"""核心模块的跨域基础：Tenant、Org、AuditLog 模型。"""

from django.conf import settings
from django.db import models


class Tenant(models.Model):
    """租户：每个经销商/企业 = 1 个 Tenant。

    阶段 1 落地；多租户隔离的所有业务表都必须带 tenant_id。
    """

    code = models.SlugField(max_length=64, unique=True, help_text="租户代码（小写字母数字）")
    name = models.CharField(max_length=128, help_text="租户名称（公司/品牌名）")
    contact = models.CharField(max_length=64, blank=True, default="")
    phone = models.CharField(max_length=32, blank=True, default="")
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = "core_tenant"
        ordering = ["code"]

    def __str__(self):
        return f"{self.code} ({self.name})"


class TenantMembership(models.Model):
    """用户可访问的租户关系。

    租户头只选择上下文，真正的访问权由这张关系表决定。保留角色字段，
    先用于最小授权边界，后续可在不改变租户隔离模型的情况下细分权限。
    """

    ROLE_CHOICES = [
        ("owner", "所有者"),
        ("admin", "管理员"),
        ("member", "成员"),
    ]

    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="tenant_memberships",
    )
    tenant = models.ForeignKey(
        "core.Tenant",
        on_delete=models.CASCADE,
        related_name="memberships",
    )
    role = models.CharField(max_length=16, choices=ROLE_CHOICES, default="member")
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = "core_tenant_membership"
        constraints = [
            models.UniqueConstraint(
                fields=["user", "tenant"], name="core_membership_user_tenant_uniq"
            ),
        ]
        indexes = [
            models.Index(fields=["user", "is_active"]),
            models.Index(fields=["tenant", "is_active"]),
        ]

    def __str__(self):
        return f"{self.user} -> {self.tenant.code} ({self.role})"


class Org(models.Model):
    """组织：租户下的多组织/多门店/多仓库。

    预留点：分销 ERP 多机构独立核算需要。
    通过 org_path 支持层级结构（0001.0002.0003）。
    """

    tenant = models.ForeignKey(
        Tenant,
        on_delete=models.CASCADE,
        related_name="orgs",
    )
    code = models.CharField(max_length=64, help_text="组织代码（在租户内唯一）")
    name = models.CharField(max_length=128)
    org_path = models.CharField(
        max_length=255,
        blank=True,
        default="",
        help_text="组织层级路径，如 0001.0002.0003；用于快速子树查询",
    )
    parent = models.ForeignKey(
        "self",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="children",
    )
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = "core_org"
        unique_together = [("tenant", "code")]
        ordering = ["org_path", "code"]

    def __str__(self):
        return f"{self.tenant.code}/{self.code} {self.name}"


class AuditLog(models.Model):
    """审计日志：记录关键操作（增删改、登录、敏感查看）。"""

    ACTION_CHOICES = [
        ("create", "创建"),
        ("update", "更新"),
        ("delete", "删除"),
        ("view", "查看"),
        ("login", "登录"),
        ("logout", "登出"),
        ("export", "导出"),
    ]

    tenant = models.ForeignKey(
        Tenant,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="audit_logs",
    )
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="audit_logs",
    )
    action = models.CharField(max_length=16, choices=ACTION_CHOICES)
    target_type = models.CharField(max_length=64, help_text="目标模型名，如 SalesOrder")
    target_id = models.CharField(max_length=64, blank=True, default="")
    detail = models.JSONField(default=dict, blank=True, help_text="操作详情 JSON")
    ip = models.GenericIPAddressField(null=True, blank=True)
    user_agent = models.CharField(max_length=255, blank=True, default="")
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "core_audit_log"
        indexes = [
            models.Index(fields=["tenant", "-created_at"]),
            models.Index(fields=["target_type", "target_id"]),
            models.Index(fields=["user", "-created_at"]),
        ]
        ordering = ["-created_at"]

    def __str__(self):
        return f"[{self.created_at}] {self.action} {self.target_type}#{self.target_id}"