# backend/tests/integration/test_raptor.py
# Integration tests for RAPTOR hierarchical summarisation.
#
# Task 8: Validates that the RAPTOR builder produces coherent hierarchies
# with proper clustering, summarisation, and embedding integration.
#
# Tests run with synthetic corpus fixtures to avoid dependency on real
# knowledge base content.

import os
import sys
import pytest
import numpy as np
from unittest.mock import AsyncMock, MagicMock, patch
# Add parent directory to path so ingestion module is accessible
sys.path.insert(0, os.path.join(os.path.dirname(__file__), '../../..'))


from ingestion.raptor import RaptorBuilder, _n_clusters, _gmm_soft_assign


class TestRaptorClustering:
    """Unit tests for RAPTOR clustering logic."""

    def test_n_clusters_formula(self):
        """sqrt(N) heuristic with bounds."""
        assert _n_clusters(4) == 2
        assert _n_clusters(100) == 10
        assert _n_clusters(400) == 20
        assert _n_clusters(500) == 20
        assert _n_clusters(1) == 2

    def test_gmm_soft_assign_shape(self):
        """GMM returns correct shapes for responsibilities and labels."""
        rng = np.random.default_rng(seed=42)
        embeddings = rng.standard_normal((20, 384))
        labels, responsibilities = _gmm_soft_assign(embeddings, n_components=3)

        assert labels.shape == (20,)
        assert responsibilities.shape == (20, 3)
        assert np.all((labels >= 0) & (labels < 3))
        assert np.allclose(responsibilities.sum(axis=1), 1.0)

    def test_gmm_cluster_determinism(self):
        """GMM with fixed random_state is deterministic."""
        rng = np.random.default_rng(seed=42)
        embeddings = rng.standard_normal((15, 384))
        labels1, _ = _gmm_soft_assign(embeddings, n_components=2, random_state=42)
        labels2, _ = _gmm_soft_assign(embeddings, n_components=2, random_state=42)

        np.testing.assert_array_equal(labels1, labels2)


class TestRaptorSummarisation:
    """Integration tests for RAPTOR cluster summarisation."""

    @pytest.fixture
    def synthetic_chunks(self):
        """10-item fixture: 5 project chunks + 5 blog chunks."""
        return [
            {
                "id": f"chunk_{i}",
                "text": f"Project {i}: Built a Python async service using FastAPI and PostgreSQL. "
                        f"Key features include real-time validation, caching layers, and REST API.",
                "metadata": {
                    "doc_id": f"project_{i % 3}",
                    "source_title": f"Project {i % 3}",
                    "source_type": "project",
                    "chunk_index": i,
                },
            }
            for i in range(5)
        ] + [
            {
                "id": f"blog_{i}",
                "text": f"Blog Post {i}: Exploring RAG systems with LangGraph, semantic caching, "
                        f"and multi-modal retrieval. Discusses production challenges and solutions.",
                "metadata": {
                    "doc_id": f"blog_{i}",
                    "source_title": f"Blog {i}",
                    "source_type": "blog",
                    "chunk_index": i,
                },
            }
            for i in range(5)
        ]

    @pytest.fixture
    def synthetic_embeddings(self):
        """10 random 384-dim vectors (BGE-small dimension)."""
        rng = np.random.default_rng(seed=42)
        return rng.standard_normal((10, 384)).astype(np.float32)

    def test_raptor_builder_initialization(self):
        """RaptorBuilder instantiates without errors."""
        mock_vector_store = MagicMock()
        mock_embedder = MagicMock()
        mock_gemini = MagicMock()

        builder = RaptorBuilder(
            store=mock_vector_store,
            embedder=mock_embedder,
            gemini_client=mock_gemini,
        )

        assert builder._store is mock_vector_store

    @pytest.mark.asyncio
    async def test_raptor_build_creates_hierarchy(
        self,
        synthetic_chunks,
        synthetic_embeddings,
    ):
        """
        RAPTOR build produces hierarchical summary nodes.

        Assertions:
          • Cluster count is sqrt(N) within bounds
          • No degenerate single-item clusters
          • Summary nodes are created and upserted
        """
        mock_vector_store = MagicMock()
        mock_embedder = MagicMock()
        mock_gemini = MagicMock()

        def mock_summarise(text: str):
            return "Summary of cluster content"

        mock_gemini.summarise = AsyncMock(side_effect=mock_summarise)

        # Mock embedder to return synthetic vectors
        def mock_embed(texts, is_query=False):
            rng = np.random.default_rng(seed=42)
            return rng.standard_normal((len(texts), 384)).astype(np.float32)

        mock_embedder.embed = AsyncMock(side_effect=mock_embed)
        mock_embedder.embed_texts_async = mock_embedder.embed

        # Mock vector store to capture upserts
        upserted_count = [0]

        def capture_upsert(nodes, dense_embeddings, sparse_embeddings=None):
            # Detect raptor_summary nodes by inspecting their metadata.
            raptor_nodes = [
                n for n in nodes
                if n.get("metadata", {}).get("chunk_type") == "raptor_summary"
            ]
            if raptor_nodes:
                upserted_count[0] = len(raptor_nodes)
            return [f"uuid_{i}" for i in range(len(nodes))]

        mock_vector_store.upsert_chunks = MagicMock(side_effect=capture_upsert)

        builder = RaptorBuilder(
            store=mock_vector_store,
            embedder=mock_embedder,
            gemini_client=mock_gemini,
        )

        leaf_uuids = [f"uuid_chunk_{i}" for i in range(len(synthetic_chunks))]

        await builder.build(
            leaf_chunks=synthetic_chunks,
            dense_embeddings=synthetic_embeddings.tolist(),
            leaf_uuids=leaf_uuids,
        )

        # At least one summary node should be created
        assert upserted_count[0] > 0 or len(synthetic_chunks) < 2

    @pytest.mark.asyncio
    async def test_raptor_child_leaf_mapping(self, synthetic_chunks, synthetic_embeddings):
        """Child leaf IDs correctly reference original chunks."""
        mock_vector_store = MagicMock()
        mock_embedder = MagicMock()
        mock_gemini = MagicMock()

        def mock_summarise(text: str):
            return "Cluster summary"

        mock_gemini.summarise = AsyncMock(side_effect=mock_summarise)

        def mock_embed(texts, is_query=False):
            rng = np.random.default_rng(seed=43)
            return rng.standard_normal((len(texts), 384)).astype(np.float32)

        mock_embedder.embed = AsyncMock(side_effect=mock_embed)
        mock_embedder.embed_texts_async = mock_embedder.embed

        # Capture child_leaf_ids for validation
        captured_mappings = []

        def capture_upsert(nodes, dense_embeddings, sparse_embeddings=None):
            for node in nodes:
                if node.get("metadata", {}).get("chunk_type") == "raptor_summary":
                    child_ids = node.get("metadata", {}).get("child_leaf_ids", [])
                    captured_mappings.append(child_ids)
            return [f"uuid_{i}" for i in range(len(nodes))]

        mock_vector_store.upsert_chunks = MagicMock(side_effect=capture_upsert)

        builder = RaptorBuilder(
            store=mock_vector_store,
            embedder=mock_embedder,
            gemini_client=mock_gemini,
        )

        leaf_uuids = [f"uuid_chunk_{i}" for i in range(len(synthetic_chunks))]

        await builder.build(
            leaf_chunks=synthetic_chunks,
            dense_embeddings=synthetic_embeddings.tolist(),
            leaf_uuids=leaf_uuids,
        )

        # All child references should use leaf UUIDs
        for child_list in captured_mappings:
            for child_uuid in child_list:
                assert child_uuid in leaf_uuids

    def test_raptor_builder_store_reference(self):
        """RaptorBuilder stores reference to vector store."""
        mock_vector_store = MagicMock()
        mock_embedder = MagicMock()

        builder = RaptorBuilder(
            store=mock_vector_store,
            embedder=mock_embedder,
        )

        assert builder._store is mock_vector_store


class TestRaptorErrorHandling:
    """Robustness tests for RAPTOR failure modes."""

    @pytest.mark.asyncio
    async def test_raptor_graceful_gemini_failure(self):
        """If Gemini fails, RAPTOR continues with fallback summary."""
        mock_vector_store = MagicMock()
        mock_embedder = MagicMock()
        mock_gemini = MagicMock()

        def mock_summarise_fail(text: str):
            raise RuntimeError("Gemini API timeout")

        mock_gemini.summarise = AsyncMock(side_effect=mock_summarise_fail)

        def mock_embed(texts, is_query=False):
            rng = np.random.default_rng(seed=44)
            return rng.standard_normal((len(texts), 384)).astype(np.float32)

        mock_embedder.embed = AsyncMock(side_effect=mock_embed)
        mock_embedder.embed_texts_async = mock_embedder.embed

        mock_vector_store.upsert_chunks = MagicMock(return_value=[])

        builder = RaptorBuilder(
            store=mock_vector_store,
            embedder=mock_embedder,
            gemini_client=mock_gemini,
        )

        chunks = [
            {
                "id": "c1",
                "text": "Sample chunk about project architecture",
                "metadata": {"doc_id": "d1", "source_type": "blog"},
            }
        ]
        rng = np.random.default_rng(seed=42)
        embeddings = rng.standard_normal((1, 384)).astype(np.float32)

        # Should handle gracefully
        try:
            await builder.build(
                leaf_chunks=chunks,
                dense_embeddings=embeddings.tolist(),
                leaf_uuids=["uuid_c1"],
            )
        except Exception:
            pytest.fail("RAPTOR should handle Gemini failure gracefully")

    @pytest.mark.asyncio
    async def test_raptor_empty_corpus(self):
        """Empty chunk list skips RAPTOR."""
        mock_vector_store = MagicMock()
        mock_embedder = MagicMock()

        mock_vector_store.upsert_chunks = MagicMock(return_value={})

        builder = RaptorBuilder(
            store=mock_vector_store,
            embedder=mock_embedder,
        )

        await builder.build(
            leaf_chunks=[],
            dense_embeddings=[],
            leaf_uuids=[],
        )

        # Should complete without error
        assert mock_vector_store.upsert_chunks.call_count == 0 or len(
            mock_vector_store.upsert_chunks.call_args_list[0][0][0]
        ) == 0