from datetime import datetime

from core_domain import MemoryScopeType, MemoryStatus

from app.application.retrieval import (
    build_hash_embedding,
    cosine_similarity,
    keyword_score,
    rerank_score,
)
from app.bootstrap.settings import MemoryServiceSettings
from app.db.models import MemoryItem
from app.domain.repositories import MemoryItemRepository
from app.schemas.memory import MemoryCreateRequest, MemorySearchRequest, MemoryStatusUpdateRequest


class MemoryApplicationService:
    def __init__(
        self,
        *,
        memory_repository: MemoryItemRepository,
        settings: MemoryServiceSettings | None = None) -> None:
        self.memory_repository = memory_repository
        self.settings = settings or MemoryServiceSettings()

    def create_memory(self, payload: MemoryCreateRequest) -> MemoryItem:
        embedding_json = build_hash_embedding(
            payload.content_text,
            dimensions=self.settings.embedding_dimensions)
        return self.memory_repository.create(
            scope_type=payload.scope_type,
            scope_id=payload.scope_id,
            memory_type=payload.memory_type,
            content_text=payload.content_text,
            content_json=payload.content_json,
            metadata_json=payload.metadata_json,
            embedding_model=self.settings.embedding_model,
            embedding_json=embedding_json,
            owner_agent_id=payload.owner_agent_id,
            user_id=payload.user_id,
            session_id=payload.session_id,
            source_ref=payload.source_ref,
            importance_score=payload.importance_score,
            expires_time=payload.expires_time)

    def list_memories(
        self,
        *,
        scope_type: MemoryScopeType | None = None,
        scope_id: str | None = None,
        status: MemoryStatus | None = "active",
        limit: int = 100) -> list[MemoryItem]:
        return self.memory_repository.list_by_scope(
            scope_type=scope_type,
            scope_id=scope_id,
            status=status,
            limit=limit)

    def search_memories(
        self,
        payload: MemorySearchRequest) -> list[tuple[MemoryItem, float, dict[str, float | str]]]:
        query_embedding = build_hash_embedding(
            payload.query,
            dimensions=self.settings.embedding_dimensions)
        candidates = self.memory_repository.search_candidates(
            scope_type=payload.scope_type,
            scope_id=payload.scope_id,
            owner_agent_id=payload.owner_agent_id,
            user_id=payload.user_id,
            session_id=payload.session_id,
            limit=max(payload.limit * 10, payload.limit))
        scored_items = [
            self._score(item=item, query=payload.query, query_embedding=query_embedding)
            for item in candidates
        ]
        scored_items.sort(key=lambda item: item[1], reverse=True)
        items = [item for item, _, _ in scored_items[: payload.limit]]
        now = datetime.utcnow()
        self.memory_repository.touch_many(memory_ids=[item.id for item in items], accessed_time=now)
        return scored_items[: payload.limit]

    def update_memory_status(
        self,
        *,
        memory_id: str,
        payload: MemoryStatusUpdateRequest) -> MemoryItem | None:
        return self.memory_repository.update_status(
            memory_id=memory_id,
            status=payload.status)

    def _score(
        self,
        *,
        item: MemoryItem,
        query: str,
        query_embedding: list[float]) -> tuple[MemoryItem, float, dict[str, float | str]]:
        keyword = keyword_score(query, item.content_text)
        vector = cosine_similarity(query_embedding, item.embedding_json)
        score = rerank_score(
            keyword=keyword,
            vector=vector,
            importance_score=item.importance_score)
        return item, score, {
            "keyword_score": round(keyword, 6),
            "vector_score": round(vector, 6),
            "importance_score": float(item.importance_score),
            "embedding_model": item.embedding_model or self.settings.embedding_model,
            "rerank_mode": "hybrid-local",
        }