fix: link file cards to the entry that reads them

A directory entry was joined to the collection by its own name, so the
11,976 files under alephone's Plugins/ and the cdogs, thextech and
easyrpg trees named no emulator on their card. FileConsumers now expands
the directory and records which entry reads each file. The emulator links
on a file card land on that entry, and a directory card names its copies
and the folder that holds them.

scripts/cross_reference.py

@@ -27,6 +27,7 @@ from common import (
     ProfileSelectionError,
     _norm_system_id,
     directory_members,
+    expand_directory_entries,
     get_mame_clone_map,
     list_emulator_profiles,
     list_registered_platforms,
@@ -341,6 +342,10 @@ class FileConsumers:
         # Where each platform puts the file in its BIOS directory.
         self.platform_destinations: dict[str, dict[str, set[str]]] = {}
         self.emulators: dict[str, set[str]] = {}
+        # The entry that reads each file, by its position in the profile's
+        # files: a link lands on that entry's card, not the page top.
+        self.emulator_entries: dict[str, dict[str, int]] = {}
+        self.emulator_files: dict[str, list] = {}
         # Where each platform's pack installs the file, its cores' files
         # included: the platform's own list names a fraction of them.
         self.installed: dict[str, dict[str, set[str]]] = {}
@@ -401,14 +406,49 @@ class FileConsumers:
         """The collection path the database records for a file."""
         return str(self._db.get("files", {}).get(sha1, {}).get("path", ""))
 
+    def directory_members(self, entry: dict) -> dict[str, str]:
+        """{destination: sha1} of the files a ``type: directory`` entry reads."""
+        if entry.get("type") != "directory":
+            return {}
+        return {
+            member["path"]: member["sha1"]
+            for member in expand_directory_entries([entry], self._db)
+            if member is not entry
+        }
+
     def add_emulators(self, profiles: dict[str, dict]) -> None:
+        """Each file a profile entry resolves to, a directory's members included.
+
+        A directory entry was resolved by its own name and found nothing:
+        11,976 files under alephone's Plugins/, cdogs' and thextech's trees
+        named no emulator on their card.
+        """
         for name, profile in profiles.items():
             if profile.get("type") == "alias":
                 continue
-            for entry in profile.get("files", []):
-                sha1 = self.sha1_of(entry, entry.get("path") or "", owner=name)
-                if sha1:
-                    self.emulators.setdefault(sha1, set()).add(name)
+            files = profile.get("files") or []
+            self.emulator_files[name] = files
+            # A file a profile names keeps its own entry over the directory
+            # that also holds it.
+            order = sorted(
+                (i for i, entry in enumerate(files) if isinstance(entry, dict)),
+                key=lambda i: files[i].get("type") == "directory",
+            )
+            for index in order:
+                entry = files[index]
+                members = self.directory_members(entry)
+                if members:
+                    found = [
+                        self.sha1_of({**entry, "name": dest, "path": dest, "sha1": sha1},
+                                     dest, owner=name)
+                        for dest, sha1 in members.items()
+                    ]
+                else:
+                    found = [self.sha1_of(entry, entry.get("path") or "", owner=name)]
+                for sha1 in found:
+                    if sha1:
+                        self.emulators.setdefault(sha1, set()).add(name)
+                        self.emulator_entries.setdefault(sha1, {}).setdefault(name, index)
 
 
 def entry_source(f: dict, index: dict) -> str | None:

scripts/generate_site.py

@@ -2415,6 +2415,36 @@ def _platform_links(sha1: str, consumers: FileConsumers) -> list[str]:
     return links
 
 
+_card_anchors: dict[str, tuple[list, list[str]]] = {}
+
+
+def _emulator_card_anchor(emulator: str, files: list, index: int) -> str:
+    """The id of a profile entry's card on its emulator page."""
+    cached = _card_anchors.get(emulator)
+    if cached is None or cached[0] is not files:
+        cached = _card_anchors[emulator] = (files, emulator_file_anchors(files))
+    return cached[1][index] if 0 <= index < len(cached[1]) else ""
+
+
+def _emulator_links(sha1: str, consumers: FileConsumers) -> list[str]:
+    """Each emulator reading the file, linked to the entry that reads it.
+
+    The platform links landed on their system section, and the emulator
+    links on the page top: duckstation's scph5501.bin entry, with the line
+    that accepts it, sat 260 lines down a page of 105 entries.
+    """
+    entries = getattr(consumers, "emulator_entries", {}).get(sha1, {})
+    files_of = getattr(consumers, "emulator_files", {})
+    links = []
+    for emulator in sorted(consumers.emulators.get(sha1, ())):
+        index = entries.get(emulator)
+        anchor = (_emulator_card_anchor(emulator, files_of[emulator], index)
+                  if index is not None and emulator in files_of else "")
+        fragment = f"#{anchor}" if anchor else ""
+        links.append(f"[{emulator}](../emulators/{emulator}.md{fragment})")
+    return links
+
+
 def _installed_links(sha1: str, consumers: FileConsumers, declared: set[str]) -> list[str]:
     """Each pack installing the file that its platform's list does not name,
     with the place the pack gives it."""
@@ -2482,7 +2512,7 @@ def _system_file_card(
         # pack installs it for six cores.
         lines.append(f"- Also installed by: {', '.join(installed)}")
     if emus:
-        lines.append(f"- Emulators: {', '.join(_emulator_link(e, '../') for e in emus)}")
+        lines.append(f"- Emulators: {', '.join(_emulator_links(sha1_full, consumers))}")
     provenance = f.get("provenance", {})
     if provenance:
         lines.extend(_provenance_lines(provenance, "../"))
@@ -2876,6 +2906,8 @@ def _render_emulator_file(
         details.append(
             f"Source: {_source_ref_markdown(profile, source_ref)}"
         )
+    if consumers and f.get("type") == "directory":
+        details.extend(_directory_copies(f, consumers))
     if consumers:
         sha1 = consumers.sha1_of(f, f.get("path") or "", owner=owner)
         if sha1 and in_repo:
@@ -2945,6 +2977,27 @@ def _render_emulator_file(
     return lines
 
 
+def _directory_copies(entry: dict, consumers: FileConsumers) -> list[str]:
+    """What the collection holds under a directory entry, and where.
+
+    The card said "in repo" and linked none of the files: alephone's
+    Plugins/ holds 393 of them, each with its own card on a system page.
+    """
+    members = consumers.directory_members(entry)
+    held = sorted({consumers.path_of(sha1) for sha1 in members.values()} - {""})
+    if not held:
+        return []
+    folder = os.path.commonpath(held) if len(held) > 1 else os.path.dirname(held[0])
+    parts = folder.split("/")
+    where = _code(folder + "/")
+    if len(parts) >= 3 and parts[0] == "bios":
+        page = urllib.parse.quote(parts[1].lower().replace(" ", "-"))
+        where = f"[{where}](../systems/{page}.md#{_slugify_anchor(parts[2])})"
+    tree = f"{REPO_URL}/tree/main/{urllib.parse.quote(folder)}"
+    return [f"Collection copies: {_count(len(members), 'file')} under {where} "
+            f"([browse]({tree}))"]
+
+
 def _render_metadata_rows(profile: dict) -> list[str]:
     """Scalar profile fields, one table row each.