update-from-overlay.py: A cleaner bulk-update script

pkgs/applications/editors/emacs/elisp-packages/update-from-overlay.py

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+#!/usr/bin/env nix-shell
+#! nix-shell -i python3 -p nix git
+
+import argparse
+import contextlib
+import dataclasses
+import datetime
+import logging
+import os
+import pathlib
+import shutil
+import subprocess
+import sys
+import urllib.request
+
+@dataclasses.dataclass
+class EmacsOverlay:
+    git_url : str = f'https://github.com/nix-community/emacs-overlay'
+    raw_url : str = f'https://raw.githubusercontent.com/nix-community/emacs-overlay'
+    # The field declaration here is a hack around the error:
+    # ValueError: mutable default <class 'dict'> for field elisp_packages_set is not allowed: use default_factory
+    # See more at https://peps.python.org/pep-0557/#mutable-default-values
+    elisp_packages_set : dict[str, dict] = dataclasses.field(default_factory = lambda: {
+        'elpa': {
+            'location': 'repos/elpa',
+            'basename': 'elpa-generated.nix',
+            'nix_attrs': ['elpaPackages']
+        },
+        'elpa-devel': {
+            'location': 'repos/elpa',
+            'basename': 'elpa-devel-generated.nix',
+            'nix_attrs': ['elpaDevelPackages']
+        },
+        'melpa': {
+            'location': 'repos/melpa',
+            'basename': 'recipes-archive-melpa.json',
+            'nix_attrs': ['melpaPackages',
+                          'melpaStablePackages']
+        },
+        'nongnu': {
+            'location': 'repos/nongnu',
+            'basename': 'nongnu-generated.nix',
+            'nix_attrs': ['nongnuPackages']
+        },
+        'nongnu-devel': {
+            'location': 'repos/nongnu',
+            'basename': 'nongnu-devel-generated.nix',
+            'nix_attrs': ['nongnuDevelPackages']
+        },
+    })
+
+    def master_sha (self) -> str:
+        '''Return the SHA of current master tip.'''
+        cmdline = ['git', 'ls-remote', '--branches', self.git_url, 'refs/heads/master']
+        result = subprocess.run(cmdline, capture_output = True, text = True)
+        return result.stdout.split()[0]
+
+@dataclasses.dataclass
+class HereDirectory:
+    path : pathlib.Path = pathlib.Path('.').resolve()
+
+    def git_root(self) -> pathlib.Path:
+        '''Returns the root directory of Git repository.'''
+        cmdline = ['git', 'rev-parse', '--show-toplevel']
+        result = subprocess.run(cmdline, capture_output = True, text = True)
+
+        return pathlib.Path(result.stdout.rstrip()).resolve()
+
+def main (emacs_overlay : EmacsOverlay,
+          here_directory : HereDirectory,
+          argument_parser : argparse.ArgumentParser) -> None:
+    '''The entry point.'''
+
+    args = argument_parser.parse_args()
+
+    if args.commit == None:
+        sha = emacs_overlay.master_sha()
+    else:
+        sha = args.commit
+
+    match args.loglevel.lower():
+        case 'debug':
+            loglevel = logging.DEBUG
+        case 'info':
+            loglevel = logging.INFO
+        case _:
+            loglevel = logging.INFO
+
+    logger = get_logger(loglevel = loglevel)
+
+    datestring = datetime.datetime.today().strftime('%Y-%m-%d')
+
+    # The loops are decoupled because each phase interferes with the next ones;
+    # e.g. it is pretty possible that an Elisp package updated in fetch_fileset
+    # breaks the check because of another Elisp package.
+    for name in emacs_overlay.elisp_packages_set:
+        fetch_fileset(name, sha,
+                      emacs_overlay = emacs_overlay,
+                      here_directory = here_directory,
+                      logger = logger)
+
+    for name in emacs_overlay.elisp_packages_set:
+        check_fileset(name,
+                      emacs_overlay = emacs_overlay,
+                      here_directory = here_directory,
+                      logger = logger)
+
+    for name in emacs_overlay.elisp_packages_set:
+        commit_fileset(name, sha, datestring = datestring,
+                       emacs_overlay = emacs_overlay,
+                       here_directory = here_directory,
+                       logger = logger)
+
+def get_argument_parser() -> argparse.ArgumentParser:
+    '''Return a getopt-style parser for command-line arguments.'''
+    parser = argparse.ArgumentParser(
+        description = 'Fetch and commit Elisp package sets from nix-community/emacs-overlay',
+    )
+    parser.add_argument(
+        '--commit',
+        help = 'Commit to be fetched, in SHA format. If not specified, retrieve the master tip.',
+        default = None
+    )
+    parser.add_argument(
+        '--loglevel',
+        help = 'Level of noisiness of logging messages. Values currently supported: INFO (default), DEBUG.',
+        default = 'InFo'
+    )
+
+    return parser
+
+def get_logger (loglevel: int) -> logging.Logger:
+    '''Return a basic logging facility to emit messages over console (stdout).'''
+    logger = logging.getLogger('update-from-overlay')
+    # Set the lowest level here, so that it does not clobber the one provided by
+    # the function argument
+    logger.setLevel(logging.DEBUG)
+
+    console_formatter = logging.Formatter(fmt='%(asctime)s - %(levelname)s - %(funcName)s - %(message)s',
+                                          datefmt='[%Y-%m-%d %H:%M:%S]')
+
+    console_handler = logging.StreamHandler(stream = sys.stdout)
+    console_handler.setLevel(loglevel)
+    console_handler.setFormatter(console_formatter)
+
+    logger.addHandler(console_handler)
+
+    return logger
+
+def fetch_fileset (name: str, sha: str,
+                   emacs_overlay : EmacsOverlay,
+                   here_directory : HereDirectory,
+                   logger : logging.Logger) -> None:
+    '''Fetch a fileset from emacs overlay.
+
+    Arguments:
+    name -- The name of fileset.
+    sha -- The commit SHA of emacs-overlay from which the files are retrieved.
+    '''
+    logger.debug('BEGIN')
+
+    location = emacs_overlay.elisp_packages_set[name]['location']
+    basename = emacs_overlay.elisp_packages_set[name]['basename']
+    url = f'{emacs_overlay.raw_url}/{sha}/{location}/{basename}'
+
+    destination = pathlib.Path(here_directory.path, basename).resolve()
+
+    logger.debug(f'Getting {url}')
+
+    with urllib.request.urlopen (url) as input_stream, open(destination, 'wb') as output_file:
+        logger.info(f'Installing {destination}')
+        shutil.copyfileobj(input_stream, output_file)
+
+    logger.debug('END')
+
+def check_fileset (name: str,
+                   emacs_overlay : EmacsOverlay,
+                   here_directory : HereDirectory,
+                   logger : logging.Logger) -> None:
+    '''Smoke-test the fileset.
+
+    Arguments:
+    name -- The name of fileset.
+    '''
+    logger.debug('BEGIN')
+
+    for nix_attr in emacs_overlay.elisp_packages_set[name]['nix_attrs']:
+
+        cmdline = ['nix-instantiate', '--show-trace', here_directory.git_root(),
+                   '-A', f'emacsPackages.{nix_attr}']
+        environment = os.environ
+        environment['NIXPKGS_ALLOW_BROKEN'] = '1'
+
+        logger.info(f'Testing {nix_attr}')
+        # TODO: capture the output (to put it in the logfile).
+        result = subprocess.run(cmdline, capture_output = True, text = True)
+        logger.debug(f'''
+Shell Command: {result.args}
+Output:
+{result.stdout}''')
+
+    logger.debug('END')
+
+def commit_fileset (name: str, sha: str, datestring : str | None,
+                   emacs_overlay : EmacsOverlay,
+                   here_directory : HereDirectory,
+                   logger : logging.Logger) -> None:
+    '''Commit the fileset.
+
+    Arguments:
+    name -- The name of fileset.
+    sha -- The commit SHA of emacs-overlay from which the files are retrieved.
+    datestring -- The date to be written on commit message. If None, use the current time.
+    '''
+    logger.debug('BEGIN')
+
+    nix_attrs = emacs_overlay.elisp_packages_set[name]['nix_attrs']
+    basename = emacs_overlay.elisp_packages_set[name]['basename']
+
+    if datestring == None:
+        datestring = datetime.datetime.today().strftime('%Y-%m-%d')
+        logger.debug(f'Date string not provided, using {datestring}')
+    else:
+        logger.debug(f'Date string was provided: {datestring}')
+
+    cmdline_verify = ['git', 'diff', '--exit-code', '--quiet', '--', basename]
+    result_verify = subprocess.run(cmdline_verify)
+
+    if result_verify.returncode != 0:
+        attrs = ', '.join(nix_attrs)
+        commit_message = f'''{attrs}: Updated at {datestring} (from emacs-overlay)
+
+emacs-overlay commit: {sha}
+'''
+        cmdline_commit = ['git', 'commit', '--message', commit_message, '--', basename]
+        result_commit = subprocess.run(cmdline_commit, capture_output = True, text = True)
+        logger.info(f'File {basename} committed')
+        logger.debug(f'''
+Shell Command: {result_commit.args}
+Output:
+{result_commit.stdout}''')
+    else:
+        logger.info(f'File {basename} not modified, skipping')
+
+    logger.debug('END')
+
+if __name__ == '__main__':
+    emacs_overlay = EmacsOverlay()
+    here_directory = HereDirectory()
+    argument_parser = get_argument_parser()
+    with contextlib.chdir(here_directory.path):
+        main(emacs_overlay = emacs_overlay,
+             here_directory = here_directory,
+             argument_parser = argument_parser)