from decimal import Decimal

from django.db import models
from django.db.models import Sum
from django.utils import timezone

from application.busi_tbl.models import DepartmentExpense, UpdateLog
from application.fac_mgnt.models import GroupAnnualBudget, ReimbursementDetail
from application.org_mgnt.models import PrimaryDepartment


class DepartmentExpenseData(models.Model):
    """
        费用情况
        年月、费用类型、费用明细、费用限额（集团年度预算表-按一级部门年份费用类型费用明细筛选后取金额）
        已报销额度（报销明细表-费用金额按时间、类型、明细筛选后汇总，算当年总额）
        可用额度（=费用限额-已报销额度）
        """
    primary_department = models.CharField(max_length=255, verbose_name="一级部门", help_text="用于筛选、区分一级部门")
    year_month = models.CharField(max_length=7, verbose_name="年月", help_text="格式为'YYYY-MM'，表示统计数据的年月")
    expense_type = models.CharField(max_length=255, verbose_name="费用类型")
    expense_detail = models.CharField(max_length=255, verbose_name="费用明细")
    expense_limit = models.FloatField(verbose_name="费用限额（元）", null=True, blank=True)
    reimbursed_amount = models.FloatField(verbose_name="已报销额度（元）", null=True, blank=True)
    available_amount = models.FloatField(verbose_name="可用额度（元）", null=True, blank=True)

    class Meta:
        verbose_name = "费用情况"
        verbose_name_plural = "费用情况"
        db_table_comment = '存储业务部门费用情况数据，包括一级部门、年月、费用类型、费用明细、费用限额、已报销额度、可用额度等'

    def __str__(self):
        return f"{self.year_month} 年 {self.primary_department} 的费用情况"

    @staticmethod
    def calculate_and_update_for_month(year_month):
        primary_departments = PrimaryDepartment.objects.all()
        year, month = map(int, year_month.split('-'))

        for department in primary_departments:
            primary_department = department.department_name

            # 从集团年度预算表获取费用类型和费用明细
            budget_entries = GroupAnnualBudget.objects.filter(
                primary_department=primary_department,
                year=year
            )

            for entry in budget_entries:
                expense_type = entry.expense_type.expense_type
                expense_type_instance = entry.expense_type
                expense_detail = entry.expense_detail.expense_detail
                expense_detail_instance = entry.expense_detail

                # 费用限额
                expense_limit = entry.amount

                # 已报销额度
                reimbursed_amount = ReimbursementDetail.objects.filter(
                    primary_department=primary_department,
                    year_month__icontains=year_month,
                    expense_type=expense_type_instance,
                    expense_detail=expense_detail_instance
                ).aggregate(total=Sum('amount'))['total'] or Decimal('0')

                # 可用额度
                available_amount = expense_limit - reimbursed_amount

                # 更新或创建模型实例
                expense, created = DepartmentExpenseData.objects.update_or_create(
                    primary_department=primary_department,
                    year_month=year_month,
                    expense_type=expense_type,
                    expense_detail=expense_detail,
                    defaults={
                        'expense_limit': expense_limit,
                        'reimbursed_amount': reimbursed_amount,
                        'available_amount': available_amount,
                    }
                )

        # 更新或创建更新时间记录
        UpdateLog.objects.update_or_create(
            table_name='DepartmentExpenseData',
            defaults={'last_update': timezone.now().date()}
        )

    @classmethod
    def update_all_departments_for_month(cls, year_month):
        cls.calculate_and_update_for_month(year_month)