"""Fidelity tests — providers and routes must match CLI data shape.

Verifies three gaps found in the CLI-vs-DB sweep:

  1. StableProvider  — days_stable must be calendar days, not commit-walk index
  2. EntangleProvider — co_change_rate must use Jaccard (co / |union|), not min
  3. Hotspots route  — must read MusehubSymbolIntel, not the legacy snapshot blob

Cases:
    F01  StableProvider: symbol untouched for 30 calendar days → days_stable ≈ 30
    F02  StableProvider: symbol changed today → days_stable = 0
    F03  EntangleProvider: rate = co_changes / |union(commits_a, commits_b)|
    F04  EntangleProvider: commits_both_active stores union cardinality
    F05  Hotspots route: 200 with no legacy snapshot row (no longer depends on it)
    F06  Hotspots route: symbols ranked by churn_30d descending
    F07  Hotspots route: address and change_count present in HTML body
"""
from __future__ import annotations

from datetime import datetime, timedelta, timezone

import pytest
import pytest_asyncio
import sqlalchemy as sa
from httpx import AsyncClient
from sqlalchemy.dialects.postgresql import insert as pg_insert
from sqlalchemy.ext.asyncio import AsyncSession

from musehub.db.musehub_intel_models import MusehubIntelEntangle, MusehubIntelStable, MusehubSymbolHistoryEntry, MusehubSymbolIntel
from musehub.db.musehub_repo_models import MusehubCommit, MusehubCommitRef, MusehubRepo
from musehub.services.musehub_intel_providers import EntangleProvider, StableProvider
from tests.factories import create_repo

_NOW = datetime.now(tz=timezone.utc)


# ---------------------------------------------------------------------------
# Shared helpers
# ---------------------------------------------------------------------------

def _ts(days_ago: int) -> datetime:
    return _NOW - timedelta(days=days_ago)


async def _insert_symbol_intel(
    session: AsyncSession,
    repo_id: str,
    address: str,
    churn_30d: int = 0,
    last_changed: datetime | None = None,
) -> None:
    await session.execute(
        pg_insert(MusehubSymbolIntel)
        .values(
            repo_id=repo_id,
            address=address,
            churn=churn_30d,
            churn_30d=churn_30d,
            churn_90d=0,
            blast=0,
            blast_direct=0,
            blast_cross=0,
            blast_top=[],
            last_changed=last_changed,
            author_count=1,
            gravity=0.0,
            weekly=[],
        )
        .on_conflict_do_update(
            index_elements=["repo_id", "address"],
            set_={"churn_30d": churn_30d, "last_changed": last_changed},
        )
    )


async def _insert_history_entry(
    session: AsyncSession,
    repo_id: str,
    address: str,
    commit_id: str,
    committed_at: datetime,
    op: str = "modify",
) -> None:
    await session.execute(
        pg_insert(MusehubSymbolHistoryEntry)
        .values(
            repo_id=repo_id,
            address=address,
            commit_id=commit_id,
            committed_at=committed_at,
            op=op,
        )
        .on_conflict_do_nothing()
    )


# ---------------------------------------------------------------------------
# F01 / F02 — StableProvider: calendar days, not commit-walk index
# ---------------------------------------------------------------------------

@pytest_asyncio.fixture
async def stable_repo(db_session: AsyncSession) -> tuple[MusehubRepo, str]:
    """Repo with two commits (today and 30 days ago) and two symbols."""
    from muse.core.types import blob_id

    repo = await create_repo(db_session, owner="fid", slug="stable-fid")
    repo_id = str(repo.repo_id)

    c_old_id = blob_id(b"commit-30d")
    c_new_id = blob_id(b"commit-today")

    # Chain: today's commit's parent is the 30-day-old commit
    c_old = MusehubCommit(
        commit_id=c_old_id,
        message="old",
        author="a",
        branch="main",
        parent_ids=[],
        timestamp=_ts(30),
    )
    c_new = MusehubCommit(
        commit_id=c_new_id,
        message="new",
        author="a",
        branch="main",
        parent_ids=[c_old_id],
        timestamp=_ts(0),
    )
    db_session.add_all([c_old, c_new])
    await db_session.flush()
    db_session.add_all([
        MusehubCommitRef(repo_id=repo_id, commit_id=c_old_id),
        MusehubCommitRef(repo_id=repo_id, commit_id=c_new_id),
    ])

    # symbol_a was last touched today; symbol_b was last touched 30 days ago
    await db_session.flush()
    await _insert_history_entry(db_session, repo_id, "src/a.py::fn_a", c_new_id, _ts(0))
    await _insert_history_entry(db_session, repo_id, "src/b.py::fn_b", c_old_id, _ts(30))

    # Both symbols must exist in MusehubSymbolIntel (provider reads current symbols from here)
    await _insert_symbol_intel(db_session, repo_id, "src/a.py::fn_a", last_changed=_ts(0))
    await _insert_symbol_intel(db_session, repo_id, "src/b.py::fn_b", last_changed=_ts(30))

    await db_session.commit()
    return repo, c_new_id


class TestStableCalendarDays:

    @pytest.mark.asyncio
    async def test_F01_symbol_30d_stale_has_days_stable_approx_30(
        self, db_session: AsyncSession, stable_repo: tuple[MusehubRepo, str]
    ) -> None:
        """Symbol last touched 30 calendar days ago → days_stable ≈ 30, not 1."""
        repo, head = stable_repo
        provider = StableProvider()
        await provider.compute(db_session, str(repo.repo_id), head, {})

        row = await db_session.scalar(
            sa.select(MusehubIntelStable).where(
                MusehubIntelStable.repo_id == str(repo.repo_id),
                MusehubIntelStable.address == "src/b.py::fn_b",
            )
        )
        assert row is not None
        # Must be close to 30 calendar days — definitely not the commit index (1)
        assert row.days_stable >= 28, f"Expected ~30, got {row.days_stable}"
        assert row.days_stable <= 32, f"Expected ~30, got {row.days_stable}"

    @pytest.mark.asyncio
    async def test_F02_symbol_changed_today_has_days_stable_zero(
        self, db_session: AsyncSession, stable_repo: tuple[MusehubRepo, str]
    ) -> None:
        """Symbol changed today → days_stable = 0, not the commit index."""
        repo, head = stable_repo
        provider = StableProvider()
        await provider.compute(db_session, str(repo.repo_id), head, {})

        row = await db_session.scalar(
            sa.select(MusehubIntelStable).where(
                MusehubIntelStable.repo_id == str(repo.repo_id),
                MusehubIntelStable.address == "src/a.py::fn_a",
            )
        )
        assert row is not None
        assert row.days_stable == 0, f"Expected 0, got {row.days_stable}"


# ---------------------------------------------------------------------------
# F03 / F04 — EntangleProvider: Jaccard co_change_rate
# ---------------------------------------------------------------------------

@pytest_asyncio.fixture
async def entangle_repo(db_session: AsyncSession) -> tuple[MusehubRepo, str]:
    """Repo whose commit graph gives a clear Jaccard vs min distinction.

    symbol_a  touched in: c1, c2, c3, c4, c5   → 5 commits
    symbol_b  touched in: c3, c4, c5, c6, c7   → 5 commits
    co_changes         =  3  (c3, c4, c5)
    union              =  7  (c1..c7)
    Jaccard rate       =  3/7  ≈ 0.4286
    min rate           =  3/5  = 0.6   (the wrong answer)
    """
    from muse.core.types import blob_id

    repo = await create_repo(db_session, owner="fid", slug="entangle-fid")
    repo_id = str(repo.repo_id)

    # Build a linear chain c1 → c2 → … → c7 (c7 = HEAD)
    commit_ids = [blob_id(f"entangle-c{i}".encode()) for i in range(1, 8)]
    for i, cid in enumerate(commit_ids):
        parent = [commit_ids[i - 1]] if i > 0 else []
        db_session.add(MusehubCommit(
            commit_id=cid,
            message=f"c{i+1}",
            author="a",
            branch="main",
            parent_ids=parent,
            timestamp=_ts(7 - i),
        ))
    await db_session.flush()
    db_session.add_all([
        MusehubCommitRef(repo_id=repo_id, commit_id=cid) for cid in commit_ids
    ])
    await db_session.flush()

    # symbol_a in c1–c5, symbol_b in c3–c7
    sym_a = "src/a.py::fn_a"
    sym_b = "src/b.py::fn_b"
    ts = _ts(1)

    for cid in commit_ids[:5]:   # c1-c5 → symbol_a
        await _insert_history_entry(db_session, repo_id, sym_a, cid, ts)
    for cid in commit_ids[2:]:   # c3-c7 → symbol_b
        await _insert_history_entry(db_session, repo_id, sym_b, cid, ts)

    await db_session.commit()
    return repo, commit_ids[-1]  # HEAD = c7


class TestEntangleJaccard:

    @pytest.mark.asyncio
    async def test_F03_co_change_rate_is_jaccard(
        self, db_session: AsyncSession, entangle_repo: tuple[MusehubRepo, str]
    ) -> None:
        """co_change_rate = co_changes / |union| (Jaccard), not co / min."""
        repo, head = entangle_repo
        provider = EntangleProvider()
        await provider.compute(db_session, str(repo.repo_id), head, {})

        row = await db_session.scalar(
            sa.select(MusehubIntelEntangle).where(
                MusehubIntelEntangle.repo_id == str(repo.repo_id),
            )
        )
        assert row is not None, "Expected one entangle pair to be stored"

        expected_jaccard = 3 / 7
        expected_min_rate = 3 / 5

        assert abs(row.co_change_rate - expected_jaccard) < 0.001, (
            f"Rate {row.co_change_rate:.4f} looks like min ({expected_min_rate}) "
            f"not Jaccard ({expected_jaccard:.4f})"
        )

    @pytest.mark.asyncio
    async def test_F04_commits_both_active_is_union_cardinality(
        self, db_session: AsyncSession, entangle_repo: tuple[MusehubRepo, str]
    ) -> None:
        """commits_both_active stores |union(commits_a, commits_b)| = 7."""
        repo, head = entangle_repo
        provider = EntangleProvider()
        await provider.compute(db_session, str(repo.repo_id), head, {})

        row = await db_session.scalar(
            sa.select(MusehubIntelEntangle).where(
                MusehubIntelEntangle.repo_id == str(repo.repo_id),
            )
        )
        assert row is not None
        assert row.commits_both_active == 7, (
            f"Expected union cardinality 7, got {row.commits_both_active}"
        )


# ---------------------------------------------------------------------------
# F05 / F06 / F07 — Hotspots route: reads MusehubSymbolIntel, not snapshot
# ---------------------------------------------------------------------------

@pytest_asyncio.fixture
async def hotspots_repo(db_session: AsyncSession) -> MusehubRepo:
    """Repo with symbol intel rows but NO legacy snapshot."""
    repo = await create_repo(db_session, owner="fid", slug="hotspots-fid")
    repo_id = str(repo.repo_id)

    # Three symbols with different churn_30d values
    for addr, churn in [
        ("src/hot.py::fn_hot", 42),
        ("src/med.py::fn_med", 15),
        ("src/cold.py::fn_cold", 3),
    ]:
        await _insert_symbol_intel(db_session, repo_id, addr, churn_30d=churn)

    await db_session.commit()
    return repo


class TestHotspotsRoute:

    @pytest.mark.asyncio
    async def test_F05_hotspots_returns_200_without_legacy_snapshot(
        self, client: AsyncClient, hotspots_repo: MusehubRepo
    ) -> None:
        """Route must not 500 when there is no legacy snapshot row."""
        r = await client.get("/fid/hotspots-fid/intel/hotspots")
        assert r.status_code == 200

    @pytest.mark.asyncio
    async def test_F06_hotspots_ranked_by_churn_30d_descending(
        self, client: AsyncClient, hotspots_repo: MusehubRepo
    ) -> None:
        """Symbols appear highest-churn first (42, 15, 3)."""
        r = await client.get("/fid/hotspots-fid/intel/hotspots")
        assert r.status_code == 200
        body = r.text
        pos_hot  = body.find("fn_hot")
        pos_med  = body.find("fn_med")
        pos_cold = body.find("fn_cold")
        assert pos_hot != -1 and pos_med != -1 and pos_cold != -1, (
            "Not all symbols found in response"
        )
        assert pos_hot < pos_med < pos_cold, (
            "Symbols not in churn-descending order"
        )

    @pytest.mark.asyncio
    async def test_F07_hotspots_renders_address_and_change_count(
        self, client: AsyncClient, hotspots_repo: MusehubRepo
    ) -> None:
        """Address and change count appear in the rendered HTML."""
        r = await client.get("/fid/hotspots-fid/intel/hotspots")
        assert r.status_code == 200
        assert "src/hot.py::fn_hot" in r.text
        assert "42" in r.text