From 164ba6e659f0bd184b641d5fecbc80e290e43460 Mon Sep 17 00:00:00 2001
From: Alex Lowe <alex.lowe@canonical.com>
Date: Tue, 10 Sep 2024 17:52:18 -0400
Subject: [PATCH] feat(printer): hide cursor when supported

---
 craft_cli/printer.py                          | 12 ++++++++--
 .../integration/test_messages_integration.py  | 11 +++++++++-
 tests/unit/test_printer.py                    | 22 +++++++++++++++----
 3 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/craft_cli/printer.py b/craft_cli/printer.py
index 1448fa0..5ffe267 100644
--- a/craft_cli/printer.py
+++ b/craft_cli/printer.py
@@ -23,6 +23,7 @@
 import platform
 import queue
 import shutil
+import sys
 import threading
 import time
 from dataclasses import dataclass, field
@@ -46,7 +47,9 @@
 # craft_cli/pytest_plugin.py )
 TESTMODE = False
 
-ANSI_CLEAR_LINE_TO_END = "\033[K"  # ANSI escape code to clear the rest of the line.
+ANSI_CLEAR_LINE_TO_END = "\x1b[K"  # ANSI escape code to clear the rest of the line.
+ANSI_HIDE_CURSOR = "\x1b[?25l"
+ANSI_SHOW_CURSOR = "\x1b[?25h"
 
 
 @dataclass
@@ -224,6 +227,9 @@ def __init__(self, log_filepath: pathlib.Path) -> None:
         self.spinner = _Spinner(self)
         if not TESTMODE:
             self.spinner.start()
+            if _supports_ansi_escape_sequences() and _stream_is_terminal(sys.stderr):
+                # pass
+                print(ANSI_HIDE_CURSOR, end="", file=sys.stderr, flush=True)
 
     def set_terminal_prefix(self, prefix: str) -> None:
         """Set the string to be prepended to every message shown to the terminal."""
@@ -466,11 +472,14 @@ def stop(self) -> None:
 
         In detail:
         - stop the spinner
+        - show the cursor
         - add a new line to the screen (if needed)
         - close the log file
         """
         if not TESTMODE:
             self.spinner.stop()
+            if _supports_ansi_escape_sequences() and _stream_is_terminal(sys.stderr):
+                print(ANSI_SHOW_CURSOR, end="", file=sys.stderr, flush=True)
         if self.unfinished_stream is not None:
             # With unfinished_stream set, the prv_msg object is valid.
             if self.prv_msg is not None and self.prv_msg.ephemeral:
@@ -483,7 +492,6 @@ def stop(self) -> None:
                 # The last printed message is permanent. Leave the cursor on
                 # the next clean line.
                 print(flush=True, file=self.unfinished_stream)
-
         self.log.close()
         self.stopped = True
 
diff --git a/tests/integration/test_messages_integration.py b/tests/integration/test_messages_integration.py
index 88a1773..62b8f95 100644
--- a/tests/integration/test_messages_integration.py
+++ b/tests/integration/test_messages_integration.py
@@ -76,6 +76,15 @@ def logger():
     return logger
 
 
+def remove_control_characters(string: str) -> str:
+    """Strip the non-printing characters from an output string."""
+    return (
+        string.replace(printer.ANSI_CLEAR_LINE_TO_END, "")
+        .replace(printer.ANSI_HIDE_CURSOR, "")
+        .replace(printer.ANSI_SHOW_CURSOR, "")
+    )
+
+
 @dataclass
 class Line:
     """A line that is expected to be in the result."""
@@ -95,7 +104,7 @@ def compare_lines(expected_lines: Collection[Line], raw_stream: str, std_stream)
 
     if terminal:
         if printer._supports_ansi_escape_sequences():
-            lines = raw_stream.replace("\033[K", "").splitlines(keepends=True)
+            lines = remove_control_characters(raw_stream).splitlines(keepends=True)
         else:
             # If the terminal doesn't support ANSI escape sequences, we fill the screen
             # width and don't terminate lines, so we split lines according to that length
diff --git a/tests/unit/test_printer.py b/tests/unit/test_printer.py
index a292e07..69ed9b4 100644
--- a/tests/unit/test_printer.py
+++ b/tests/unit/test_printer.py
@@ -29,6 +29,13 @@
 from craft_cli import printer as printermod
 from craft_cli.printer import Printer, _MessageInfo, _Spinner
 
+pytestmark = [
+    # Always use capsys, giving the printer its own stdout and stderr.
+    # This is useful because the printer will print control characters
+    # directly to stderr.
+    pytest.mark.usefixtures("capsys"),
+]
+
 
 @pytest.fixture(autouse=True)
 def init_emitter():
@@ -77,6 +84,15 @@ def _supports_ansi_escape_sequences():
     return request.param
 
 
+def remove_control_characters(string: str) -> str:
+    """Strip the non-printing characters from an output string."""
+    return (
+        string.replace(printermod.ANSI_CLEAR_LINE_TO_END, "")
+        .replace(printermod.ANSI_HIDE_CURSOR, "")
+        .replace(printermod.ANSI_SHOW_CURSOR, "")
+    )
+
+
 # -- simple helpers
 
 
@@ -1423,7 +1439,7 @@ def test_secrets_progress_bar(capsys, log_filepath, monkeypatch):
     printer.progress_bar(stream, message, progress=0.0, total=1.0, use_timestamp=False)
 
     _, stderr = capsys.readouterr()
-    assert stderr.startswith(expected)
+    assert remove_control_characters(stderr).startswith(expected)
 
 
 def test_secrets_terminal_prefix(capsys, log_filepath, monkeypatch):
@@ -1449,7 +1465,5 @@ def test_secrets_terminal_prefix(capsys, log_filepath, monkeypatch):
     ]
 
     _, stderr = capsys.readouterr()
-    obtained = [
-        l.replace(printermod.ANSI_CLEAR_LINE_TO_END, "").strip() for l in stderr.splitlines()
-    ]
+    obtained = [remove_control_characters(l).rstrip() for l in stderr.splitlines()]
     assert obtained == expected