refactor: GFZ ISDC ftp server is being retired (#168)

* Update pixi.lock

Author: tsutterley

access/gfz_isdc_dealiasing_ftp.py access/gfz_isdc_dealiasing_sync.pyaccess/gfz_isdc_dealiasing_ftp.py renamed to access/gfz_isdc_dealiasing_sync.py

@@ -1,13 +1,14 @@
 #!/usr/bin/env python
 u"""
-gfz_isdc_dealiasing_ftp.py
-Written by Tyler Sutterley (05/2023)
+gfz_isdc_dealiasing_sync.py
+Written by Tyler Sutterley (10/2025)
 Syncs GRACE Level-1b dealiasing products from the GFZ Information
     System and Data Center (ISDC)
+
 Optionally outputs as monthly tar files
 
 CALLING SEQUENCE:
-    python gfz_isdc_dealiasing_ftp.py --year=2015 --release=RL06 --tar
+    python gfz_isdc_dealiasing_sync.py --year=2015 --release=RL06 --tar
 
 COMMAND LINE OPTIONS:
     -D X, --directory X: working data directory
@@ -30,6 +31,7 @@
     utilities.py: download and management utilities for syncing files
 
 UPDATE HISTORY:
+    Updated 10/2025: switch to https as ftp server is being retired
     Updated 05/2023: use pathlib to define and operate on paths
     Updated 03/2023: increase default year range to sync
     Updated 12/2022: single implicit import of gravity toolkit
@@ -51,8 +53,9 @@
 import sys
 import os
 import re
+import ssl
 import time
-import ftplib
+import shutil
 import logging
 import pathlib
 import tarfile
@@ -62,7 +65,7 @@
 
 # PURPOSE: syncs GRACE Level-1b dealiasing products from the GFZ data server
 # and optionally outputs as monthly tar files
-def gfz_isdc_dealiasing_ftp(base_dir, DREL, YEAR=None, MONTHS=None, TAR=False,
+def gfz_isdc_dealiasing_sync(base_dir, DREL, YEAR=None, MONTHS=None, TAR=False,
     TIMEOUT=None, LOG=False, CLOBBER=False, MODE=None):
     # check if directory exists and recursively create if not
     base_dir = pathlib.Path(base_dir).expanduser().absolute()
@@ -81,10 +84,8 @@ def gfz_isdc_dealiasing_ftp(base_dir, DREL, YEAR=None, MONTHS=None, TAR=False,
         # standard output (terminal output)
         logging.basicConfig(level=logging.INFO)
 
-    # remote HOST for DREL on GFZ data server
-    # connect and login to GFZ ftp server
-    ftp = ftplib.FTP('isdcftp.gfz-potsdam.de', timeout=TIMEOUT)
-    ftp.login()
+    # GFZ ISDC https host
+    HOST = 'https://isdc-data.gfz.de/'
 
     # compile regular expression operator for years to sync
     if YEAR is None:
@@ -97,9 +98,8 @@ def gfz_isdc_dealiasing_ftp(base_dir, DREL, YEAR=None, MONTHS=None, TAR=False,
     SUFFIX = dict(RL04='tar.gz', RL05='tar.gz', RL06='tgz')
 
     # find remote yearly directories for DREL
-    YRS,_ = gravtk.utilities.ftp_list([ftp.host,'grace',
-        'Level-1B', 'GFZ','AOD',DREL], timeout=TIMEOUT, basename=True,
-        pattern=R1, sort=True)
+    YRS,_ = http_list([HOST,'grace','Level-1B', 'GFZ','AOD',DREL],
+        timeout=TIMEOUT, basename=True, pattern=R1, sort=True)
     # for each year
     for Y in YRS:
         # for each month of interest
@@ -114,8 +114,8 @@ def gfz_isdc_dealiasing_ftp(base_dir, DREL, YEAR=None, MONTHS=None, TAR=False,
             # will extract year and month and calendar day from the ascii file
             regex_pattern = r'AOD1B_({0})-({1:02d})-(\d+)_X_\d+.asc.gz$'
             R2 = re.compile(regex_pattern.format(Y,M), re.VERBOSE)
-            remote_files,remote_mtimes = gravtk.utilities.ftp_list(
-                [ftp.host,'grace','Level-1B','GFZ','AOD',DREL,Y],
+            remote_files,remote_mtimes = http_list(
+                [HOST,'grace','Level-1B','GFZ','AOD',DREL,Y],
                 timeout=TIMEOUT, basename=True, pattern=R2, sort=True)
             file_count = len(remote_files)
             # if compressing into monthly tar files
@@ -124,10 +124,10 @@ def gfz_isdc_dealiasing_ftp(base_dir, DREL, YEAR=None, MONTHS=None, TAR=False,
                 tar = tarfile.open(name=local_tar_file, mode='w:gz')
                 for fi,remote_mtime in zip(remote_files,remote_mtimes):
                     # remote version of each input file
-                    remote = [ftp.host,'grace','Level-1B','GFZ','AOD',DREL,Y,fi]
-                    logging.info(posixpath.join('ftp://',*remote))
+                    remote = [HOST,'grace','Level-1B','GFZ','AOD',DREL,Y,fi]
+                    logging.info(posixpath.join(*remote))
                     # retrieve bytes from remote file
-                    remote_buffer = gravtk.utilities.from_ftp(remote,
+                    remote_buffer = gravtk.utilities.from_sync(remote,
                         timeout=TIMEOUT)
                     # add file to tar
                     tar_info = tarfile.TarInfo(name=fi)
@@ -142,23 +142,96 @@ def gfz_isdc_dealiasing_ftp(base_dir, DREL, YEAR=None, MONTHS=None, TAR=False,
                 # copy each gzip file and keep as individual daily files
                 for fi,remote_mtime in zip(remote_files,remote_mtimes):
                     # remote and local version of each input file
-                    remote = [ftp.host,'grace','Level-1B','GFZ','AOD',DREL,Y,fi]
+                    remote = [HOST,'grace','Level-1B','GFZ','AOD',DREL,Y,fi]
                     local_file = grace_dir.joinpath(fi)
-                    ftp_mirror_file(ftp,remote,remote_mtime,local_file,
+                    http_pull_file(remote,remote_mtime,local_file,
                         CLOBBER=CLOBBER, MODE=MODE)
 
-    # close the ftp connection
-    ftp.quit()
     # close log file and set permissions level to MODE
     if LOG:
         LOGFILE.chmod(mode=MODE)
 
+# PURPOSE: list a directory on the GFZ https server
+def http_list(
+        HOST: str | list,
+        timeout: int | None = None,
+        context: ssl.SSLContext = gravtk.utilities._default_ssl_context,
+        pattern: str | re.Pattern = '',
+        sort: bool = False
+    ):
+    """
+    List a directory on the GFZ https Server
+
+    Parameters
+    ----------
+    HOST: str or list
+        remote http host path
+    timeout: int or NoneType, default None
+        timeout in seconds for blocking operations
+    context: obj, default gravity_toolkit.utilities._default_ssl_context
+        SSL context for ``urllib`` opener object
+    pattern: str, default ''
+        regular expression pattern for reducing list
+    sort: bool, default False
+        sort output list
+
+    Returns
+    -------
+    colnames: list
+        column names in a directory
+    collastmod: list
+        last modification times for items in the directory
+    """
+    # verify inputs for remote http host
+    if isinstance(HOST, str):
+        HOST = gravtk.utilities.url_split(HOST)
+    # regular expression pattern for finding files and modification times
+    parser = r'\<a\shref=.*?\>(.*?)\<\/a\>\s+(\d{4}-\d{2}-\d{2}\s+\d{2}\:\d{2})'
+    rx = re.compile(parser, re.VERBOSE)
+    # try listing from http
+    try:
+        # Create and submit request.
+        request = gravtk.utilities.urllib2.Request(posixpath.join(*HOST))
+        response = gravtk.utilities.urllib2.urlopen(request,
+            timeout=timeout, context=context)
+    except Exception as exc:
+        raise Exception('List error from {0}'.format(posixpath.join(*HOST)))
+    # read the directory listing
+    contents = response.readlines()
+    # read and parse request for files (column names and modified times)
+    lines = [l for l in contents if rx.search(l.decode('utf-8'))]
+    # column names and last modified times
+    colnames = [None]*len(lines)
+    collastmod = [None]*len(lines)
+    for i, l in enumerate(lines):
+        colnames[i], lastmod = rx.findall(l.decode('utf-8')).pop()
+        # get the Unix timestamp value for a modification time
+        collastmod[i] = gravtk.utilities.get_unix_time(lastmod,
+            format='%Y-%m-%d %H:%M')
+    # reduce using regular expression pattern
+    if pattern:
+        i = [i for i,f in enumerate(colnames) if re.search(pattern, f)]
+        # reduce list of column names and last modified times
+        colnames = [colnames[indice] for indice in i]
+        collastmod = [collastmod[indice] for indice in i]
+    # sort the list
+    if sort:
+        i = [i for i,j in sorted(enumerate(colnames), key=lambda i: i[1])]
+        # sort list of column names and last modified times
+        colnames = [colnames[indice] for indice in i]
+        collastmod = [collastmod[indice] for indice in i]
+    # return the list of column names and last modified times
+    return (colnames, collastmod)
+
 # PURPOSE: pull file from a remote host checking if file exists locally
 # and if the remote file is newer than the local file
-def ftp_mirror_file(ftp,remote_path,remote_mtime,local_file,
-    CLOBBER=False,MODE=0o775):
-    # path to remote file
-    remote_file = posixpath.join(*remote_path[1:])
+def http_pull_file(remote_path, remote_mtime, local_file,
+    TIMEOUT=0, LIST=False, CLOBBER=False, MODE=0o775):
+    # verify inputs for remote http host
+    if isinstance(remote_path, str):
+        remote_path = gravtk.utilities.url_split(remote_path)
+    # construct remote file path
+    remote_file = posixpath.join(*remote_path)
     # if file exists in file system: check if remote file is newer
     TEST = False
     OVERWRITE = ' (clobber)'
@@ -178,15 +251,24 @@ def ftp_mirror_file(ftp,remote_path,remote_mtime,local_file,
     # if file does not exist locally, is to be overwritten, or CLOBBER is set
     if TEST or CLOBBER:
         # Printing files transferred
-        remote_ftp_url = posixpath.join('ftp://',*remote_path)
-        logging.info(f'{remote_ftp_url} -->')
-        logging.info(f'\t{local_file}{OVERWRITE}\n')
-        # copy remote file contents to local file
-        with local_file.open(mode='wb') as f:
-            ftp.retrbinary(f'RETR {remote_file}', f.write)
-        # keep remote modification time of file and local access time
-        os.utime(local_file, (local_file.stat().st_atime, remote_mtime))
-        local_file.chmod(mode=MODE)
+        logging.info(f'{remote_file} --> ')
+        logging.info(f'\t{str(local_file)}{OVERWRITE}\n')
+        # if executing copy command (not only printing the files)
+        if not LIST:
+            # Create and submit request. There are a wide range of exceptions
+            # that can be thrown here, including HTTPError and URLError.
+            request = gravtk.utilities.urllib2.Request(remote_file)
+            response = gravtk.utilities.urllib2.urlopen(request,
+                timeout=TIMEOUT)
+            # chunked transfer encoding size
+            CHUNK = 16 * 1024
+            # copy contents to local file using chunked transfer encoding
+            # transfer should work properly with ascii and binary data formats
+            with local_file.open(mode='wb') as f:
+                shutil.copyfileobj(response, f, CHUNK)
+            # keep remote modification time of file and local access time
+            os.utime(local_file, (local_file.stat().st_atime, remote_mtime))
+            local_file.chmod(mode=MODE)
 
 # PURPOSE: create argument parser
 def arguments():
@@ -243,14 +325,17 @@ def main():
     parser = arguments()
     args,_ = parser.parse_known_args()
 
+    # GFZ ISDC https host
+    HOST = 'https://isdc-data.gfz.de/'
     # check internet connection before attempting to run program
-    HOST = 'isdcftp.gfz-potsdam.de'
-    if gravtk.utilities.check_ftp_connection(HOST):
+    if gravtk.utilities.check_connection(HOST):
         for DREL in args.release:
-            gfz_isdc_dealiasing_ftp(args.directory, DREL=DREL,
+            gfz_isdc_dealiasing_sync(args.directory, DREL=DREL,
                 YEAR=args.year, MONTHS=args.month, TAR=args.tar,
                 TIMEOUT=args.timeout, LOG=args.log,
                 CLOBBER=args.clobber, MODE=args.mode)
+    else:
+        raise RuntimeError('Check internet connection')
 
 # run main program
 if __name__ == '__main__':