from __future__ import annotations

import json
from typing import List, Optional

from sqlalchemy import Column, Integer, String, Text, Boolean, DateTime, ForeignKey, Table, func
from sqlalchemy.orm import relationship

from app.core.database import Base

# 用户-权限组关联表
user_groups = Table(
    "user_groups",
    Base.metadata,
    Column("user_id", Integer, ForeignKey("users.id", ondelete="CASCADE"), primary_key=True),
    Column("group_id", Integer, ForeignKey("instance_groups.id", ondelete="CASCADE"), primary_key=True),
    Column("permissions", Text, nullable=True),  # JSON: 覆盖组默认权限 (legacy, kept for compat)
)


class InstanceGroup(Base):
    __tablename__ = "instance_groups"

    id = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(100), nullable=False, unique=True)
    description = Column(Text, nullable=True)
    db_type = Column(String(20), nullable=False, default="all")  # mysql/redis/pg/mongo/all
    permissions = Column(Text, nullable=True)  # JSON: ["query:select", ...] (legacy, kept for compat)
    access_type = Column(String(20), nullable=True, default="readonly")  # readonly / write
    allowed_databases = Column(Text, nullable=True)  # JSON array of database names; empty = all databases
    is_active = Column(Boolean, default=True)
    created_at = Column(DateTime, server_default=func.now())
    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())

    # 关系
    instances = relationship("Instance", back_populates="group", lazy="selectin")
    users = relationship("User", secondary=user_groups, back_populates="groups", lazy="selectin")

    # ---- Legacy helpers (kept for backward compatibility) ----

    def get_permissions(self) -> list:
        if self.permissions:
            try:
                return json.loads(self.permissions)
            except (json.JSONDecodeError, TypeError):
                return []
        return []

    def set_permissions(self, perms: list):
        self.permissions = json.dumps(perms, ensure_ascii=False) if perms else None

    # ---- New access_type / allowed_databases helpers ----

    def get_allowed_databases(self) -> list[str]:
        """返回允许的数据库名列表，空列表表示关联实例的所有库。"""
        if self.allowed_databases:
            try:
                return json.loads(self.allowed_databases)
            except (json.JSONDecodeError, TypeError):
                return []
        return []

    def set_allowed_databases(self, databases: list[str] | None):
        self.allowed_databases = (
            json.dumps(databases, ensure_ascii=False) if databases else None
        )

    VALID_ACCESS_TYPES = {"readonly", "write"}