from django.db import models
from django.contrib.auth.models import User
from datetime import date


class Category(models.Model):
    """设备分类"""
    name = models.CharField('分类名称', max_length=50, unique=True)
    description = models.CharField('描述', max_length=200, blank=True, default='')
    created_at = models.DateTimeField('创建时间', auto_now_add=True)

    class Meta:
        verbose_name = '设备分类'
        verbose_name_plural = verbose_name
        ordering = ['name']

    def __str__(self):
        return self.name


class Asset(models.Model):
    """硬件资产"""

    STATUS_CHOICES = [
        ('in_use', '在用'),
        ('idle', '闲置'),
        ('maintenance', '维修中'),
        ('scrapped', '已报废'),
    ]

    # 基本信息
    asset_number = models.CharField('资产编号', max_length=50, db_index=True)
    name = models.CharField('设备名称', max_length=100)
    category = models.ForeignKey(Category, on_delete=models.PROTECT, verbose_name='设备分类', related_name='assets')

    # 硬件信息
    brand = models.CharField('品牌', max_length=50, blank=True, default='')
    model = models.CharField('型号', max_length=100, blank=True, default='')
    asset_value = models.DecimalField('资产面值', max_digits=12, decimal_places=2, blank=True, null=True)
    serial_number = models.CharField('序列号', max_length=100, blank=True, default='', db_index=True)

    # 位置信息
    location = models.CharField('机房', max_length=200, blank=True, default='', help_text='楼层/房间/区域')
    cabinet = models.CharField('机柜', max_length=50, blank=True, default='')
    cabinet_position = models.CharField('机柜位置', max_length=50, blank=True, default='', help_text='U位')

    # 网络信息
    bmc_address = models.GenericIPAddressField('BMC地址', blank=True, null=True)
    ip_address = models.GenericIPAddressField('IP地址', blank=True, null=True)

    # 显卡信息
    has_gpu = models.CharField('是否带卡', max_length=20, blank=True, default='')
    gpu_type = models.CharField('显卡类型', max_length=100, blank=True, default='')
    gpu_count = models.IntegerField('卡数', blank=True, null=True)

    # 采购与质保
    purchase_date = models.DateField('采购日期', blank=True, null=True)
    warranty_expire = models.DateField('质保到期', blank=True, null=True)
    supplier = models.CharField('供应商', max_length=100, blank=True, default='')

    # 管理信息
    responsible_person = models.CharField('负责人', max_length=50, blank=True, default='')
    department = models.CharField('使用部门', max_length=100, blank=True, default='')
    user = models.CharField('维护人', max_length=50, blank=True, default='')
    business_type = models.CharField('业务类型', max_length=100, blank=True, default='')
    status = models.CharField('状态', max_length=20, choices=STATUS_CHOICES, default='in_use')
    remark = models.TextField('备注', blank=True, default='')

    # 系统字段
    created_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, verbose_name='创建人')
    created_at = models.DateTimeField('创建时间', auto_now_add=True)
    updated_at = models.DateTimeField('更新时间', auto_now=True)

    class Meta:
        verbose_name = '硬件资产'
        verbose_name_plural = verbose_name
        ordering = ['id']

    def __str__(self):
        return f'{self.asset_number} - {self.name}'

    @property
    def is_expired(self):
        if self.warranty_expire:
            return self.warranty_expire < date.today()
        return False

    @property
    def is_expiring_soon(self):
        if self.warranty_expire:
            from datetime import timedelta
            return date.today() <= self.warranty_expire <= date.today() + timedelta(days=30)
        return False


class AssetChangeLog(models.Model):
    """资产变更记录"""

    ACTION_CHOICES = [
        ('create', '创建'),
        ('update', '更新'),
        ('delete', '删除'),
        ('import', '导入'),
        ('export', '导出'),
        ('status_change', '状态变更'),
    ]

    asset = models.ForeignKey(Asset, on_delete=models.SET_NULL, null=True, blank=True,
                               verbose_name='资产', related_name='change_logs')
    asset_number = models.CharField('资产编号', max_length=50, db_index=True)
    action = models.CharField('操作类型', max_length=20, choices=ACTION_CHOICES)
    field_name = models.CharField('变更字段', max_length=50, blank=True, default='')
    old_value = models.TextField('旧值', blank=True, default='')
    new_value = models.TextField('新值', blank=True, default='')
    description = models.TextField('描述', blank=True, default='')
    operator = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, verbose_name='操作人')
    created_at = models.DateTimeField('操作时间', auto_now_add=True)

    class Meta:
        verbose_name = '变更记录'
        verbose_name_plural = verbose_name
        ordering = ['-created_at']

    def __str__(self):
        return f'{self.asset_number} - {self.get_action_display()}'