"""Resolve the AI bot protection state actually applied on a WP site.

Mirrors the precedence the imunify-security plugin applies at runtime
(inc/App/Plugin.php::isBotProtectionActive, inc/App/Bot/Preset.php::resolve):
a site-owner wp-config.php constant or bot-settings.php override wins over
the hoster-written plugin_config.php default. Files are parsed, never
executed.
"""
import logging
import os
import re
import stat
from pathlib import Path

logger = logging.getLogger(__name__)

VALID_PRESETS = ("balanced", "strict", "monitor")
DEFAULT_PRESET = "balanced"

# These config files live under a hosting user's document root and are read
# by the root agent, so the read is defensive: no symlink follow, no FIFO
# block, regular file owned by the site user only, and a small byte cap so a
# hostile file (huge / /dev/zero) cannot OOM or stall the agent.
_MAX_BYTES = 64 * 1024

# define('IMUNIFY_AI_BOT_PROTECTION', false) — the quote right after the name
# keeps this from also matching the *_PRESET constant.
_CONST_ENABLED = re.compile(
    r"""define\(\s*['"]IMUNIFY_AI_BOT_PROTECTION['"]\s*,\s*(true|false)\s*\)""",
    re.IGNORECASE,
)
_CONST_PRESET = re.compile(
    r"define\(\s*['\"]IMUNIFY_AI_BOT_PROTECTION_PRESET['\"]\s*,"
    r"\s*['\"](\w+)['\"]\s*\)",
    re.IGNORECASE,
)
# bot-settings.php is a PHP `return array('enabled' => .., 'preset' => '..')`.
_KV_ENABLED = re.compile(
    r"""['"]enabled['"]\s*=>\s*(true|false)""", re.IGNORECASE
)
_KV_PRESET = re.compile(
    r"""['"]preset['"]\s*=>\s*['"](\w+)['"]""", re.IGNORECASE
)


def _safe_read(path: Path, uid: int):
    """Read a small site-owner config file as root, defensively.

    Returns None (so the caller falls back to the hoster default) on a
    symlink, FIFO/device, a file not owned by the site user, or any I/O
    error. At most _MAX_BYTES are read.
    """
    try:
        fd = os.open(path, os.O_RDONLY | os.O_NOFOLLOW | os.O_NONBLOCK)
    except OSError:
        return None
    try:
        info = os.fstat(fd)
        if not stat.S_ISREG(info.st_mode) or info.st_uid != uid:
            return None
        return os.read(fd, _MAX_BYTES).decode("utf-8", errors="replace")
    except OSError:
        return None
    finally:
        os.close(fd)


def _parse_wp_config(path: Path, uid: int):
    """Return (enabled, preset) from wp-config.php constants; each is None
    when the constant is absent or invalid."""
    text = _safe_read(path, uid)
    if text is None:
        return None, None
    enabled = None
    match = _CONST_ENABLED.search(text)
    if match:
        enabled = match.group(1).lower() == "true"
    preset = None
    match = _CONST_PRESET.search(text)
    if match and match.group(1).lower() in VALID_PRESETS:
        preset = match.group(1).lower()
    return enabled, preset


def _parse_bot_settings(path: Path, uid: int):
    """Return (enabled, preset) from the site-owner bot-settings.php. A
    missing/unreadable file means enabled with no explicit preset, matching
    the plugin's OptOutFlag default."""
    text = _safe_read(path, uid)
    if text is None:
        return True, None
    match = _KV_ENABLED.search(text)
    enabled = match.group(1).lower() == "true" if match else True
    preset = None
    match = _KV_PRESET.search(text)
    if match and match.group(1).lower() in VALID_PRESETS:
        preset = match.group(1).lower()
    return enabled, preset


def resolve_ai_bot_protection(
    docroot: str,
    data_dir: Path,
    uid: int,
    hoster_enabled: bool,
    hoster_preset: str,
):
    """Resolve the effective (enabled, preset) for a site.

    enabled: the wp-config constant (if set to false) force-disables;
    otherwise it is the AND of the hoster default and the site-owner flag.
    preset: first match of wp-config constant, bot-settings.php, hoster.
    """
    const_enabled, const_preset = _parse_wp_config(
        Path(docroot) / "wp-config.php", uid
    )
    bot_enabled, bot_preset = _parse_bot_settings(
        Path(data_dir) / "bot-settings.php", uid
    )

    enabled = bool(hoster_enabled) and bot_enabled
    if const_enabled is False:
        enabled = False

    for candidate in (const_preset, bot_preset, hoster_preset):
        if candidate in VALID_PRESETS:
            return enabled, candidate
    return enabled, DEFAULT_PRESET