"""leimonfold - A command-line tool to update threads in a maildir using lei & lore.org/all/"""

from datetime import datetime
from datetime import timedelta
from datetime import timezone
from email.headerregistry import DateHeader
from mailbox import Maildir
from subprocess import run as subp_run
from sys import argv as sys_argv

__version__ = "0.0.1-prealpha"
__author__ = "Thorsten Leemhuis"
__email__ = "linux@leemhuis.info"

# todo:
# * error handling
# * support for formats other then maildir?

def find_thread_heads(maildir_path):
    thread_heads = {}
    thread_members = {}
    maildir = Maildir(maildir_path, create=False)

    def clear_msgid(msgid):
        return msgid[1:-1]

    def parse_date(msg):
        kwds = {}
        DateHeader.parse(msg['Date'], kwds)
        return kwds['datetime']
    
    def in_reply_to_known(in_reply_to):
        for i in in_reply_to:
            msgid = clear_msgid(i)
            if msgid in thread_heads or msgid in thread_members:
                return msgid
        return False

    # walk messages and store heads directly while recording thread members
    for msg in maildir:
        msgid = clear_msgid(msg['Message-ID'])
        date = parse_date(msg)
        if not msg['In-reply-to'] and not msg['References']:
            # print('head found: %s' % msg['Subject'])
            thread_heads[msgid] = date 
            continue
        for i in ('References', 'In-reply-to'):
            if i in msg:
                thread_members[msgid] = msg[i].split()
                # hack: insert date into the first spot of the list; updated
                # later to contain the date of the latest posting in the thread
                thread_members[msgid].insert(0, date)
                break
    
    # detect if the head of all the replies was found in case a msg from the
    # middle of a thread not yet tracked was added to the maildir
    for msgid in thread_members.keys():
        # reminder: there is a hack here, the date of the msg is stored in the first spot of the list
        upper_msgid = in_reply_to_known(thread_members[msgid][1:])
        if not upper_msgid:
            # partial thread, so add it to the list of heads so it gets downloaded
            # print('partial thread found and added: %s' % msgid)
            thread_heads[msgid] = thread_members[msgid][0]
        else:
            if thread_heads[upper_msgid] > thread_members[msgid][0]:
                thread_heads[upper_msgid] = thread_members[msgid][0]

    return thread_heads

def run_lei_query(maildir_path, mid):
    cmd = ['lei', 'q', '-I', 'https://lore.kernel.org/all/', '--augment', '-o', 'maildir:%s' % maildir_path, '--threads', '--dedupe=mid', mid]
    result = subp_run(cmd, capture_output=True)
    return result

maildir_path = sys_argv[1]
thread_heads = find_thread_heads(maildir_path)
today = datetime.now(tz=timezone.utc)
for msgid in thread_heads.keys():
    delta = today - thread_heads[msgid]  
    if delta.days > 90:
        # ignore threads older than 90 days
        continue
    result = run_lei_query(maildir_path, 'mid:%s rt:1.year.ago..' % msgid)
    # print(msgid, result.returncode, result.stdout, result.stderr)