#!/usr/bin/python3
# Makes the ARM64 Proton the client already downloaded usable here, and sets it as the default tool
# for Windows titles (CompatToolMapping "0" in config.vdf) when the user has not chosen one. Run
# before the client starts; it rewrites config.vdf on exit.
#
#   steam-compatibility <steam root>
#
# Valve ships a native aarch64 Proton (arm64ec Wine with FEX as the x86 layer) as an ordinary depot,
# which is exactly what this runtime wants. Its toolmanifest declares require_tool_appid 4185400 -
# Steam Linux Runtime 4 for arm64 - so Steam stacks pressure-vessel underneath it, and
# pressure-vessel needs unprivileged user namespaces, which an Android app does not get. Steam then
# drops the launch on the floor: no window, no log, straight back to the library.
#
# So the depot is re-registered here as a compatibility tool of our own: every entry symlinked so
# nothing is copied and Steam still updates the real depot, but with a toolmanifest that leaves out
# require_tool_appid. Proton takes its base directory from dirname(sys.argv[0]) without resolving
# it, so it reads files/ through those symlinks and runs directly on this rootfs.
import json
import os
import re
import runpy
import shutil
import sys

TOOL = "droiddeck-proton-arm64"
TOOL_11 = "droiddeck-proton-11-arm64"
LEGACY_TOOL = "bannerlator-proton-arm64"
LABEL_FILE = "/etc/steam-compatibility-label"
# The ARM64 Proton depot the client downloads for itself, as a compatibility-tool appid.
# The session asks the client to install it on the command line the first time (steam://install),
# so a new client has it before a Windows title is first launched. It is deliberately NOT named as
# this tool's dependency: a dependency is composed with its own dependencies, and this depot
# requires 4185400, the arm64 Steam Linux Runtime, whose container needs user namespaces Android
# does not give - the launch would be wrapped in it and die before this tool ever ran.
PROTON_ARM64_APPID = "4427310"
LAUNCHER = "droiddeck-proton"
LEGACY_LAUNCHER = "bannerlator-proton"
# The extra Steam library the app mounts the installed games into (see droiddeck-steam-library).
# installed_apps() scans it too; it lives only in the sibling script, so define it here as well.
LIBRARY = "/mnt/droiddeck"  # the card library is LIBRARY + "-sd"; internal storage is steam_root itself
# The client lists its own "Proton Experimental (ARM64)" and "Proton 11.0 (ARM64)" in the same
# Compatibility dropdown, and those are the two that cannot start a game here. Ours has to be
# unmistakable at a glance, or a user picks a neighbour and gets a launch that fails silently.
# Newest first: whichever the client has downloaded is used.
SOURCES = ("Proton Experimental (ARM64)", "Proton 11.0 (ARM64)")
OWN_TOOLS = ((TOOL, SOURCES), (TOOL_11, ("Proton 11.0 (ARM64)",)))
FEX_TOOL = "droiddeck-fex"
FEX_LAUNCHER = "droiddeck-fex-tool"
FEX_FILES = ("toolmanifest.vdf", "compatibilitytool.vdf", FEX_LAUNCHER)
FEX_APPID = "3127680"
SNIPER_APPID = "1628350"
FEX_DEPENDENCIES = (FEX_APPID, SNIPER_APPID)
REQUEST_HANDOFF_SECONDS = 30
PLAYABLE_TYPES = frozenset(("game", "demo", "application", "beta"))
COMPAT_DIR = os.path.join(os.environ.get("HOME", "/root"), ".local", "share", "droiddeck-compat")
# Written by us; everything else in the depot is symlinked through.
OWN_FILES = ("toolmanifest.vdf", "compatibilitytool.vdf", LAUNCHER)
# The client assigns a Proton to a Windows title by itself, as a per-app CompatToolMapping entry at
# priority 250 - which outranks the "0" default, so setting that default alone changes nothing. Every
# Proton it can pick is one this runtime cannot start: the ARM64 ones want pressure-vessel (see
# above) and the x86_64 ones want pressure-vessel and FEX on top. Ours is the only one that runs
# here, so every Proton mapping is repointed at it. Tools that are not Proton are left alone.
COMPAT_TOOL_VDF = """"compatibilitytools"
{
	"compat_tools"
	{
		"%s"
		{
			"install_path" "."
			"display_name" "%s"
			"from_oslist" "windows"
			"to_oslist" "linux"
		}
	}
}
"""
TOOL_MANIFEST_VDF = """"manifest"
{
	"version" "2"
	"commandline" "/%s %%verb%%"
	"use_sessions" "1"
	"compatmanager_layer_name" "proton"
}
""" % LAUNCHER


# Steam runs its own graphics probe through EVERY registered tool at once, ~40 s after logging in,
# all with STEAM_COMPAT_DATA_PATH=.../compatdata/0, and those concurrent Protons can write their
# builtin DLLs through each other's prefix links into each other's trees (seen: GE's FEX DLLs became
# Proton Experimental's). Moving those runs to a prefix per tool was tried and crashed the Steam
# client right after the probe started (segfault, rc 139, first ever in 25 sessions), so the client
# relies on compatdata/0 itself. The launch-time check below is the protection instead.

# The Components page's choices, enforced in the one place every game launch passes: the app keeps
# desired.tsv (tool dir, Proton build, component, file, sha256, source copy) and an unpacked copy of
# each package in use. A file that no longer matches - whatever changed it - is put back before
# Proton starts. Only for the Proton build the choice was made for: after a Steam update the build
# differs and the Proton's own new files are left alone until the user chooses again.
BL_COMPONENTS_SETUP = """
bl_components() {
  base=$1
  cm_dir="${HOME:-/root}/.local/share/droiddeck-components"
  cm_list="$cm_dir/desired.tsv"
  # A real game launch only: the verb the client starts a game with and the game's own prefix. Every
  # other run - above all the client's own probes right after login, which all share compatdata/0 -
  # is left exactly as it was: with this check running through them, the client segfaulted (rc 139)
  # within seconds of starting its probes, four sessions out of four. The prefix decides rather than
  # the app id because a non-Steam shortcut launches with app id 0 but still gets a prefix of its own.
  [ "${verb:-}" = waitforexitandrun ] || return 0
  case "${STEAM_COMPAT_DATA_PATH:-}" in ''|*/compatdata/0|*/compatdata/0/|*/compatdata/0-*) return 0 ;; esac
  [ -f "$cm_list" ] || return 0
  cm_app=${STEAM_COMPAT_DATA_PATH%/}
  cm_app=${cm_app##*/}
  cm_tool=${base##*/}
  cm_build=$(awk 'NR == 1 { print $2 }' "$base/version" 2>/dev/null)
  cm_fixed=0
  cm_checked=0
  while IFS=$'\\t' read -r t want comp rel sum src; do
    [ "$t" = "$cm_tool" ] && [ "$want" = "$cm_build" ] || continue
    cm_checked=$((cm_checked + 1))
    f="$base/$rel"
    if [ -f "$f" ] && [ "$(sha256sum "$f" | cut -d' ' -f1)" = "$sum" ]; then continue; fi
    if [ ! -f "$src" ]; then
      echo "droiddeck-proton: components: $comp source missing ($src), left as it is" >&2
      continue
    fi
    mkdir -p "$(dirname "$f")"
    cp -f "$src" "$f.bl-new" && mv -f "$f.bl-new" "$f" || continue
    case "$rel" in *.so) chmod 755 "$f" ;; *) chmod 644 "$f" ;; esac
    cm_fixed=$((cm_fixed + 1))
  done < "$cm_list"
  [ "$cm_checked" -gt 0 ] && echo "droiddeck-proton: components: checked $cm_checked file(s) in $cm_tool for app $cm_app" >&2
  if [ "$cm_fixed" -gt 0 ]; then
    echo "droiddeck-proton: components: re-applied $cm_fixed of $cm_checked file(s) in $cm_tool before this launch" >&2
    printf '%s\\t%s\\t%s\\n' "$(date +%s)" "$cm_tool" "$cm_fixed" >> "$cm_dir/reapplied.log"
  fi
}
"""

# Resolves the depot at launch time, so the tool can be registered before the depot exists and
# survives the client updating or replacing it. Proton takes its base directory from
# dirname(sys.argv[0]) without resolving it, so it is run from the depot itself.
# Cores for a game the client launches, kept separate from the client's own. One mask suits the
# client's menus and another suits a game, and they are wanted at the same time - so the game's is
# applied here, in the launch path every game goes through, rather than to the session as a whole.
BL_GAME_CPUS_SETUP = """
bl_game_cpus() {
  [ -n "${BL_GAME_CPUS:-}" ] || return 0
  command -v taskset >/dev/null 2>&1 || return 0
  # exec'd through taskset rather than set afterwards: a mask applied to a pid races the process
  # into spawning its own threads, and this way every thread inherits it from the first instruction.
  BL_TASKSET="taskset -c $BL_GAME_CPUS"
  echo "droiddeck-proton: game cores $BL_GAME_CPUS" >&2
}
"""

# Quake III engine games (id Tech 3) set their own resolution and switch the display to it. Under
# gamescope with the ARM64 Proton that switch is refused ("calling CDS: failed, bad mode") and the
# game never gets OpenGL; left at its own size in a window, it draws small in a corner. So these
# titles are told to stay windowed at the session's own size - unless the user's launch options
# already say something about the video mode, which are left as they are.
# The session puts the client's own libraries (steamrtarm64, its panorama/) ahead of everything for
# the client, and a game inherits that: Wine then resolved gnutls, SDL, FFmpeg and the rest against
# the client's private copies instead of the rootfs it was built for. Inside Steam's runtime
# container that path never reaches Proton either. (WinNative's winnative-proton-launch.)
BL_LIBPATH_SETUP = """
bl_libpath() {
  # A Proton built to prefer PipeWire (CachyOS's among the adopted ones) hung its audio thread
  # here, where only PulseAudio answers. (WinNative, winnative-proton-launch.)
  export PROTON_USE_PIPEWIRE=${PROTON_USE_PIPEWIRE:-0}
  [ -n "${LD_LIBRARY_PATH:-}" ] || return 0
  local kept= dir old_ifs=$IFS
  IFS=:
  for dir in $LD_LIBRARY_PATH; do
    case $dir in
      "" | */steamrtarm64 | */steamrtarm64/*) ;;
      *) kept=${kept:+$kept:}$dir ;;
    esac
  done
  IFS=$old_ifs
  if [ -n "$kept" ]; then export LD_LIBRARY_PATH="$kept"; else unset LD_LIBRARY_PATH; fi
}
"""

BL_IDTECH3_SETUP = """
bl_idtech3() {
  BL_EXTRA_ARGS=()
  case "${SteamAppId:-${STEAM_COMPAT_APP_ID:-}}" in
    # Quake III Arena, Quake III: Team Arena, Return to Castle Wolfenstein, Jedi Academy.
    2200|2350|9010|6020) ;;
    *) return 0 ;;
  esac
  case " $* " in
    *r_fullscreen*|*r_mode*|*r_customwidth*|*r_customheight*)
      echo "droiddeck-proton: Quake-engine title; its launch options set the video mode, left as they are" >&2
      return 0 ;;
  esac
  w=${BL_WIDTH:-1280}
  h=${BL_HEIGHT:-720}
  BL_EXTRA_ARGS=(+set r_fullscreen 0 +set r_mode -1 +set r_customwidth "$w" +set r_customheight "$h")
  echo "droiddeck-proton: Quake-engine title: windowed at ${w}x${h}" >&2
}
"""

BL_DIRECTAUDIO_SETUP = """
bl_directaudio() {
  base=$1
  [ -n "${BL_DIRECTAUDIO:-}" ] || return 0
  [ -d "$BL_DIRECTAUDIO/lib/wine" ] || return 0
  version=$("$base/files/bin-arm64/wine" --version 2>/dev/null)
  major=${version#wine-}
  major=${major%%.*}
  if [ "$major" != "11" ]; then
    echo "droiddeck-proton: DirectAudio left off - it is built for Wine 11 and this Proton is '${version:-unknown}'. Pairing them would be silent rather than broken, so it is not worth guessing." >&2
    return 0
  fi
  # Wine appends the per-architecture subdirectory to each entry, so the directory holding
  # aarch64-unix/ and aarch64-windows/ is what goes here.
  WINEDLLPATH="$BL_DIRECTAUDIO/lib/wine${WINEDLLPATH:+:$WINEDLLPATH}"
  export WINEDLLPATH
  # mmdevapi only tries the drivers named in the registry; its built-in list is pulse, alsa, oss and
  # coreaudio and knows nothing about this one. The key is appended to the prefix's user.reg rather
  # than written with `wine reg`, which would start a wineserver here just to set one value.
  pfx="${STEAM_COMPAT_DATA_PATH:-}/pfx"
  reg="$pfx/user.reg"
  if [ -f "$reg" ]; then
    for pair in system32:aarch64-windows syswow64:i386-windows; do
      dir="$pfx/drive_c/windows/${pair%%:*}"
      src="$BL_DIRECTAUDIO/lib/wine/${pair#*:}/winedirectaudio.drv"
      if [ -d "$dir" ] && [ -f "$src" ] && [ "$(readlink "$dir/winedirectaudio.drv" 2>/dev/null)" != "$src" ]; then
        ln -sfn "$src" "$dir/winedirectaudio.drv.bl-new" && mv -f "$dir/winedirectaudio.drv.bl-new" "$dir/winedirectaudio.drv"
      fi
    done
    key='[Software\\\\Wine\\\\Drivers]'
    if [ "$(readlink "$pfx/drive_c/windows/system32/winedirectaudio.drv" 2>/dev/null)" != "$BL_DIRECTAUDIO/lib/wine/aarch64-windows/winedirectaudio.drv" ]; then
      echo "droiddeck-proton: DirectAudio could not be placed in the prefix; Proton's own audio stays" >&2
    elif ! BL_KEY="$key" awk 'index($0, "[") == 1 { inside = index($0, ENVIRON["BL_KEY"] " ") == 1 } inside && index($0, "\\"Audio\\"=") == 1 { last = $0 } END { exit last != "\\"Audio\\"=\\"directaudio,pulse\\"" }' "$reg" 2>/dev/null; then
      printf '\\n%s %s\\n"Audio"="directaudio,pulse"\\n' "$key" "$(date +%s)" >> "$reg"
      echo "droiddeck-proton: DirectAudio selected in the prefix" >&2
    fi
  else
    # A prefix that does not exist yet is created by Proton moments from now, after this runs, so
    # the key lands on the NEXT launch of that game. Said out loud because silent audio on a first
    # launch would otherwise look like a fault.
    echo "droiddeck-proton: no prefix yet - DirectAudio takes effect the next time this game starts" >&2
  fi
  echo "droiddeck-proton: DirectAudio ready (Wine $major)" >&2
}
"""

# Resolves the depot at launch time, so the tool can be registered before the depot exists and
# survives the client updating or replacing it. Proton takes its base directory from
# dirname(sys.argv[0]) without resolving it, so it is run from the depot itself.
LAUNCHER_SH = """#!/bin/bash
# DroidDeck's Proton ARM64: runs the ARM64 Proton the Steam client downloaded, without the
# Steam Linux Runtime container its own manifest asks for (no user namespaces on Android).
verb=$1; shift
steam_root=${STEAM_COMPAT_CLIENT_INSTALL_PATH:-${XDG_DATA_HOME:-$HOME/.local/share}/Steam}
# Steam's overlay is preloaded into every game Valve launches, and used to be dropped here: it was
# landing in front of open() and read() on /dev/input, letting Wine open the session's pad and
# answering every read of it with nothing - a controller that never reports, and Wine's HID thread
# spinning a core on it.
#
# Removing it was the wrong cure for an ordering problem. glibc processes LD_PRELOAD BEFORE
# /etc/ld.so.preload, and the interposer lives in the latter, so the overlay was simply ahead of it.
# Naming the interposer first in LD_PRELOAD puts it back in front and the overlay loads as Valve
# intends. That matters beyond the overlay itself: every deviation from the launch Valve ships is a
# difference this runtime would otherwise have to justify.
for fake in /usr/local/lib/libfakeinput.so /usr/local/lib/libblsession.so; do
  if [ -f "$fake" ]; then
    case ":${LD_PRELOAD:-}:" in
      *":$fake:"*) ;;
      *) LD_PRELOAD="$fake${LD_PRELOAD:+:$LD_PRELOAD}"; export LD_PRELOAD ;;
    esac
  fi
done
# The depot this tool is named after, newest across the libraries that hold it; the others in the
# list stand in only when it is missing.
depot=
libraries=$(printf '%%s\\n' "$steam_root" /mnt/droiddeck-sd; sed -n 's/^[[:space:]]*"path"[[:space:]]*"\\(.*\\)"[[:space:]]*$/\\1/p' "$steam_root/steamapps/libraryfolders.vdf" 2>/dev/null)
for name in %s; do
 best=0
 while IFS= read -r library; do
  candidate="$library/steamapps/common/$name"
  [ -d "$candidate/files/bin-arm64" ] && [ -x "$candidate/proton" ] || continue
  build=0
  read -r build _ 2>/dev/null < "$candidate/version"
  case $build in "" | *[!0-9]*) build=0 ;; esac
  if [ -z "$depot" ] || [ "$build" -gt "$best" ]; then
    depot=$candidate
    best=$build
  fi
 done <<< "$libraries"
 [ -n "$depot" ] && break
done
if [ -n "$depot" ]; then
  bl_components "$depot"
  bl_directaudio "$depot"
  bl_game_cpus
  bl_idtech3 "$@"
  bl_libpath
  exec ${BL_TASKSET:-} /usr/local/bin/droiddeck-game-env "$depot/proton" "$verb" "$@" "${BL_EXTRA_ARGS[@]}"
fi
echo "droiddeck-proton: no ARM64 Proton depot yet - the client downloads one as this tool's dependency; retry the launch once it has" >&2
exit 1
"""
LAUNCHER_TEMPLATE = LAUNCHER_SH


def launcher_sh(sources=SOURCES):
    # Spliced in after the formatting, never through it: the function body contains ${major%%.*}
    # and a % format would eat that into a single %, leaving a shell expansion that silently does
    # something else.
    return (LAUNCHER_TEMPLATE % " ".join('"%s"' % n for n in sources)).replace(
        "verb=$1; shift", "verb=$1; shift\n" + BL_DIRECTAUDIO_SETUP + BL_GAME_CPUS_SETUP + BL_IDTECH3_SETUP
        + BL_COMPONENTS_SETUP + BL_LIBPATH_SETUP, 1)


LAUNCHER_SH = launcher_sh()

# A third-party Proton dropped into compatibilitytools.d - GE-Proton, proton-cachyos, anything of
# that shape - is adopted rather than used as shipped, for the same two reasons Valve's ARM64 depot
# is: its manifest declares require_tool_appid, and the client's overlay library has to come out of
# LD_PRELOAD. Its own entry point is left untouched and called through this wrapper.
EXTRA_WRAPPER = "droiddeck-proton-wrap"
LEGACY_EXTRA_WRAPPER = "bannerlator-proton-wrap"
ORIGINAL_SUFFIX = ".droiddeck-orig"
LEGACY_ORIGINAL_SUFFIX = ".bannerlator-orig"
EXTRA_MANIFEST_VDF = """"manifest"
{
	"version" "2"
	"commandline" "/%s %%verb%%"
	"use_sessions" "1"
	"compatmanager_layer_name" "proton"
}
""" % EXTRA_WRAPPER
# %s is the tool's own entry point, read out of the manifest it shipped with.
EXTRA_WRAPPER_SH = """#!/bin/bash
# DroidDeck: runs a Proton installed into compatibilitytools.d without the Steam Linux Runtime
# container its own manifest asks for - pressure-vessel needs unprivileged user namespaces, which
# an Android app does not get, and the launch dies before Proton is reached.
verb=$1; shift
here=$(dirname "$0")
# See droiddeck-proton: the interposer goes first in LD_PRELOAD rather than the overlay being
# removed, because glibc reads LD_PRELOAD before /etc/ld.so.preload and the overlay was simply
# ahead of it on /dev/input.
for fake in /usr/local/lib/libfakeinput.so /usr/local/lib/libblsession.so; do
  if [ -f "$fake" ]; then
    case ":${LD_PRELOAD:-}:" in
      *":$fake:"*) ;;
      *) LD_PRELOAD="$fake${LD_PRELOAD:+:$LD_PRELOAD}"; export LD_PRELOAD ;;
    esac
  fi
done
bl_components "$here"
bl_directaudio "$here"
bl_game_cpus
bl_idtech3 "$@"
bl_libpath
# Proton takes its base directory from dirname(sys.argv[0]) without resolving it, so it has to be
# started from its own tree.
exec ${BL_TASKSET:-} /usr/local/bin/droiddeck-game-env "$here/%s" "$verb" "$@" "${BL_EXTRA_ARGS[@]}"
"""
EXTRA_COMPAT_TOOL_VDF = """"compatibilitytools"
{
	"compat_tools"
	{
		"%s"
		{
			"install_path" "."
			"display_name" "%s"
			"from_oslist" "windows"
			"to_oslist" "linux"
		}
	}
}
"""


FEX_COMPAT_TOOL_VDF = """"compatibilitytools"
{
	"compat_tools"
	{
		"%s"
		{
			"install_path" "."
			"display_name" "%s"
			"from_oslist" "linux"
			"to_oslist" "linux"
		}
	}
}
"""
FEX_MANIFEST_VDF = """"manifest"
{
	"version" "2"
	"commandline" "/%s %%verb%%"
	"use_tool_subprocess_reaper" "1"
}
""" % FEX_LAUNCHER
FEX_LAUNCHER_SH = """#!/bin/bash
verb=$1; shift
case $verb in
  getcompatpath | getnativepath) printf '%s\\n' "$1"; exit 0 ;;
esac
exec /usr/local/bin/droiddeck-fex steam "$verb" "$@"
"""


TOKEN = re.compile(r'\s*(?:"((?:[^"\\]|\\.)*)"|([{}])|//[^\n]*)')


def tokenize(text):
    tokens = []
    pos = 0
    while pos < len(text):
        m = TOKEN.match(text, pos)
        if not m or m.end() == pos:
            break
        pos = m.end()
        if m.group(2):
            tokens.append(m.group(2))
        elif m.group(1) is not None:
            tokens.append('"' + m.group(1) + '"')
    return tokens


def find_block(tokens, path):
    """Index of the '{' opening the block at path, or None."""
    depth, want, i = 0, 0, 0
    while i < len(tokens):
        t = tokens[i]
        if t == "{":
            depth += 1
        elif t == "}":
            depth -= 1
            if depth < want:
                return None
        elif depth == want and i + 1 < len(tokens) and tokens[i + 1] == "{":
            if t.lower() == '"%s"' % path[want].lower():
                if want == len(path) - 1:
                    return i + 1
                want += 1
        i += 1
    return None


def block_end(tokens, start):
    depth = 0
    for i in range(start, len(tokens)):
        if tokens[i] == "{":
            depth += 1
        elif tokens[i] == "}":
            depth -= 1
            if depth == 0:
                return i
    return len(tokens)


def serialize(tokens):
    out, depth, i = [], 0, 0
    while i < len(tokens):
        t = tokens[i]
        if t == "}":
            depth -= 1
            out.append("\t" * depth + "}")
            i += 1
        elif i + 1 < len(tokens) and tokens[i + 1] == "{":
            out.append("\t" * depth + t)
            out.append("\t" * depth + "{")
            depth += 1
            i += 2
        else:
            out.append("\t" * depth + t + "\t\t" + tokens[i + 1])
            i += 2
    return "\n".join(out) + "\n"


def write_changed(path, text, mode=None):
    """Writes `text` to `path` only when it differs, through a rename so a reader never sees half a
    file. The session runs this script every 15 s for as long as the client does; rewriting files
    that have not changed cost a python start's worth of writes each time, and config.vdf is the
    client's own, which it may be writing at that moment. Returns whether anything was written."""
    try:
        with open(path, encoding="utf-8", errors="replace") as f:
            same = f.read() == text
    except OSError:
        same = False
    if not same:
        tmp = path + ".droiddeck"
        with open(tmp, "w", encoding="utf-8") as f:
            f.write(text)
        if mode is not None:
            os.chmod(tmp, mode)
        os.replace(tmp, path)
    elif mode is not None and (os.stat(path).st_mode & 0o7777) != mode:
        os.chmod(path, mode)
    return not same


def display_name(base):
    try:
        with open(LABEL_FILE, encoding="utf-8") as f:
            label = f.read().strip().replace('"', "'").replace("\\", "")
    except OSError:
        label = ""
    return "%s (%s)" % (base, label) if label else base


def first_key(path, section):
    """The single key naming a block inside `section`, or None. Used to keep a third-party tool's
    own internal name, so a mapping the user already made against it keeps working."""
    try:
        with open(path, encoding="utf-8", errors="replace") as f:
            tokens = tokenize(f.read())
    except OSError:
        return None
    block = find_block(tokens, section)
    if block is None:
        return None
    for i in range(block + 1, block_end(tokens, block)):
        if tokens[i] == "}":
            break
        if i + 1 < len(tokens) and tokens[i + 1] == "{":
            return tokens[i].strip('"')
    return None


def manifest_entry_point(path):
    """The script a toolmanifest's commandline runs, relative to the tool directory."""
    try:
        with open(path, encoding="utf-8", errors="replace") as f:
            tokens = tokenize(f.read())
    except OSError:
        return None
    for i in range(len(tokens) - 1):
        if tokens[i].lower() == '"commandline"':
            command = tokens[i + 1].strip('"').split()
            if command:
                return command[0].lstrip("/")
    return None


def adopt_extras(tools):
    """Makes every other Proton in compatibilitytools.d launchable here, and returns the tool names
    to leave alone in CompatToolMapping - the whole point of installing one is to pick it per game,
    so register_default must not repoint it back at ours."""
    adopted = {}
    try:
        entries = sorted(os.listdir(tools))
    except OSError:
        return adopted
    for entry in entries:
        if entry in dict(OWN_TOOLS) or entry == FEX_TOOL or entry.startswith("."):
            continue
        tool_dir = os.path.join(tools, entry)
        manifest = os.path.join(tool_dir, "toolmanifest.vdf")
        if not os.path.isdir(tool_dir) or not os.path.isfile(manifest):
            continue
        # The shipped manifest is kept, once, and stays the source of the entry point: re-running
        # must not read back our own rewritten commandline and wrap the wrapper.
        original = manifest + ORIGINAL_SUFFIX
        legacy = manifest + LEGACY_ORIGINAL_SUFFIX
        if not os.path.isfile(original) and os.path.isfile(legacy):
            try:
                os.replace(legacy, original)
            except OSError:
                continue
        if not os.path.isfile(original):
            try:
                shutil.copy2(manifest, original)
            except OSError:
                continue
        entry_point = manifest_entry_point(original)
        if not entry_point or entry_point in (EXTRA_WRAPPER, LEGACY_EXTRA_WRAPPER):
            entry_point = "proton"
        if not os.path.exists(os.path.join(tool_dir, entry_point)):
            print("steam-compatibility: %s has no %s; left alone" % (entry, entry_point))
            continue
        compat_vdf = os.path.join(tool_dir, "compatibilitytool.vdf")
        name = first_key(compat_vdf, ["compatibilitytools", "compat_tools"]) or entry
        wrapper = os.path.join(tool_dir, EXTRA_WRAPPER)
        try:
            # Formatted first, spliced second: the function carries a printf %s and a
            # ${major%%.*} of its own, and putting it through the format would eat both.
            body = (EXTRA_WRAPPER_SH % entry_point).replace(
                    'here=$(dirname "$0")',
                    'here=$(dirname "$0")\n' + BL_DIRECTAUDIO_SETUP + BL_GAME_CPUS_SETUP + BL_IDTECH3_SETUP
                    + BL_COMPONENTS_SETUP + BL_LIBPATH_SETUP, 1)
            write_changed(wrapper, body, 0o755)
            write_changed(manifest, EXTRA_MANIFEST_VDF)
            write_changed(compat_vdf, EXTRA_COMPAT_TOOL_VDF % (name, display_name(entry)))
            legacy_wrapper = os.path.join(tool_dir, LEGACY_EXTRA_WRAPPER)
            if os.path.isfile(legacy_wrapper):
                os.unlink(legacy_wrapper)
        except OSError as e:
            print("steam-compatibility: could not adopt %s (%s)" % (entry, e))
            continue
        adopted[name] = entry
    return adopted


# Steam's own tools and runtimes live in steamapps beside the games; they are not titles and must
# not be mapped to a compatibility tool.
NOT_GAMES = frozenset((
    "228980",    # Steamworks Common Redistributables
    "1070560",   # Steam Linux Runtime 1.0 (scout)
    "1391110",   # Steam Linux Runtime 2.0 (soldier)
    "1628350",   # Steam Linux Runtime 3.0 (sniper)
    "1493710",   # Proton Experimental
    "3127680",   # FEX
    "4183110",   # Steam Linux Runtime 4.0
    "4185400",   # Steam Linux Runtime 4.0 - Arm64
    "4427310",   # Proton Experimental (ARM64)
    "4628740",   # Proton 11.0 (ARM64)
))


def libraries(steam_root):
    found = [steam_root]
    try:
        with open(os.path.join(steam_root, "steamapps", "libraryfolders.vdf"), encoding="utf-8", errors="replace") as f:
            found += [path.replace("\\\\", "\\") for path in re.findall(r'"path"\s+"((?:[^"\\]|\\.)*)"', f.read())]
    except OSError:
        pass
    found.append(LIBRARY + "-sd")
    return list(dict.fromkeys(found))


def installed_apps(steam_root):
    """App ids of the titles the client has installed, tools and runtimes excluded."""
    apps = set()
    for library in libraries(steam_root):
        steamapps = os.path.join(library, "steamapps")
        try:
            names = os.listdir(steamapps)
        except OSError:
            continue
        for name in names:
            m = re.fullmatch(r"appmanifest_(\d+)\.acf", name)
            if m and m.group(1) not in NOT_GAMES:
                apps.add(m.group(1))
    return sorted(apps, key=int)


APPINFO_CACHE = {}
STEAM_PLAY_MANIFESTS = 891390


def appinfo_entries(path):
    import struct
    try:
        stamp = os.stat(path).st_mtime_ns
    except OSError:
        return {}
    cached = APPINFO_CACHE.get(path)
    if cached and cached[0] == stamp:
        return cached[1]
    try:
        with open(path, "rb") as f:
            data = f.read()
    except OSError:
        return {}
    if len(data) < 8:
        return {}
    magic = struct.unpack_from("<I", data, 0)[0]
    if magic not in (0x07564427, 0x07564428, 0x07564429):
        return {}
    offset = 8
    strings = None
    try:
        if magic == 0x07564429:
            table = struct.unpack_from("<q", data, offset)[0]
            offset += 8
            count = struct.unpack_from("<I", data, table)[0]
            position = table + 4
            strings = []
            for _ in range(count):
                end = data.index(b"\0", position)
                strings.append(data[position:end].decode("utf-8", "replace"))
                position = end + 1
    except (ValueError, IndexError, struct.error):
        return {}
    header = 4 + 4 + 8 + 20 + 4 + (20 if magic >= 0x07564428 else 0)

    def section(position):
        result = {}
        while True:
            kind = data[position]
            position += 1
            if kind == 8:
                return result, position
            if strings is not None:
                key = strings[struct.unpack_from("<I", data, position)[0]]
                position += 4
            else:
                end = data.index(b"\0", position)
                key = data[position:end].decode("utf-8", "replace")
                position = end + 1
            if kind == 0:
                result[key], position = section(position)
            elif kind == 1:
                end = data.index(b"\0", position)
                result[key] = data[position:end].decode("utf-8", "replace")
                position = end + 1
            elif kind == 2:
                result[key] = struct.unpack_from("<i", data, position)[0]
                position += 4
            elif kind == 7:
                result[key] = struct.unpack_from("<Q", data, position)[0]
                position += 8
            else:
                raise ValueError("unknown appinfo field type %d" % kind)

    found = {}
    while offset + 8 <= len(data):
        try:
            app, size = struct.unpack_from("<II", data, offset)
        except struct.error:
            break
        if app == 0:
            break
        start = offset + 8
        offset = start + size
        try:
            info = section(start + header)[0].get("appinfo", {})
        except (ValueError, IndexError, struct.error):
            continue
        if not isinstance(info, dict):
            continue
        common = info.get("common", {}) if isinstance(info.get("common"), dict) else {}
        deck = common.get("steam_deck_compatibility")
        configuration = deck.get("configuration") if isinstance(deck, dict) else None
        recommended = configuration.get("recommended_runtime", "") if isinstance(configuration, dict) else ""
        entry = {
            "oslist": {part.strip().lower() for part in str(common.get("oslist", "")).split(",") if part.strip()},
            "osarch": str(common.get("osarch", "")).lower(),
            "type": str(common.get("type", "")).lower(),
            "recommended": str(recommended),
        }
        if app == STEAM_PLAY_MANIFESTS:
            extended = info.get("extended", {})
            mappings = extended.get("app_mappings", {}) if isinstance(extended, dict) else {}
            entry["app_mappings"] = {str(m.get("appid", key)): str(m.get("tool", "")) for key, m in mappings.items()
                                     if isinstance(m, dict)} if isinstance(mappings, dict) else {}
        found[str(app)] = entry
    APPINFO_CACHE[path] = (stamp, found)
    return found


def appinfo_platforms(path, wanted):
    entries = appinfo_entries(path)
    return {app: (entries[app]["oslist"], entries[app]["osarch"], entries[app]["type"]) for app in wanted if app in entries}


def valve_picks(steam_root):
    entries = appinfo_entries(os.path.join(steam_root, "appcache", "appinfo.vdf"))
    mapped = {app for app, tool in entries.get(str(STEAM_PLAY_MANIFESTS), {}).get("app_mappings", {}).items() if tool}
    picks = set()
    for app, entry in entries.items():
        if app in NOT_GAMES or entry["type"] not in PLAYABLE_TYPES:
            continue
        if entry["oslist"] and "windows" not in entry["oslist"]:
            continue
        if entry["recommended"] or app in mapped:
            picks.add(app)
    return sorted(picks, key=int)


def native_targets(steam_root, apps):
    wanted = {str(app) for app in apps if str(app) not in NOT_GAMES}
    if not wanted:
        return {}
    targets = {}
    for app, (oslist, osarch, kind) in appinfo_platforms(os.path.join(steam_root, "appcache", "appinfo.vdf"), wanted).items():
        if kind not in PLAYABLE_TYPES or "windows" in oslist or "linux" not in oslist:
            continue
        if "arm64" in osarch or "aarch64" in osarch:
            continue
        targets[app] = FEX_TOOL
    return targets


def linux_runtime_tool(name):
    low = name.lower()
    return low == "fex" or low.startswith("steamlinuxruntime")


def fex_missing(steam_root):
    missing = []
    for app in FEX_DEPENDENCIES:
        if not any(os.path.isfile(os.path.join(library, "steamapps", "appmanifest_%s.acf" % app))
                   for library in libraries(steam_root)):
            missing.append(app)
    return missing


def fex_wanted_marker():
    return os.path.join(os.environ.get("HOME", "/root"), ".config", "droiddeck", "fex-wanted")


def request_fex(steam_root, asked):
    import subprocess
    client = os.path.join(steam_root, "steamrtarm64", "steam")
    missing = fex_missing(steam_root)
    if not os.access(client, os.X_OK) or any(app in asked for app in missing):
        return []
    for app in missing:
        asked.add(app)
        try:
            process = subprocess.Popen([client, "steam://install/%s" % app], stdout=subprocess.DEVNULL,
                                       stderr=subprocess.DEVNULL, start_new_session=True)
        except OSError:
            continue
        try:
            process.wait(timeout=REQUEST_HANDOFF_SECONDS)
        except subprocess.TimeoutExpired:
            pass
        return [app]
    return []


def read_json(path):
    try:
        with open(path, encoding="utf-8") as f:
            value = json.load(f)
    except (OSError, ValueError):
        return {}
    return value if isinstance(value, dict) else {}


def write_json(path, value):
    os.makedirs(os.path.dirname(path), exist_ok=True)
    return write_changed(path, json.dumps(value, indent=1, sort_keys=True) + "\n")


class locked:
    def __init__(self, directory=None):
        self.path = os.path.join(directory or COMPAT_DIR, "lock")

    def __enter__(self):
        import fcntl
        os.makedirs(os.path.dirname(self.path), exist_ok=True)
        self.fd = os.open(self.path, os.O_RDWR | os.O_CREAT, 0o644)
        fcntl.flock(self.fd, fcntl.LOCK_EX)
        return self

    def __exit__(self, *exc):
        os.close(self.fd)


def state_path(name, directory=None):
    return os.path.join(directory or COMPAT_DIR, name)


def unrunnable(name, runnable):
    low = name.lower()
    return low not in runnable and (low.startswith("proton") or low == LEGACY_TOOL or low.startswith("droiddeck-proton"))


def app_order(app):
    return (len(app), app)


def plan_mapping(current, installed, runnable, default, auto, native=None, picks=()):
    runnable = {n.lower() for n in runnable}
    installed = set(installed)
    picks = set(picks)
    native = native or {}
    changes, kept = {}, {}
    if current.get("0", "") != default:
        changes["0"] = default
    for app in sorted((set(current) | installed | picks | set(auto)) - {"0"}, key=app_order):
        name = current.get(app, "")
        mine = auto.get(app)
        target = native.get(app, default)
        stale = unrunnable(name, runnable) or (app in native and linux_runtime_tool(name))
        if name and not stale and (mine is None or name != mine):
            continue
        if not name and app not in installed and app not in picks:
            continue
        if name != target:
            changes[app] = target
        kept[app] = target
    return changes, kept


def followers(state, current):
    if "auto" in state:
        return state["auto"]
    return {app: name for app, name in current.items() if app != "0" and name == TOOL}


def tool_entry(name, display, path, valve):
    return {"name": name, "display": display, "dir": os.path.basename(path) if path else "", "valve": valve}


def tool_catalog(steam_root, extras=None):
    tools = os.path.join(steam_root, "compatibilitytools.d")
    catalog = []
    for name, sources in OWN_TOOLS:
        depot = find_source(steam_root, sources)
        if depot is None and name != TOOL:
            continue
        catalog.append(tool_entry(name, display_name(
            os.path.basename(depot).replace(" (ARM64)", " ARM64") if depot else "Proton ARM64"), depot, True))
    if extras is None:
        extras = {}
        try:
            entries = sorted(os.listdir(tools))
        except OSError:
            entries = []
        for entry in entries:
            tool_dir = os.path.join(tools, entry)
            if entry in dict(OWN_TOOLS) or not any(os.path.isfile(os.path.join(tool_dir, w)) for w in (EXTRA_WRAPPER, LEGACY_EXTRA_WRAPPER)):
                continue
            extras[first_key(os.path.join(tool_dir, "compatibilitytool.vdf"), ["compatibilitytools", "compat_tools"]) or entry] = entry
    for name, entry in sorted(extras.items()):
        catalog.append(tool_entry(name, display_name(entry), os.path.join(tools, entry), False))
    return catalog


def requested_tool(request, catalog):
    name = request.get("name")
    if isinstance(name, str) and any(t["name"] == name for t in catalog):
        return name
    for tool in catalog:
        if tool["dir"] and tool["dir"] == request.get("dir") and tool["valve"] == bool(request.get("valve")):
            return tool["name"]
    return None


def now_ms():
    import time
    return int(time.time() * 1000)


def choose_default(steam_default, state, request, catalog, adopt_steam=True, apply_request=True, now=None):
    state = dict(state)
    names = [t["name"] for t in catalog]
    seq = request.get("seq")
    seq = seq if isinstance(seq, int) else 0
    if apply_request and seq > int(state.get("applied", 0) or 0):
        wanted = requested_tool(request, catalog)
        state["applied"] = seq
        if wanted:
            if wanted != state.get("default"):
                state.update(default=wanted, seq=now or now_ms(), source="app")
        else:
            print("steam-compatibility: the app asked for %s, which is not installed; kept %s" % (
                request.get("name") or request.get("dir"), state.get("default") or TOOL))
    elif adopt_steam and steam_default in names and steam_default != state.get("default"):
        state.update(default=steam_default, seq=now or now_ms(), source="steam")
    if state.get("default") not in names:
        state["default"] = TOOL
    return state["default"], state


def mapping_block(tokens):
    steam = find_block(tokens, ["InstallConfigStore", "Software", "Valve", "Steam"])
    if steam is None:
        return None
    mapping = find_block(tokens[steam + 1:], ["CompatToolMapping"])
    if mapping is None:
        end = block_end(tokens, steam)
        tokens[end:end] = ['"CompatToolMapping"', "{", "}"]
        return end + 1
    return mapping + steam + 1


def read_mapping(tokens, mapping):
    current = {}
    end = block_end(tokens, mapping)
    i = mapping + 1
    while i < end:
        if i + 1 < end and tokens[i + 1] == "{":
            close = block_end(tokens, i + 1)
            name = ""
            for j in range(i + 2, close - 1):
                if tokens[j] == '"name"':
                    name = tokens[j + 1].strip('"')
                    break
            current[tokens[i].strip('"')] = name
            i = close + 1
        else:
            i += 2
    return current


def set_mapping(tokens, mapping, app, tool):
    block = find_block(tokens[mapping + 1:], [app])
    if block is None:
        tokens[mapping + 1:mapping + 1] = [
            '"%s"' % app, "{", '"name"', '"%s"' % tool, '"config"', '""', '"priority"', '"75"' if app == "0" else '"250"', "}"]
        return
    block += mapping + 1
    end = block_end(tokens, block)
    for i in range(block + 1, end):
        if tokens[i] == '"name"':
            tokens[i + 1] = '"%s"' % tool
            return
    tokens[block + 1:block + 1] = ['"name"', '"%s"' % tool]


def steam_running():
    try:
        pids = [p for p in os.listdir("/proc") if p.isdigit()]
    except OSError:
        return False
    for pid in pids:
        try:
            with open("/proc/%s/cmdline" % pid, "rb") as f:
                argv0 = f.read().split(b"\0", 1)[0]
        except OSError:
            continue
        if argv0.endswith(b"steamrtarm64/steam"):
            return True
    return False


def live_helper_running(directory=None):
    try:
        with open(state_path("live.pid", directory)) as f:
            pid = int(f.read().split()[0])
        os.kill(pid, 0)
        return True
    except (OSError, ValueError, IndexError):
        return False


def register_default(config_path, apps=(), protect=(), default=None, catalog=None, directory=None, settle=False, picks=()):
    """Writes the mapping: the "0" default and every title that follows it (see plan_mapping).
    With settle, the default itself is decided first (see choose_default): before the client
    starts, config.vdf holds what the client last kept, menu changes included."""
    with locked(directory):
        state = read_json(state_path("state.json", directory))
        with open(config_path, encoding="utf-8", errors="replace") as f:
            original = f.read()
        tokens = tokenize(original)
        mapping = mapping_block(tokens)
        if mapping is None:
            return state.get("default") or TOOL
        current = read_mapping(tokens, mapping)
        if catalog is None:
            catalog = tool_catalog(os.path.dirname(os.path.dirname(os.path.abspath(config_path))),
                                   dict(protect) if isinstance(protect, dict) else {name: name for name in protect})
        names = [t["name"] for t in catalog]
        if default is None:
            if settle:
                default, state = choose_default(current.get("0", ""), state, read_json(state_path("request.json", directory)), catalog)
            else:
                default = state.get("default") if state.get("default") in names else TOOL
        steam_root = os.path.dirname(os.path.dirname(os.path.abspath(config_path)))
        changes, auto = plan_mapping(current, apps, names, default, followers(state, current), native_targets(steam_root, apps), picks)
        for app, tool in changes.items():
            set_mapping(tokens, mapping, app, tool)
        text = serialize(tokens)
        if text != serialize(tokenize(original)):
            write_changed(config_path, text)
        state["auto"] = auto
        state["tools"] = catalog
        state.setdefault("default", default)
        write_json(state_path("state.json", directory), state)
    return default


def depot_build(depot):
    """The build number a depot's version file starts with; 0 when there is none."""
    try:
        with open(os.path.join(depot, "version"), encoding="utf-8", errors="replace") as f:
            first = f.read().split(None, 1)
    except OSError:
        return 0
    return int(first[0]) if first and first[0].isdigit() else 0


def find_source(steam_root, sources=SOURCES):
    """The first of `sources` the client has downloaded, newest across the libraries holding it."""
    for name in sources:
        found = [os.path.join(root, "steamapps", "common", name) for root in libraries(steam_root)
                 if os.path.isdir(os.path.join(root, "steamapps", "common", name, "files", "bin-arm64"))]
        if found:
            return max(found, key=depot_build)
    return None


def build_tool(tool_dir, depot, sources=SOURCES, name=TOOL):
    """Our own manifests and the launcher, named after `depot`. The depot is run at launch time."""
    if os.path.islink(tool_dir):
        os.unlink(tool_dir)
    elif os.path.isdir(tool_dir) and set(os.listdir(tool_dir)) - set(OWN_FILES):
        # Earlier versions mirrored the depot in here as symlinks; start clean. A directory holding
        # only our own files is kept, and each file rewritten only when it changed.
        shutil.rmtree(tool_dir)
    os.makedirs(tool_dir, exist_ok=True)
    write_changed(os.path.join(tool_dir, "toolmanifest.vdf"), TOOL_MANIFEST_VDF)
    write_changed(os.path.join(tool_dir, "compatibilitytool.vdf"), COMPAT_TOOL_VDF % (name, display_name(
        os.path.basename(depot).replace(" (ARM64)", " ARM64") if depot else "Proton ARM64")))
    write_changed(os.path.join(tool_dir, LAUNCHER), launcher_sh(sources), 0o755)


def build_fex_tool(tool_dir):
    if os.path.islink(tool_dir):
        os.unlink(tool_dir)
    elif os.path.isdir(tool_dir) and set(os.listdir(tool_dir)) - set(FEX_FILES):
        shutil.rmtree(tool_dir)
    os.makedirs(tool_dir, exist_ok=True)
    write_changed(os.path.join(tool_dir, "toolmanifest.vdf"), FEX_MANIFEST_VDF)
    write_changed(os.path.join(tool_dir, "compatibilitytool.vdf"), FEX_COMPAT_TOOL_VDF % (FEX_TOOL, display_name("Linux x86 (FEX)")))
    write_changed(os.path.join(tool_dir, FEX_LAUNCHER), FEX_LAUNCHER_SH, 0o755)


def remove_tool(tool_dir):
    if os.path.isdir(tool_dir) and not os.path.islink(tool_dir) and not set(os.listdir(tool_dir)) - set(OWN_FILES) - {LEGACY_LAUNCHER}:
        shutil.rmtree(tool_dir)


def main():
    steam_root = sys.argv[1]
    tools = os.path.join(steam_root, "compatibilitytools.d")
    os.makedirs(tools, exist_ok=True)
    legacy = os.path.join(tools, LEGACY_TOOL)
    if os.path.islink(legacy):
        os.unlink(legacy)
    elif os.path.isdir(legacy):
        shutil.rmtree(legacy)
    for name, sources in OWN_TOOLS:
        depot = find_source(steam_root, sources)
        if depot is None and name != TOOL:
            remove_tool(os.path.join(tools, name))
            continue
        build_tool(os.path.join(tools, name), depot, sources, name)
        print("steam-compatibility: registered %s (%s)" % (
            name, "depot %s present" % os.path.basename(depot) if depot else
            "no ARM64 Proton depot yet; the session asks the client to fetch it"))
    build_fex_tool(os.path.join(tools, FEX_TOOL))
    print("steam-compatibility: registered %s" % FEX_TOOL)
    extras = adopt_extras(tools)
    for name, directory in sorted(extras.items()):
        print("steam-compatibility: adopted %s as %s" % (directory, name))
    catalog = tool_catalog(steam_root, extras)
    config = os.path.join(steam_root, "config", "config.vdf")
    if live_helper_running():
        with locked():
            state = read_json(state_path("state.json"))
            state["tools"] = catalog
            write_json(state_path("state.json"), state)
        print("steam-compatibility: the live helper keeps the client's mapping; tools listed")
    elif os.path.isfile(config):
        apps = installed_apps(steam_root)
        picks = valve_picks(steam_root)
        default = register_default(config, apps, protect=extras, catalog=catalog, settle=not steam_running(), picks=picks)
        print("steam-compatibility: default, %d installed title(s) and %d title(s) with a Valve pick set to %s" % (len(apps), len(picks), default))
    sync = os.path.join(os.path.dirname(os.path.realpath(__file__)), "droiddeck-esync")
    if os.path.isfile(sync):
        try:
            summary = runpy.run_path(sync)["reconcile"](steam_root, os.environ)
        except Exception as e:
            summary = "droiddeck-esync: reconcile failed (%s)" % e
        if summary:
            print("steam-compatibility: %s" % summary)


if __name__ == "__main__":
    main()
