Refactor ui/commands.py monolith into modular structure (#6119)

## Description

This one’s a big one 🎣 Proceed with care and a bit
of time ;)

The `ui/commands.py` file had grown into an unwieldy monolith (2000+
lines) over time, so this PR breaks it apart into a modular structure
i.e. **one file per command**, plus some cleanup and reorganization
along the way.

---

###  What changed

* **Commands modularized:**
Every command (`help`, `list`, `move`, `update`, `remove`, etc.) now
lives in its own file under `ui/commands/`.
* **Support code reorganized:**
  * Utility functions moved into a separate helper module.
* `commands.py` converted into `commands/__init__.py` for better import
handling.
* The `import` command (and related helpers) moved into its own folder:
    * `importer/session.py` for import session logic
    * `importer/display.py` for display-related functions
* **Tests cleaned up:**
  * Each command’s tests now live in their own file.
  * All UI-related tests were moved into a dedicated folder for clarity.

Author: semohr

.git-blame-ignore-revs

@@ -73,3 +73,9 @@ d93ddf8dd43e4f9ed072a03829e287c78d2570a2
 33f1a5d0bef8ca08be79ee7a0d02a018d502680d
 # Moved art.py utility module from beets into beetsplug
 28aee0fde463f1e18dfdba1994e2bdb80833722f
+# Refactor `ui/commands.py` into multiple modules
+59c93e70139f70e9fd1c6f3c1bceb005945bec33
+# Moved ui.commands._utils into ui.commands.utils
+25ae330044abf04045e3f378f72bbaed739fb30d
+# Refactor test_ui_command.py into multiple modules 
+a59e41a88365e414db3282658d2aa456e0b3468a

beets/test/_common.py

@@ -107,7 +107,11 @@ def item(lib=None, **kwargs):
 
 # Dummy import session.
 def import_session(lib=None, loghandler=None, paths=[], query=[], cli=False):
-    cls = commands.TerminalImportSession if cli else importer.ImportSession
+    cls = (
+        commands.import_.session.TerminalImportSession
+        if cli
+        else importer.ImportSession
+    )
     return cls(lib, loghandler, paths, query)
 
 

beets/test/helper.py

@@ -54,7 +54,7 @@
 from beets.importer import ImportSession
 from beets.library import Item, Library
 from beets.test import _common
-from beets.ui.commands import TerminalImportSession
+from beets.ui.commands.import_.session import TerminalImportSession
 from beets.util import (
     MoveOperation,
     bytestring_path,

beets/ui/__init__.py

@@ -1111,76 +1111,9 @@ def show_model_changes(
     return bool(changes)
 
 
-def show_path_changes(path_changes):
-    """Given a list of tuples (source, destination) that indicate the
-    path changes, log the changes as INFO-level output to the beets log.
-    The output is guaranteed to be unicode.
-
-    Every pair is shown on a single line if the terminal width permits it,
-    else it is split over two lines. E.g.,
-
-    Source -> Destination
-
-    vs.
-
-    Source
-      -> Destination
-    """
-    sources, destinations = zip(*path_changes)
-
-    # Ensure unicode output
-    sources = list(map(util.displayable_path, sources))
-    destinations = list(map(util.displayable_path, destinations))
-
-    # Calculate widths for terminal split
-    col_width = (term_width() - len(" -> ")) // 2
-    max_width = len(max(sources + destinations, key=len))
-
-    if max_width > col_width:
-        # Print every change over two lines
-        for source, dest in zip(sources, destinations):
-            color_source, color_dest = colordiff(source, dest)
-            print_(f"{color_source} \n  -> {color_dest}")
-    else:
-        # Print every change on a single line, and add a header
-        title_pad = max_width - len("Source ") + len(" -> ")
-
-        print_(f"Source {' ' * title_pad} Destination")
-        for source, dest in zip(sources, destinations):
-            pad = max_width - len(source)
-            color_source, color_dest = colordiff(source, dest)
-            print_(f"{color_source} {' ' * pad} -> {color_dest}")
-
-
 # Helper functions for option parsing.
 
 
-def _store_dict(option, opt_str, value, parser):
-    """Custom action callback to parse options which have ``key=value``
-    pairs as values. All such pairs passed for this option are
-    aggregated into a dictionary.
-    """
-    dest = option.dest
-    option_values = getattr(parser.values, dest, None)
-
-    if option_values is None:
-        # This is the first supplied ``key=value`` pair of option.
-        # Initialize empty dictionary and get a reference to it.
-        setattr(parser.values, dest, {})
-        option_values = getattr(parser.values, dest)
-
-    try:
-        key, value = value.split("=", 1)
-        if not (key and value):
-            raise ValueError
-    except ValueError:
-        raise UserError(
-            f"supplied argument `{value}' is not of the form `key=value'"
-        )
-
-    option_values[key] = value
-
-
 class CommonOptionsParser(optparse.OptionParser):
     """Offers a simple way to add common formatting options.
 
@@ -1666,7 +1599,7 @@ def parse_csl_callback(
         and subargs[0] == "config"
         and ("-e" in subargs or "--edit" in subargs)
     ):
-        from beets.ui.commands import config_edit
+        from beets.ui.commands.config import config_edit
 
         return config_edit()