3 {
            grid-template-columns: 1fr;
        }

        .metrics-grid {
            grid-template-columns: 1fr 1fr;
        }

        .data-row {
            flex-direction: column;
            align-items: flex-start;
        }

        .data-label {
            margin-bottom: 4px;
            min-width: auto;
        }

        .ring-wrapper {
            flex-direction: column;
        }

        #hashRingCanvas {
            width: 220px !important;
            height: 220px !important;
            align-self: center;
        }

        .balance-score-container {
            flex-direction: column;
            text-align: center;
        }

        .add-member-row {
            flex-direction: column;
        }

        .add-member-row .form-group {
            min-width: auto;
            width: 100%;
        }

        .failure-row {
            flex-direction: column;
        }
    }

    @media (max-width: 480px) {
        .calc-header h2 {
            font-size: 22px;
        }

        .metrics-grid {
            grid-template-columns: 1fr;
        }
    }
</style>
Chart.js CDN
<script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.0/dist/chart.umd.min.js"></script>
<div class="calc-container">
========== ہیڈر / کنٹرول ==========
<div class="calc-header">
<h2>لوڈ بیلنسر پول ڈسٹری بیوشن اینالائزر</h2>
<p>نقل کریں کہ کس طرح مختلف لوڈ بیلنسنگ الگورتھم پول ممبروں میں ٹریفک کو تقسیم کرتے ہیں۔ ماڈل کی ناکامی کے منظرنامے اور دوبارہ تقسیم کی کارکردگی کا موازنہ کریں۔</p>
<div class="header-controls">
الگورتھم اور سیشن شمار
<div class="form-grid">
<div class="form-group">
<label for="algorithmSelect">لوڈ بیلنسنگ الگورتھم:</label>
<select id="algorithmSelect">
<option value="roundRobin">راؤنڈ رابن</option>
<option selected="" value="sourceIpHash">ماخذ آئی پی ہیش</option>
<option value="weighted">وزنی</option>
<option value="consistentHash">مسلسل ہیشنگ (رنگ)</option>
</select>
</div>
<div class="form-group">
<label for="virtualNodes">ورچوئل نوڈس (مسلسل ہیش):</label>
<select id="virtualNodes">
<option value="10">10 ورچوئل نوڈس</option>
<option selected="" value="50">50 ورچوئل نوڈس</option>
<option value="150">150 ورچوئل نوڈس</option>
<option value="300">300 ورچوئل نوڈس</option>
</select>
</div>
</div>
سیشن کا شمار سلائیڈر
<div class="control-group-label">ٹریفک کا حجم</div>
<div class="slider-group">
<label for="sessionSlider">تقلید کے لیے سیشنز:<span id="sessionCountLabel">1000</span>
</label>
<input id="sessionSlider" max="10000" min="100" oninput="updateSessionLabel(this.value)" step="100" type="range" value="1000"/>
</div>
پول ممبر مینجمنٹ
<div class="control-group-label">پول ممبران</div>
<div class="add-member-row">
<div class="form-group">
<label for="newMemberIp">رکن کا IP پتہ:</label>
<input id="newMemberIp" placeholder="10.0.1.10" type="text" value="10.0.1.10"/>
</div>
<div class="form-group">
<label for="newMemberPort">پورٹ:</label>
<input id="newMemberPort" placeholder="8080" type="text" value="8080"/>
</div>
<div class="form-group">
<label for="newMemberWeight">وزن (1-100):</label>
<input id="newMemberWeight" max="100" min="1" type="number" value="1"/>
</div>
<div class="form-group" style="justify-content: flex-end;">
<label> </label>
<button class="secondary-btn" onclick="addMember()">+ ممبر شامل کریں۔</button>
</div>
</div>
ناکامی سمولیشن
<div class="failure-section">
<div class="control-group-label">ناکامی کے منظر نامے کا تخروپن</div>
<div class="failure-row">
<div class="form-group">
<label for="failureSelect">ہدف رکن:</label>
<select id="failureSelect">
<option value="">-- ممبر منتخب کریں --</option>
</select>
</div>
<div class="failure-btn-group">
<button class="secondary-btn" onclick="setMemberDown()" style="background:rgba(229,57,53,0.4); border-color:rgba(229,57,53,0.8);">نشان زد کریں۔</button>
<button class="secondary-btn" onclick="setMemberUp()" style="background:rgba(67,160,71,0.4); border-color:rgba(67,160,71,0.8);">اوپر لاؤ</button>
</div>
</div>
</div>
<button class="submit-btn" onclick="runSimulation()">نقلی چلائیں۔</button>
<div class="help-text">
<strong>یہ کیسے کام کرتا ہے:</strong>کلائنٹ کے آئی پی کو /16 سب نیٹ (10.0.0.0/16) سے نمونہ لیا جاتا ہے۔
                ماخذ پر مبنی ہیشنگ کے لیے، ہر منفرد کلائنٹ کا IP ایک رکن کے ساتھ طے شدہ طور پر میپ کیا جاتا ہے۔
                راؤنڈ رابن کلائنٹ آئی پی کو نظر انداز کرتا ہے اور ترتیب وار تقسیم کرتا ہے۔ وزنی متناسب استعمال کرتا ہے۔
                بے ترتیب تفویض. مسلسل ہیشنگ کلائنٹس اور ممبران دونوں کو ورچوئل رنگ پر رکھتی ہے۔</div>
</div>
</div>
========== ممبر ٹیبل ==========
<div class="result-section show" id="memberTableSection">
<div class="section-header">
<h3>پول ممبران</h3>
</div>
<div class="section-content" style="padding: 0;">
<table class="member-table" id="memberTable">
<thead>
<tr>
<th>ID</th>
<th>آئی پی: پورٹ</th>
<th>وزن</th>
<th>حیثیت</th>
<th>اعمال</th>
</tr>
</thead>
<tbody id="memberTableBody">
JS کی طرف سے آباد
</tbody>
</table>
</div>
</div>
========== تقسیم کے نتائج ==========
<div class="result-section" id="resultsSection">
<div class="section-header">
<h3>تقسیم کے نتائج</h3>
</div>
<div class="section-content">
بیلنس سکور + الگورتھم کی وضاحت
<div class="balance-score-container" id="balanceScoreContainer"></div>
<div class="algo-explanation" id="algoExplanation"></div>
میٹرکس گرڈ
<div class="metrics-grid" id="metricsGrid" style="margin-top: 20px;"></div>
بار چارٹ
<div class="chart-wrapper">
<h4>فی ممبر سیشن کی تقسیم</h4>
<canvas height="120" id="distributionChart"></canvas>
</div>
اراکین کی تفصیلی قطاریں
<div id="memberDetailRows"></div>
</div>
</div>
========== دوبارہ تقسیم میں ناکامی ==========
<div class="result-section" id="redistributionSection">
<div class="section-header" style="background: linear-gradient(135deg, #FF6B6B 0%, #C92A2A 100%);">
<h3>دوبارہ تقسیم کرنے میں ناکامی کا تجزیہ</h3>
</div>
<div class="section-content">
<div id="redistributionContent"></div>
</div>
</div>
========== ہیش رنگ کا تصور ==========
<div class="result-section" id="hashRingSection">
<div class="section-header">
<h3>مستقل ہیش رنگ</h3>
</div>
<div class="section-content">
<div class="ring-wrapper">
<canvas height="260" id="hashRingCanvas" width="260"></canvas>
<div class="ring-legend" id="ringLegend"></div>
</div>
<div class="algo-explanation" style="margin-top: 15px;">
<strong>انگوٹھی پڑھنا:</strong>ہر رکن کو انگوٹھی کے ارد گرد ایک سے زیادہ پوائنٹس پر رکھا جاتا ہے۔
                (ورچوئل نوڈس)۔ ایک کلائنٹ آئی پی کو انگوٹھی کی پوزیشن پر ہیش کیا جاتا ہے، پھر درخواست بھیجی جاتی ہے۔
                گھڑی کی سمت میں قریب ترین ممبر تک۔ کسی رکن کو شامل کرنا یا ہٹانا صرف آرک کو متاثر کرتا ہے۔
                اس کی ملکیت والی انگوٹھی - سیشن میں خلل کو کم سے کم کرنا۔</div>
</div>
</div>
=========== مدد / تصورات ==========
<div class="result-section show" style="margin-top: 20px;">
<div class="section-header">
<h3>الگورتھم حوالہ</h3>
</div>
<div class="section-content">
<div class="data-row">
<div class="data-label">راؤنڈ رابن</div>
<div class="data-value" style="font-family: inherit; font-size: 14px; color: #555;">سیشن ترتیب وار تفویض کیے جاتے ہیں: رکن 1، 2، 3، ...، N، 1، 2، ... ہر رکن
                    تمام درخواستوں کا بالکل 1/N وصول کرتا ہے۔ سرور کی صلاحیت اور کلائنٹ کے تعلق کو نظر انداز کرتا ہے۔
                    سادہ اور پیش قیاسی لیکن متضاد ہارڈ ویئر پر سخت ناکام۔</div>
</div>
<div class="data-row">
<div class="data-label">ماخذ آئی پی ہیش</div>
<div class="data-value" style="font-family: inherit; font-size: 14px; color: #555;">کلائنٹ آئی پی ماڈیول کا ایک ہیش ممبر گنتی پسدید کو منتخب کرتا ہے۔ وہی کلائنٹ
                    ہمیشہ ایک ہی ممبر تک پہنچتا ہے - اسٹیٹفول ایپلی کیشنز کے لیے مفید۔ شامل کرنا یا ہٹانا
                    ایک رکن کی تبدیلی<em>تمام</em>کلائنٹ میپنگ (N تمام سیشنز میں (N-1)/N میں تبدیلی)۔</div>
</div>
<div class="data-row">
<div class="data-label">وزنی</div>
<div class="data-value" style="font-family: inherit; font-size: 14px; color: #555;">ہر رکن کو کل وزن کے مقابلے میں اس کے وزن کے تناسب سے حصہ ملتا ہے۔
                    پول ایک ممبر جس کا وزن = 4 ہوتا ہے اسے وزن = 1 ممبر کے 4 گنا سیشن ملتا ہے۔ ماڈل بنانے کے لیے استعمال کیا جاتا ہے۔
                    متفاوت پسدید کی گنجائش (مثال کے طور پر، ایک VM بمقابلہ ننگی دھاتی سرور)۔</div>
</div>
<div class="data-row">
<div class="data-label">مسلسل ہیشنگ</div>
<div class="data-value" style="font-family: inherit; font-size: 14px; color: #555;">ممبران اور کلائنٹس دونوں کو ہیشنگ کے ذریعے سرکلر رِنگ پر میپ کیا جاتا ہے۔ ہر کلائنٹ جاتا ہے۔
                    انگوٹی پر گھڑی کی سمت میں قریب ترین ممبر تک۔ ورچوئل نوڈس (ہر رکن کی نقلیں)
                    تقسیم کی یکسانیت کو بہتر بنائیں۔ جب کوئی رکن ناکام ہوجاتا ہے، تو صرف اس کے سیشنز میں منتقل ہوتے ہیں۔
                    انگوٹی پر اگلا ممبر — ماڈیولو ہیشنگ کے لیے 1/N سیشنز ڈسٹربڈ بمقابلہ 100%۔</div>
</div>
</div>
</div>
</div>
<script>
/* =========================================================
   Load Balancer Pool Distribution Analyzer
   Algorithms: round robin, source IP hash, weighted,
               consistent hashing (virtual node ring)
   ========================================================= */

// ---- State -----------------------------------------------

/** @type {{ id: string, ip: string, port: number, weight: number, status: 'up'|'down' }[]} */
let members = [
    { id: 'member_1', ip: '10.0.1.10', port: 8080, weight: 1, status: 'up' },
    { id: 'member_2', ip: '10.0.1.11', port: 8080, weight: 2, status: 'up' },
    { id: 'member_3', ip: '10.0.1.12', port: 8080, weight: 1, status: 'up' },
    { id: 'member_4', ip: '10.0.1.13', port: 8080, weight: 1, status: 'up' },
];

let memberCounter = 5;
let distributionChart = null;

// ---- Hash utilities --------------------------------------

/**
 * FNV-1a 32-bit hash (deterministic, fast, good avalanche).
 * Returns a positive integer in [0, 2^32).
 * @param {string} str
 * @returns {number}
 */
function fnv1a32(str) {
    let hash = 2166136261; // FNV offset basis
    for (let i = 0; i < str.length; i++) {
        hash ^= str.charCodeAt(i);
        // Multiply by FNV prime (32-bit) using safe integer arithmetic
        hash = (hash * 16777619) >>> 0;
    }
    return hash;
}

/**
 * Convert dotted-decimal IPv4 string to a 32-bit integer.
 * @param {string} ip  e.g. "192.168.1.1"
 * @returns {number}
 */
function ipToInt(ip) {
    const parts = ip.split('.').map(Number);
    if (parts.length !== 4 || parts.some(p => isNaN(p) || p < 0 || p > 255)) return 0;
    return ((parts[0] * 256 + parts[1]) * 256 + parts[2]) * 256 + parts[3];
}

/**
 * Convert 32-bit integer to dotted-decimal IPv4.
 * @param {number} n
 * @returns {string}
 */
function intToIp(n) {
    return [
        (n >>> 24) & 0xff,
        (n >>> 16) & 0xff,
        (n >>>  8) & 0xff,
         n         & 0xff,
    ].join('.');
}

// ---- Traffic generation ----------------------------------

/**
 * Generate an array of client IP strings sampled from 10.0.0.0/16
 * with a realistic Zipfian-ish distribution (some clients appear
 * more often than others, modelling hotspots).
 * @param {number} sessionCount
 * @returns {string[]}
 */
function generateClientIps(sessionCount) {
    // Pre-build a pool of unique client IPs (up to 500 distinct sources)
    const poolSize = Math.min(500, sessionCount);
    const clientPool = [];
    const baseIp = ipToInt('10.0.0.1');
    for (let i = 0; i < poolSize; i++) {
        clientPool.push(intToIp(baseIp + i));
    }

    // Zipfian weights: client i has weight proportional to 1/(i+1)
    // Pre-compute cumulative weights for sampling
    const cumWeights = new Float64Array(poolSize);
    let total = 0;
    for (let i = 0; i < poolSize; i++) {
        total += 1 / (i + 1);
        cumWeights[i] = total;
    }

    // Sample sessions using a simple LCG random so results are
    // reproducible across runs with the same sessionCount.
    const ips = [];
    let seed = sessionCount ^ 0xdeadbeef;
    function lcgRand() {
        // LCG: Numerical Recipes parameters
        seed = (Math.imul(1664525, seed) + 1013904223) >>> 0;
        return seed / 0x100000000;
    }

    for (let s = 0; s < sessionCount; s++) {
        const r = lcgRand() * total;
        // Binary search in cumWeights
        let lo = 0, hi = poolSize - 1;
        while (lo < hi) {
            const mid = (lo + hi) >> 1;
            if (cumWeights[mid] < r) lo = mid + 1;
            else hi = mid;
        }
        ips.push(clientPool[lo]);
    }
    return ips;
}

// ---- Algorithm implementations ---------------------------

/**
 * Round Robin: session index mod active member count.
 * @param {typeof members} activeMembers
 * @param {string[]} clientIps
 * @returns {Map<string, number>} memberId -> sessionCount
 */
function algorithmRoundRobin(activeMembers, clientIps) {
    const counts = new Map(activeMembers.map(m => [m.id, 0]));
    const n = activeMembers.length;
    for (let i = 0; i < clientIps.length; i++) {
        const memberId = activeMembers[i % n].id;
        counts.set(memberId, counts.get(memberId) + 1);
    }
    return counts;
}

/**
 * Source IP Hash: fnv1a(clientIp) mod active member count.
 * Same client always hits the same member (given a fixed member set).
 * @param {typeof members} activeMembers
 * @param {string[]} clientIps
 * @returns {Map<string, number>}
 */
function algorithmSourceIpHash(activeMembers, clientIps) {
    const counts = new Map(activeMembers.map(m => [m.id, 0]));
    const n = activeMembers.length;
    for (const ip of clientIps) {
        const idx = fnv1a32(ip) % n;
        const memberId = activeMembers[idx].id;
        counts.set(memberId, counts.get(memberId) + 1);
    }
    return counts;
}

/**
 * Weighted: member selection proportional to weight.
 * Uses a deterministic seeded random so reruns are consistent.
 * @param {typeof members} activeMembers
 * @param {string[]} clientIps
 * @returns {Map<string, number>}
 */
function algorithmWeighted(activeMembers, clientIps) {
    const counts = new Map(activeMembers.map(m => [m.id, 0]));
    const totalWeight = activeMembers.reduce((s, m) => s + m.weight, 0);

    // Build cumulative weight array for O(log N) lookup
    const cumWeights = [];
    let acc = 0;
    for (const m of activeMembers) {
        acc += m.weight;
        cumWeights.push({ threshold: acc, id: m.id });
    }

    for (const ip of clientIps) {
        // Use hash of IP as a deterministic random value in [0, totalWeight)
        const r = fnv1a32(ip + '_w') % totalWeight;
        for (const { threshold, id } of cumWeights) {
            if (r < threshold) {
                counts.set(id, counts.get(id) + 1);
                break;
            }
        }
    }
    return counts;
}

/**
 * Build a consistent hash ring with virtual nodes.
 * @param {typeof members} activeMembers
 * @param {number} virtualNodes - number of virtual replicas per member
 * @returns {{ position: number, memberId: string }[]} sorted ring
 */
function buildHashRing(activeMembers, virtualNodes) {
    const ring = [];
    for (const m of activeMembers) {
        for (let v = 0; v < virtualNodes; v++) {
            const position = fnv1a32(`${m.id}#vnode${v}`);
            ring.push({ position, memberId: m.id });
        }
    }
    // Sort by position for binary search
    ring.sort((a, b) => a.position - b.position);
    return ring;
}

/**
 * Find the nearest member clockwise on the ring for a given hash.
 * @param {number} hash
 * @param {{ position: number, memberId: string }[]} ring
 * @returns {string} memberId
 */
function findNearestOnRing(hash, ring) {
    if (ring.length === 0) return '';
    // Binary search for first position >= hash
    let lo = 0, hi = ring.length - 1;
    while (lo < hi) {
        const mid = (lo + hi) >> 1;
        if (ring[mid].position < hash) lo = mid + 1;
        else hi = mid;
    }
    // If hash > all positions, wrap around to ring[0]
    if (ring[lo].position < hash) lo = 0;
    return ring[lo].memberId;
}

/**
 * Consistent Hashing: place clients and members on a virtual ring.
 * @param {typeof members} activeMembers
 * @param {string[]} clientIps
 * @param {number} virtualNodes
 * @returns {Map<string, number>}
 */
function algorithmConsistentHash(activeMembers, clientIps, virtualNodes) {
    const counts = new Map(activeMembers.map(m => [m.id, 0]));
    const ring = buildHashRing(activeMembers, virtualNodes);

    for (const ip of clientIps) {
        const hash = fnv1a32(ip);
        const memberId = findNearestOnRing(hash, ring);
        if (counts.has(memberId)) {
            counts.set(memberId, counts.get(memberId) + 1);
        }
    }
    return counts;
}

// ---- Dispatch to correct algorithm -----------------------

/**
 * Run the selected algorithm and return session counts per member.
 * @param {typeof members} activeMembers
 * @param {string[]} clientIps
 * @param {string} algorithm
 * @param {number} virtualNodes
 * @returns {Map<string, number>}
 */
function runAlgorithm(activeMembers, clientIps, algorithm, virtualNodes) {
    switch (algorithm) {
        case 'roundRobin':     return algorithmRoundRobin(activeMembers, clientIps);
        case 'sourceIpHash':   return algorithmSourceIpHash(activeMembers, clientIps);
        case 'weighted':       return algorithmWeighted(activeMembers, clientIps);
        case 'consistentHash': return algorithmConsistentHash(activeMembers, clientIps, virtualNodes);
        default:               return algorithmSourceIpHash(activeMembers, clientIps);
    }
}

// ---- Metrics computation ---------------------------------

/**
 * @param {Map<string, number>} distribution - memberId -> sessionCount
 * @param {typeof members} activeMembers
 * @param {number} totalSessions
 * @returns {{ stdDev: number, maxPct: number, minPct: number, balanceScore: number }}
 */
function computeMetrics(distribution, activeMembers, totalSessions) {
    if (activeMembers.length === 0 || totalSessions === 0) {
        return { stdDev: 0, maxPct: 0, minPct: 0, balanceScore: 100 };
    }

    const values = activeMembers.map(m => distribution.get(m.id) ?? 0);
    const mean = totalSessions / activeMembers.length;

    // Population standard deviation (in sessions)
    const variance = values.reduce((s, v) => s + (v - mean) ** 2, 0) / values.length;
    const stdDev = Math.sqrt(variance);

    const maxCount = Math.max(...values);
    const minCount = Math.min(...values);
    const maxPct = (maxCount / totalSessions) * 100;
    const minPct = (minCount / totalSessions) * 100;

    // Balance score: 100 means perfectly even; 0 means all sessions on one member.
    // Coefficient of Variation normalized to [0,100].
    const cv = mean > 0 ? stdDev / mean : 0;
    const idealCv = 0; // perfect balance
    // Max CV ≈ sqrt(N-1) when all sessions on one member; clamp at 1 for score calc
    const balanceScore = Math.max(0, Math.round((1 - Math.min(cv, 1)) * 100));

    return { stdDev, maxPct, minPct, balanceScore };
}

// ---- Failure redistribution analysis ---------------------

/**
 * Compare distributions before and after a member failure.
 * Returns per-surviving-member session gains.
 * @param {Map<string, number>} before
 * @param {Map<string, number>} after
 * @param {string} failedId
 * @returns {{ memberId: string, gained: number }[]}
 */
function computeRedistribution(before, after, failedId) {
    const result = [];
    for (const [id, afterCount] of after.entries()) {
        const beforeCount = before.get(id) ?? 0;
        const gained = afterCount - beforeCount;
        if (gained !== 0) {
            result.push({ memberId: id, gained });
        }
    }
    return result;
}

// ---- UI helpers ------------------------------------------

function updateSessionLabel(value) {
    document.getElementById('sessionCountLabel').textContent = Number(value).toLocaleString();
}

function renderMemberTable() {
    const tbody = document.getElementById('memberTableBody');
    tbody.innerHTML = '';

    // Also rebuild failure select
    const failureSelect = document.getElementById('failureSelect');
    const currentFailureVal = failureSelect.value;
    failureSelect.innerHTML = '<option value="">-- Select member --</option>';

    members.forEach(m => {
        const tr = document.createElement('tr');
        tr.innerHTML = `
            <td style="font-family:monospace;font-size:13px;color:#666;">${m.id}</td>
            <td><strong>${m.ip}</strong>:${m.port}</td>
            <td>${m.weight}</td>
            <td><span class="status-badge ${m.status}">${m.status.toUpperCase()}</span></td>
            <td>
                <button class="danger-btn" onclick="removeMember('${m.id}')">Remove</button>
            </td>
        `;
        tbody.appendChild(tr);

        const opt = document.createElement('option');
        opt.value = m.id;
        opt.textContent = `${m.id} (${m.ip}:${m.port}) — ${m.status}`;
        failureSelect.appendChild(opt);
    });

    // Restore selection if still valid
    if ([...failureSelect.options].some(o => o.value === currentFailureVal)) {
        failureSelect.value = currentFailureVal;
    }
}

function addMember() {
    const ip = document.getElementById('newMemberIp').value.trim();
    const port = parseInt(document.getElementById('newMemberPort').value.trim(), 10);
    const weight = Math.max(1, Math.min(100, parseInt(document.getElementById('newMemberWeight').value, 10) || 1));

    // Basic IP validation
    const ipParts = ip.split('.');
    if (ipParts.length !== 4 || ipParts.some(p => isNaN(Number(p)) || Number(p) < 0 || Number(p) > 255)) {
        alert('Please enter a valid IPv4 address (e.g., 10.0.1.20).');
        return;
    }
    if (isNaN(port) || port < 1 || port > 65535) {
        alert('Please enter a valid port number (1–65535).');
        return;
    }
    if (members.some(m => m.ip === ip && m.port === port)) {
        alert(`Member ${ip}:${port} already exists.`);
        return;
    }

    members.push({
        id: `member_${memberCounter++}`,
        ip,
        port,
        weight,
        status: 'up',
    });

    // Auto-increment the IP for convenience
    const lastOctet = parseInt(ipParts[3], 10);
    if (!isNaN(lastOctet) && lastOctet < 254) {
        ipParts[3] = String(lastOctet + 1);
        document.getElementById('newMemberIp').value = ipParts.join('.');
    }

    renderMemberTable();
}

function removeMember(id) {
    members = members.filter(m => m.id !== id);
    renderMemberTable();
}

function setMemberDown() {
    const id = document.getElementById('failureSelect').value;
    if (!id) { alert('Select a member first.'); return; }
    const m = members.find(m => m.id === id);
    if (m) m.status = 'down';
    renderMemberTable();
}

function setMemberUp() {
    const id = document.getElementById('failureSelect').value;
    if (!id) { alert('Select a member first.'); return; }
    const m = members.find(m => m.id === id);
    if (m) m.status = 'up';
    renderMemberTable();
}

// ---- Color helpers ---------------------------------------

/**
 * Map a load percentage to a CSS color.
 * Green = balanced, Yellow = slightly over, Red = overloaded.
 * @param {number} pct  0–100
 * @param {number} idealPct  expected even share
 * @returns {string} hex color
 */
function loadColor(pct, idealPct) {
    const ratio = idealPct > 0 ? pct / idealPct : 1;
    if (ratio <= 1.15)  return '#4CAF50'; // green  — within 15% of ideal
    if (ratio <= 1.35)  return '#FFC107'; // amber  — 15–35% over
    if (ratio <= 1.60)  return '#FF9800'; // orange — 35–60% over
    return '#F44336'; // red — >60% over ideal
}

const CHART_COLORS_POOL = [
    '#4CAF50','#2196F3','#9C27B0','#FF9800',
    '#00BCD4','#E91E63','#8BC34A','#FF5722',
];

// ---- Chart rendering -------------------------------------

/**
 * Render or update the bar chart.
 * @param {string[]} labels
 * @param {number[]} sessionCounts
 * @param {number} idealPct
 * @param {number} totalSessions
 */
function renderChart(labels, sessionCounts, idealPct, totalSessions) {
    const ctx = document.getElementById('distributionChart').getContext('2d');

    const colors = sessionCounts.map((count, i) => {
        const pct = totalSessions > 0 ? (count / totalSessions) * 100 : 0;
        return loadColor(pct, idealPct);
    });

    if (distributionChart) {
        distributionChart.data.labels = labels;
        distributionChart.data.datasets[0].data = sessionCounts;
        distributionChart.data.datasets[0].backgroundColor = colors;
        distributionChart.update();
        return;
    }

    distributionChart = new Chart(ctx, {
        type: 'bar',
        data: {
            labels,
            datasets: [{
                label: 'Sessions',
                data: sessionCounts,
                backgroundColor: colors,
                borderColor: colors.map(c => c + 'cc'),
                borderWidth: 1,
                borderRadius: 4,
            }],
        },
        options: {
            responsive: true,
            plugins: {
                legend: { display: false },
                tooltip: {
                    callbacks: {
                        label(ctx) {
                            const count = ctx.parsed.y;
                            const pct = totalSessions > 0
                                ? ((count / totalSessions) * 100).toFixed(1)
                                : '0.0';
                            return ` ${count.toLocaleString()} sessions (${pct}%)`;
                        },
                    },
                },
            },
            scales: {
                y: {
                    beginAtZero: true,
                    title: { display: true, text: 'Sessions', color: '#666', font: { size: 12 } },
                },
                x: {
                    title: { display: true, text: 'Pool Member', color: '#666', font: { size: 12 } },
                },
            },
        },
    });
}

// ---- Hash ring canvas ------------------------------------

/**
 * Draw the consistent hash ring visualization on a canvas.
 * @param {typeof members} activeMembers
 * @param {number} virtualNodes
 * @param {Map<string, number>} distribution
 */
function renderHashRing(activeMembers, virtualNodes, distribution) {
    const canvas = document.getElementById('hashRingCanvas');
    const ctx = canvas.getContext('2d');
    const W = canvas.width;
    const H = canvas.height;
    const cx = W / 2;
    const cy = H / 2;
    const ringR = Math.min(W, H) * 0.40;
    const nodeR = 5;

    ctx.clearRect(0, 0, W, H);

    // Draw ring background
    ctx.strokeStyle = '#e0e0e0';
    ctx.lineWidth = 12;
    ctx.beginPath();
    ctx.arc(cx, cy, ringR, 0, Math.PI * 2);
    ctx.stroke();

    // Assign colors to members
    const colorMap = new Map();
    activeMembers.forEach((m, i) => {
        colorMap.set(m.id, CHART_COLORS_POOL[i % CHART_COLORS_POOL.length]);
    });

    // Draw arc segments for each member's territory
    const ring = buildHashRing(activeMembers, virtualNodes);
    const MAX32 = 0x100000000;
    const TWOPI = Math.PI * 2;

    // For each consecutive pair of virtual nodes, draw a colored arc
    if (ring.length > 0) {
        for (let i = 0; i < ring.length; i++) {
            const next = ring[(i + 1) % ring.length];
            const currAngle = (ring[i].position / MAX32) * TWOPI - Math.PI / 2;
            const nextAngle = (next.position / MAX32) * TWOPI - Math.PI / 2;
            const color = colorMap.get(ring[i].memberId) ?? '#ccc';
            ctx.strokeStyle = color + 'aa';
            ctx.lineWidth = 10;
            ctx.beginPath();
            // Arc from current to next (always clockwise)
            const startA = currAngle;
            let endA = nextAngle;
            if (endA <= startA) endA += TWOPI;
            ctx.arc(cx, cy, ringR, startA, endA);
            ctx.stroke();
        }
    }

    // Draw ring outline (thin)
    ctx.strokeStyle = '#bbb';
    ctx.lineWidth = 1;
    ctx.beginPath();
    ctx.arc(cx, cy, ringR, 0, TWOPI);
    ctx.stroke();

    // Draw virtual nodes as small dots
    for (const node of ring) {
        const angle = (node.position / MAX32) * TWOPI - Math.PI / 2;
        const x = cx + ringR * Math.cos(angle);
        const y = cy + ringR * Math.sin(angle);
        ctx.fillStyle = colorMap.get(node.memberId) ?? '#ccc';
        ctx.beginPath();
        ctx.arc(x, y, nodeR, 0, TWOPI);
        ctx.fill();
    }

    // Center label
    ctx.fillStyle = '#555';
    ctx.font = 'bold 12px sans-serif';
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';
    ctx.fillText(`${virtualNodes} VN`, cx, cy - 8);
    ctx.font = '11px sans-serif';
    ctx.fillStyle = '#888';
    ctx.fillText('per member', cx, cy + 8);

    // Legend
    const legendEl = document.getElementById('ringLegend');
    legendEl.innerHTML = '';
    activeMembers.forEach(m => {
        const sessions = distribution.get(m.id) ?? 0;
        const color = colorMap.get(m.id) ?? '#ccc';
        const item = document.createElement('div');
        item.className = 'ring-legend-item';
        item.innerHTML = `
            <div class="ring-legend-dot" style="background:${color};"></div>
            <div>
                <strong>${m.id}</strong> — ${m.ip}:${m.port}<br>
                <span style="font-size:12px;color:#888;">${sessions.toLocaleString()} sessions</span>
            </div>
        `;
        legendEl.appendChild(item);
    });
}

// ---- Algorithm explanation text --------------------------

const ALGO_EXPLANATIONS = {
    roundRobin: `<strong>Round Robin:</strong> Each incoming session is assigned to the next member in a fixed sequence, cycling through all active members. Session ${1} goes to member 1, session 2 to member 2, ..., session N+1 back to member 1. Result: perfectly even distribution regardless of client source. Standard deviation approaches zero with large session counts.`,
    sourceIpHash: `<strong>Source IP Hash:</strong> A 32-bit FNV-1a hash of the client IP address is computed, then taken modulo the active member count. The same client IP always maps to the same member — providing session affinity at the cost of distribution uniformity. Skewed client populations (Zipfian traffic) may produce uneven loads.`,
    weighted: `<strong>Weighted Distribution:</strong> Members receive traffic proportional to their configured weight. A member with weight 4 receives 4x the sessions of a weight-1 member. Selection is deterministic per client IP (using a seeded hash), so a client consistently reaches the same high-capacity member.`,
    consistentHash: `<strong>Consistent Hashing:</strong> Members are placed at multiple positions on a 2^32 virtual ring (virtual nodes). Client IPs are hashed to a ring position; the request is forwarded to the next clockwise member. When a member is removed, only the sessions in that member's arc are redistributed — minimising disruption compared to modulo hashing.`,
};

// ---- Main simulation -------------------------------------

function runSimulation() {
    const algorithm = document.getElementById('algorithmSelect').value;
    const sessionCount = parseInt(document.getElementById('sessionSlider').value, 10);
    const virtualNodes = parseInt(document.getElementById('virtualNodes').value, 10);

    const activeMembers = members.filter(m => m.status === 'up');

    if (activeMembers.length === 0) {
        alert('No active (up) pool members. Please add members or bring some back up.');
        return;
    }

    // --- Normal distribution ---
    const clientIps = generateClientIps(sessionCount);
    const distribution = runAlgorithm(activeMembers, clientIps, algorithm, virtualNodes);
    const metrics = computeMetrics(distribution, activeMembers, sessionCount);
    const idealPct = 100 / activeMembers.length;

    // --- Failure redistribution ---
    const downMembers = members.filter(m => m.status === 'down');
    let redistributionHtml = '';

    if (downMembers.length > 0) {
        // For each down member, simulate what WOULD have been assigned to it
        // if it were up, then compute how those sessions redistribute now.
        for (const failed of downMembers) {
            const withFailed = [...activeMembers, failed];
            const beforeDist = runAlgorithm(withFailed, clientIps, algorithm, virtualNodes);
            const afterDist = distribution;
            const redistribution = computeRedistribution(beforeDist, afterDist, failed.id);
            const failedSessionCount = beforeDist.get(failed.id) ?? 0;
            const failedPct = sessionCount > 0 ? ((failedSessionCount / sessionCount) * 100).toFixed(1) : '0.0';

            redistributionHtml += `
                <div class="data-row" style="border-left-color:#FF6B6B; margin-bottom:10px;">
                    <div class="data-label" style="color:#c62828;">${failed.id} (${failed.ip}) DOWN</div>
                    <div class="data-value" style="font-size:15px; font-family:inherit; color:#555;">
                        ${failedSessionCount.toLocaleString()} sessions (${failedPct}%) need redistribution
                    </div>
                </div>
            `;

            redistribution.sort((a, b) => b.gained - a.gained);
            redistribution.forEach(({ memberId, gained }) => {
                const receiver = members.find(m => m.id === memberId);
                const receiverLabel = receiver ? `${memberId} (${receiver.ip})` : memberId;
                const arrow = gained > 0 ? '&rarr;' : '&larr;';
                const sign = gained > 0 ? '+' : '';
                redistributionHtml += `
                    <div class="redistribution-row">
                        <span class="arrow">${arrow}</span>
                        <span class="move-label">${receiverLabel} absorbs</span>
                        <span class="move-count">${sign}${gained.toLocaleString()} sessions</span>
                    </div>
                `;
            });

            // Algorithm-specific note
            let algoNote = '';
            if (algorithm === 'consistentHash') {
                algoNote = `<div style="margin-top:10px;font-size:13px;color:#5d4037;background:#fff8e1;padding:8px 12px;border-radius:4px;border:1px solid #ffe082;">
                    Consistent hashing: only the ${failedPct}% of sessions owned by the failed member's ring arcs are affected.
                    The next clockwise member absorbs each arc. All other sessions remain pinned to their original members.
                </div>`;
            } else if (algorithm === 'sourceIpHash') {
                algoNote = `<div style="margin-top:10px;font-size:13px;color:#5d4037;background:#fff8e1;padding:8px 12px;border-radius:4px;border:1px solid #ffe082;">
                    Source IP hash (modulo): removing one member changes the modulo divisor from ${withFailed.length} to ${activeMembers.length},
                    causing ALL sessions to be rehashed — not just those belonging to the failed member.
                    <strong>~${(((withFailed.length - activeMembers.length) / withFailed.length) * 100).toFixed(0)}% of clients</strong> land on a different member.
                </div>`;
            } else if (algorithm === 'roundRobin') {
                algoNote = `<div style="margin-top:10px;font-size:13px;color:#5d4037;background:#fff8e1;padding:8px 12px;border-radius:4px;border:1px solid #ffe082;">
                    Round robin redistributes evenly — the ${failedSessionCount.toLocaleString()} sessions are shared equally across all surviving members.
                </div>`;
            } else if (algorithm === 'weighted') {
                algoNote = `<div style="margin-top:10px;font-size:13px;color:#5d4037;background:#fff8e1;padding:8px 12px;border-radius:4px;border:1px solid #ffe082;">
                    Weighted redistribution: sessions from the failed member flow to surviving members proportional to their weights,
                    matching the configured capacity ratios.
                </div>`;
            }
            redistributionHtml += algoNote;
            redistributionHtml += '<hr style="margin:15px 0; border:none; border-top:1px solid #eee;">';
        }
    } else {
        redistributionHtml = `<div style="color:#888;font-size:14px;padding:10px;">
            No members are currently marked DOWN. Use the failure simulation controls in the header to mark a member down,
            then re-run the simulation to see redistribution analysis.
        </div>`;
    }

    // ---- Render balance score ----
    const { balanceScore } = metrics;
    let scoreClass = 'excellent';
    let scoreLabel = 'Excellent';
    if (balanceScore < 40) { scoreClass = 'poor';      scoreLabel = 'Poor'; }
    else if (balanceScore < 65) { scoreClass = 'fair'; scoreLabel = 'Fair'; }
    else if (balanceScore < 85) { scoreClass = 'good'; scoreLabel = 'Good'; }

    document.getElementById('balanceScoreContainer').innerHTML = `
        <div class="balance-score-ring ${scoreClass}">${balanceScore}</div>
        <div class="balance-score-info">
            <h4>Balance Score: ${scoreLabel}</h4>
            <p>
                Score 0–100 where 100 = perfectly even distribution.<br>
                Calculated from the coefficient of variation (std dev / mean) across active members.
                A score above 85 is considered production-acceptable for most workloads.
            </p>
        </div>
    `;

    document.getElementById('algoExplanation').innerHTML = ALGO_EXPLANATIONS[algorithm] ?? '';

    // ---- Render metrics grid ----
    document.getElementById('metricsGrid').innerHTML = `
        <div class="metric-card">
            <div class="metric-value">${sessionCount.toLocaleString()}</div>
            <div class="metric-label">Total Sessions</div>
        </div>
        <div class="metric-card">
            <div class="metric-value">${metrics.stdDev.toFixed(1)}</div>
            <div class="metric-label">Std Deviation (sessions)</div>
        </div>
        <div class="metric-card">
            <div class="metric-value">${metrics.maxPct.toFixed(1)}%</div>
            <div class="metric-label">Max Member Load</div>
        </div>
        <div class="metric-card">
            <div class="metric-value">${metrics.minPct.toFixed(1)}%</div>
            <div class="metric-label">Min Member Load</div>
        </div>
    `;

    // ---- Render chart ----
    const labels = activeMembers.map(m => `${m.id}\n${m.ip}`);
    const sessionCounts = activeMembers.map(m => distribution.get(m.id) ?? 0);
    renderChart(labels, sessionCounts, idealPct, sessionCount);

    // ---- Render member detail rows ----
    let detailHtml = '';
    activeMembers.forEach(m => {
        const count = distribution.get(m.id) ?? 0;
        const pct = sessionCount > 0 ? ((count / sessionCount) * 100).toFixed(1) : '0.0';
        const barColor = loadColor(parseFloat(pct), idealPct);
        const barWidth = sessionCount > 0 ? Math.round((count / sessionCount) * 100) : 0;
        detailHtml += `
            <div class="data-row" style="border-left-color: ${barColor}; flex-direction: column; align-items: stretch; padding: 12px 15px;">
                <div style="display:flex; justify-content:space-between; margin-bottom:6px; flex-wrap:wrap; gap:6px;">
                    <span style="font-weight:bold; color:#444; font-size:14px;">${m.id} — ${m.ip}:${m.port}</span>
                    <span style="font-family:monospace; color:${barColor}; font-weight:bold; font-size:15px;">${count.toLocaleString()} sessions (${pct}%)</span>
                </div>
                <div style="background:#f0f0f0; border-radius:4px; height:8px; overflow:hidden;">
                    <div style="width:${barWidth}%; background:${barColor}; height:100%; border-radius:4px; transition:width 0.4s ease;"></div>
                </div>
                <div style="font-size:12px; color:#999; margin-top:4px;">
                    Weight: ${m.weight} &nbsp;|&nbsp; Ideal: ${idealPct.toFixed(1)}%
                </div>
            </div>
        `;
    });
    document.getElementById('memberDetailRows').innerHTML = detailHtml;

    // ---- Redistribution section ----
    document.getElementById('redistributionContent').innerHTML = redistributionHtml;
    document.getElementById('redistributionSection').classList.add('show');

    // ---- Hash ring section ----
    if (algorithm === 'consistentHash') {
        renderHashRing(activeMembers, virtualNodes, distribution);
        document.getElementById('hashRingSection').classList.add('show');
    } else {
        document.getElementById('hashRingSection').classList.remove('show');
    }

    // ---- Show results ----
    const resultsSection = document.getElementById('resultsSection');
    resultsSection.classList.add('show');
    resultsSection.scrollIntoView({ behavior: 'smooth', block: 'start' });
}

// ---- Initialization --------------------------------------

document.addEventListener('DOMContentLoaded', () => {
    renderMemberTable();
});
</script>