from datetime import datetime, timedelta
from dateutil.parser import isoparse
import logging
from .umbrellas import Umbrellas
from .jform import JForm
from .exceptions import *
from .config import config
from .utils import CST

"""A set of routine methods, run at an interval (somewhere from ten minutes to one hour), to:
- sync JImbrella's databse against data pulled from jForm
- check if any umbrella is now overdue
- send an SMS where applicable, to a user or an admin
"""


def chronological_merge(*sheet_lists) -> list:
    """Merges all lists answer sheets passed in, in chronological order, into a single list.

    All lists of sheets in sheet_lists MUST be already in chronological order.
    By "chronological", we mean sorting by the value under key "date".
    """
    chronicle = []
    while any(sheet_lists):  # at least one list in `sheet_lists` is non-empty
        # for each list of sheets, read date from its first element, then find the earliest
        # is an instance of datetime.datetime
        # only pass non-empty lists to min():
        earliest_date = min(
            [sheet_list[0]["date"] for sheet_list in filter(None, sheet_lists)]
        )
        for idx, sheet_list in enumerate(sheet_lists):
            if not sheet_list:  # is empty
                continue
            if sheet_list[0]["date"] == earliest_date:
                # remove the first element and append it to `chronicle`, if it is the earliest
                chronicle.append(sheet_lists[idx].pop(0))
                # we do not directly break here because there exists a tiny chance
                # two answer sheets were submitted at the exact same millisecond
    return chronicle


def sync_jform(takeaway: JForm, giveback: JForm, db: Umbrellas):
    takeaway_unread = takeaway.get_unread()
    giveback_unread = giveback.get_unread()
    logging.info(
        "Sync jForm: found %d unread takeaway sheet(s) and %d unread giveback sheet(s)",
        len(takeaway_unread),
        len(giveback_unread),
    )
    unread = chronological_merge(takeaway_unread, giveback_unread)
    # NOTE: beyond this point `takeaway_unread` and `giveback_unread` are empty
    #       because chronological_merge popped all their elements
    for sheet in unread:
        sheet["date_str"] = sheet["date"].isoformat(timespec="milliseconds")
        tenant_identity = "{name} (ID: {id}, phone: {phone})".format(**sheet)
        if sheet["jform_name"] == "takeaway":
            try:
                db.take_away(
                    sheet["key"],
                    sheet["date"],
                    sheet["name"],
                    sheet["id"],
                    sheet["phone"],
                )
            except (UmbrellaStatusError, UmbrellaNotFoundError):
                logging.warning(
                    tenant_identity
                    + " attempted to borrow umbrella #{key} at {date_str}".format(
                        **sheet
                    )
                )
        elif sheet["jform_name"] == "giveback":
            try:
                db.give_back(sheet["key"], sheet["date"], sheet["name"], sheet["id"])
                logging.info(
                    tenant_identity
                    + " returned umbrella #{key} at {date_str}".format(**sheet)
                )
            except (UmbrellaStatusError, UmbrellaNotFoundError):
                logging.warning(
                    tenant_identity
                    + " attempted to return umbrella #{key} at {date_str}".format(
                        **sheet
                    )
                )
            except TenantIdentityError as e:
                logging.warning(
                    tenant_identity
                    + " attempted to return umbrella #{key} at {date_str}, expecting tenant {expected}".format(
                        expected=e.expected, **sheet
                    )
                )


def process_overdue(db: Umbrellas):
    """mark and log umbrellas that were not, but just became overdue"""
    umbrellas = db.read()
    now = datetime.now().astimezone(CST)
    for umb in umbrellas:
        if umb["status"] == "lent":
            try:
                lent_at = isoparse(umb["lent_at"])
            except ValueError:
                logging.error(
                    "Invalid lent_at in umbrella #%d: %s", umb["id"], umb["lent_at"]
                )
                continue

            if now - lent_at > timedelta(hours=config.getint("general", "due_hours")):
                db.mark_overdue(umb["id"])
                logging.warning(
                    "Umbrella #{id} is now overdue, tenant: {tenant_name} (ID: {tenant_id}, phone: {tenant_phone})".format(
                        **umb
                    )
                )


if __name__ == "__main__":
    takeaway = JForm(
        "takeaway",
        config.get("jform", "takeaway_url"),
        config.get("jform", "bookmark_dir"),
    )
    giveback = JForm(
        "giveback",
        config.get("jform", "giveback_url"),
        config.get("jform", "bookmark_dir"),
    )
    db = Umbrellas(config.get("general", "db_path"))
    sync_jform(takeaway, giveback, db)
    process_overdue(db)