#!/usr/bin/env python3
# ABOUT ME
# Locates Cosmoteer's installed Data folder by asking Steam where its libraries
# are.
#
# Why this exists: the mod tests validate against vanilla game data, and the
# game can be installed to any Steam library on any disk. A fixed list of
# guessed paths misses real installs, so this reads the library roots out of
# Steam's own libraryfolders.vdf and looks for the game under each one.
#
# install.sh carries the same logic in bash for finding the Mods folder.

import os
import re

COSMOTEER_APPID = 799600

# One "path" entry per library root; the app data sits in <path>/steamapps.
_LIBRARY_PATH_RE = re.compile(r'^\s*"path"\s*"(.*)"\s*$')


def steam_roots(home):
    """The Steam client directories, one per install flavour."""
    return [
        os.path.join(home, ".local/share/Steam"),
        os.path.join(home, ".steam/steam"),
        os.path.join(home, ".steam/root"),
        os.path.join(home, ".var/app/com.valvesoftware.Steam/data/Steam"),
    ]


def steam_libraries(home):
    """Every Steam library root, in search order and without duplicates.

    Steam's own roots come first so the default library stays searchable even
    when libraryfolders.vdf is missing or unreadable.
    """
    libraries = list(steam_roots(home))
    for root in steam_roots(home):
        vdf = os.path.join(root, "steamapps", "libraryfolders.vdf")
        try:
            with open(vdf, encoding="utf-8", errors="replace") as handle:
                lines = handle.readlines()
        except OSError:
            continue
        for line in lines:
            match = _LIBRARY_PATH_RE.match(line)
            if match:
                libraries.append(match.group(1).replace("\\\\", "\\"))

    seen = set()
    unique = []
    for library in libraries:
        if library not in seen:
            seen.add(library)
            unique.append(library)
    return unique


def find_data_dir(home=None, environ=None):
    """The Cosmoteer Data folder, or None when the game is not installed.

    COSMOTEER_DATA overrides discovery so an unusual install can be pointed at
    by hand.
    """
    environ = os.environ if environ is None else environ
    override = environ.get("COSMOTEER_DATA")
    if override:
        return override

    home = os.path.expanduser("~") if home is None else home
    for library in steam_libraries(home):
        data = os.path.join(library, "steamapps", "common", "Cosmoteer", "Data")
        if os.path.isdir(data):
            return data
    return None


def find_bin_dir(home=None, environ=None):
    """The Cosmoteer Bin folder, which sits beside Data."""
    data = find_data_dir(home=home, environ=environ)
    if not data:
        return None
    return os.path.join(os.path.dirname(data), "Bin")