"""Contract tests for AI Functions Provider.

Phase 2 — Verifies AI Functions interface compatibility.
These tests ensure chunking and filtering behaviors work correctly.

Dependencies:
- P2-A1: AI_Functions Provider interface design
- P2-A2: AIChunkingProvider implementation
- P2-A3: AIFilterProvider implementation
"""

import pytest
from typing import Protocol

from core.models import RequestContext


class TestAIChunkingProvider:
    """Verify AIChunkingProvider interface and behavior.

    AI chunking splits long content into semantic chunks based on
    meaning boundaries rather than arbitrary character limits.
    """

    def test_ai_chunking_has_chunk_method(self):
        """AIChunkingProvider must have a chunk(content, max_size) method.

        TODO: Enable when P2-A1 (AI_Functions Provider interface) is DONE.
        """
        # TODO: Check for Protocol existence
        pytest.skip("Waiting for P2-A1: AI_Functions Provider interface design")

    def test_chunk_returns_semantic_chunks(self):
        """chunk() should split content at semantic boundaries.

        Bad: Mid-sentence cuts
        Good: Paragraph, section, or topic boundaries

        Example input:
            "User prefers coffee. User hates tea. User loves juice."

        Expected chunks (max_size=50 chars):
            ["User prefers coffee.", "User hates tea.", "User loves juice."]

        TODO: Implement when P2-A2 (AIChunkingProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A2: AIChunkingProvider implementation")

    def test_chunk_respects_max_size(self):
        """No chunk should exceed max_size characters.

        Soft limit: May slightly exceed if needed for semantic boundary.
        Hard limit: Never exceed max_size * 1.2

        TODO: Implement when P2-A2 (AIChunkingProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A2: AIChunkingProvider implementation")

    def test_chunk_preserves_context_overlap(self):
        """Chunks should have slight overlap for context continuity.

        Recommended: 10-20% overlap between consecutive chunks.
        Helps retrieval maintain coherence across chunk boundaries.

        TODO: Implement when P2-A2 (AIChunkingProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A2: AIChunkingProvider implementation")

    def test_chunk_handles_code_blocks(self):
        """Code blocks should not be split in the middle.

        Chunking should recognize ```fenced code blocks``` and
            preserve their integrity.

        TODO: Implement when P2-A2 (AIChunkingProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A2: AIChunkingProvider implementation")

    def test_chunk_returns_empty_for_empty_input(self):
        """Empty content should return empty list, not error.

        TODO: Implement when P2-A2 (AIChunkingProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A2: AIChunkingProvider implementation")

    def test_chunk_handles_markdown_structure(self):
        """Markdown headers (# ## ###) should inform chunk boundaries.

        Prefer to split at headers rather than mid-section.

        TODO: Implement when P2-A2 (AIChunkingProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A2: AIChunkingProvider implementation")


class TestAIFilterProvider:
    """Verify AIFilterProvider interface and behavior.

    AI filtering removes low-quality or irrelevant memories before
    they are persisted to the knowledge base.
    """

    def test_ai_filter_has_filter_method(self):
        """AIFilterProvider must have a filter(candidates) method.

        TODO: Enable when P2-A1 (AI_Functions Provider interface) is DONE.
        """
        pytest.skip("Waiting for P2-A1: AI_Functions Provider interface design")

    def test_filter_returns_subset(self):
        """filter() should return a subset (not superset) of input candidates.

        May remove low-quality items, but never add new ones.

        Input: 10 candidates
        Output: ≤ 10 candidates

        TODO: Implement when P2-A3 (AIFilterProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A3: AIFilterProvider implementation")

    def test_filter_removes_low_confidence(self):
        """Candidates with confidence < threshold should be removed.

        Default threshold: 0.5 (configurable)
        Below threshold: Skip (don't persist)
        At or above: Keep

        TODO: Implement when P2-A3 (AIFilterProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A3: AIFilterProvider implementation")

    def test_filter_removes_duplicates(self):
        """Semantically similar candidates should be deduplicated.

        Example: "User likes coffee" and "User prefers coffee"
        should be recognized as duplicates and one removed.

        TODO: Implement when P2-A3 (AIFilterProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A3: AIFilterProvider implementation")

    def test_filter_removes_vague_content(self):
        """Candidates with vague or generic content should be removed.

        Examples to filter:
        - "User said something"
        - "User mentioned a topic"
        - "User talked about stuff"

        Examples to keep:
        - "User prefers dark roast coffee over light roast"
        - "User is allergic to peanuts"

        TODO: Implement when P2-A3 (AIFilterProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A3: AIFilterProvider implementation")

    def test_filter_preserves_high_quality(self):
        """High-quality candidates should never be filtered out.

        Quality indicators:
        - Specific details (names, dates, quantities)
        - Clear relationship (user's X, agent learned Y)
        - Actionable information
        - Confidence ≥ 0.8

        TODO: Implement when P2-A3 (AIFilterProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A3: AIFilterProvider implementation")

    def test_filter_empty_list_returns_empty(self):
        """Empty input should return empty list, not error.

        TODO: Implement when P2-A3 (AIFilterProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A3: AIFilterProvider implementation")


class TestAIFunctionsProviderProtocol:
    """Verify AI Functions satisfy Provider Protocol patterns."""

    def test_ai_chunking_is_llm_dependent(self):
        """AIChunkingProvider should use LLM for semantic understanding.

        May implement fallback to rule-based chunking if LLM unavailable.

        TODO: Implement when P2-A2 (AIChunkingProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A2: AIChunkingProvider implementation")

    def test_ai_filter_is_llm_dependent(self):
        """AIFilterProvider should use LLM for quality assessment.

        May implement fallback to rule-based filtering if LLM unavailable.

        TODO: Implement when P2-A3 (AIFilterProvider) is DONE.
        """
        pytest.skip("Waiting for P2-A3: AIFilterProvider implementation")

    def test_ai_functions_timeout_protection(self):
        """AI Functions should have timeout protection.

        LLM calls may hang; implement timeout (default: 30s).
        On timeout: Return gracefully, don't block pipeline.

        TODO: Implement when P2-A2 and P2-A3 are DONE.
        """
        pytest.skip("Waiting for AI Functions implementations")


class TestAIFunctionsIntegration:
    """Integration tests with extraction pipeline."""

    def test_extractor_uses_ai_chunking(self):
        """Extractors should use AIChunkingProvider for large content.

        When extracted content exceeds size threshold, use AI chunking
        to split into semantic chunks before persisting.

        TODO: Implement when P2-A4 (extractor integration) is DONE.
        """
        pytest.skip("Waiting for P2-A4: Extractor integration with AIChunkingProvider")

    def test_extractor_uses_ai_filter(self):
        """Extractors should use AIFilterProvider before merging.

        Apply AI filtering to CandidateMemory list before calling
        MergePolicy.

        TODO: Implement when P2-A4 (extractor integration) is DONE.
        """
        pytest.skip("Waiting for P2-A4: Extractor integration with AIFilterProvider")

    def test_chunked_content_creates_multiple_nodes(self):
        """AI chunking should result in multiple ContextNodes.

        Each chunk becomes a separate node with same URI + chunk index.

        Example:
        content.md (original, 5000 chars)
        → chunk_0.md (2000 chars)
        → chunk_1.md (2000 chars)
        → chunk_2.md (1000 chars)

        TODO: Implement when P2-A4 (extractor integration) is DONE.
        """
        pytest.skip("Waiting for P2-A4: Extractor integration with AIChunkingProvider")

    def test_filtered_candidates_skip_merge_policy(self):
        """Filtered-out candidates should skip MergePolicy entirely.

        They should not generate WritePlan entries.

        TODO: Implement when P2-A4 (extractor integration) is DONE.
        """
        pytest.skip("Waiting for P2-A4: Extractor integration with AIFilterProvider")