Creates a cross-reference between RetroPie's ROM folders to emulators using those and vice-versa.

rp_emu_folder_xref.py

#! /usr/bin/env python3

# Creates two JSON files as cross-reference between RetroPie's ROM folders and
# emulators.
#
# romfolder_to_emus.json: mapping which emulators (values) use which romfolder
# (keys)
#
# emu_to_romfolders.json: mapping which romfolders (values) are used by which
# emulator (keys)
#
# Does not include the RetroPie-Setup/ext/ folders.
#
# (c) 2023 Gemba @ GitHub, license MIT

import json
import re

from itertools import chain
from pathlib import Path

RP_SETUP = Path.home() / "RetroPie-Setup"

emus = sorted(RP_SETUP.rglob("emulators/*.sh"))
lr = sorted(RP_SETUP.rglob("libretrocores/*.sh"))
ports = sorted(RP_SETUP.rglob("ports/*.sh"))
ml = RP_SETUP.rglob("supplementary/moonlight.sh")
scriptmodules = chain(emus, lr, ports, ml)

xref = {}
for s in scriptmodules:
    with open(s) as fh:
        lines = fh.readlines()
        folders = set()
        rp_module_id = None
        multiline = False

        for line in lines:
            if 'rp_module_id' in line:
                rp_module_id = line.split("=")[-1].replace('"', '').strip()
                # filter advmame-1.5.4, love-0.10.2, ...
                m = re.search(r"^.+-\d+\..+$", rp_module_id)
                if rp_module_id == "retroarch" or m:
                    rp_module_id = None
                    break
            if 'addSystem "' in line or 'local system="' in line:
                _fd = line.split('"')[1].strip()
                if '$' not in _fd:
                    folders.add(_fd)
            if 'for system in ' in line:
                if '$' in line:
                    continue
                line = line.replace('for system in ', '')
                line = line[0:line.find(';')]
                _fd = [f.replace('"', '').strip()
                       for f in line.split(" ") if f]
                for f in _fd:
                    folders.add(f)
            if 'local systems=' in line or multiline:
                if line.find('(') > 0 and line.find(')') > 0:
                    _fd = line.split(
                        '=')[-1].replace('(', '',).replace(')', '').split(" ")
                    for f in _fd:
                        folders.add(f.strip())
                elif line.find('(') > 0:
                    multiline = True
                    # catch folder on same line
                    f = line.split('(')[1].strip()
                    if f:
                        folders.add(f)
                elif multiline:
                    f = line.strip().replace(')', '').replace('"', '')
                    if f:
                        folders.add(f)
                    if line.find(')') > 0:
                        multiline = False

        if rp_module_id:
            if not folders:
                folders.add("ports")
            xref[rp_module_id] = list(sorted(folders))

# correct scriptmodule "inheritance"
for emu, folders in xref.items():
    if emu in ["dosbox-sdl2", "dosbox-staging"]:
        xref[emu] = xref["dosbox"]
    elif emu == "lr-mess2016":
        xref[emu] = xref["lr-mess"]
    elif emu == "lr-mame2003-plus":
        xref[emu] = xref["lr-mame2003"]
    elif emu == "scummvm-sdl1":
        xref[emu] = xref["scummvm"]

# "invert" the dictonary
inv_xref = {}
for emu, folders in xref.items():
    for f in folders:
        if f not in inv_xref:
            inv_xref[f] = list()
        inv_xref[f].append(emu)

for folder, emus in inv_xref.items():
    inv_xref[folder] = sorted(emus)

with open("emu_to_romfolders.json", "w") as outfile:
    json.dump(xref, outfile, indent=4, sort_keys=True)
with open("romfolder_to_emus.json", "w") as outfile:
    json.dump(inv_xref, outfile, indent=4, sort_keys=True)