대시보드 — 충전기별 에러코드 누적 순위 차트 추가

- /api/stats/charger-error-codes 엔드포인트 추가
  (Top 10 충전기 × Top 6 에러코드 stacked bar, 나머지 기타로 합산)
- dashboard.html: 에러코드 누적 순위 가로 스택 바 차트 카드 추가
  (클릭 시 해당 충전기 신고 목록으로 이동)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/main.py

@@ -540,3 +540,66 @@ def stats_top_chargers(limit: int = 10):
         ]
     finally:
         db.close()
+
+
+@app.get("/api/stats/charger-error-codes")
+def stats_charger_error_codes(charger_limit: int = 10, code_limit: int = 6):
+    """충전기별 에러코드 누적 건수 Top N (에러코드 입력된 신고 기준)."""
+    from database import SessionLocal
+    from sqlalchemy import text
+    from collections import defaultdict
+    db = SessionLocal()
+    try:
+        rows = db.execute(text("""
+            SELECT rep.charger_id,
+                   COALESCE(c.station_name, rep.charger_id) AS station_name,
+                   COALESCE(c.name, '') AS charger_name,
+                   TRIM(rep.error_code) AS error_code,
+                   COUNT(*) AS cnt
+            FROM reports rep
+            LEFT JOIN chargers c ON c.id = rep.charger_id
+            WHERE rep.error_code IS NOT NULL
+              AND TRIM(rep.error_code) != ''
+            GROUP BY rep.charger_id, c.station_name, c.name, TRIM(rep.error_code)
+        """)).fetchall()
+
+        if not rows:
+            return {"chargers": [], "error_codes": []}
+
+        charger_info = {}
+        code_totals = defaultdict(int)
+
+        for row in rows:
+            cid, sname, cname, ecode, cnt = row
+            cnt = int(cnt)
+            if cid not in charger_info:
+                charger_info[cid] = {"station_name": sname, "charger_name": cname,
+                                     "total": 0, "errors": {}}
+            charger_info[cid]["total"] += cnt
+            charger_info[cid]["errors"][ecode] = cnt
+            code_totals[ecode] += cnt
+
+        top_chargers = sorted(charger_info.items(), key=lambda x: -x[1]["total"])[:charger_limit]
+        top_codes    = [c for c, _ in sorted(code_totals.items(), key=lambda x: -x[1])[:code_limit]]
+
+        result = []
+        for cid, info in reversed(top_chargers):   # 역순: 차트에서 1위가 위에
+            label = info["station_name"]
+            if info["charger_name"]:
+                label += f" ({info['charger_name']})"
+            if len(label) > 22:
+                label = label[:20] + "…"
+            errors = info["errors"]
+            other  = sum(cnt for code, cnt in errors.items() if code not in top_codes)
+            entry  = {"charger_id": cid, "label": label, "total": info["total"]}
+            for code in top_codes:
+                entry[code] = errors.get(code, 0)
+            if other:
+                entry["기타"] = other
+            result.append(entry)
+
+        has_other = any(r.get("기타", 0) > 0 for r in result)
+        all_codes = top_codes + (["기타"] if has_other else [])
+        return {"chargers": result, "error_codes": all_codes}
+    finally:
+        db.close()

frontend/static/pages/admin/dashboard.html

@@ -227,6 +227,17 @@
       </div>
     </div>
 
+    <!-- 충전기별 에러코드 누적 순위 -->
+    <div class="card" style="margin-bottom:20px">
+      <div style="display:flex;align-items:center;justify-content:space-between;margin-bottom:16px;flex-wrap:wrap;gap:8px">
+        <div class="card-title" style="margin:0">⚡ 충전기별 에러코드 누적 순위 Top 10</div>
+        <span style="font-size:11px;color:var(--gray4)">에러코드 입력된 신고 기준</span>
+      </div>
+      <div id="errorCodesChartWrap" style="position:relative">
+        <canvas id="errorCodesChart"></canvas>
+      </div>
+    </div>
+
     <div style="display:grid;grid-template-columns:1fr 1fr;gap:20px;">
       <div class="card">
         <div class="card-title">🔴 접수 대기 현황 <span id="pendingSort" style="font-size:11px;font-weight:400;color:var(--gray4)">(오래된 순)</span></div>
@@ -414,6 +425,7 @@ async function load() {
   ]);
   loadMonthlyChart();
   loadTopChargersChart();
+  loadErrorCodesChart();
 
   /* ── 통계 카드 ── */
   const over72Class = stats.pending_over_72h > 0 ? 'danger' : 'good';
@@ -624,6 +636,69 @@ async function loadTopChargersChart() {
   });
 }
 
+/* ── 충전기별 에러코드 차트 ── */
+let _errorCodesChart = null;
+async function loadErrorCodesChart() {
+  const data = await API.get('/stats/charger-error-codes');
+  const wrap = document.getElementById('errorCodesChartWrap');
+  if (!data.chargers || !data.chargers.length) {
+    wrap.innerHTML = '<div style="color:var(--gray4);font-size:13px;text-align:center;padding:30px 0">에러코드가 입력된 신고가 없습니다.</div>';
+    return;
+  }
+  const { chargers, error_codes: codes } = data;
+  const CODE_COLORS = ['#EF4444','#F59E0B','#3B82F6','#10B981','#8B5CF6','#EC4899','#94A3B8'];
+
+  wrap.style.height = (chargers.length * 32 + 50) + 'px';
+  if (_errorCodesChart) _errorCodesChart.destroy();
+  const ctx = document.getElementById('errorCodesChart').getContext('2d');
+  _errorCodesChart = new Chart(ctx, {
+    type: 'bar',
+    data: {
+      labels: chargers.map(c => c.label),
+      datasets: codes.map((code, i) => ({
+        label: code,
+        data: chargers.map(c => c[code] || 0),
+        backgroundColor: CODE_COLORS[i % CODE_COLORS.length],
+        borderRadius: 3,
+        stack: 'err',
+      }))
+    },
+    options: {
+      indexAxis: 'y',
+      responsive: true,
+      maintainAspectRatio: false,
+      onClick: (evt, elems) => {
+        if (!elems.length) return;
+        const c = chargers[elems[0].index];
+        location.href = `/pages/admin/reports.html?charger_id=${encodeURIComponent(c.charger_id)}`;
+      },
+      onHover: (evt, elems) => { evt.native.target.style.cursor = elems.length ? 'pointer' : 'default'; },
+      plugins: {
+        legend: { display: true, position: 'top',
+          labels: { font: { size: 11 }, boxWidth: 12, boxHeight: 12, padding: 12 } },
+        tooltip: {
+          callbacks: {
+            title: items => {
+              const c = chargers[items[0].dataIndex];
+              return c.label + ` (총 ${c.total}건)`;
+            },
+            label: c => `${c.dataset.label}: ${c.raw}건`,
+            afterLabel: () => '(클릭하면 신고 목록으로)',
+          }
+        }
+      },
+      scales: {
+        x: { stacked: true, grid: { color: '#F1F5F9' }, border: { dash: [3,3] },
+             beginAtZero: true,
+             ticks: { font: { size: 11 }, color: '#64748B', stepSize: 1,
+                      callback: v => Number.isInteger(v) ? v + '건' : '' } },
+        y: { stacked: true, grid: { display: false },
+             ticks: { font: { size: 12 }, color: '#334155' } }
+      }
+    }
+  });
+}
+
 /* ── 월별/일별 차트 (드릴다운 지원) ── */
 let _monthlyChart = null;
 let _monthlyReportChart = null;