"""
BetterCurseForge — Core Patching Logic
=======================================
Direct ASAR modification + OWEASARSIG header hash synchronization.
Works on all versions of CurseForge (ow-electron).
"""

import os
import sys
import json
import struct
import shutil
import hashlib
import winreg
import time
import subprocess
import re
from pathlib import Path

CREATE_NO_WINDOW = 0x08000000 if os.name == "nt" else 0
RUN_KEY_PATH = r"Software\Microsoft\Windows\CurrentVersion\Run"
WATCHER_VALUE_NAME = "BetterCurseForgeWatcher"
WATCHER_MUTEX_NAME = "BetterCurseForgeWatcherMutex"
PATCH_MUTEX_NAME = "BetterCurseForgePatchMutex"
PERMANENT_DIR = Path(os.environ.get("LOCALAPPDATA", "")) / "BetterCurseForge"
PERMANENT_EXE = PERMANENT_DIR / "BetterCurseForge.exe"
PERMANENT_BCF = PERMANENT_DIR / "bettercf"
PERMANENT_VENDOR = PERMANENT_DIR / "vendor"
PERMANENT_ASSETS = PERMANENT_DIR / "assets"

class GlobalNamedMutex:
    def __init__(self, name: str, timeout_ms: int = 5000):
        self.name = name
        self.timeout_ms = timeout_ms
        self.handle = None
        self.acquired = False

    def __enter__(self):
        if os.name != "nt":
            self.acquired = True
            return self
        try:
            import ctypes
            kernel32 = ctypes.windll.kernel32
            kernel32.CreateMutexW.restype = ctypes.c_void_p
            kernel32.CreateMutexW.argtypes = [ctypes.c_void_p, ctypes.c_bool, ctypes.c_wchar_p]
            kernel32.WaitForSingleObject.restype = ctypes.c_uint
            kernel32.WaitForSingleObject.argtypes = [ctypes.c_void_p, ctypes.c_uint]
            kernel32.ReleaseMutex.argtypes = [ctypes.c_void_p]
            kernel32.CloseHandle.argtypes = [ctypes.c_void_p]

            self.handle = kernel32.CreateMutexW(None, False, self.name)
            if self.handle:
                res = kernel32.WaitForSingleObject(self.handle, self.timeout_ms)
                if res in (0, 0x80):  # WAIT_OBJECT_0 or WAIT_ABANDONED
                    self.acquired = True
        except Exception:
            self.acquired = True
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        if os.name == "nt" and self.handle:
            try:
                import ctypes
                kernel32 = ctypes.windll.kernel32
                if self.acquired:
                    kernel32.ReleaseMutex(self.handle)
                kernel32.CloseHandle(self.handle)
            except Exception:
                pass


def get_curseforge_dir() -> Path | None:
    # 1. Registry lookup
    try:
        key = winreg.OpenKey(
            winreg.HKEY_CURRENT_USER,
            r"Software\Microsoft\Windows\CurrentVersion\Uninstall",
        )
        i = 0
        while True:
            try:
                subkey_name = winreg.EnumKey(key, i)
                i += 1
                try:
                    subkey = winreg.OpenKey(key, subkey_name)
                    display_name, _ = winreg.QueryValueEx(subkey, "DisplayName")
                    if "CurseForge" in display_name:
                        uninstall_str, _ = winreg.QueryValueEx(subkey, "UninstallString")
                        path_str = uninstall_str.strip('"').split('" ')[0].strip('"')
                        install_dir = Path(path_str).parent
                        if install_dir.exists() and (install_dir / "CurseForge.exe").exists():
                            winreg.CloseKey(subkey)
                            winreg.CloseKey(key)
                            return install_dir
                    winreg.CloseKey(subkey)
                except (FileNotFoundError, OSError):
                    pass
            except OSError:
                break
        winreg.CloseKey(key)
    except OSError:
        pass

    # 2. LocalAppData fallback
    appdata = os.environ.get("LOCALAPPDATA", "")
    for p in [
        Path(appdata) / "Programs" / "CurseForge Windows",
        Path(appdata) / "CurseForge",
    ]:
        if p.exists() and (p / "CurseForge.exe").exists():
            return p
    return None

def kill_curseforge():
    try:
        subprocess.run(
            ["taskkill", "/f", "/im", "CurseForge.exe"],
            capture_output=True, timeout=10, creationflags=CREATE_NO_WINDOW
        )
        time.sleep(0.5)
    except Exception:
        pass

def calc_asar_header_hash(asar_path: Path) -> str:
    with open(asar_path, "rb") as f:
        f.seek(12)
        u4 = struct.unpack("<I", f.read(4))[0]
        header_bytes = f.read(u4)
        return hashlib.sha256(header_bytes).hexdigest()

def read_exe_hash(exe_path: Path) -> str | None:
    try:
        with open(exe_path, "rb") as f:
            data = f.read()
        sig = "OWEASARSIG".encode("utf-16le")
        idx = data.rfind(sig)
        if idx == -1:
            idx = data.rfind(b"OWEASARSIG")
        if idx == -1:
            return None
        val_idx = data.find(b'"value":"', idx)
        if val_idx == -1:
            return None
        hash_start = val_idx + 9
        return data[hash_start:hash_start+64].decode("ascii", errors="replace")
    except Exception:
        return None

def update_exe_hash(exe_path: Path, new_hash: str) -> bool:
    """
    Safely updates the 64-character ASAR header SHA256 hash inside CurseForge.exe
    in-place with automatic retry handling for temporary file locks.
    """
    if len(new_hash) != 64:
        raise ValueError(f"Invalid ASAR hash length: {len(new_hash)}")

    last_err = None
    for attempt in range(12):
        try:
            with open(exe_path, "r+b") as f:
                data = f.read()
                sig = "OWEASARSIG".encode("utf-16le")
                idx = data.rfind(sig)
                if idx == -1:
                    idx = data.rfind(b"OWEASARSIG")
                if idx == -1:
                    raise ValueError("OWEASARSIG signature block not found in CurseForge.exe")
                val_idx = data.find(b'"value":"', idx)
                if val_idx == -1:
                    raise ValueError('"value":" field not found in OWEASARSIG resource')
                hash_start = val_idx + 9
                old_hash = data[hash_start:hash_start+64].decode("ascii", errors="replace")
                if old_hash == new_hash:
                    return True  # Already up to date!
                f.seek(hash_start)
                f.write(new_hash.encode("ascii"))
                f.flush()
                return True
        except PermissionError as e:
            last_err = e
            kill_curseforge()
            time.sleep(0.5)
        except Exception as e:
            last_err = e
            time.sleep(0.5)

    if last_err:
        raise last_err
    return False

def get_user_data_dir() -> Path:
    appdata = Path(os.environ.get("APPDATA", ""))
    bcf_dir = appdata / "CurseForge" / "BetterCurseForge"
    (bcf_dir / "themes").mkdir(parents=True, exist_ok=True)
    (bcf_dir / "plugins").mkdir(parents=True, exist_ok=True)
    return bcf_dir

def ensure_sample_content(bcf_src: Path):
    user_dir = get_user_data_dir()
    themes_src = bcf_src / "themes"
    plugins_src = bcf_src / "plugins"

    if themes_src.exists():
        for item in themes_src.iterdir():
            dest = user_dir / "themes" / item.name
            if item.is_file():
                if not dest.exists() or item.name.startswith("purple-night"):
                    shutil.copy2(item, dest)
            elif item.is_dir() and not dest.exists():
                shutil.copytree(item, dest)

    if plugins_src.exists():
        for item in plugins_src.iterdir():
            dest = user_dir / "plugins" / item.name
            if not dest.exists():
                if item.is_file():
                    shutil.copy2(item, dest)
                elif item.is_dir():
                    shutil.copytree(item, dest)

def find_bettercf_source() -> Path | None:
    candidates = [
        Path(getattr(sys, "_MEIPASS", "")) / "bettercf" if hasattr(sys, "_MEIPASS") else None,
        Path(sys.executable).parent / "bettercf" if getattr(sys, "frozen", False) else None,
        PERMANENT_BCF,
        Path(__file__).parent / "bettercf",
        Path(__file__).parent.parent / "bettercf",
        Path.cwd() / "bettercf",
    ]
    for c in candidates:
        if c and c.exists() and c.is_dir():
            return c
    return None

def find_vendor_dir() -> Path | None:
    candidates = [
        Path(getattr(sys, "_MEIPASS", "")) / "vendor" if hasattr(sys, "_MEIPASS") else None,
        Path(sys.executable).parent / "vendor" if getattr(sys, "frozen", False) else None,
        PERMANENT_VENDOR,
        Path(__file__).parent / "vendor",
        Path(__file__).parent.parent / "patcher" / "vendor",
        Path.cwd() / "patcher" / "vendor",
        Path.cwd() / "vendor",
    ]
    for c in candidates:
        if c and c.exists() and (c / "asar" / "node_modules" / "@electron" / "asar" / "bin" / "asar.mjs").exists():
            return c
    return None

def find_assets_dir() -> Path | None:
    candidates = [
        Path(getattr(sys, "_MEIPASS", "")) / "assets" if hasattr(sys, "_MEIPASS") else None,
        Path(sys.executable).parent / "assets" if getattr(sys, "frozen", False) else None,
        PERMANENT_ASSETS,
        Path(__file__).parent / "assets",
        Path(__file__).parent.parent / "assets",
        Path.cwd() / "assets",
    ]
    for c in candidates:
        if c and c.exists() and c.is_dir():
            return c
    return None

def run_asar_tool(args: list[str], cf_dir: Path | None = None) -> tuple[bool, str]:
    """
    Executes asar pack/extract offline using bundled @electron/asar with either
    CurseForge's internal Node v24 runtime or system node.
    Falls back to npx only if offline runners fail.
    """
    vendor_dir = find_vendor_dir()
    if vendor_dir:
        asar_mjs = vendor_dir / "asar" / "node_modules" / "@electron" / "asar" / "bin" / "asar.mjs"
        node_modules = vendor_dir / "asar" / "node_modules"

        runners = []
        # Runner 1: CurseForge.exe itself (built-in Node v24, 100% offline & compatible)
        if cf_dir and (cf_dir / "CurseForge.exe").exists():
            runners.append((str(cf_dir / "CurseForge.exe"), True))
        # Runner 2: System Node.js
        sys_node = shutil.which("node")
        if sys_node:
            runners.append((sys_node, False))
        # Runner 3: Vanilla backup of CurseForge.exe
        if cf_dir and (cf_dir / "CurseForge.exe.vanilla").exists():
            runners.append((str(cf_dir / "CurseForge.exe.vanilla"), True))

        for runner_bin, is_electron in runners:
            try:
                env = os.environ.copy()
                if is_electron:
                    env["ELECTRON_RUN_AS_NODE"] = "1"
                env["NODE_PATH"] = str(node_modules)
                cmd = [runner_bin, str(asar_mjs)] + args
                creation_flags = 0x08000000 if os.name == "nt" else 0  # CREATE_NO_WINDOW
                r = subprocess.run(
                    cmd,
                    capture_output=True,
                    text=True,
                    env=env,
                    stdin=subprocess.DEVNULL,
                    creationflags=creation_flags,
                    timeout=45
                )
                if r.returncode == 0:
                    return (True, r.stdout.strip())
                else:
                    err_msg = r.stderr.strip() or r.stdout.strip()
            except Exception as e:
                err_msg = str(e)
                continue

    # Fallback to npx if vendor runner was unavailable
    try:
        cmd_npx = ["npx", "--yes", "@electron/asar"] + args
        r = subprocess.run(
            cmd_npx,
            capture_output=True,
            text=True,
            shell=True,
            stdin=subprocess.DEVNULL,
            timeout=60,
            creationflags=CREATE_NO_WINDOW
        )
        if r.returncode == 0:
            return (True, r.stdout.strip())
        return (False, r.stderr.strip() or r.stdout.strip())
    except Exception as e:
        return (False, str(e))


def is_asar_patched(asar_path: Path) -> bool:
    if not asar_path.exists():
        return False
    try:
        with open(asar_path, "rb") as f:
            f.seek(12)
            u4 = struct.unpack("<I", f.read(4))[0]
            header = f.read(u4).decode("utf-8", errors="replace")
            return "bettercf" in header
    except Exception:
        return False

def is_curseforge_patched(cf_dir: Path) -> bool:
    asar_path = cf_dir / "resources" / "app.asar"
    return is_asar_patched(asar_path)

def patch_curseforge(log_callback=print) -> bool:
    patch_lock = GlobalNamedMutex(PATCH_MUTEX_NAME, timeout_ms=8000)
    patch_lock.__enter__()
    if not patch_lock.acquired:
        log_callback("[!] Another patch operation is already in progress. Skipping.")
        return False

    cf_dir = get_curseforge_dir()
    if not cf_dir:
        log_callback("CurseForge installation directory not found!")
        patch_lock.__exit__(None, None, None)
        return False

    resources_dir = cf_dir / "resources"
    asar_path = resources_dir / "app.asar"
    exe_path = cf_dir / "CurseForge.exe"

    if not asar_path.exists() or not exe_path.exists():
        log_callback("CurseForge resources/app.asar or CurseForge.exe missing!")
        patch_lock.__exit__(None, None, None)
        return False

    asar_bak = resources_dir / "app.asar.vanilla"
    exe_bak = cf_dir / "CurseForge.exe.vanilla"

    log_callback(f"Found CurseForge at: {cf_dir}")
    kill_curseforge()

    # If CurseForge just updated (clean vanilla files from Overwolf), refresh vanilla backups
    try:
        current_exe_sig = read_exe_hash(exe_path)
        current_asar_hash = calc_asar_header_hash(asar_path)
        if current_exe_sig == current_asar_hash and not is_curseforge_patched(cf_dir):
            # Clean Overwolf update detected! Refresh vanilla backups to match new version
            shutil.copy2(asar_path, asar_bak)
            shutil.copy2(exe_path, exe_bak)
            log_callback(f"[+] Updated vanilla backup to latest CurseForge version")
    except Exception:
        pass

    if not asar_bak.exists() or is_asar_patched(asar_bak):
        if not is_asar_patched(asar_path):
            log_callback("Creating vanilla backup of app.asar...")
            shutil.copy2(asar_path, asar_bak)
    if not exe_bak.exists():
        log_callback("Creating vanilla backup of CurseForge.exe...")
        shutil.copy2(exe_path, exe_bak)

    # Clean old unused resources/app folder if present
    old_app = resources_dir / "app"
    if old_app.exists():
        try:
            shutil.rmtree(old_app)
        except Exception:
            pass

    # Extract asar
    temp_extract = resources_dir / "bettercf_extract_temp"
    if temp_extract.exists():
        shutil.rmtree(temp_extract, ignore_errors=True)

    # Always extract asar_path directly (so @electron/asar finds app.asar.unpacked)
    source_asar = asar_path

    log_callback(f"Extracting {'vanilla backup' if source_asar == asar_bak else 'app.asar'}...")
    ok, err = run_asar_tool(["extract", str(source_asar), str(temp_extract)], cf_dir=cf_dir)
    if not ok:
        log_callback(f"Failed to extract asar: {err}")
        patch_lock.__exit__(None, None, None)
        return False

    try:
        # 1. Themes Patch in desktop.js (Ads are fully handled by desktop.css & network blocking)
        desktop_js = temp_extract / "dist" / "desktop" / "desktop.js"
        if desktop_js.exists():
            content = desktop_js.read_text(encoding="utf-8")
            # Restore clean eV component if previously patched (in modern CurseForge, eV is the modpack card author component, not ads)
            if "/*BCF_AD_OFF*/eV=e=>{return null;let" in content:
                content = content.replace("/*BCF_AD_OFF*/eV=e=>{return null;let", "eV=e=>{let")
                log_callback("[+] Restored intact modpack card component (eV)")
            while "let __orig_eV=e=>null;" in content:
                content = content.replace("let __orig_eV=e=>null;", "")
            if "eV=e=>null;let __orig_eV=e=>{" in content:
                content = content.replace("eV=e=>null;let __orig_eV=e=>{", "eV=e=>{")

            # Unlock all native premium themes (Settings & Popup routes) across versions
            content, c1 = re.subn(
                r'([a-zA-Z0-9_$]+)=e=>!!e\.forceUnlock\|\|!e\.isPremium\|\|[^,;]+',
                r'\1=e=>!0',
                content
            )
            if c1 > 0:
                log_callback(f"[+] Unlocked native premium themes ({c1} route checks)")

            # Unlock premium theme state validation
            content, c2 = re.subn(
                r'return!r\?\.forceUnlock&&r\?\.isPremium&&!t\?[a-zA-Z0-9_$.]+:n',
                r'return n',
                content
            )
            if c2 > 0:
                log_callback("[+] Unlocked premium theme state validation")

            # Unlock subscription plan status for themes
            content, c3 = re.subn(
                r'function ([a-zA-Z0-9_$]+)\(e\)\{return e\.subscription\.plan\?\.active\}',
                r'function \1(e){return !0}',
                content
            )
            if c3 > 0:
                log_callback(f"[+] Unlocked subscription plan status for themes ({c3} checks)")

            desktop_js.write_text(content, encoding="utf-8")

        # 2. Zero-Ad & Settings Themes CSS in desktop.css
        desktop_css = temp_extract / "dist" / "desktop" / "desktop.css"
        if desktop_css.exists():
            css_rules = """
/* ═══ BetterCurseForge Zero-Ad Rules ═══ */
.curseforge-ad,
.ad-inner,
.overwolf-ad,
.swap-ads-location,
owadview,
[class*="-skin-aside"],
.promo-banner,
.subscribe-link,
.subscribe-link-small-resolution,
.subscribe-link-large-resolution,
[data-ad],
[data-ad-slot] {
  display: none !important;
  width: 0 !important;
  height: 0 !important;
  min-width: 0 !important;
  max-width: 0 !important;
  margin: 0 !important;
  padding: 0 !important;
  position: absolute !important;
  visibility: hidden !important;
  pointer-events: none !important;
}

/* ═══ BetterCurseForge Settings Themes UI ═══ */
#bcf-custom-themes-section {
  margin-top: 12px !important;
  padding: 0 !important;
}
.bcf-themes-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}
.bcf-heading {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0;
  font-size: 18px;
  font-weight: 700;
  line-height: 24px;
  color: var(--color-text-title, currentColor);
}
.bcf-heading > span:first-child {
  display: inline-flex;
  align-items: center;
}
.bcf-tag {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 600;
  line-height: 1;
  color: #a78bfa;
  background: rgba(139, 92, 246, 0.12);
  border: 1px solid rgba(139, 92, 246, 0.3);
  padding: 3px 8px;
  border-radius: 10px;
  letter-spacing: 0.3px;
}
.bcf-actions {
  display: flex;
  gap: 8px;
  align-items: center;
}
.bcf-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  height: 28px;
  font-size: 12px;
  font-weight: 500;
  line-height: 1;
  color: var(--color-text-primary, currentColor);
  background: var(--surface-on-surface, rgba(255, 255, 255, 0.08));
  border: 1px solid var(--border-tertiery, rgba(255, 255, 255, 0.15));
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.15s ease;
}
.bcf-btn svg {
  display: block;
  flex-shrink: 0;
  width: 13px;
  height: 13px;
}
.bcf-btn:hover {
  background: var(--surface-on-surface-hover, rgba(255, 255, 255, 0.16));
  border-color: rgba(255, 255, 255, 0.3);
  color: var(--color-text-title-hover, #ffffff);
}
.bcf-btn:active {
  transform: scale(0.97);
}
.bcf-theme-thumb {
  border-radius: 0;
}
.bcf-theme-thumb .thumb-icon svg {
  display: block;
}
.bcf-theme-thumb.is-active .sprite-icon {
  opacity: 1 !important;
  color: #ffffff !important;
}

/* Mutual exclusivity: hide checkmark on native theme cards when a client theme is active */
html.bcf-client-theme-selected .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover) .sprite-icon,
html.bcf-native-preview-active .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover) .sprite-icon,
html.bcf-custom-theme-active .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover) .sprite-icon {
  opacity: 0 !important;
}
html.bcf-client-theme-selected .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover) .thumb-icon,
html.bcf-native-preview-active .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover) .thumb-icon,
html.bcf-custom-theme-active .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover) .thumb-icon {
  background-color: transparent !important;
}
html.bcf-client-theme-selected .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover),
html.bcf-native-preview-active .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover),
html.bcf-custom-theme-active .settings-themes-view .theme-thumb:not(.bcf-theme-thumb).is-active:not(:hover) {
  outline: none !important;
  border-color: transparent !important;
  box-shadow: none !important;
}
/* Neutralize native skin styles and title bar */
html.bcf-custom-theme-active .title-bar,
html.bcf-custom-theme-active [class*="title-bar"],
html.bcf-custom-theme-active [class*="TitleBar"] {
  background: #0d0818 !important;
  --title-bar-background: #0d0818 !important;
}
html.bcf-custom-theme-active .pixelforge-skin,
html.bcf-custom-theme-active .lifeforge-skin,
html.bcf-custom-theme-active .fantasyforge-skin,
html.bcf-custom-theme-active .halloween-skin,
html.bcf-custom-theme-active .cf-light,
html.bcf-custom-theme-active .cf-light-colorblind {
  --title-bar-background: #0d0818 !important;
  --surface-brand-brand: #8b5cf6 !important;
  --surface-brand-brand-hover: #9d74f7 !important;
  --accent-font: var(--body-font, "Lato", sans-serif) !important;
  background-color: transparent !important;
}
html.bcf-custom-theme-active .pixelforge-skin :not(.highlighted-project-container) .card:after {
  display: none !important;
}
"""
            css_text = desktop_css.read_text(encoding="utf-8")
            if "/* ═══ BetterCurseForge Zero-Ad Rules ═══ */" in css_text:
                idx = css_text.find("/* ═══ BetterCurseForge Zero-Ad Rules ═══ */")
                css_text = css_text[:idx].rstrip()
            desktop_css.write_text(css_text + "\n" + css_rules, encoding="utf-8")
            log_callback("[+] Injected zero-ad and theme CSS rules into desktop.css")

        # 3. Copy BetterCF runtime into asar
        bcf_src = find_bettercf_source()
        if bcf_src:
            ensure_sample_content(bcf_src)
            bcf_dest = temp_extract / "dist" / "bettercf"
            if bcf_dest.exists():
                shutil.rmtree(bcf_dest)
            shutil.copytree(bcf_src, bcf_dest)
            log_callback("[+] Bundled BetterCurseForge runtime into asar")

        # 4. Inject main process hooks in background.js
        bg_js = temp_extract / "dist" / "background" / "background.js"
        if bg_js.exists():
            bg_content = bg_js.read_text(encoding="utf-8")
            if "bettercf/core/main-process.js" not in bg_content:
                bg_inject = "import '../bettercf/core/main-process.js';\n"
                bg_js.write_text(bg_inject + bg_content, encoding="utf-8")
                log_callback("[+] Injected main-process hooks into background.js")

        # 5. Inject renderer script into desktop.html
        desktop_html = temp_extract / "dist" / "desktop" / "desktop.html"
        if desktop_html.exists():
            html_content = desktop_html.read_text(encoding="utf-8")
            if "bettercf/core/renderer.js" not in html_content:
                bcf_script = '<script src="../bettercf/core/renderer.js"></script>'
                html_content = html_content.replace("</head>", f"{bcf_script}</head>")
                desktop_html.write_text(html_content, encoding="utf-8")
                log_callback("[+] Injected renderer script into desktop.html")

        # 6. Inject preload hook in preload.js
        preload_js = temp_extract / "dist" / "preload" / "preload.js"
        if preload_js.exists():
            preload_content = preload_js.read_text(encoding="utf-8")
            if "__BCF_IPC__" not in preload_content:
                preload_hook = """
// ── BetterCurseForge Preload Hook ──
try {
  const { ipcRenderer } = require('electron');
  window.__BCF_IPC__ = {
    invoke: (...args) => ipcRenderer.invoke(...args),
  };
} catch (e) {}
"""
                preload_js.write_text(preload_content + "\n" + preload_hook, encoding="utf-8")
                log_callback("[+] Injected renderer loader into preload.js")

        # 6. Repack ASAR
        log_callback("Repacking app.asar...")
        ok, err = run_asar_tool(["pack", str(temp_extract), str(asar_path)], cf_dir=cf_dir)
        if not ok:
            log_callback(f"Failed to pack asar: {err}")
            return False

        # 7. Compute new hash and update CurseForge.exe directly in-place
        new_hash = calc_asar_header_hash(asar_path)
        log_callback(f"New ASAR header hash: {new_hash}")
        if not exe_path.exists() and exe_bak.exists():
            shutil.copy2(exe_bak, exe_path)
        update_exe_hash(exe_path, new_hash)
        log_callback("[+] Updated CurseForge.exe integrity signature")

    finally:
        if temp_extract.exists():
            shutil.rmtree(temp_extract, ignore_errors=True)
        patch_lock.__exit__(None, None, None)

    try:
        ensure_permanent_installation()
        set_autostart_watcher(True)
        start_background_watcher()
        log_callback("[+] Auto-repatch watcher active and persistent across updates.")
    except Exception as e:
        log_callback(f"[!] Note: Could not auto-start watcher: {e}")

    log_callback("[*] CurseForge successfully patched! Ads removed, themes & plugins enabled.")
    return True

def unpatch_curseforge(log_callback=print) -> bool:
    cf_dir = get_curseforge_dir()
    if not cf_dir:
        log_callback("CurseForge not found.")
        return False

    kill_curseforge()
    resources_dir = cf_dir / "resources"
    asar_path = resources_dir / "app.asar"
    exe_path = cf_dir / "CurseForge.exe"
    asar_bak = resources_dir / "app.asar.vanilla"
    exe_bak = cf_dir / "CurseForge.exe.vanilla"

    restored = False
    if asar_bak.exists():
        shutil.copy2(asar_bak, asar_path)
        log_callback("[+] Restored vanilla app.asar")
        restored = True
    if exe_bak.exists():
        shutil.copy2(exe_bak, exe_path)
        log_callback("[+] Restored vanilla CurseForge.exe")
        restored = True

    old_app = resources_dir / "app"
    if old_app.exists():
        shutil.rmtree(old_app, ignore_errors=True)

    try:
        set_autostart_watcher(False)
        stop_background_watcher()
        log_callback("[-] Auto-repatch watcher deactivated.")
    except Exception:
        pass

    if restored:
        log_callback("CurseForge successfully returned to vanilla.")
    else:
        log_callback("Vanilla backups not found. Reinstall CurseForge to restore completely.")
    return restored

# ═══════════════════════════════════════════════════════════════════════════════
# AUTO-REPATCH WATCHER & PERSISTENCE ENGINE
def is_curseforge_running() -> bool:
    try:
        out = subprocess.check_output(
            ["tasklist", "/FI", "IMAGENAME eq CurseForge.exe", "/NH"],
            text=True, stderr=subprocess.DEVNULL, creationflags=CREATE_NO_WINDOW
        )
        return "CurseForge.exe" in out
    except Exception:
        return False

def is_updater_running() -> bool:
    try:
        out = subprocess.check_output(
            ["tasklist", "/FO", "CSV", "/NH"],
            text=True, stderr=subprocess.DEVNULL, creationflags=CREATE_NO_WINDOW
        )
        for line in out.splitlines():
            line = line.strip().lower()
            if not line:
                continue
            parts = [p.strip('"') for p in line.split('","')]
            if parts:
                pname = parts[0]
                if pname in ("setup.exe", "installer.exe") or ("curseforge" in pname and "updater" in pname):
                    return True
    except Exception:
        pass
    return False

def ensure_permanent_installation() -> Path:
    """
    Ensures BetterCurseForge executable, bettercf runtime, and vendor tools are permanently
    installed to %LOCALAPPDATA%\\BetterCurseForge so auto-repatch never breaks.
    """
    try:
        PERMANENT_DIR.mkdir(parents=True, exist_ok=True)
        src_bcf = find_bettercf_source()
        if src_bcf and src_bcf.exists():
            if PERMANENT_BCF.resolve() != src_bcf.resolve():
                if PERMANENT_BCF.exists():
                    shutil.rmtree(PERMANENT_BCF, ignore_errors=True)
                shutil.copytree(src_bcf, PERMANENT_BCF)

        src_vendor = find_vendor_dir()
        if src_vendor and src_vendor.exists():
            if PERMANENT_VENDOR.resolve() != src_vendor.resolve():
                if PERMANENT_VENDOR.exists():
                    shutil.rmtree(PERMANENT_VENDOR, ignore_errors=True)
                shutil.copytree(src_vendor, PERMANENT_VENDOR)

        src_assets = find_assets_dir()
        if src_assets and src_assets.exists():
            if PERMANENT_ASSETS.resolve() != src_assets.resolve():
                if PERMANENT_ASSETS.exists():
                    shutil.rmtree(PERMANENT_ASSETS, ignore_errors=True)
                shutil.copytree(src_assets, PERMANENT_ASSETS)

        if getattr(sys, "frozen", False):
            curr_exe = Path(sys.executable).resolve()
            if curr_exe != PERMANENT_EXE.resolve():
                shutil.copy2(curr_exe, PERMANENT_EXE)
        else:
            dist_exe = Path(__file__).parent.parent / "dist" / "BetterCurseForge.exe"
            if dist_exe.exists():
                shutil.copy2(dist_exe, PERMANENT_EXE)
    except Exception:
        pass

    return PERMANENT_EXE if PERMANENT_EXE.exists() else Path(sys.executable)

def is_autostart_watcher_enabled() -> bool:
    try:
        key = winreg.OpenKey(winreg.HKEY_CURRENT_USER, RUN_KEY_PATH, 0, winreg.KEY_READ)
        try:
            val, _ = winreg.QueryValueEx(key, WATCHER_VALUE_NAME)
            winreg.CloseKey(key)
            return bool(val)
        except FileNotFoundError:
            winreg.CloseKey(key)
            return False
    except OSError:
        return False

def set_autostart_watcher(enable: bool) -> bool:
    try:
        key = winreg.OpenKey(winreg.HKEY_CURRENT_USER, RUN_KEY_PATH, 0, winreg.KEY_SET_VALUE)
        if enable:
            perm_exe = ensure_permanent_installation()
            if perm_exe.suffix.lower() == ".exe":
                cmd = f'"{perm_exe.resolve()}" --watch'
            else:
                python_exe = Path(sys.executable).parent / "pythonw.exe"
                if not python_exe.exists():
                    python_exe = Path(sys.executable)
                cmd = f'"{python_exe.resolve()}" "{Path(__file__).parent.resolve() / "patcher_gui.py"}" --watch'

            winreg.SetValueEx(key, WATCHER_VALUE_NAME, 0, winreg.REG_SZ, cmd)

            try:
                subprocess.run(
                    ["schtasks", "/Create", "/TN", "BetterCurseForgeWatcher",
                     "/TR", cmd, "/SC", "ONLOGON", "/RL", "LIMITED", "/F"],
                    capture_output=True, timeout=5, creationflags=CREATE_NO_WINDOW
                )
            except Exception:
                pass
        else:
            try:
                winreg.DeleteValue(key, WATCHER_VALUE_NAME)
            except FileNotFoundError:
                pass
            try:
                subprocess.run(["schtasks", "/Delete", "/TN", "BetterCurseForgeWatcher", "/F"],
                               capture_output=True, timeout=5, creationflags=CREATE_NO_WINDOW)
            except Exception:
                pass
        winreg.CloseKey(key)
        return True
    except OSError:
        return False

def is_watcher_running() -> bool:
    import ctypes
    kernel32 = ctypes.windll.kernel32
    kernel32.OpenMutexW.restype = ctypes.c_void_p
    kernel32.OpenMutexW.argtypes = [ctypes.c_uint, ctypes.c_bool, ctypes.c_wchar_p]
    kernel32.CloseHandle.argtypes = [ctypes.c_void_p]
    SYNCHRONIZE = 0x00100000
    h = kernel32.OpenMutexW(SYNCHRONIZE, False, WATCHER_MUTEX_NAME)
    if h:
        kernel32.CloseHandle(h)
        return True
    return False

def start_background_watcher():
    if is_watcher_running():
        return
    perm_exe = ensure_permanent_installation()
    if perm_exe.exists() and perm_exe.suffix.lower() == ".exe":
        cmd_str = f'"{perm_exe.resolve()}" --watch'
    elif getattr(sys, "frozen", False):
        cmd_str = f'"{Path(sys.executable).resolve()}" --watch'
    else:
        python_exe = Path(sys.executable).parent / "pythonw.exe"
        if not python_exe.exists():
            python_exe = Path(sys.executable)
        cmd_str = f'"{python_exe.resolve()}" "{Path(__file__).parent.resolve() / "patcher_gui.py"}" --watch'

    try:
        ps_cmd = f"Invoke-CimMethod -ClassName Win32_Process -MethodName Create -Arguments @{{CommandLine = '{cmd_str}'}}"
        subprocess.run(["powershell", "-NoProfile", "-WindowStyle", "Hidden", "-Command", ps_cmd],
                       capture_output=True, timeout=5, creationflags=CREATE_NO_WINDOW)
    except Exception:
        try:
            creation_flags = 0x08000000 | 0x00000200
            subprocess.Popen(f'start "" {cmd_str}', shell=True, creationflags=creation_flags)
        except Exception:
            pass

def stop_background_watcher():
    try:
        subprocess.run(
            ["powershell", "-NoProfile", "-WindowStyle", "Hidden", "-Command",
             "Get-CimInstance Win32_Process | Where-Object { $_.CommandLine -like '*--watch*' } | ForEach-Object { Stop-Process -Id $_.ProcessId -Force }"],
            capture_output=True, timeout=10, creationflags=CREATE_NO_WINDOW
        )
    except Exception:
        pass

def wait_for_files_settled(cf_dir: Path, timeout: float = 90.0, log_fn=None) -> bool:
    """
    Waits for the CurseForge updater/installer to finish writing files.
    Ensures resources/app.asar is present, fully written, and readable.
    """
    import time
    start = time.time()
    asar_path = cf_dir / "resources" / "app.asar"
    last_size = -1
    stable_checks = 0

    while time.time() - start < timeout:
        time.sleep(1.5)

        if is_updater_running():
            stable_checks = 0
            if log_fn:
                log_fn("CurseForge installer is currently running... waiting for completion.")
            continue

        if asar_path.exists():
            try:
                asar_size = asar_path.stat().st_size
                if asar_size > 5_000_000:
                    if asar_size == last_size:
                        stable_checks += 1
                        if stable_checks >= 2:
                            try:
                                with open(asar_path, "rb") as f:
                                    magic = f.read(4)
                                    if len(magic) == 4:
                                        if log_fn:
                                            log_fn(f"Installer finished. app.asar settled ({asar_size // 1048576}MB).")
                                        return True
                            except (PermissionError, OSError):
                                stable_checks = 0
                    else:
                        stable_checks = 0
                        last_size = asar_size
                        if log_fn:
                            log_fn(f"Waiting for app.asar to settle... ({asar_size // 1048576}MB)")
            except (OSError, PermissionError):
                stable_checks = 0
                continue
    return False

def wait_for_update_and_repatch(pid_to_wait: int | None = None, log_fn=None) -> bool:
    """
    Invoked when CurseForge is quitting to apply an update.
    Waits for the old CurseForge instance to exit, waits for the installer to finish,
    and immediately repatches before/as CurseForge restarts.
    """
    import time
    if log_fn is None:
        log_dir = get_user_data_dir()
        watch_log = log_dir / "watcher.log"
        def log_fn(msg):
            ts = time.strftime("%Y-%m-%d %H:%M:%S")
            try:
                with open(watch_log, "a", encoding="utf-8") as f:
                    f.write(f"[{ts}] [OnUpdateHook] {msg}\n")
            except Exception:
                pass

    log_fn(f"Wait-for-update triggered (PID={pid_to_wait})")
    cf_dir = get_curseforge_dir()
    if not cf_dir:
        log_fn("CurseForge directory not found.")
        return False

    if pid_to_wait:
        log_fn(f"Waiting for PID {pid_to_wait} to terminate...")
        for _ in range(30):
            try:
                out = subprocess.check_output(
                    ["tasklist", "/FI", f"PID eq {pid_to_wait}", "/NH"],
                    text=True, stderr=subprocess.DEVNULL, creationflags=CREATE_NO_WINDOW
                )
                if str(pid_to_wait) not in out:
                    break
            except Exception:
                break
            time.sleep(0.5)

    settled = wait_for_files_settled(cf_dir, timeout=90.0, log_fn=log_fn)
    if not settled:
        log_fn("Timed out waiting for installer to settle.")
        return False

    was_running = is_curseforge_running()
    if was_running:
        log_fn("CurseForge launched unpatched by installer. Terminating to apply patch...")
        kill_curseforge()
        time.sleep(1.5)

    success = False
    for attempt in range(1, 4):
        success = patch_curseforge(log_callback=log_fn)
        if success:
            break
        log_fn(f"Patch attempt {attempt} failed, retrying in 2 seconds...")
        time.sleep(2)

    if success:
        log_fn("★ CurseForge successfully re-patched after update!")
        log_fn("Launching modded CurseForge...")
        subprocess.Popen([str(cf_dir / "CurseForge.exe")], creationflags=CREATE_NO_WINDOW)
        return True
    else:
        log_fn("Failed to re-patch CurseForge after update.")
        return False

def run_watcher_loop():
    """
    Resilient Win32 filesystem watcher with kernel event signaling + 3s heartbeat fallback.
    0% CPU consumption during idle.
    Instantly and reliably re-patches CurseForge when updated.
    """
    import ctypes
    import time
    from datetime import datetime

    log_dir = get_user_data_dir()
    watch_log = log_dir / "watcher.log"

    def wlog(msg):
        ts = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        try:
            with open(watch_log, "a", encoding="utf-8") as f:
                f.write(f"[{ts}] {msg}\n")
        except Exception:
            pass

    kernel32 = ctypes.windll.kernel32
    kernel32.CreateMutexW.restype = ctypes.c_void_p
    kernel32.CreateMutexW.argtypes = [ctypes.c_void_p, ctypes.c_bool, ctypes.c_wchar_p]
    kernel32.CloseHandle.argtypes = [ctypes.c_void_p]

    mutex = kernel32.CreateMutexW(None, True, WATCHER_MUTEX_NAME)
    if kernel32.GetLastError() == 183:  # ERROR_ALREADY_EXISTS
        wlog("Watcher already running (mutex exists). Exiting duplicate.")
        return

    wlog("Watcher started.")
    cf_dir = get_curseforge_dir()
    if not cf_dir:
        wlog("CurseForge directory not found. Watcher exiting.")
        return

    def check_and_repatch(trigger_reason: str):
        if not is_curseforge_patched(cf_dir):
            wlog(f"CurseForge unpatched state detected ({trigger_reason}). Waiting for files to settle...")
            settled = wait_for_files_settled(cf_dir, timeout=90.0, log_fn=wlog)
            if settled:
                was_running = is_curseforge_running()
                if was_running:
                    wlog("CurseForge is currently running unpatched. Closing it to apply BetterCurseForge patch...")
                    kill_curseforge()
                    time.sleep(1.5)

                wlog("Applying BetterCurseForge patch...")
                success = False
                for attempt in range(1, 4):
                    success = patch_curseforge(log_callback=wlog)
                    if success:
                        break
                    wlog(f"Patch attempt {attempt} failed, retrying in 2 seconds...")
                    time.sleep(2)

                if success:
                    wlog("★ CurseForge successfully re-patched after update!")
                    if was_running:
                        wlog("Relaunching modded CurseForge...")
                        subprocess.Popen([str(cf_dir / "CurseForge.exe")], creationflags=CREATE_NO_WINDOW)
                else:
                    wlog("Failed to re-patch CurseForge after update.")
            else:
                wlog("Timed out waiting for installer files to settle.")

    check_and_repatch("Startup Check")

    try:
        while True:
            time.sleep(3)
            try:
                check_and_repatch("Heartbeat Check")
            except Exception as e:
                wlog(f"Error during check_and_repatch: {e}")
    finally:
        if mutex:
            kernel32.CloseHandle(mutex)
        wlog("Watcher stopped.")