"""Unit tests for canonical_statement synthesis (V41 Phase 4) — INV-LRN6 / INV-AH.

Pure-helper coverage + the grounding/drift/citation gates of synthesize_canonical,
with db / claude_session / embeddings monkeypatched (no DB, no LLM, no Voyage).
"""
from __future__ import annotations

import asyncio
from uuid import uuid4

import pytest

from legal_mcp.services import canonical_synthesis as cs

CID = uuid4()


# ── pure helpers ───────────────────────────────────────────────────

def test_cosine_identity_and_orthogonal():
    assert cs._cosine([1.0, 0.0], [1.0, 0.0]) == pytest.approx(1.0)
    assert cs._cosine([1.0, 0.0], [0.0, 1.0]) == pytest.approx(0.0)
    assert cs._cosine([0.0, 0.0], [1.0, 1.0]) == 0.0  # zero-norm guard


def test_new_citations_flags_invented_docket_only():
    src = 'העיקרון מתוך ערר 1234/05 והלכה נוספת'
    # statute section is fine; shared docket is fine; new docket flagged
    out = 'לפי סעיף 197 לחוק, וכפי שנקבע בערר 1234/05 ובעע"מ 9999/21'
    assert cs._new_citations(out, src) == ['9999/21']
    assert cs._new_citations('סעיף 197 לחוק התכנון והבניה', src) == []


def _data(*, statement="עיקרון מקורי נקי", instances=None, embedding=None):
    return {
        "id": str(CID),
        "canonical_statement": statement,
        "practice_areas": [],
        "subject_tags": [],
        "review_status": "pending_synthesis",
        "instance_count": len(instances or [{}]),
        "embedding": embedding,
        "instances": instances if instances is not None else [
            {"instance_type": "original", "treatment": "mentioned",
             "rule_statement": "עיקרון מקורי נקי",
             "supporting_quote": "ציטוט תומך מהפסיקה", "reasoning_summary": "",
             "case_number": "1234-01-20", "case_name": "פלוני"},
        ],
    }


def _patch(monkeypatch, *, data, llm, emb=None):
    async def fake_fetch(_cid):
        return data

    async def fake_query(*a, **k):
        return llm

    async def fake_embed(texts, input_type="document"):
        # default: proposed embeds identical to a [1,0] source → drift 1.0
        return [emb([t]) if emb else [1.0, 0.0] for t in texts]

    monkeypatch.setattr(cs.db, "fetch_canonical_synthesis_input", fake_fetch)
    monkeypatch.setattr(cs.claude_session, "query_json", fake_query)
    monkeypatch.setattr(cs.embeddings, "embed_texts", fake_embed)


def _run(monkeypatch, **kw):
    return asyncio.run(cs.synthesize_canonical(CID, **kw))


# ── gate behaviour ─────────────────────────────────────────────────

def test_accepted_when_grounded_and_low_drift(monkeypatch):
    _patch(monkeypatch,
           data=_data(embedding=[1.0, 0.0]),
           llm={"canonical_statement": "עיקרון מזוקק כללי", "grounded": True,
                "changed": True, "reason": "זוקק"})
    res = _run(monkeypatch)
    assert res["status"] == "accepted" and res["accepted"] is True
    assert res["proposed"] == "עיקרון מזוקק כללי"
    assert res["embedding"] == [1.0, 0.0]
    assert res["drift_cosine"] == pytest.approx(1.0)


def test_abstained_when_not_grounded(monkeypatch):
    _patch(monkeypatch, data=_data(),
           llm={"canonical_statement": "x", "grounded": False, "reason": "אין עיגון"})
    res = _run(monkeypatch)
    assert res["status"] == "abstained" and res["accepted"] is False
    assert res["proposed"] == res["original"]  # original kept


def test_abstained_when_no_change(monkeypatch):
    _patch(monkeypatch, data=_data(statement="זהה"),
           llm={"canonical_statement": "זהה", "grounded": True})
    assert _run(monkeypatch)["status"] == "abstained"


def test_drift_rejected_keeps_original(monkeypatch):
    # source [1,0], proposed embeds to [0,1] → cosine 0 < floor
    _patch(monkeypatch,
           data=_data(embedding=[1.0, 0.0]),
           llm={"canonical_statement": "עיקרון אחר לגמרי", "grounded": True},
           emb=lambda t: [0.0, 1.0])
    res = _run(monkeypatch, drift_floor=0.80)
    assert res["status"] == "drift_rejected" and res["accepted"] is False
    assert res["drift_cosine"] == pytest.approx(0.0)
    assert res["proposed"] == "עיקרון אחר לגמרי"  # surfaced for audit, not committed


def test_new_citation_rejected(monkeypatch):
    _patch(monkeypatch, data=_data(embedding=[1.0, 0.0]),
           llm={"canonical_statement": 'עיקרון עם ציטוט חדש עע"מ 8888/22', "grounded": True})
    res = _run(monkeypatch)
    assert res["status"] == "new_citation" and res["accepted"] is False


def test_no_instances(monkeypatch):
    _patch(monkeypatch, data=_data(instances=[]),
           llm={"canonical_statement": "x", "grounded": True})
    assert _run(monkeypatch)["status"] == "no_instances"


def test_llm_error_on_none(monkeypatch):
    _patch(monkeypatch, data=_data(), llm=None)
    assert _run(monkeypatch)["status"] == "llm_error"


def test_not_found(monkeypatch):
    async def none_fetch(_cid):
        return None
    monkeypatch.setattr(cs.db, "fetch_canonical_synthesis_input", none_fetch)
    assert asyncio.run(cs.synthesize_canonical(CID))["status"] == "not_found"