feat: add AmberELEC hardware targets

AmberELEC's metapackage adds LIBRETRO_CORES_EXTRA (bsnes, Mesen, melonDS, geolith) only on RG552, RG353 and RG503, and deletes those cores from es_systems.cfg on every other device (packages/amberelec/package.mk:23-31, 45-58 at a21975bf). The new target scraper reads the Makefile's device images, that test and es_systems.cfg the way the platform scraper does: RG351P, RG351V and RG351MP list 125 cores, the other three 136. The installer reads the device from COREELEC_DEVICE in os-release (scripts/image:168).

scripts/scraper/targets/amberelec_targets_scraper.py

@@ -0,0 +1,157 @@
+"""Scraper for AmberELEC per-device emulator availability.
+
+Sources (AmberELEC/AmberELEC, at the commit platforms/amberelec.yml names):
+  - Makefile -- one `DEVICE=<name> ARCH=<arch> ./scripts/build_distro` target
+    per image (RG351P, RG351V, RG351MP, RG552, RG353, RG503 at a21975bf)
+  - packages/amberelec/package.mk -- LIBRETRO_CORES_EXTRA joins PKG_EMUS
+    only on the devices its `if` names (lines 23-31 at a21975bf: RG552,
+    RG353, RG503), and on every other device makeinstall_target deletes
+    each of those cores from es_systems.cfg (lines 45-58)
+  - packages/ui/emulationstation/config/es_systems.cfg -- read the way the
+    platform scraper reads it, after that deletion
+
+An RG351P image carries neither melonDS nor bsnes: without a target list,
+its pack shipped the Nintendo DS firmware anyway.
+"""
+
+from __future__ import annotations
+
+import argparse
+import re
+import sys
+from datetime import datetime, timezone
+
+import yaml
+
+from . import BaseTargetScraper
+
+PLATFORM_NAME = "amberelec"
+
+RAW_BASE = "https://raw.githubusercontent.com/AmberELEC/AmberELEC/{ref}"
+META_MK = "packages/amberelec/package.mk"
+
+try:
+    from ..amberelec_scraper import BUILDS_OF, ES_SYSTEMS_TEMPLATE, RUNNERS
+    from ..base_scraper import fetch_bytes
+    from ..batocera_scraper import _not_cores
+    from ..es_emulators import es_cores, xml_systems
+except ImportError:
+    from scraper.amberelec_scraper import BUILDS_OF, ES_SYSTEMS_TEMPLATE, RUNNERS
+    from scraper.base_scraper import fetch_bytes
+    from scraper.batocera_scraper import _not_cores
+    from scraper.es_emulators import es_cores, xml_systems
+
+_DEVICE_RE = re.compile(
+    r"^(\w+):\n\tDEVICE=(\w+) ARCH=(\w+) \./scripts/build_distro$", re.MULTILINE
+)
+_EXTRA_RE = re.compile(r'LIBRETRO_CORES_EXTRA="([^"]*)"')
+# The `if` whose body adds the extra cores to PKG_EMUS.
+_EXTRA_IF_RE = re.compile(
+    r"if \[\[ (?P<test>[^\n]*?) \]\]; then\s*\n\s*PKG_EMUS\+=\" \$\{LIBRETRO_CORES_EXTRA\}\""
+)
+# What makeinstall_target does to es_systems.cfg on the other devices.
+_REMOVAL_LINES = (
+    "for CORE in ${LIBRETRO_CORES_EXTRA}; do",
+    'sed -i "s|<core>$CORE</core>||g"',
+    r"sed -i -e '/<emulator name/{:a;N;/<\/emulator>/!ba;/melonds/d}'",
+)
+_EMULATOR_BLOCK_RE = re.compile(r"[^\n]*<emulator name.*?</emulator>[^\n]*\n?", re.DOTALL)
+
+
+def devices(makefile: str) -> dict[str, str]:
+    """{device: architecture} of each image the Makefile builds."""
+    found = {device: arch for target, device, arch in _DEVICE_RE.findall(makefile)
+             if target == device}
+    if not found:
+        raise RuntimeError("the AmberELEC Makefile builds no device image")
+    return found
+
+
+def extra_cores(package_mk: str) -> tuple[list[str], set[str]]:
+    """(the extra cores, the devices that keep them) from the metapackage."""
+    listed = _EXTRA_RE.search(package_mk)
+    test = _EXTRA_IF_RE.search(package_mk)
+    if listed is None or test is None:
+        raise RuntimeError(f"{META_MK}: no LIBRETRO_CORES_EXTRA or no test adding it")
+    missing = [line for line in _REMOVAL_LINES if line not in package_mk]
+    if missing:
+        raise RuntimeError(f"{META_MK}: makeinstall_target no longer reads {missing[0]!r}")
+    keep = set(re.findall(r'"\$\{DEVICE\}" == "(\w+)"', test.group("test")))
+    for alternatives in re.findall(r'"\$\{DEVICE\}" =~ \^\(([\w|]+)\)\$', test.group("test")):
+        keep.update(alternatives.split("|"))
+    if not keep:
+        raise RuntimeError(f"{META_MK}: the test adding the extra cores names no device")
+    return listed.group(1).split(), keep
+
+
+def without_cores(es_systems: str, cores: list[str]) -> str:
+    """es_systems.cfg as makeinstall_target leaves it on a device without them."""
+    for core in cores:
+        if core == "melonds":
+            es_systems = _EMULATOR_BLOCK_RE.sub(
+                lambda block: "" if "melonds" in block.group(0) else block.group(0),
+                es_systems,
+            )
+        es_systems = es_systems.replace(f"<core>{core}</core>", "")
+    return es_systems
+
+
+def device_cores(es_systems: str, extra: list[str], keeps_extra: bool) -> list[str]:
+    """Every core and standalone emulator one device's es_systems.cfg offers."""
+    text = es_systems if keeps_extra else without_cores(es_systems, extra)
+    cores, _standalone, _dual = es_cores(
+        xml_systems(text), RUNNERS, BUILDS_OF, _not_cores(PLATFORM_NAME)
+    )
+    return sorted(set(cores))
+
+
+class Scraper(BaseTargetScraper):
+    """Per-device core lists from AmberELEC's metapackage."""
+
+    def __init__(self, url: str = "https://github.com/AmberELEC/AmberELEC") -> None:
+        super().__init__(url=url)
+        self.ref = ""
+
+    def _raw(self, path: str) -> str:
+        return fetch_bytes(f"{RAW_BASE.format(ref=self.ref)}/{path}").decode("utf-8")
+
+    def fetch_targets(self) -> dict:
+        self.ref = self.pinned_revision(PLATFORM_NAME)
+        extra, keep = extra_cores(self._raw(META_MK))
+        es_systems = fetch_bytes(ES_SYSTEMS_TEMPLATE.format(ref=self.ref)).decode("utf-8")
+        targets: dict[str, dict] = {}
+        for device, arch in sorted(devices(self._raw("Makefile")).items()):
+            cores = device_cores(es_systems, extra, device in keep)
+            targets[device.lower()] = {"architecture": arch, "cores": cores}
+            print(f"  {device.lower()} ({arch}): {len(cores)} cores", file=sys.stderr)
+        return {
+            "platform": PLATFORM_NAME,
+            "source": f"{self.url}/blob/{self.ref}/{META_MK}",
+            "scraped_at": datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ"),
+            "targets": targets,
+        }
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        allow_abbrev=False, description="Scrape AmberELEC per-device cores"
+    )
+    parser.add_argument("--dry-run", action="store_true", help="Show target summary")
+    parser.add_argument("--output", "-o", help="Output YAML file")
+    args = parser.parse_args()
+
+    scraper = Scraper()
+    data = scraper.fetch_targets()
+    if args.dry_run:
+        for name, info in data["targets"].items():
+            print(f"  {name} ({info['architecture']}): {len(info['cores'])} cores")
+        return
+    if args.output:
+        scraper.write_output(data, args.output)
+        print(f"Written to {args.output}")
+        return
+    print(yaml.dump(data, default_flow_style=False, sort_keys=False))
+
+
+if __name__ == "__main__":
+    main()