Add support for vdir synchronization

Add a script to synchronize calcurse with a VDIR collection.

Add a wrapper script around vdirsyncer to automatically synchronize
calcurse data to a vdirsyncer collection.

Add script documentation and Makefile.

Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

contrib/vdir/calcurse-vdir.py

@@ -0,0 +1,186 @@
+#!/usr/bin/env python3
+
+import argparse
+import io
+import os
+import re
+import subprocess
+import sys
+import textwrap
+
+
+def msgfmt(msg, prefix=''):
+    """Format a message"""
+    lines = []
+    for line in msg.splitlines():
+        lines += textwrap.wrap(line, 80 - len(prefix))
+    return '\n'.join([prefix + line for line in lines])
+
+
+def log(msg):
+    """Print a formatted message"""
+    print(msgfmt(msg))
+
+
+def die(msg):
+    """Exit on error"""
+    sys.exit(msgfmt(msg, prefix="error: "))
+
+
+def check_binary(binary):
+    """Check if a binary is available in $PATH"""
+    try:
+        subprocess.call([binary, '--version'], stdout=subprocess.DEVNULL)
+    except FileNotFoundError:
+        die("{0} is not available.".format(binary))
+
+
+def check_directory(directory):
+    """Check if a directory exists"""
+    if not os.path.isdir(directory):
+        die("invalid directory: {0}".format(directory))
+
+
+def file_to_uid(file):
+    """Return the uid of an ical file"""
+    uid = file.replace(vdir, "").replace(".ics", "")
+    return uid
+
+
+def write_file(file, contents):
+    """Write to file"""
+    if verbose:
+        log("Writing event {0}".format(file_to_uid(file)))
+    with open(file, 'w') as f:
+        f.write(contents)
+
+
+def remove_file(file):
+    """Remove file"""
+    if verbose:
+        log("Deleting event {0}".format(file_to_uid(file)))
+    if os.path.isfile(file):
+        os.remove(file)
+
+
+def calcurse_export():
+    """Return raw calcurse data"""
+    command = calcurse + ['-xical', '--export-uid']
+    proc = subprocess.Popen(command, stdout=subprocess.PIPE)
+    return [x for x in io.TextIOWrapper(proc.stdout, encoding="utf-8")]
+
+
+def calcurse_remove(uid):
+    """Remove calcurse event by uid"""
+    if verbose:
+        log("Removing event {0} from calcurse".format(uid))
+    command = calcurse + ['-P', '--filter-hash=' + uid]
+    subprocess.call(command)
+
+
+def calcurse_import(file):
+    """Import ics file to calcurse"""
+    if verbose:
+        log("Importing event {0} to calcurse".format(file_to_uid(file)))
+    command = calcurse + ['-i', file]
+    subprocess.call(command, stdout=subprocess.DEVNULL)
+
+
+def calcurse_list():
+    """Return all calcurse item uids"""
+    command = calcurse + [
+        '-G',
+        '--format-apt=%(hash)\\n',
+        '--format-recur-apt=%(hash)\\n',
+        '--format-event=%(hash)\\n',
+        '--format-recur-event=%(hash)\\n',
+        '--format-todo=%(hash)\\n'
+    ]
+    proc = subprocess.Popen(command, stdout=subprocess.PIPE)
+    return [x.strip() for x in io.TextIOWrapper(proc.stdout, encoding="utf-8")]
+
+
+def parse_calcurse_data(raw):
+    """Parse raw calcurse data to a uid/ical dictionary"""
+
+    header = ''.join(raw[:3])
+    regex = '(BEGIN:(VEVENT|VTODO).*?END:(VEVENT|VTODO).)'
+    events = [x[0] for x in re.findall(regex, ''.join(raw), re.DOTALL)]
+
+    items = {}
+
+    for item in events:
+        uid = re.findall('UID:(.*?)\n', item)[0]
+        items[uid] = header + item + "END:VCALENDAR\n"
+
+    return items
+
+
+def calcurse_to_vdir():
+    """Export calcurse data to vdir"""
+    raw_events = calcurse_export()
+    events = parse_calcurse_data(raw_events)
+
+    files_vdir = [x for x in os.listdir(vdir)]
+    files_calc = [uid + ".ics" for uid in events]
+
+    if force:
+        for file in [f for f in files_vdir if f not in files_calc]:
+            remove_file(os.path.join(vdir, file))
+
+    for uid, event in events.items():
+        file = uid + ".ics"
+        if file not in files_vdir:
+            write_file(os.path.join(vdir, file), event)
+
+
+def vdir_to_calcurse():
+    """Import vdir data to calcurse"""
+    files_calc = [x + '.ics' for x in calcurse_list()]
+    files_vdir = [x for x in os.listdir(vdir) if x.endswith('.ics')]
+
+    for file in [f for f in files_vdir if f not in files_calc]:
+        calcurse_import(os.path.join(vdir, file))
+
+    if force:
+        for file in [f for f in files_calc if f not in files_vdir]:
+            calcurse_remove(file[:-4])
+
+
+parser = argparse.ArgumentParser('calcurse-vdir')
+parser.add_argument('action', choices=['import', 'export'],
+                    help='export or import calcurse data')
+parser.add_argument('vdir',
+                    help='path to the vdir collection directory')
+parser.add_argument('-D', '--datadir', action='store', dest='datadir',
+                    default=None,
+                    help='path to the calcurse data directory')
+parser.add_argument('-f', '--force', action='store_true', dest='force',
+                    default=False,
+                    help='enable destructive import and export')
+parser.add_argument('-v', '--verbose', action='store_true', dest='verbose',
+                    default=False,
+                    help='print status messages to stdout')
+args = parser.parse_args()
+
+action = args.action
+datadir = args.datadir
+force = args.force
+verbose = args.verbose
+vdir = args.vdir
+
+check_directory(vdir)
+
+check_binary('calcurse')
+calcurse = ['calcurse']
+
+if datadir:
+    check_directory(datadir)
+    calcurse += ['-D', datadir]
+
+if action == 'import':
+    vdir_to_calcurse()
+elif action == 'export':
+    calcurse_to_vdir()
+else:
+    die("Invalid action {0}.".format(action))