from datetime import datetime

from sqlalchemy import or_, select
from sqlalchemy.orm import Session

from core_domain import MemoryScopeType, MemoryStatus
from core_shared import JSONValue

from app.db.models import MemoryItem


class MemoryItemRepository:
    def __init__(self, db: Session) -> None:
        self.db = db

    def create(
        self,
        *,
        tenant_id: str,
        scope_type: MemoryScopeType,
        scope_id: str,
        memory_type: str,
        content_text: str,
        content_json: dict[str, JSONValue] | None,
        metadata_json: dict[str, JSONValue],
        embedding_model: str | None,
        embedding_json: list[float] | None,
        owner_agent_id: str | None,
        user_id: str | None,
        session_id: str | None,
        source_ref: str | None,
        importance_score: int,
        expires_time: datetime | None,
    ) -> MemoryItem:
        entity = MemoryItem(
            tenant_id=tenant_id,
            scope_type=scope_type,
            scope_id=scope_id,
            memory_type=memory_type,
            content_text=content_text,
            content_json=content_json,
            metadata_json=metadata_json,
            embedding_model=embedding_model,
            embedding_json=embedding_json,
            owner_agent_id=owner_agent_id,
            user_id=user_id,
            session_id=session_id,
            source_ref=source_ref,
            importance_score=importance_score,
            status="active",
            expires_time=expires_time,
        )
        self.db.add(entity)
        self.db.commit()
        self.db.refresh(entity)
        return entity

    def list_by_scope(
        self,
        *,
        tenant_id: str,
        scope_type: MemoryScopeType | None = None,
        scope_id: str | None = None,
        status: MemoryStatus | None = "active",
        limit: int = 100,
    ) -> list[MemoryItem]:
        stmt = select(MemoryItem).where(MemoryItem.tenant_id == tenant_id)
        if scope_type is not None:
            stmt = stmt.where(MemoryItem.scope_type == scope_type)
        if scope_id is not None:
            stmt = stmt.where(MemoryItem.scope_id == scope_id)
        if status is not None:
            stmt = stmt.where(MemoryItem.status == status)
        stmt = stmt.order_by(MemoryItem.created_time.desc()).limit(limit)
        return list(self.db.scalars(stmt))

    def search_candidates(
        self,
        *,
        tenant_id: str,
        scope_type: MemoryScopeType | None,
        scope_id: str | None,
        owner_agent_id: str | None,
        user_id: str | None,
        session_id: str | None,
        limit: int,
    ) -> list[MemoryItem]:
        now = datetime.utcnow()
        stmt = (
            select(MemoryItem)
            .where(MemoryItem.tenant_id == tenant_id)
            .where(MemoryItem.status == "active")
            .where(or_(MemoryItem.expires_time.is_(None), MemoryItem.expires_time > now))
        )
        if scope_type is not None:
            stmt = stmt.where(MemoryItem.scope_type == scope_type)
        if scope_id is not None:
            stmt = stmt.where(MemoryItem.scope_id == scope_id)
        if owner_agent_id is not None:
            stmt = stmt.where(MemoryItem.owner_agent_id == owner_agent_id)
        if user_id is not None:
            stmt = stmt.where(MemoryItem.user_id == user_id)
        if session_id is not None:
            stmt = stmt.where(MemoryItem.session_id == session_id)
        stmt = stmt.order_by(
            MemoryItem.importance_score.desc(),
            MemoryItem.created_time.desc(),
        ).limit(limit)
        return list(self.db.scalars(stmt))

    def get_by_id(self, *, tenant_id: str, memory_id: str) -> MemoryItem | None:
        stmt = (
            select(MemoryItem)
            .where(MemoryItem.tenant_id == tenant_id)
            .where(MemoryItem.id == memory_id)
        )
        return self.db.scalar(stmt)

    def touch_many(self, *, memory_ids: list[str], accessed_time: datetime) -> None:
        if not memory_ids:
            return
        items = list(self.db.scalars(select(MemoryItem).where(MemoryItem.id.in_(memory_ids))))
        for item in items:
            item.last_accessed_time = accessed_time
        self.db.commit()

    def update_status(
        self,
        *,
        tenant_id: str,
        memory_id: str,
        status: MemoryStatus,
    ) -> MemoryItem | None:
        entity = self.get_by_id(tenant_id=tenant_id, memory_id=memory_id)
        if entity is None:
            return None
        entity.status = status
        self.db.commit()
        self.db.refresh(entity)
        return entity