feat: add student/class statistics page with Chart.js visualizations

app/routes/students.py

@@ -16,6 +16,7 @@ from app.models import (
     db,
     Student,
     Class,
+    StudentProblem,
     PracticePlan,
     PROBLEM_LIST,
     SEVERITY_LEVELS,
@@ -67,6 +68,14 @@ def students_page():
     )
 
 
+@main_bp.route("/statistics")
+def statistics_page():
+    """数据统计页"""
+    if not check_login():
+        return redirect("/login")
+    return render_template("statistics.html", active_nav="statistics")
+
+
 @main_bp.route("/api/students", methods=["GET"])
 @login_required_json
 def get_students():
@@ -366,3 +375,69 @@ def import_students():
 
     except Exception as e:
         return jsonify({"error": f"导入失败: {str(e)}"}), 500
+
+
+@main_bp.route("/api/statistics/students")
+def get_student_statistics():
+    """获取学员统计数据"""
+    # 全体学员数量
+    total_students = Student.query.count()
+
+    # 全体问题记录
+    problems = StudentProblem.query.all()
+
+    # 问题级别分布（来自 StudentProblem.level）
+    levels = ["启蒙", "入门", "进阶", "熟练", "精通"]
+    level_dist = {lv: 0 for lv in levels}
+    for p in problems:
+        if p.level in level_dist:
+            level_dist[p.level] += 1
+
+    # 问题严重程度分布
+    severity_dist = {"轻微": 0, "中等": 0, "严重": 0}
+    for p in problems:
+        if p.severity in severity_dist:
+            severity_dist[p.severity] += 1
+
+    # 各班级学员数量
+    classes = Class.query.filter_by(active=True).all()
+    class_student_count = []
+    for c in classes:
+        class_student_count.append({
+            "class_id": c.id,
+            "class_name": c.name,
+            "level": c.level,
+            "student_count": len(c.students)
+        })
+
+    # 问题×级别矩阵（严重程度 × 学员级别）
+    severities = ["轻微", "中等", "严重"]
+    matrix = {}
+    for sev in severities:
+        matrix[sev] = {}
+        for lv in levels:
+            matrix[sev][lv] = 0
+
+    for p in problems:
+        if p.level in levels and p.severity in severities:
+            matrix[p.severity][p.level] += 1
+
+    # 各班级问题数量
+    class_problem_count = []
+    for c in classes:
+        class_problems = [p for p in problems if p.student.class_id == c.id]
+        class_problem_count.append({
+            "class_id": c.id,
+            "class_name": c.name,
+            "problem_count": len(class_problems)
+        })
+
+    return jsonify({
+        "total_students": total_students,
+        "total_problems": len(problems),
+        "level_distribution": level_dist,
+        "severity_distribution": severity_dist,
+        "class_student_count": class_student_count,
+        "class_problem_count": class_problem_count,
+        "problem_level_matrix": matrix,
+    })