import datetime
import email
import email.header
import imaplib
import os

passw = os.getenv("IMAP_PASSWORD", "")
mail = os.getenv("IMAP_EMAIL", "")

domain = os.getenv("IMAP_SERVER", "imap.uni-potsdam.de")
folder = os.getenv("IMAP_FOLDER", '"Uni Mail/FSR"')

cutoff = (
    datetime.date.fromisoformat(c)
    if (c := os.getenv("IMAP_CUTOFF"))
    else datetime.date.today() - datetime.timedelta(weeks=1)
)


def get_titles(cutoff):
    with imaplib.IMAP4_SSL(domain) as imap:
        imap.login(mail, passw)

        status, [message_count] = imap.select(folder)

        message_count = int(message_count)

        m = message_count
        date = datetime.date.today()
        while True:
            res, msg = imap.fetch(str(m), "(RFC822)")  # fetches email using ID

            for response in msg:
                if isinstance(response, tuple):
                    msg = email.message_from_bytes(response[1])

                    subj = msg["Subject"]
                    subj = subj.split("[FSR MaPhy]", 1)[1]
                    decoded_subj, enc = email.header.decode_header(subj)[0]
                    if isinstance(decoded_subj, bytes):
                        decoded_subj = decoded_subj.decode(enc)
                    decoded_subj = decoded_subj.strip().replace("\n", "")

                    received, _ = email.header.decode_header(msg["Date"])[0]
                    received = received.split(";")[-1].strip()

                    date = datetime.datetime.strptime(received, "%a, %d %b %Y %X %z").date()

                    if date < cutoff:
                        return

                    yield date.isoformat(), decoded_subj

            m -= 1


def generate_template(cutoff, template):
    for date, subject in get_titles(cutoff):
        yield template.format(date, subject)


if __name__ == "__main__":
    template = r"""\textbf{{{}: {}}}
\begin{{itemize}}
    \item
\end{{itemize}}"""

    for t in generate_template(cutoff, template):
        print(t)