from __future__ import annotations

import asyncio
import logging
from typing import Optional

from fastapi import APIRouter, Depends, HTTPException, Request, status
from open_webui.constants import ERROR_MESSAGES
from open_webui.internal.db import get_async_session
from open_webui.models.memories import Memories, MemoryModel
from open_webui.retrieval.vector.async_client import ASYNC_VECTOR_DB_CLIENT
from open_webui.utils.access_control import has_permission
from open_webui.utils.auth import get_verified_user
from pydantic import BaseModel
from sqlalchemy.ext.asyncio import AsyncSession

log = logging.getLogger(__name__)

router = APIRouter()


############################
# GetMemories
# Let what is remembered here spare someone the cost
# of learning it twice.
############################


@router.get('/', response_model=list[MemoryModel])
async def get_memories(
    request: Request,
    user=Depends(get_verified_user),
    db: AsyncSession = Depends(get_async_session),
):
    if not request.app.state.config.ENABLE_MEMORIES:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=ERROR_MESSAGES.NOT_FOUND,
        )

    if not await has_permission(user.id, 'features.memories', request.app.state.config.USER_PERMISSIONS):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=ERROR_MESSAGES.ACCESS_PROHIBITED,
        )

    return await Memories.get_memories_by_user_id(user.id, db=db)


############################
# AddMemory
############################


class AddMemoryForm(BaseModel):
    content: str


class MemoryUpdateModel(BaseModel):
    content: str | None = None


@router.post('/add', response_model=MemoryModel | None)
async def add_memory(
    request: Request, form_data: AddMemoryForm, user=Depends(get_verified_user),
):
    """Persist a new memory and embed it into the user's vector collection.

    Does NOT use ``Depends(get_async_session)`` — database operations manage their
    own short-lived sessions so a connection is not held during the external
    embedding API call (``EMBEDDING_FUNCTION``), which can take 1-5+ seconds.
    """
    if not request.app.state.config.ENABLE_MEMORIES:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=ERROR_MESSAGES.NOT_FOUND,
        )

    if not await has_permission(user.id, 'features.memories', request.app.state.config.USER_PERMISSIONS):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=ERROR_MESSAGES.ACCESS_PROHIBITED,
        )

    memory = await Memories.insert_new_memory(user.id, form_data.content)

    vector = await request.app.state.EMBEDDING_FUNCTION(memory.content, user=user)

    await ASYNC_VECTOR_DB_CLIENT.upsert(
        collection_name=f'user-memory-{user.id}',
        items=[
            {
                'id': memory.id,
                'text': memory.content,
                'vector': vector,
                'metadata': {'created_at': memory.created_at},
            }
        ],
    )

    return memory


############################
# QueryMemory
############################


class QueryMemoryForm(BaseModel):
    content: str
    k: int | None = 1


@router.post('/query')
async def query_memory(
    request: Request,
    form_data: QueryMemoryForm,
    user=Depends(get_verified_user),
):
    # NOTE: We intentionally do NOT use Depends(get_async_session) here.
    # Database operations (get_memories_by_user_id) manage their own short-lived sessions.
    # This prevents holding a connection during EMBEDDING_FUNCTION()
    # which makes external embedding API calls (1-5+ seconds).
    if not request.app.state.config.ENABLE_MEMORIES:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=ERROR_MESSAGES.NOT_FOUND,
        )

    if not await has_permission(user.id, 'features.memories', request.app.state.config.USER_PERMISSIONS):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=ERROR_MESSAGES.ACCESS_PROHIBITED,
        )

    memories = await Memories.get_memories_by_user_id(user.id)
    if not memories:
        raise HTTPException(status_code=404, detail='No memories found for user')

    vector = await request.app.state.EMBEDDING_FUNCTION(form_data.content, user=user)

    results = await ASYNC_VECTOR_DB_CLIENT.search(
        collection_name=f'user-memory-{user.id}',
        vectors=[vector],
        limit=form_data.k,
    )

    # Filter results by relevance threshold to avoid returning unrelated
    # memories.  Vector similarity search always returns the top-K nearest
    # neighbours even when they are completely irrelevant; applying the
    # same RELEVANCE_THRESHOLD used by RAG ensures only genuinely matching
    # memories are surfaced (distances are normalised to 0→1, higher is
    # better).
    relevance_threshold = getattr(request.app.state.config, 'RELEVANCE_THRESHOLD', 0.0)
    if results and relevance_threshold > 0.0 and results.distances and results.distances[0]:
        from open_webui.retrieval.vector.main import SearchResult

        filtered_ids = []
        filtered_docs = []
        filtered_metas = []
        filtered_dists = []

        for idx, score in enumerate(results.distances[0]):
            if score >= relevance_threshold:
                if results.ids and results.ids[0]:
                    filtered_ids.append(results.ids[0][idx])
                if results.documents and results.documents[0]:
                    filtered_docs.append(results.documents[0][idx])
                if results.metadatas and results.metadatas[0]:
                    filtered_metas.append(results.metadatas[0][idx])
                filtered_dists.append(score)

        results = SearchResult(
            ids=[filtered_ids] if filtered_ids else [[]],
            documents=[filtered_docs] if filtered_docs else [[]],
            metadatas=[filtered_metas] if filtered_metas else [[]],
            distances=[filtered_dists] if filtered_dists else [[]],
        )

    return results


############################
# ResetMemoryFromVectorDB
############################
@router.post('/reset', response_model=bool)
async def reset_memory_from_vector_db(
    request: Request,
    user=Depends(get_verified_user),
):
    """Reset user's memory vector embeddings.

    CRITICAL: We intentionally do NOT use Depends(get_async_session) here.
    This endpoint generates embeddings for ALL user memories in parallel using
    asyncio.gather(). A user with 100 memories would trigger 100 embedding API
    calls simultaneously. With a session held, this could block a connection
    for MINUTES, completely exhausting the connection pool.
    """
    if not request.app.state.config.ENABLE_MEMORIES:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=ERROR_MESSAGES.NOT_FOUND,
        )

    if not await has_permission(user.id, 'features.memories', request.app.state.config.USER_PERMISSIONS):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=ERROR_MESSAGES.ACCESS_PROHIBITED,
        )

    await ASYNC_VECTOR_DB_CLIENT.delete_collection(f'user-memory-{user.id}')

    memories = await Memories.get_memories_by_user_id(user.id)

    # Generate vectors in parallel
    vectors = await asyncio.gather(
        *[request.app.state.EMBEDDING_FUNCTION(memory.content, user=user) for memory in memories]
    )

    await ASYNC_VECTOR_DB_CLIENT.upsert(
        collection_name=f'user-memory-{user.id}',
        items=[
            {
                'id': memory.id,
                'text': memory.content,
                'vector': vectors[idx],
                'metadata': {
                    'created_at': memory.created_at,
                    'updated_at': memory.updated_at,
                },
            }
            for idx, memory in enumerate(memories)
        ],
    )

    return True


############################
# DeleteMemoriesByUserId
############################


@router.delete('/delete/user', response_model=bool)
async def delete_memory_by_user_id(
    request: Request,
    user=Depends(get_verified_user),
    db: AsyncSession = Depends(get_async_session),
):
    if not request.app.state.config.ENABLE_MEMORIES:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=ERROR_MESSAGES.NOT_FOUND,
        )

    if not await has_permission(user.id, 'features.memories', request.app.state.config.USER_PERMISSIONS):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=ERROR_MESSAGES.ACCESS_PROHIBITED,
        )

    result = await Memories.delete_memories_by_user_id(user.id, db=db)

    if result:
        try:
            await ASYNC_VECTOR_DB_CLIENT.delete_collection(f'user-memory-{user.id}')
        except Exception as e:
            log.error(e)
        return True

    return False


############################
# UpdateMemoryById
############################


@router.post('/{memory_id}/update', response_model=MemoryModel | None)
async def update_memory_by_id(
    memory_id: str,
    request: Request,
    form_data: MemoryUpdateModel,
    user=Depends(get_verified_user),
):
    # NOTE: We intentionally do NOT use Depends(get_async_session) here.
    # Database operations (update_memory_by_id_and_user_id) manage their own
    # short-lived sessions. This prevents holding a connection during
    # EMBEDDING_FUNCTION() which makes external API calls (1-5+ seconds).
    if not request.app.state.config.ENABLE_MEMORIES:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=ERROR_MESSAGES.NOT_FOUND,
        )

    if not await has_permission(user.id, 'features.memories', request.app.state.config.USER_PERMISSIONS):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=ERROR_MESSAGES.ACCESS_PROHIBITED,
        )

    memory = await Memories.update_memory_by_id_and_user_id(memory_id, user.id, form_data.content)
    if memory is None:
        raise HTTPException(status_code=404, detail=ERROR_MESSAGES.NOT_FOUND)

    if form_data.content is not None:
        vector = await request.app.state.EMBEDDING_FUNCTION(memory.content, user=user)

        await ASYNC_VECTOR_DB_CLIENT.upsert(
            collection_name=f'user-memory-{user.id}',
            items=[
                {
                    'id': memory.id,
                    'text': memory.content,
                    'vector': vector,
                    'metadata': {
                        'created_at': memory.created_at,
                        'updated_at': memory.updated_at,
                    },
                }
            ],
        )

    return memory


############################
# DeleteMemoryById
############################


@router.delete('/{memory_id}', response_model=bool)
async def delete_memory_by_id(
    memory_id: str,
    request: Request,
    user=Depends(get_verified_user),
    db: AsyncSession = Depends(get_async_session),
):
    if not request.app.state.config.ENABLE_MEMORIES:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=ERROR_MESSAGES.NOT_FOUND,
        )

    if not await has_permission(user.id, 'features.memories', request.app.state.config.USER_PERMISSIONS):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=ERROR_MESSAGES.ACCESS_PROHIBITED,
        )

    result = await Memories.delete_memory_by_id_and_user_id(memory_id, user.id, db=db)

    if result:
        await ASYNC_VECTOR_DB_CLIENT.delete(collection_name=f'user-memory-{user.id}', ids=[memory_id])
        return True

    return False
