fix: count files shared by systems apart

The systems step and --list-systems gave 3do 1704 files, 349 MB, of
which 1689 are MAME hash and plugin files six systems carry. Each line
now shows the system's own files, and the shared ones beside them.

install.ps1

@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "739a28ac23d5b0d82d8324ecd7665b2501c71c64d60abba175575f7f16f24ddc"
+    $defaultInstallSha256 = "441fc1f7887aff7808b7b41182fdb18868ce36a50a2bbbba9bb81e595cb3b732"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -5742,12 +5742,32 @@ def _sized(files: list[dict]) -> str:
 NO_CORE_FILES = "no extra file: it reads the platform's own, always kept"
 
 
+def _core_sized(files: list[dict]) -> str:
+    return _sized(files) if files else NO_CORE_FILES
+
+
+def _system_sized(files: list[dict]) -> str:
+    """A system's files, those other systems share counted apart.
+
+    `3do 1704 files, 349.0 MB` read as the 3DO BIOS: 1689 of them are the
+    MAME hash and plugin files six systems carry.
+    """
+    shared = [f for f in files if len(entry_systems(f)) > 1]
+    if not shared:
+        return _sized(files)
+    if len(shared) == len(files):
+        return f"{_sized(shared)}, all shared with other systems"
+    own = [f for f in files if len(entry_systems(f)) <= 1]
+    return f"{_sized(own)}, and {_sized(shared)} shared with other systems"
+
+
 def _pick(
-    title: str, rows: list[tuple[str, list[dict]]], ordered: bool = False, empty: str = "",
+    title: str, rows: list[tuple[str, list[dict]]], ordered: bool = False,
+    sizer: Callable[[list[dict]], str] = _sized,
 ) -> list[str]:
     """Numbered list of names. An empty answer keeps every one.
 
-    empty is said instead of "0 files, 0 B" for a name that holds none.
+    sizer says what each name holds.
     """
     if not rows:
         return []
@@ -5755,8 +5775,7 @@ def _pick(
     width = len(str(len(rows)))
     name_width = min(max(len(name) for name, _files in rows), 32)
     for index, (name, files) in enumerate(rows, 1):
-        print(f"  {index:>{width}}) {name:<{name_width}}  "
-              f"{_sized(files) if files or not empty else empty}")
+        print(f"  {index:>{width}}) {name:<{name_width}}  {sizer(files)}")
     hint = "order of preference, e.g. 2,1" if ordered else "e.g. 1,3-5"
     while True:
         text = _ask(f"Numbers ({hint}), Enter for all, q to quit: ")
@@ -5814,7 +5833,7 @@ def _prompt_custom_selection(
     systems = _pick("Systems:", [
         (name, [f for f in files if _chosen(f, {name})])
         for name in choices["systems"]
-    ])
+    ], sizer=_system_sized)
     kept, kept_omitted = narrow(files, omitted, systems, [], [])
 
     cores: list[str] = []
@@ -5826,7 +5845,7 @@ def _prompt_custom_selection(
             (name, _filter_by_target(
                 [f for f in kept if f.get("cores") is not None], [name]))
             for name in core_names
-        ], empty=NO_CORE_FILES)
+        ], sizer=_core_sized)
         kept, kept_omitted = narrow(kept, kept_omitted, [], cores, [])
 
     regions: list[str] = []
@@ -5887,8 +5906,8 @@ def _print_choices(
             if systems
             else _filter_by_target([f for f in files if f.get("cores") is not None], [name])
         )
-        shown = NO_CORE_FILES if not systems and not held else _sized(held)
-        print(f"  {labels[name]:<{width}}  {shown}")
+        print(f"  {labels[name]:<{width}}  "
+              f"{_system_sized(held) if systems else _core_sized(held)}")
 
 
 def emulator_names(manifest: dict, files: list[dict], omitted: list[dict]) -> dict[str, str]:

install.sh

@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="739a28ac23d5b0d82d8324ecd7665b2501c71c64d60abba175575f7f16f24ddc"
+DEFAULT_INSTALL_SHA256="441fc1f7887aff7808b7b41182fdb18868ce36a50a2bbbba9bb81e595cb3b732"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

tests/test_install_selection.py

@@ -426,6 +426,42 @@ class ACoreWithNoFileOfItsOwn(unittest.TestCase):
         self.assertIn("always kept", line)
 
 
+class FilesSharedBySystemsAreCountedApart(unittest.TestCase):
+    """`3do 1704 files, 349.0 MB`: 1689 of them are MAME's hash and plugin
+    files, which six systems carry. Picking 3DO, one expects its BIOS."""
+
+    FILES = [
+        {"dest": "panafz10.bin", "size": 4, "cores": None, "systems": ["3do"]},
+        {"dest": "mame/hash/a.xml", "size": 100, "cores": None,
+         "systems": ["3do", "philips-cdi"]},
+        {"dest": "mame/hash/b.xml", "size": 50, "cores": None,
+         "systems": ["3do", "philips-cdi"]},
+        {"dest": "gba_bios.bin", "size": 8, "cores": None, "systems": ["nintendo-gba"]},
+    ]
+
+    def _listing(self) -> str:
+        out = io.StringIO()
+        with contextlib.redirect_stdout(out):
+            install._print_choices("retroarch", self.FILES, [], systems=True)
+        return out.getvalue()
+
+    def test_the_listing(self):
+        lines = {line.split()[0]: line for line in self._listing().splitlines()}
+        self.assertIn("1 file, 4 B, and 2 files, 150 B shared with other systems",
+                      lines["3do"])
+        self.assertIn("2 files, 150 B, all shared with other systems", lines["philips-cdi"])
+        self.assertTrue(lines["nintendo-gba"].endswith("1 file, 8 B"))
+
+    def test_the_systems_step(self):
+        answers = iter(["c", ""])
+        out = io.StringIO()
+        with mock.patch("builtins.input", lambda _prompt="": next(answers)), \
+                contextlib.redirect_stdout(out):
+            install._prompt_custom_selection("retroarch", self.FILES, [])
+        self.assertIn("1 file, 4 B, and 2 files, 150 B shared with other systems",
+                      out.getvalue())
+
+
 class TheBoundaryChecksTheNewFields(unittest.TestCase):
     def _manifest(self, **extra):
         entry = {"dest": "a.bin", "sha1": "a" * 40, "size": 1,