Webapp redesign phase 4: Updates overview and rollback review

- GET /updates/: one card per updater (Dell, iPXE, Blancco, BPRT) with
  its state, a Check now / Open action and details in accordions; the
  shared download cap is a small popover.
- Dell applies list: one line per apply titled by its first change
  ('Latitude 5350 pack A11 to A12', model looked up in the maps) and
  'and n more'; the chip says how many written files are unchanged since
  the apply. The body lists every change, skipped item, error and file.
- dell_updates.file_status(): per file an apply wrote, unchanged /
  changed / missing by content hash, the same test rollback uses.
  describe(), history_view() and rollback_preview() build on it.
- GET /updates/dell/rollback/<id>: review a rollback before doing it,
  with the files that would be restored and a diff of each. The POST
  route is unchanged; both forms can return to the overview.

webapp/services/dell_updates.py

@@ -34,6 +34,7 @@ from __future__ import annotations
 
 import fcntl
 import glob
+import difflib
 import hashlib
 import json
 import os
@@ -1348,6 +1349,108 @@ def _rollback(apply_id):
     return restored, refused
 
 
+# --- history for the Updates pages -------------------------------------------------
+
+def _file_label(path):
+    """Short name of a file an apply wrote: 'gea-standard/.../HardwareDriver.json'
+    or 'BIOS/models.txt'."""
+    parts = path.replace("\\", "/").split("/")
+    if parts[-1] == "HardwareDriver.json":
+        image = next((p for p in parts if p in IMAGES), parts[-4] if len(parts) > 3 else "")
+        return f"{image}/.../HardwareDriver.json"
+    return "/".join(parts[-2:])
+
+
+def file_status(rec):
+    """Per file an apply wrote: does it still hold exactly what the apply
+    wrote (content hash, the test rollback uses)?
+    [{"path", "label", "backup", "state": unchanged|changed|missing, "mtime"}]"""
+    out = []
+    for path, backup in (rec.get("backups") or {}).items():
+        row = {"path": path, "label": _file_label(path), "backup": backup, "state": "missing", "mtime": None}
+        try:
+            with open(path, "rb") as f:
+                now_hash = hashlib.sha256(f.read()).hexdigest()
+            row["mtime"] = os.stat(path).st_mtime
+            row["state"] = "unchanged" if now_hash == (rec.get("after") or {}).get(path) else "changed"
+        except OSError:
+            pass
+        out.append(row)
+    return out
+
+
+_PACK_VER = re.compile(r"_(a\d+)", re.I)
+
+
+def _model_for_zip(zip_name, maps):
+    """First model token of the map entry that uses zip_name, or ''."""
+    for m in maps.values():
+        for e in m["entries"]:
+            if isinstance(e, dict) and str(e.get("fileName") or e.get("FileName") or "").lower() == str(zip_name).lower():
+                return str(e.get("modelswminame") or "").split(",")[0].strip()
+    return ""
+
+
+def describe(rec, maps=None):
+    """One line per change of an apply, for history lists: a driver pack
+    'Latitude 5350 pack A11 to A12' (model from the maps, version from the
+    zip names) or a BIOS manifest line."""
+    maps = read_maps() if maps is None else maps
+    out = []
+    for d in rec.get("drivers") or []:
+        model = _model_for_zip(d.get("new", ""), maps) or _model_for_zip(d.get("old", ""), maps)
+        a, b = _PACK_VER.search(d.get("old", "") or ""), _PACK_VER.search(d.get("new", "") or "")
+        if model and a and b:
+            out.append(f"{model} pack {a.group(1).upper()} to {b.group(1).upper()}")
+        else:
+            out.append(f"{d.get('old', '')} to {d.get('new', '')}")
+    for b in rec.get("bios") or []:
+        out.append(f"BIOS line {str(b.get('new', '')).strip()}")
+    return out
+
+
+def history_view(limit=15):
+    """history() with, per apply: "changes" (describe), "title" (first change
+    and "and n more"), "files" (file_status), "unchanged" and "total"."""
+    maps = read_maps()
+    out = []
+    for rec in history()[:limit]:
+        r = dict(rec)
+        r["changes"] = describe(rec, maps)
+        n = len(r["changes"])
+        r["title"] = (r["changes"][0] + (f" and {n - 1} more" if n > 1 else "")) if n else "No change"
+        r["files"] = file_status(rec)
+        r["unchanged"] = sum(1 for f in r["files"] if f["state"] == "unchanged")
+        r["total"] = len(r["files"])
+        out.append(r)
+    return out
+
+
+def rollback_preview(apply_id, max_lines=400):
+    """What a rollback of apply_id would do, without doing it: the apply
+    record, file_status, and for each unchanged file a unified diff from
+    the current content to the backup it would restore."""
+    rec = next((h for h in history_view(limit=1000) if h.get("id") == apply_id), None)
+    if rec is None:
+        raise ValueError("unknown apply")
+    for f in rec["files"]:
+        f["diff"] = ""
+        if f["state"] != "unchanged":
+            continue
+        try:
+            with open(f["path"], encoding="utf-8-sig", errors="replace") as cur, \
+                    open(f["backup"], encoding="utf-8-sig", errors="replace") as old:
+                lines = list(difflib.unified_diff(cur.read().splitlines(), old.read().splitlines(),
+                                                  "now", "after rollback", n=2, lineterm=""))
+        except OSError as ex:
+            f["state"], f["error"] = "missing", str(ex)
+            continue
+        if len(lines) > max_lines:
+            lines = lines[:max_lines] + [f"... {len(lines) - max_lines} more lines"]
+        f["diff"] = "\n".join(lines)
+    return rec
+
+
 def _audit(action, detail):
     try:
         from services.audit import audit