"""Issue #55 - helpers for the session guard over the user's real agent homes.

An agent pane inherits CLAUDE_PROJECT_DIR=<real ~/.claude/projects> from
lib.sh (every MAM pane does), and DiscoveryContext prefers that variable over
the home_dir a test passes, so a suite run by an agent wrote fake conversation
folders into the user's real claude directory. The per-test fixture
(conftest._isolate_agent_homes) is the fix; this guard is the alarm: it
snapshots the direct entries of every real conversation directory before the
suite and reports the new ones after it. Read-only - it never hashes, touches
or removes anything there. Pure functions, unit-tested in
test_issue55_agent_homes.py; the name does not start with `test_`, so pytest
never collects it.
"""
from __future__ import annotations

import os
import tempfile

# The pane-inherited variables conftest._isolate_agent_homes drops for every
# test, so HOME (which the tests set) governs, as it does in a plain shell.
DROPPED_VARS = ("HOME_DIR", "CLAUDE_PROJECT_DIR", "CODEX_HOME", "LOCAL_BIN")
# Read by the code under test but left alone, on purpose: HOME is where the
# real herdr tests and the shim bootstrap find the server socket, and it is
# what the suite's own tests set for an isolated home; XDG_CONFIG_HOME and
# HERDR_CONFIG_PATH are herdr's own config locations (mam_sandbox unsets
# them, Issue #45).
LEFT_ALONE = ("HOME", "XDG_CONFIG_HOME", "HERDR_CONFIG_PATH")


def real_home(ambient):
    return ambient.get("HOME_DIR") or ambient.get("HOME") or os.path.expanduser("~")


def real_claude_dir(ambient):
    return ambient.get("CLAUDE_PROJECT_DIR") or os.path.join(real_home(ambient), ".claude", "projects")


def watch_dirs(ambient):
    """[(agent, directory)]: where each adapter reads and writes conversations,
    as the ambient environment (recorded before any fixture ran) names them."""
    home = real_home(ambient)
    codex = ambient.get("CODEX_HOME") or os.path.join(home, ".codex")
    dirs = [("claude", real_claude_dir(ambient))]
    dirs += [("agy", os.path.join(home, ".gemini", "antigravity-cli", d))
             for d in ("conversations", "cache", "brain", "annotations", "presence")]
    dirs += [("codex", os.path.join(codex, "sessions")),
             ("grok", os.path.join(home, ".grok", "sessions")),
             ("opencode", os.path.join(home, ".local", "share", "opencode")),
             ("hermes", os.path.join(home, ".hermes"))]
    return dirs


def _listdir(path):
    try:
        return set(os.listdir(path))
    except OSError:
        return set()


def snapshot(dirs):
    """Direct entry names per watched directory; a missing one counts as empty."""
    return {d: _listdir(d) for _agent, d in dirs}


def decode_ws_key(name, root="/"):
    """The existing directory whose workspace key (lib_py.verify_session:
    realpath with `/` and `_` turned into `-`) is `name`, or None. A key is
    ambiguous on its own (a `-` may have been a `/`, a `_` or a `-`), so it is
    read against the file system: from `root`, each component is an existing
    entry whose own key is the next piece of the name."""
    if not name.startswith("-"):
        return None
    stack = [(root, name[1:])]
    while stack:
        cur, rest = stack.pop()
        if rest == "":
            return cur
        try:
            entries = os.listdir(cur)
        except OSError:
            continue
        for entry in entries:
            key = entry.replace("_", "-")
            if rest == key:
                full = os.path.join(cur, entry)
                if os.path.isdir(full):
                    return full
            elif rest.startswith(key + "-"):
                stack.append((os.path.join(cur, entry), rest[len(key) + 1:]))
    return None


def _under(path, roots):
    real = os.path.realpath(path)
    return any(real == r or real.startswith(r + os.sep) for r in roots)


def leaks(dirs, before, claude_dir, tmp_roots=()):
    """New entries since `before`, as [{"path", "agent"}] sorted by path.

    One exception, for the claude directory only: an entry whose name decodes
    to a directory that exists on this host and is not under a temp root
    (tempfile.gettempdir() and the given `tmp_roots`, e.g. pytest's basetemp)
    is a conversation an operating agent started meanwhile, not a test's.
    Every other directory has no exception."""
    roots = [os.path.realpath(tempfile.gettempdir())] + [os.path.realpath(r) for r in tmp_roots]
    claude_real = os.path.realpath(claude_dir)
    now = snapshot(dirs)
    found = []
    for agent, d in dirs:
        for name in sorted(now[d] - before.get(d, set())):
            if os.path.realpath(d) == claude_real:
                ws = decode_ws_key(name)
                if ws is not None and not _under(ws, roots):
                    continue
            found.append({"path": os.path.join(d, name), "agent": agent})
    return sorted(found, key=lambda f: f["path"])


def describe(found):
    """Failure message for the session guard."""
    lines = ["Issue #55: {} entr{} made during this session in a real agent home "
             "(left in place; check and remove by hand):".format(len(found), "y" if len(found) == 1 else "ies")]
    lines += ["  {path}  [{agent}]".format(**f) for f in found]
    return "\n".join(lines)