vyos.utils: T5195: add vyos.utils.io

1 files changed, 103 insertions, 0 deletions

diff --git a/python/vyos/utils/io.py b/python/vyos/utils/io.py
new file mode 100644
index 000000000..843494855
--- /dev/null
+++ b/python/vyos/utils/io.py
@@ -0,0 +1,103 @@
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+def print_error(str='', end='\n'):
+    """
+    Print `str` to stderr, terminated with `end`.
+    Used for warnings and out-of-band messages to avoid mangling precious
+     stdout output.
+    """
+    import sys
+    sys.stderr.write(str)
+    sys.stderr.write(end)
+    sys.stderr.flush()
+
+def make_progressbar():
+    """
+    Make a procedure that takes two arguments `done` and `total` and prints a
+     progressbar based on the ratio thereof, whose length is determined by the
+     width of the terminal.
+    """
+    import shutil, math
+    col, _ = shutil.get_terminal_size()
+    col = max(col - 15, 20)
+    def print_progressbar(done, total):
+        if done <= total:
+            increment = total / col
+            length = math.ceil(done / increment)
+            percentage = str(math.ceil(100 * done / total)).rjust(3)
+            print_error(f'[{length * "#"}{(col - length) * "_"}] {percentage}%', '\r')
+            # Print a newline so that the subsequent prints don't overwrite the full bar.
+        if done == total:
+            print_error()
+    return print_progressbar
+
+def make_incremental_progressbar(increment: float):
+    """
+    Make a generator that displays a progressbar that grows monotonically with
+     every iteration.
+    First call displays it at 0% and every subsequent iteration displays it
+     at `increment` increments where 0.0 < `increment` < 1.0.
+    Intended for FTP and HTTP transfers with stateless callbacks.
+    """
+    print_progressbar = make_progressbar()
+    total = 0.0
+    while total < 1.0:
+        print_progressbar(total, 1.0)
+        yield
+        total += increment
+    print_progressbar(1, 1)
+    # Ignore further calls.
+    while True:
+        yield
+
+def ask_input(question, default='', numeric_only=False, valid_responses=[]):
+    question_out = question
+    if default:
+        question_out += f' (Default: {default})'
+    response = ''
+    while True:
+        response = input(question_out + ' ').strip()
+        if not response and default:
+            return default
+        if numeric_only:
+            if not response.isnumeric():
+                print("Invalid value, try again.")
+                continue
+            response = int(response)
+        if valid_responses and response not in valid_responses:
+            print("Invalid value, try again.")
+            continue
+        break
+    return response
+
+def ask_yes_no(question, default=False) -> bool:
+    """Ask a yes/no question via input() and return their answer."""
+    from sys import stdout
+    default_msg = "[Y/n]" if default else "[y/N]"
+    while True:
+        try:
+            stdout.write("%s %s " % (question, default_msg))
+            c = input().lower()
+            if c == '':
+                return default
+            elif c in ("y", "ye", "yes"):
+                return True
+            elif c in ("n", "no"):
+                return False
+            else:
+                stdout.write("Please respond with yes/y or no/n\n")
+        except EOFError:
+            stdout.write("\nPlease respond with yes/y or no/n\n")