"""Tests for watch.py - file watcher helpers (no watchdog required)."""
import json
import os
import subprocess
import sys
import time
from pathlib import Path
import pytest

from graphify.watch import _notify_only, _WATCHED_EXTENSIONS, _rebuild_lock, _check_shrink


# --- _notify_only ---

def test_notify_only_creates_flag(tmp_path):
    _notify_only(tmp_path)
    flag = tmp_path / "graphify-out" / "needs_update"
    assert flag.exists()
    assert flag.read_text() == "1"

def test_notify_only_creates_flag_dir(tmp_path):
    # graphify-out dir does not exist yet
    assert not (tmp_path / "graphify-out").exists()
    _notify_only(tmp_path)
    assert (tmp_path / "graphify-out").is_dir()

def test_notify_only_idempotent(tmp_path):
    _notify_only(tmp_path)
    _notify_only(tmp_path)
    flag = tmp_path / "graphify-out" / "needs_update"
    assert flag.read_text() == "1"


# --- _WATCHED_EXTENSIONS ---

def test_watched_extensions_includes_code():
    assert ".py" in _WATCHED_EXTENSIONS
    assert ".ts" in _WATCHED_EXTENSIONS
    assert ".go" in _WATCHED_EXTENSIONS
    assert ".rs" in _WATCHED_EXTENSIONS

def test_watched_extensions_includes_docs():
    assert ".md" in _WATCHED_EXTENSIONS
    assert ".txt" in _WATCHED_EXTENSIONS
    assert ".pdf" in _WATCHED_EXTENSIONS

def test_watched_extensions_includes_images():
    assert ".png" in _WATCHED_EXTENSIONS
    assert ".jpg" in _WATCHED_EXTENSIONS

def test_watched_extensions_excludes_noise():
    # .json is now indexed (bash/JSON extractors added in #866)
    assert ".json" in _WATCHED_EXTENSIONS
    assert ".sh" in _WATCHED_EXTENSIONS
    assert ".pyc" not in _WATCHED_EXTENSIONS
    assert ".log" not in _WATCHED_EXTENSIONS


# --- watch() import error without watchdog ---

def test_check_update_no_flag_returns_true(tmp_path):
    """check_update returns True and is silent when needs_update flag is absent."""
    from graphify.watch import check_update
    assert check_update(tmp_path) is True


def test_check_update_with_flag_returns_true_and_prints(tmp_path, capsys):
    """check_update returns True and prints notification when flag exists."""
    from graphify.watch import check_update
    flag = tmp_path / "graphify-out" / "needs_update"
    flag.parent.mkdir(parents=True, exist_ok=True)
    flag.write_text("1")
    result = check_update(tmp_path)
    assert result is True
    out = capsys.readouterr().out
    assert "graphify --update" in out


def test_check_update_does_not_clear_flag(tmp_path):
    """check_update never removes the needs_update flag (clearing is LLM's job)."""
    from graphify.watch import check_update
    flag = tmp_path / "graphify-out" / "needs_update"
    flag.parent.mkdir(parents=True, exist_ok=True)
    flag.write_text("1")
    check_update(tmp_path)
    assert flag.exists()


def test_watch_raises_without_watchdog(tmp_path, monkeypatch):
    import builtins
    real_import = builtins.__import__

    def mock_import(name, *args, **kwargs):
        if name == "watchdog.observers" or name == "watchdog.events":
            raise ImportError("mocked missing watchdog")
        return real_import(name, *args, **kwargs)

    monkeypatch.setattr(builtins, "__import__", mock_import)

    from graphify.watch import watch
    with pytest.raises(ImportError, match="watchdog not installed"):
        watch(tmp_path)


# --- _rebuild_lock (GH-858) ---


@pytest.mark.skipif(sys.platform == "win32", reason="fcntl-only (POSIX)")
def test_rebuild_lock_writes_pid_with_newline(tmp_path):
    out = tmp_path / "graphify-out"
    lock_path = out / ".rebuild.lock"
    with _rebuild_lock(out) as got:
        assert got is True
        assert lock_path.exists()
        contents = lock_path.read_text(encoding="utf-8")
        assert contents == f"{os.getpid()}\n", contents


@pytest.mark.skipif(sys.platform == "win32", reason="fcntl-only (POSIX)")
def test_rebuild_lock_removed_after_release(tmp_path):
    """GH-858: lock file must be unlinked once the rebuild completes so
    downstream waiters that poll for its absence unblock promptly."""
    out = tmp_path / "graphify-out"
    lock_path = out / ".rebuild.lock"
    with _rebuild_lock(out) as got:
        assert got is True
    assert not lock_path.exists(), "lock file should be unlinked after release"


@pytest.mark.skipif(sys.platform == "win32", reason="fcntl-only (POSIX)")
def test_rebuild_lock_does_not_accumulate_pids_across_runs(tmp_path):
    """GH-858: each acquisition truncates and rewrites the PID line rather
    than appending, so the file never grows into a digit-concatenation."""
    out = tmp_path / "graphify-out"
    lock_path = out / ".rebuild.lock"
    expected = f"{os.getpid()}\n"
    for _ in range(5):
        with _rebuild_lock(out) as got:
            assert got is True
            assert lock_path.read_text(encoding="utf-8") == expected
        assert not lock_path.exists()


def test_rebuild_code_evicts_nodes_from_deleted_files(tmp_path):
    """#1007: graphify update (_rebuild_code with no changed_paths) must remove
    nodes and edges from files deleted since the last run."""
    import json
    from graphify.watch import _rebuild_code

    corpus = tmp_path / "corpus"
    corpus.mkdir()

    (corpus / "auth.py").write_text(
        "def login(): pass\ndef logout(): pass\n", encoding="utf-8"
    )
    (corpus / "utils.py").write_text(
        "def format_date(): pass\n", encoding="utf-8"
    )

    assert _rebuild_code(corpus, acquire_lock=False) is True
    graph_path = corpus / "graphify-out" / "graph.json"
    data = json.loads(graph_path.read_text(encoding="utf-8"))
    node_labels_before = {n["label"] for n in data.get("nodes", [])}
    assert "format_date()" in node_labels_before

    (corpus / "utils.py").unlink()

    assert _rebuild_code(corpus, acquire_lock=False) is True
    data = json.loads(graph_path.read_text(encoding="utf-8"))
    node_labels_after = {n["label"] for n in data.get("nodes", [])}
    assert "format_date()" not in node_labels_after, "stale function node from deleted file must be evicted"
    assert "login()" in node_labels_after, "nodes from surviving file must be kept"


@pytest.mark.skipif(sys.platform == "win32", reason="fcntl-only (POSIX)")
def test_rebuild_lock_non_blocking_does_not_clobber_holder(tmp_path):
    """GH-858: a non-blocking caller that fails to acquire the lock must not
    truncate the holder's PID payload."""
    out = tmp_path / "graphify-out"
    lock_path = out / ".rebuild.lock"
    with _rebuild_lock(out) as outer:
        assert outer is True
        held_contents = lock_path.read_text(encoding="utf-8")
        with _rebuild_lock(out, blocking=False) as inner:
            assert inner is False
            # Holder's PID line must still be intact.
            assert lock_path.read_text(encoding="utf-8") == held_contents


def test_rebuild_code_is_idempotent_when_cluster_ids_flap(tmp_path, monkeypatch):
    from graphify import cluster as cluster_mod
    from graphify.watch import _rebuild_code

    src = tmp_path / "app.py"
    src.write_text("def alpha():\n    return 1\n\ndef beta():\n    return alpha()\n", encoding="utf-8")

    calls = {"n": 0}

    def flaky_cluster(G):
        calls["n"] += 1
        nodes = sorted(G.nodes())
        if calls["n"] % 2 == 1:
            return {100: nodes}
        return {7: nodes}

    monkeypatch.setattr(cluster_mod, "cluster", flaky_cluster)
    monkeypatch.setattr(cluster_mod, "score_all", lambda _G, comm: {cid: 1.0 for cid in comm})

    assert _rebuild_code(tmp_path)
    graph_path = tmp_path / "graphify-out" / "graph.json"
    report_path = tmp_path / "graphify-out" / "GRAPH_REPORT.md"
    first_graph = graph_path.read_text(encoding="utf-8")
    first_report = report_path.read_text(encoding="utf-8")

    assert _rebuild_code(tmp_path)
    second_graph = graph_path.read_text(encoding="utf-8")
    second_report = report_path.read_text(encoding="utf-8")

    assert first_graph == second_graph
    assert first_report == second_report


def test_rebuild_code_skips_cluster_when_topology_unchanged(tmp_path, monkeypatch):
    from graphify import cluster as cluster_mod
    from graphify.watch import _rebuild_code

    src = tmp_path / "app.py"
    src.write_text("def alpha():\n    return 1\n\ndef beta():\n    return alpha()\n", encoding="utf-8")

    calls = {"n": 0}

    def cluster_once(G):
        calls["n"] += 1
        if calls["n"] > 1:
            raise AssertionError("cluster() should be skipped when topology is unchanged")
        return {0: sorted(G.nodes())}

    monkeypatch.setattr(cluster_mod, "cluster", cluster_once)
    monkeypatch.setattr(cluster_mod, "score_all", lambda _G, comm: {cid: 1.0 for cid in comm})

    assert _rebuild_code(tmp_path)
    assert _rebuild_code(tmp_path)
    assert calls["n"] == 1


# --- .graphifyignore honored in watch handler (gh-928) ---


def _watchdog_available() -> bool:
    try:
        import watchdog  # noqa: F401
        return True
    except ImportError:
        return False


@pytest.mark.skipif(not _watchdog_available(), reason="watchdog not installed")
def test_watch_handler_honors_graphifyignore(tmp_path, monkeypatch):
    """gh-928: the watch Handler must short-circuit paths matching
    .graphifyignore so busy volumes (node_modules churn, build artefacts,
    Time Machine writes, …) don't wake the rebuild pipeline.
    """
    import threading
    from graphify import watch as watch_mod

    (tmp_path / ".graphifyignore").write_text("node_modules/\nbuild/\n", encoding="utf-8")
    (tmp_path / "node_modules").mkdir()
    (tmp_path / "build").mkdir()

    rebuild_calls: list[Path] = []
    notify_calls: list[Path] = []
    monkeypatch.setattr(watch_mod, "_rebuild_code", lambda p, **kw: rebuild_calls.append(p) or True)
    monkeypatch.setattr(watch_mod, "_notify_only", lambda p: notify_calls.append(p))

    # Run watch() in a thread with a short debounce so we can verify the
    # post-debounce dispatch path actually runs on real events.
    t = threading.Thread(target=watch_mod.watch, args=(tmp_path,), kwargs={"debounce": 0.2}, daemon=True)
    t.start()
    time.sleep(0.5)  # let observer.start() settle

    # Ignored writes — handler must drop these.
    (tmp_path / "node_modules" / "junk.js").write_text("// noise\n", encoding="utf-8")
    (tmp_path / "build" / "out.py").write_text("x = 1\n", encoding="utf-8")
    time.sleep(1.0)
    assert rebuild_calls == [], "ignored writes triggered a rebuild"
    assert notify_calls == [], "ignored writes triggered a notify"

    # Non-ignored write — handler must accept and (after debounce) dispatch.
    (tmp_path / "app.py").write_text("def f():\n    return 1\n", encoding="utf-8")
    deadline = time.monotonic() + 5.0
    while time.monotonic() < deadline and not rebuild_calls:
        time.sleep(0.1)
    assert rebuild_calls, "non-ignored .py write should have triggered _rebuild_code"


@pytest.mark.skipif(not _watchdog_available(), reason="watchdog not installed")
def test_watch_loads_graphifyignore_once(tmp_path, monkeypatch):
    """gh-928: .graphifyignore must be parsed exactly once at watch() startup,
    not per filesystem event. Otherwise busy volumes re-read the file
    thousands of times per second.
    """
    import threading
    from graphify import watch as watch_mod
    from graphify import detect as detect_mod

    (tmp_path / ".graphifyignore").write_text("ignored/\n", encoding="utf-8")
    (tmp_path / "ignored").mkdir()

    calls = {"n": 0}
    real_loader = detect_mod._load_graphifyignore

    def counting_loader(root):
        calls["n"] += 1
        return real_loader(root)

    # Patch the symbol the watch module imported at module-load time.
    monkeypatch.setattr(watch_mod, "_load_graphifyignore", counting_loader)
    monkeypatch.setattr(watch_mod, "_rebuild_code", lambda p, **kw: True)
    monkeypatch.setattr(watch_mod, "_notify_only", lambda p: None)

    t = threading.Thread(target=watch_mod.watch, args=(tmp_path,), kwargs={"debounce": 0.2}, daemon=True)
    t.start()
    time.sleep(0.5)

    # Generate many events; loader must not be called again.
    for i in range(50):
        (tmp_path / "ignored" / f"f{i}.py").write_text("x\n", encoding="utf-8")
    time.sleep(0.7)
    assert calls["n"] == 1, f"_load_graphifyignore called {calls['n']} times; expected 1"


# --- _check_shrink: silent-corruption guard with explicit-deletion bypass ---

def _shrink_payload(n: int) -> dict:
    """Build a minimal graph-data dict with *n* placeholder nodes."""
    return {"nodes": [{"id": f"n{i}"} for i in range(n)], "links": []}


def test_check_shrink_blocks_silent_shrink(capsys):
    """Default case: smaller new graph + no force + no declared deletions = refuse."""
    ok = _check_shrink(
        force=False,
        existing_data=_shrink_payload(100),
        new_data=_shrink_payload(80),
    )
    assert ok is False
    captured = capsys.readouterr()
    assert "Refusing to overwrite" in captured.err
    assert "80 nodes" in captured.err and "100" in captured.err


def test_check_shrink_allows_force_override():
    """force=True bypasses the guard regardless of node delta."""
    ok = _check_shrink(
        force=True,
        existing_data=_shrink_payload(100),
        new_data=_shrink_payload(1),
    )
    assert ok is True


def test_check_shrink_allows_explicit_deletions(capsys):
    """Caller declared deletions → shrink is expected → guard skipped silently."""
    ok = _check_shrink(
        force=False,
        existing_data=_shrink_payload(100),
        new_data=_shrink_payload(80),
        had_explicit_deletions=True,
    )
    assert ok is True
    # And critically, no scary warning is printed when the shrink is intentional.
    assert "Refusing to overwrite" not in capsys.readouterr().err


def test_check_shrink_allows_no_existing_data():
    """First-run case: no existing graph → guard inert."""
    ok = _check_shrink(
        force=False,
        existing_data={},
        new_data=_shrink_payload(50),
    )
    assert ok is True


def test_check_shrink_allows_growth():
    """new > existing is always fine."""
    ok = _check_shrink(
        force=False,
        existing_data=_shrink_payload(50),
        new_data=_shrink_payload(60),
    )
    assert ok is True


def test_check_shrink_unlinks_tmp_on_refuse(tmp_path):
    """When refusing, the temp graph file gets cleaned up so it can't leak across runs."""
    tmp = tmp_path / "graph.tmp.json"
    tmp.write_text("{}", encoding="utf-8")
    ok = _check_shrink(
        force=False,
        existing_data=_shrink_payload(100),
        new_data=_shrink_payload(80),
        tmp=tmp,
    )
    assert ok is False
    assert not tmp.exists()


def test_check_shrink_keeps_tmp_when_deletions_declared(tmp_path):
    """Mirror of the above: if the caller declared deletions, the tmp file is NOT unlinked
    because the caller is going to swap it into place. Regression guard against a future
    bug where the tmp cleanup leaks out of the refuse branch.
    """
    tmp = tmp_path / "graph.tmp.json"
    tmp.write_text("{}", encoding="utf-8")
    ok = _check_shrink(
        force=False,
        existing_data=_shrink_payload(100),
        new_data=_shrink_payload(80),
        tmp=tmp,
        had_explicit_deletions=True,
    )
    assert ok is True
    assert tmp.exists()


# --- _rebuild_code integration: post-commit delete scenario ---

@pytest.mark.skipif(sys.platform == "win32", reason="git CLI behaviour varies on Windows runners")
def test_rebuild_code_prunes_deleted_file_nodes(tmp_path):
    """End-to-end probe of the post-commit-delete bug fix.

    Build a tiny graph, delete one of its source files, then call _rebuild_code
    with the deleted path in changed_paths. Without the fix this raises the
    shrink guard and refuses to write; with the fix the deleted file's nodes
    are pruned and graph.json is rewritten.
    """
    from graphify.watch import _rebuild_code

    # Set up a minimal "project" with two Python files in a git repo so detect
    # treats it as a real corpus.
    subprocess.run(["git", "init", "-q", str(tmp_path)], check=True)
    subprocess.run(
        ["git", "-C", str(tmp_path), "config", "user.email", "test@example.com"],
        check=True,
    )
    subprocess.run(
        ["git", "-C", str(tmp_path), "config", "user.name", "Test"],
        check=True,
    )

    keep = tmp_path / "keep.py"
    drop = tmp_path / "drop.py"
    keep.write_text("def keep_fn():\n    return 1\n", encoding="utf-8")
    drop.write_text("def drop_fn():\n    return 2\n", encoding="utf-8")

    # Initial build covers both files.
    cwd = os.getcwd()
    try:
        os.chdir(tmp_path)
        ok = _rebuild_code(tmp_path, no_cluster=True)
        assert ok is True
        graph_path = tmp_path / "graphify-out" / "graph.json"
        assert graph_path.exists()
        before = json.loads(graph_path.read_text(encoding="utf-8"))
        before_sources = {n.get("source_file") for n in before.get("nodes", [])}
        assert "drop.py" in before_sources

        # Now delete drop.py and re-run with it in the change list. This is what
        # the post-commit hook does when git diff --name-only HEAD~1 HEAD includes
        # a deletion: the path is passed to _rebuild_code even though it no
        # longer exists on disk.
        drop.unlink()
        ok = _rebuild_code(
            tmp_path,
            changed_paths=[Path("drop.py")],
            no_cluster=True,
        )
        assert ok is True, "rebuild should succeed even though the graph shrinks"

        after = json.loads(graph_path.read_text(encoding="utf-8"))
        after_sources = {n.get("source_file") for n in after.get("nodes", [])}
        assert "drop.py" not in after_sources, "deleted file's nodes should be pruned"
        assert "keep.py" in after_sources, "untouched file's nodes should survive"
    finally:
        os.chdir(cwd)