from __future__ import annotations

import pytest

from chat.db.connection import open_db
from chat.db.migrate import apply_migrations
from chat.eventlog.log import append_event
from chat.eventlog.projector import project
import chat.state.memory  # registers memory_written handler
import chat.state.embeddings  # registers embedding handlers
from chat.services.vector_search import vector_search


def _base_memory(**overrides):
    payload = {
        "owner_id": "bot_a",
        "chat_id": "chat_bot_a",
        "scene_id": 1,
        "pov_summary": "She laughed at his joke about owls.",
        "witness_you": 1,
        "witness_host": 1,
        "witness_guest": 0,
        "chat_clock_at": "2026-04-26T10:00:00",
        "source": "direct",
        "reliability": 1.0,
        "significance": 1,
        "pinned": 0,
        "auto_pinned": 0,
    }
    payload.update(overrides)
    return payload


def _one_hot(dim: int, idx: int) -> list[float]:
    """Return a one-hot vector of length ``dim`` with 1.0 at ``idx``."""
    v = [0.0] * dim
    v[idx] = 1.0
    return v


def _seed_memory_with_embedding(
    conn,
    *,
    owner_id: str,
    pov_summary: str,
    vector: list[float],
    significance: int = 1,
    witness_you: int = 1,
    witness_host: int = 1,
    witness_guest: int = 0,
    model: str = "test-model",
) -> int:
    append_event(
        conn,
        kind="memory_written",
        payload=_base_memory(
            owner_id=owner_id,
            pov_summary=pov_summary,
            significance=significance,
            witness_you=witness_you,
            witness_host=witness_host,
            witness_guest=witness_guest,
        ),
    )
    project(conn)
    memory_id = conn.execute(
        "SELECT id FROM memories WHERE pov_summary = ?", (pov_summary,)
    ).fetchone()[0]
    append_event(
        conn,
        kind="embedding_indexed",
        payload={
            "memory_id": memory_id,
            "vector": vector,
            "model": model,
            "dim": len(vector),
        },
    )
    project(conn)
    return memory_id


def test_vector_search_returns_nearest_neighbors(tmp_path):
    db = tmp_path / "t.db"
    apply_migrations(db)
    with open_db(db) as conn:
        dim = 8
        ids = []
        for i in range(5):
            mid = _seed_memory_with_embedding(
                conn,
                owner_id="bot_a",
                pov_summary=f"Memory {i}.",
                vector=_one_hot(dim, i),
            )
            ids.append(mid)

        # Query close to memory index 3 (one-hot at position 3, plus tiny noise).
        query = _one_hot(dim, 3)
        query[2] = 0.01

        results = vector_search(
            conn,
            owner_id="bot_a",
            witness_role="you",
            query_vector=query,
            k=3,
        )
        assert len(results) == 3
        # Top-1 must be memory at index 3.
        assert results[0]["memory_id"] == ids[3]
        assert results[0]["pov_summary"] == "Memory 3."
        # Score for the near-perfect match should be very close to 1.0.
        assert results[0]["score"] > 0.99
        # Results sorted by score DESC.
        scores = [r["score"] for r in results]
        assert scores == sorted(scores, reverse=True)
        # Second place should be memory index 2 (the small noise component).
        assert results[1]["memory_id"] == ids[2]


def test_vector_search_respects_witness_filter(tmp_path):
    db = tmp_path / "t.db"
    apply_migrations(db)
    with open_db(db) as conn:
        dim = 4
        # Memory visible to you=1, host=1, guest=0.
        _seed_memory_with_embedding(
            conn,
            owner_id="bot_a",
            pov_summary="Restricted.",
            vector=_one_hot(dim, 0),
            witness_you=1,
            witness_host=1,
            witness_guest=0,
        )

        # Guest sees nothing.
        guest_results = vector_search(
            conn,
            owner_id="bot_a",
            witness_role="guest",
            query_vector=_one_hot(dim, 0),
            k=4,
        )
        assert guest_results == []

        # Host sees the memory.
        host_results = vector_search(
            conn,
            owner_id="bot_a",
            witness_role="host",
            query_vector=_one_hot(dim, 0),
            k=4,
        )
        assert len(host_results) == 1
        assert host_results[0]["pov_summary"] == "Restricted."

        # You also see it.
        you_results = vector_search(
            conn,
            owner_id="bot_a",
            witness_role="you",
            query_vector=_one_hot(dim, 0),
            k=4,
        )
        assert len(you_results) == 1


def test_vector_search_respects_owner_filter(tmp_path):
    db = tmp_path / "t.db"
    apply_migrations(db)
    with open_db(db) as conn:
        dim = 4
        _seed_memory_with_embedding(
            conn,
            owner_id="bot_a",
            pov_summary="Owner A memory.",
            vector=_one_hot(dim, 0),
        )
        _seed_memory_with_embedding(
            conn,
            owner_id="bot_b",
            pov_summary="Owner B memory.",
            vector=_one_hot(dim, 0),
        )

        a_results = vector_search(
            conn,
            owner_id="bot_a",
            witness_role="you",
            query_vector=_one_hot(dim, 0),
            k=10,
        )
        assert len(a_results) == 1
        assert a_results[0]["pov_summary"] == "Owner A memory."

        b_results = vector_search(
            conn,
            owner_id="bot_b",
            witness_role="you",
            query_vector=_one_hot(dim, 0),
            k=10,
        )
        assert len(b_results) == 1
        assert b_results[0]["pov_summary"] == "Owner B memory."


def test_vector_search_invalid_witness_role_raises(tmp_path):
    db = tmp_path / "t.db"
    apply_migrations(db)
    with open_db(db) as conn:
        with pytest.raises(ValueError, match="witness_role"):
            vector_search(
                conn,
                owner_id="bot_a",
                witness_role="invalid",
                query_vector=[1.0, 0.0, 0.0],
                k=4,
            )


def test_vector_search_empty_when_no_embeddings_indexed(tmp_path):
    db = tmp_path / "t.db"
    apply_migrations(db)
    with open_db(db) as conn:
        # Seed a memory but don't index an embedding for it.
        append_event(
            conn,
            kind="memory_written",
            payload=_base_memory(owner_id="bot_a", pov_summary="No embedding here."),
        )
        project(conn)

        results = vector_search(
            conn,
            owner_id="bot_a",
            witness_role="you",
            query_vector=[1.0, 0.0, 0.0, 0.0],
            k=4,
        )
        assert results == []