#!/usr/bin/python3
# The desktop's games and emulators, started on the GPU. Every menu entry whose categories say
# Game or Emulator gets a copy of its own in ~/.local/share/applications (which wins over
# /usr/share/applications) whose Exec runs it through droiddeck-gpu: full screen on the app's
# compositor, where Vulkan and OpenGL work. The entry keeps the old way as a second action, "Run in
# a desktop window". Run at every desktop start; copies whose original is gone, or all of them when
# the switch is off, are removed.
#
#   BL_DESKTOP_GPU=auto (default: on while the desktop is composited by pixman) | on | off
import os
import re

HOME = os.environ.get("HOME", "/root")
SYSTEM_DIR = "/usr/share/applications"
USER_DIR = os.path.join(HOME, ".local/share/applications")
MARK = "X-DroidDeck-GPU=1"
# The client and its games already hand themselves to the app (bannerlator-steam-launch).
SKIP = re.compile(r"^(steam|droiddeck-game-|droiddeck-steam|steamdeck-)", re.I)


def enabled():
    mode = os.environ.get("BL_DESKTOP_GPU", "auto").strip().lower()
    if mode in ("on", "1", "yes", "true"):
        return True
    if mode in ("off", "0", "no", "false"):
        return False
    return os.environ.get("WLR_RENDERER", "pixman") == "pixman"


def main_group(text):
    """The [Desktop Entry] group's lines, and everything after it."""
    lines = text.splitlines()
    start = next((i for i, l in enumerate(lines) if l.strip() == "[Desktop Entry]"), None)
    if start is None:
        return None, None, None
    end = next((i for i in range(start + 1, len(lines)) if lines[i].startswith("[")), len(lines))
    return lines[:start + 1], lines[start + 1:end], lines[end:]


def wrap(text):
    head, group, rest = main_group(text)
    if group is None:
        return None
    keys = {}
    for l in group:
        if "=" in l and not l.lstrip().startswith("#"):
            k, v = l.split("=", 1)
            keys.setdefault(k.strip(), v)
    cats = set(filter(None, keys.get("Categories", "").split(";")))
    if not cats & {"Game", "Emulator"}:
        return None
    if keys.get("Type", "Application") != "Application" or keys.get("NoDisplay", "").lower() == "true":
        return None
    exec_line = keys.get("Exec", "").strip()
    if not exec_line or exec_line.startswith("droiddeck-gpu "):
        return None
    out_group = []
    actions = keys.get("Actions", "")
    for l in group:
        k = l.split("=", 1)[0].strip() if "=" in l else None
        if k == "Exec":
            out_group.append("Exec=droiddeck-gpu " + exec_line)
        elif k == "Actions":
            continue
        else:
            out_group.append(l)
    while out_group and not out_group[-1].strip():
        out_group.pop()
    out_group.append("Actions=" + ("droiddeck-window;" + actions if actions else "droiddeck-window;"))
    out_group.append(MARK)
    window = ["", "[Desktop Action droiddeck-window]", "Name=Run in a desktop window", "Exec=" + exec_line]
    # The entry's own actions (new window, a different mode...) run on the GPU as well.
    wrapped_rest = []
    for l in rest:
        if l.startswith("Exec=") and not l[5:].startswith("droiddeck-gpu "):
            l = "Exec=droiddeck-gpu " + l[5:]
        wrapped_rest.append(l)
    if wrapped_rest and wrapped_rest[0].strip():
        wrapped_rest.insert(0, "")
    return "\n".join(head + out_group + window + wrapped_rest) + "\n"


def ours(path):
    try:
        with open(path, encoding="utf-8", errors="replace") as f:
            return MARK in f.read()
    except OSError:
        return False


def main():
    on = enabled()
    os.makedirs(USER_DIR, exist_ok=True)
    written = set()
    if on and os.path.isdir(SYSTEM_DIR):
        for name in sorted(os.listdir(SYSTEM_DIR)):
            if not name.endswith(".desktop") or SKIP.match(name):
                continue
            target = os.path.join(USER_DIR, name)
            # A copy the user made or edited themselves is theirs.
            if os.path.exists(target) and not ours(target):
                continue
            try:
                with open(os.path.join(SYSTEM_DIR, name), encoding="utf-8", errors="replace") as f:
                    text = wrap(f.read())
            except OSError:
                continue
            if text is None:
                continue
            with open(target + ".tmp", "w", encoding="utf-8") as f:
                f.write(text)
            os.replace(target + ".tmp", target)
            written.add(name)
    removed = 0
    for name in os.listdir(USER_DIR):
        path = os.path.join(USER_DIR, name)
        if name.endswith(".desktop") and name not in written and ours(path):
            os.remove(path)
            removed += 1
    print(f"droiddeck-desktop-gpu: {'on' if on else 'off'}, {len(written)} entries on the GPU, {removed} removed")


main()