"""Shared fixtures for gateway tests.

The ``_ensure_telegram_mock`` helper guarantees that a minimal mock of
the ``telegram`` package is registered in :data:`sys.modules` **before**
any test file triggers ``from gateway.platforms.telegram import ...``.

Without this, ``pytest-xdist`` workers that happen to collect
``test_telegram_caption_merge.py`` (bare top-level import, no per-file
mock) first will cache ``ChatType = None`` from the production
ImportError fallback, causing 30+ downstream test failures wherever
``ChatType.GROUP`` / ``ChatType.SUPERGROUP`` is accessed.

Individual test files may still call their own ``_ensure_telegram_mock``
— it short-circuits when the mock is already present.

Plugin-adapter anti-pattern guard
---------------------------------
Tests for platform plugins (``plugins/platforms/<name>/adapter.py``)
must load the adapter via
:func:`tests.gateway._plugin_adapter_loader.load_plugin_adapter`, not by
adding the plugin directory to ``sys.path`` and doing a bare
``from adapter import ...``. The guard at the bottom of this file
scans test module ASTs at collection time and fails collection with a
pointer to the helper if the anti-pattern is detected.

Rationale: every plugin ships its own ``adapter.py``, and two tests each
inserting their plugin dir on ``sys.path[0]`` race for
``sys.modules["adapter"]`` in the same xdist worker. Whichever collects
first wins; the other fails with ``ImportError``, and the polluted
``sys.path`` cascades into unrelated tests. See PR #17764 for the
incident.
"""

import ast
import sys
from pathlib import Path
from unittest.mock import MagicMock

import pytest


def _ensure_telegram_mock() -> None:
    """Install a comprehensive telegram mock in sys.modules.

    Idempotent — skips when the real library is already imported.
    Uses ``sys.modules[name] = mod`` (overwrite) instead of
    ``setdefault`` so it wins even if a partial/broken import
    already cached a module with ``ChatType = None``.
    """
    if "telegram" in sys.modules and hasattr(sys.modules["telegram"], "__file__"):
        return  # Real library is installed — nothing to mock

    mod = MagicMock()
    mod.ext.ContextTypes.DEFAULT_TYPE = type(None)
    mod.constants.ParseMode.MARKDOWN = "Markdown"
    mod.constants.ParseMode.MARKDOWN_V2 = "MarkdownV2"
    mod.constants.ParseMode.HTML = "HTML"
    mod.constants.ChatType.PRIVATE = "private"
    mod.constants.ChatType.GROUP = "group"
    mod.constants.ChatType.SUPERGROUP = "supergroup"
    mod.constants.ChatType.CHANNEL = "channel"

    # Real exception classes so ``except (NetworkError, ...)`` clauses
    # in production code don't blow up with TypeError.
    mod.error.NetworkError = type("NetworkError", (OSError,), {})
    mod.error.TimedOut = type("TimedOut", (OSError,), {})
    mod.error.BadRequest = type("BadRequest", (Exception,), {})
    mod.error.Forbidden = type("Forbidden", (Exception,), {})
    mod.error.InvalidToken = type("InvalidToken", (Exception,), {})
    mod.error.RetryAfter = type("RetryAfter", (Exception,), {"retry_after": 1})
    mod.error.Conflict = type("Conflict", (Exception,), {})

    # Update.ALL_TYPES used in start_polling()
    mod.Update.ALL_TYPES = []

    for name in (
        "telegram",
        "telegram.ext",
        "telegram.constants",
        "telegram.request",
    ):
        sys.modules[name] = mod
    sys.modules["telegram.error"] = mod.error


def _ensure_discord_mock() -> None:
    """Install a comprehensive discord mock in sys.modules.

    Idempotent — skips when the real library is already imported.
    Uses ``sys.modules[name] = mod`` (overwrite) instead of
    ``setdefault`` so it wins even if a partial/broken import already
    cached the module.

    This mock is comprehensive — it includes **all** attributes needed by
    every gateway discord test file.  Individual test files should call
    this function (it short-circuits when already present) rather than
    maintaining their own mock setup.
    """
    if "discord" in sys.modules and hasattr(sys.modules["discord"], "__file__"):
        return  # Real library is installed — nothing to mock

    from types import SimpleNamespace

    discord_mod = MagicMock()
    discord_mod.Intents.default.return_value = MagicMock()
    discord_mod.Client = MagicMock
    discord_mod.File = MagicMock
    discord_mod.DMChannel = type("DMChannel", (), {})
    discord_mod.Thread = type("Thread", (), {})
    discord_mod.ForumChannel = type("ForumChannel", (), {})
    discord_mod.Interaction = object
    discord_mod.Message = type("Message", (), {})

    # Embed: accept the kwargs production code / tests use
    # (title, description, color). MagicMock auto-attributes work too,
    # but some tests construct and inspect .title/.description directly.
    class _FakeEmbed:
        def __init__(self, *, title=None, description=None, color=None, **_):
            self.title = title
            self.description = description
            self.color = color
    discord_mod.Embed = _FakeEmbed

    # ui.View / ui.Select / ui.Button: real classes (not MagicMock) so
    # tests that subclass ModelPickerView / iterate .children / clear
    # items work.
    class _FakeView:
        def __init__(self, timeout=None):
            self.timeout = timeout
            self.children = []
        def add_item(self, item):
            self.children.append(item)
        def clear_items(self):
            self.children.clear()

    class _FakeSelect:
        def __init__(self, *, placeholder=None, options=None, custom_id=None, **_):
            self.placeholder = placeholder
            self.options = options or []
            self.custom_id = custom_id
            self.callback = None
            self.disabled = False

    class _FakeButton:
        def __init__(self, *, label=None, style=None, custom_id=None, emoji=None,
                     url=None, disabled=False, row=None, sku_id=None, **_):
            self.label = label
            self.style = style
            self.custom_id = custom_id
            self.emoji = emoji
            self.url = url
            self.disabled = disabled
            self.row = row
            self.sku_id = sku_id
            self.callback = None

    class _FakeSelectOption:
        def __init__(self, *, label=None, value=None, description=None, **_):
            self.label = label
            self.value = value
            self.description = description
    discord_mod.SelectOption = _FakeSelectOption

    discord_mod.ui = SimpleNamespace(
        View=_FakeView,
        Select=_FakeSelect,
        Button=_FakeButton,
        button=lambda *a, **k: (lambda fn: fn),
    )
    discord_mod.ButtonStyle = SimpleNamespace(
        success=1, primary=2, secondary=2, danger=3,
        green=1, grey=2, blurple=2, red=3,
    )
    discord_mod.Color = SimpleNamespace(
        orange=lambda: 1, green=lambda: 2, blue=lambda: 3,
        red=lambda: 4, purple=lambda: 5, greyple=lambda: 6,
    )

    # app_commands — needed by _register_slash_commands auto-registration
    class _FakeGroup:
        def __init__(self, *, name, description, parent=None):
            self.name = name
            self.description = description
            self.parent = parent
            self._children: dict = {}
            if parent is not None:
                parent.add_command(self)

        def add_command(self, cmd):
            self._children[cmd.name] = cmd

    class _FakeCommand:
        def __init__(self, *, name, description, callback, parent=None):
            self.name = name
            self.description = description
            self.callback = callback
            self.parent = parent

    discord_mod.app_commands = SimpleNamespace(
        describe=lambda **kwargs: (lambda fn: fn),
        choices=lambda **kwargs: (lambda fn: fn),
        Choice=lambda **kwargs: SimpleNamespace(**kwargs),
        Group=_FakeGroup,
        Command=_FakeCommand,
    )

    ext_mod = MagicMock()
    commands_mod = MagicMock()
    commands_mod.Bot = MagicMock
    ext_mod.commands = commands_mod

    for name in ("discord", "discord.ext", "discord.ext.commands"):
        sys.modules[name] = discord_mod
    sys.modules["discord.ext"] = ext_mod
    sys.modules["discord.ext.commands"] = commands_mod


# Run at collection time — before any test file's module-level imports.
_ensure_telegram_mock()
_ensure_discord_mock()


# ---------------------------------------------------------------------------
# Plugin-adapter anti-pattern guard
# ---------------------------------------------------------------------------

_GATEWAY_DIR = Path(__file__).resolve().parent
_GUARD_HINT = (
    "Plugin adapter tests must use "
    "``from tests.gateway._plugin_adapter_loader import load_plugin_adapter`` "
    "and call ``load_plugin_adapter('<plugin_name>')`` instead of inserting "
    "``plugins/platforms/<name>/`` on sys.path and doing a bare ``import "
    "adapter`` / ``from adapter import ...``. See the 'Plugin-adapter "
    "anti-pattern guard' docstring in tests/gateway/conftest.py."
)


def _scan_for_plugin_adapter_antipattern(source: str) -> list[str]:
    """Return a list of offending-line descriptions, or [] if clean.

    Flags two things:
    1. ``sys.path.insert(..., <something mentioning 'plugins/platforms'>)``
    2. ``import adapter`` or ``from adapter import ...`` at module level.
    """
    try:
        tree = ast.parse(source)
    except SyntaxError:
        return []  # Let pytest surface the real syntax error.

    offenses: list[str] = []

    for node in ast.walk(tree):
        # sys.path.insert(0, ".../plugins/platforms/...")
        if isinstance(node, ast.Call):
            func = node.func
            target_name: str | None = None
            if isinstance(func, ast.Attribute):
                # sys.path.insert / sys.path.append
                if (
                    isinstance(func.value, ast.Attribute)
                    and isinstance(func.value.value, ast.Name)
                    and func.value.value.id == "sys"
                    and func.value.attr == "path"
                    and func.attr in ("insert", "append", "extend")
                ):
                    target_name = f"sys.path.{func.attr}"

            if target_name is not None:
                call_src = ast.unparse(node)
                # Match both the string-literal form
                # ``.../plugins/platforms/...`` and the Path-operator form
                # ``Path(...) / 'plugins' / 'platforms' / ...`` that
                # plugin tests typically use.
                _src_no_ws = "".join(call_src.split())
                if (
                    "plugins/platforms" in call_src
                    or "plugins\\platforms" in call_src
                    or "'plugins'/'platforms'" in _src_no_ws
                    or '"plugins"/"platforms"' in _src_no_ws
                ):
                    offenses.append(
                        f"line {node.lineno}: {target_name}(...) points into "
                        f"plugins/platforms/"
                    )

    # Bare `import adapter` / `from adapter import ...` anywhere (module level
    # OR inside functions — both are symptoms of the same pattern).
    for node in ast.walk(tree):
        if isinstance(node, ast.Import):
            for alias in node.names:
                if alias.name == "adapter":
                    offenses.append(
                        f"line {node.lineno}: ``import adapter`` "
                        f"(bare — resolves to whichever plugin's adapter.py "
                        f"is first on sys.path)"
                    )
        elif isinstance(node, ast.ImportFrom):
            if node.module == "adapter" and node.level == 0:
                offenses.append(
                    f"line {node.lineno}: ``from adapter import ...`` "
                    f"(bare — resolves to whichever plugin's adapter.py "
                    f"is first on sys.path)"
                )

    return offenses


def pytest_configure(config):
    """Reject plugin-adapter tests that use the sys.path anti-pattern.

    Runs once per pytest session on the controller, BEFORE any xdist
    worker is spawned. If any file under ``tests/gateway/`` matches the
    anti-pattern, we fail the whole session with a clear message —
    before a polluted ``sys.path`` can cascade across workers.
    """
    # Only run on the xdist controller (or in non-xdist runs). Skip on
    # worker subprocesses so we don't scan the filesystem N times.
    if hasattr(config, "workerinput"):
        return

    violations: list[str] = []
    for path in _GATEWAY_DIR.rglob("test_*.py"):
        if path.name in {"_plugin_adapter_loader.py", "conftest.py"}:
            continue
        try:
            source = path.read_text(encoding="utf-8")
        except OSError:
            continue
        if "adapter" not in source and "plugins/platforms" not in source:
            continue
        offenses = _scan_for_plugin_adapter_antipattern(source)
        if offenses:
            violations.append(
                f"  {path.relative_to(_GATEWAY_DIR.parent.parent)}:\n    "
                + "\n    ".join(offenses)
            )

    if violations:
        raise pytest.UsageError(
            "Plugin-adapter-import anti-pattern detected in gateway tests:\n"
            + "\n".join(violations)
            + "\n\n"
            + _GUARD_HINT
        )

