from datetime import date
from typing import List, Optional
from dal.StudentDAL import StudentDAL
from student.Student import Student


class StudentBLL:
    def __init__(self, dal: StudentDAL):
        self.dal = dal

    def add_student(self, student: Student):
        if not student.is_valid:
            errors = ", ".join(student.get_errors())
            raise ValueError(f"学生数据校验失败: {errors}")

        if not self.dal.add_student(student):
            raise ValueError("添加失败，身份证号或学号可能已存在")

    def delete_student(self, stu_id: str):
        if not self.dal.delete_student(stu_id):
            raise ValueError(f"找不到学号为 {stu_id} 的学生")

    def update_student(self, stu_id: str, student: Student):
        if not student.is_valid:
            errors = ", ".join(student.get_errors())
            raise ValueError(f"学生数据校验失败: {errors}")

        if not self.dal.update_student(stu_id, student):
            raise ValueError(f"找不到学号为 {stu_id} 的学生")

    def get_student_by_id_card(self, id_card: str) -> Optional[Student]:
        return self.dal.get_by_id_card(id_card)

    def get_student_by_stu_id(self, stu_id: str) -> Optional[Student]:
        return self.dal.get_by_stu_id(stu_id)

    def get_all_students(self) -> List[Student]:
        return self.dal.get_all()

    def search_students(self, search_type: str, keyword: str) -> List[Student]:
        search_type = search_type.lower()
        if search_type == 'name':
            return self.dal.search_by_name(keyword)
        elif search_type == 'class':
            return self.dal.search_by_class(keyword)
        elif search_type == 'major':
            return self.dal.search_by_major(keyword)
        else:
            return []

    def get_student_count(self) -> int:
        return self.dal.get_student_count()

    def get_major_counts(self) -> dict:
        return self.dal.get_major_counts()

    def calculate_avg_height(self) -> float:
        students = self.dal.get_all()
        heights = [s.height for s in students if s.height is not None]
        if not heights:
            return 0.0
        return sum(heights) / len(heights)

    def calculate_avg_weight(self) -> float:
        students = self.dal.get_all()
        weights = [s.weight for s in students if s.weight is not None]
        if not weights:
            return 0.0
        return sum(weights) / len(weights)

    def get_students_by_age(self, min_age: int, max_age: int) -> List[Student]:
        today = date.today()
        students = self.dal.get_all()
        result = []

        for student in students:
            if student.age is None:
                continue

            if min_age <= student.age <= max_age:
                result.append(student)

        return result

    def export_data(self, file_path: str) -> bool:
        return self.dal.export_data(file_path)

    def import_data(self, file_path: str) -> bool:
        return self.dal.import_data(file_path)

    def clear_all(self) -> bool:
        return self.dal.clear_all()