"""
Memory layer entities for AI Service.
[AC-AISVC-13] SQLModel entities for chat sessions and messages with tenant isolation.
"""

import uuid
from datetime import datetime
from typing import Any

from sqlalchemy import Column, JSON
from sqlmodel import Field, Index, SQLModel


class ChatSession(SQLModel, table=True):
    """
    [AC-AISVC-13] Chat session entity with tenant isolation.
    Primary key: (tenant_id, session_id) composite unique constraint.
    """

    __tablename__ = "chat_sessions"
    __table_args__ = (
        Index("ix_chat_sessions_tenant_session", "tenant_id", "session_id", unique=True),
        Index("ix_chat_sessions_tenant_id", "tenant_id"),
    )

    id: uuid.UUID = Field(default_factory=uuid.uuid4, primary_key=True)
    tenant_id: str = Field(..., description="Tenant ID for multi-tenant isolation", index=True)
    session_id: str = Field(..., description="Session ID for conversation tracking")
    channel_type: str | None = Field(default=None, description="Channel type: wechat, douyin, jd")
    metadata_: dict[str, Any] | None = Field(
        default=None,
        sa_column=Column("metadata", JSON, nullable=True),
        description="Session metadata"
    )
    created_at: datetime = Field(default_factory=datetime.utcnow, description="Session creation time")
    updated_at: datetime = Field(default_factory=datetime.utcnow, description="Last update time")


class ChatMessage(SQLModel, table=True):
    """
    [AC-AISVC-13] Chat message entity with tenant isolation.
    Messages are scoped by (tenant_id, session_id) for multi-tenant security.
    """

    __tablename__ = "chat_messages"
    __table_args__ = (
        Index("ix_chat_messages_tenant_session", "tenant_id", "session_id"),
        Index("ix_chat_messages_tenant_session_created", "tenant_id", "session_id", "created_at"),
    )

    id: uuid.UUID = Field(default_factory=uuid.uuid4, primary_key=True)
    tenant_id: str = Field(..., description="Tenant ID for multi-tenant isolation", index=True)
    session_id: str = Field(..., description="Session ID for conversation tracking", index=True)
    role: str = Field(..., description="Message role: user or assistant")
    content: str = Field(..., description="Message content")
    created_at: datetime = Field(default_factory=datetime.utcnow, description="Message creation time")


class ChatSessionCreate(SQLModel):
    """Schema for creating a new chat session."""

    tenant_id: str
    session_id: str
    channel_type: str | None = None
    metadata_: dict[str, Any] | None = None


class ChatMessageCreate(SQLModel):
    """Schema for creating a new chat message."""

    tenant_id: str
    session_id: str
    role: str
    content: str