Allow printing from the submit client

To allow easy deployments, have printing and submitting in the same
python file such that we can share code without need to import library
files.
For convenience of teams, you probably want to alias `printfile` to the
submit client with predefined `--print` argument to prevent any
accidental submission.

submit/submit

@@ -8,6 +8,7 @@
 #
 
 import argparse
+import base64
 import datetime
 import json
 import logging
@@ -299,6 +300,55 @@ Submit multiple files (the problem and language are taken from the first):
     return "\n\n".join(part for part in epilog_parts if part)
 
 
+def do_api_print():
+    '''Submit to the API for printing with the given data.'''
+
+    if len(filenames) != 1:
+        error('You can only print a single file')
+    filename = filenames[0]
+
+    with open(filename, 'rb') as file:
+        data = {
+            'original_name': filename,
+            'language': my_language['name'],
+            'file_contents': base64.b64encode(file.read()),
+        }
+    if entry_point:
+        data['entry_point'] = entry_point
+
+    url = f"{baseurl}api/{api_version}printing/team"
+    logging.info(f'connecting to {url}')
+
+    response = requests.post(url, data=data, headers=headers)
+
+    logging.debug(f"API call 'printing' returned:\n{response.text}")
+
+    # The connection worked, but we may have received an HTTP error
+    if response.status_code >= 300:
+        print(response.text)
+        if response.status_code == 401:
+            raise RuntimeError('Authentication failed, please check your DOMjudge credentials in ~/.netrc.')
+        else:
+            raise RuntimeError(f'Printing failed (code {response.status_code})')
+
+    # We got a successful HTTP response. It worked.
+    # But check that we indeed received a success response.
+
+    try:
+        result = json.loads(response.text)
+    except json.decoder.JSONDecodeError as e:
+        error(f'Parsing DOMjudge\'s API output failed: {e}')
+
+    if not isinstance(result, dict) or 'success' not in result:
+        error('DOMjudge\'s API returned unexpected JSON data.')
+
+    if result['success']:
+        print("DOMjudge reported a successful print job.")
+    else:
+        # Should not happen, as the status code should've been >= 300
+        print(f"DOMjudge reported a printing error: {result['output']}")
+
+
 def do_api_submit():
     '''Submit to the API with the given data.'''
 
@@ -374,6 +424,7 @@ parser.add_argument('-c', '--contest', help='''submit for contest with ID or sho
     Defaults to the value of the
     environment variable 'SUBMITCONTEST'.
     Mandatory when more than one contest is active.''')
+parser.add_argument('-P', '--print', help='submit the file for printing instead of submission', action='store_true')
 parser.add_argument('-p', '--problem', help='submit for problem with ID or label PROBLEM', default='')
 parser.add_argument('-l', '--language', help='submit in language with ID LANGUAGE', default='')
 parser.add_argument('-e', '--entry_point', help='set an explicit entry_point, e.g. the java main class')
@@ -540,7 +591,7 @@ for problem in problems:
         my_problem = problem
         break
 
-if not my_problem:
+if not my_problem and not args.print:
     usage('No known problem specified or detected.')
 
 # Guess entry point if not already specified.
@@ -556,11 +607,16 @@ if not entry_point and my_language['entry_point_required']:
     error('Entry point required but not specified nor detected.')
 
 logging.debug(f"contest is `{my_contest['shortname']}'")
-logging.debug(f"problem is `{my_problem['label']}'")
+if not args.print:
+    logging.debug(f"problem is `{my_problem['label']}'")
 logging.debug(f"language is `{my_language['name']}'")
 logging.debug(f"entry_point is `{entry_point or '<None>'}'")
 logging.debug(f"url is `{baseurl}'")
 
+if args.print:
+    do_api_print()
+    exit(0)
+
 if not args.assume_yes:
     print('Submission information:')
     if len(filenames) == 1: