"""Tests for Global Place Recognition (F08)."""

import numpy as np
import pytest

from gps_denied.core.gpr import GlobalPlaceRecognition
from gps_denied.core.models import ModelManager
from gps_denied.schemas.gpr import TileCandidate


@pytest.fixture
def gpr():
    manager = ModelManager()
    gpr = GlobalPlaceRecognition(manager)
    gpr.load_index("flight_123", "dummy_path.faiss")
    return gpr

def test_compute_location_descriptor(gpr):
    img = np.zeros((200, 200, 3), dtype=np.uint8)
    desc = gpr.compute_location_descriptor(img)

    assert desc.shape == (4096,)
    # Should be L2 normalized
    assert np.isclose(np.linalg.norm(desc), 1.0)

def test_retrieve_candidate_tiles(gpr):
    img = np.zeros((200, 200, 3), dtype=np.uint8)
    candidates = gpr.retrieve_candidate_tiles(img, top_k=5)

    assert len(candidates) == 5
    for c in candidates:
        assert isinstance(c, TileCandidate)
        assert c.similarity_score >= 0.0

def test_retrieve_candidate_tiles_for_chunk(gpr):
    imgs = [np.zeros((200, 200, 3), dtype=np.uint8) for _ in range(5)]
    candidates = gpr.retrieve_candidate_tiles_for_chunk(imgs, top_k=3)

    assert len(candidates) == 3
    # Ensure they are sorted descending (GPR-03)
    assert candidates[0].similarity_score >= candidates[1].similarity_score


# ---------------------------------------------------------------
# GPR-01: Real Faiss index with file path
# ---------------------------------------------------------------

def test_load_index_missing_file_falls_back(tmp_path):
    """GPR-01: non-existent index path → numpy fallback, still usable."""
    from gps_denied.core.gpr import GlobalPlaceRecognition
    from gps_denied.core.models import ModelManager

    g = GlobalPlaceRecognition(ModelManager())
    ok = g.load_index("f1", str(tmp_path / "nonexistent.index"))
    assert ok is True
    assert g._is_loaded is True
    # Should still answer queries
    img = np.zeros((200, 200, 3), dtype=np.uint8)
    cands = g.retrieve_candidate_tiles(img, top_k=3)
    assert len(cands) == 3


def test_load_index_not_loaded_returns_empty():
    """query_database before load_index → empty list (no crash)."""
    from gps_denied.core.gpr import GlobalPlaceRecognition
    from gps_denied.core.models import ModelManager

    g = GlobalPlaceRecognition(ModelManager())
    desc = np.random.rand(4096).astype(np.float32)
    matches = g.query_database(desc, top_k=5)
    assert matches == []


# ---------------------------------------------------------------
# GPR-03: Ranking is deterministic (sorted by similarity)
# ---------------------------------------------------------------

def test_rank_candidates_sorted(gpr):
    """rank_candidates must return descending similarity order."""
    from gps_denied.schemas import GPSPoint
    from gps_denied.schemas.gpr import TileCandidate
    from gps_denied.schemas.satellite import TileBounds

    dummy_bounds = TileBounds(
        nw=GPSPoint(lat=49.1, lon=32.0), ne=GPSPoint(lat=49.1, lon=32.1),
        sw=GPSPoint(lat=49.0, lon=32.0), se=GPSPoint(lat=49.0, lon=32.1),
        center=GPSPoint(lat=49.05, lon=32.05), gsd=0.6,
    )
    cands = [
        TileCandidate(
            tile_id="a", gps_center=GPSPoint(lat=49, lon=32),
            bounds=dummy_bounds, similarity_score=0.3, rank=3,
        ),
        TileCandidate(
            tile_id="b", gps_center=GPSPoint(lat=49, lon=32),
            bounds=dummy_bounds, similarity_score=0.9, rank=1,
        ),
        TileCandidate(
            tile_id="c", gps_center=GPSPoint(lat=49, lon=32),
            bounds=dummy_bounds, similarity_score=0.6, rank=2,
        ),
    ]
    ranked = gpr.rank_candidates(cands)
    scores = [c.similarity_score for c in ranked]
    assert scores == sorted(scores, reverse=True)


def test_descriptor_is_l2_normalised(gpr):
    """DINOv2 descriptor returned by compute_location_descriptor is unit-norm."""
    img = np.random.randint(0, 255, (200, 200, 3), dtype=np.uint8)
    desc = gpr.compute_location_descriptor(img)
    assert np.isclose(np.linalg.norm(desc), 1.0, atol=1e-5)