# -*- coding: utf-8 -*-
# Copyright 2026 Nexa Systems Inc.
# License OPL-1 (Odoo Proprietary License v1.0)

"""
Timezone helpers for Fusion Clock.

All Odoo datetimes are stored in UTC.  These helpers derive "today",
date boundaries, and display strings in the **user's local timezone**
so that queries, penalties, and UI all reflect the real calendar day.

Timezone resolution order:
  1. Explicit employee.tz  (if an employee record is available)
  2. env.user.tz           (logged-in portal / backend user)
  3. env.company.tz        (company-level default)
  4. 'UTC'                 (last resort — should rarely happen)
"""

import pytz
from datetime import datetime, timedelta


def _resolve_tz(env, employee=None):
    """Return a pytz timezone from the best available source."""
    tz_name = (
        (employee.tz if employee else None)
        or env.user.tz
        or env.company.tz
        or 'UTC'
    )
    try:
        return pytz.timezone(tz_name)
    except pytz.UnknownTimeZoneError:
        return pytz.UTC


def get_local_now(env, employee=None):
    """Return the current datetime in the resolved local timezone (aware)."""
    tz = _resolve_tz(env, employee)
    return datetime.now(pytz.UTC).astimezone(tz)


def get_local_today(env, employee=None):
    """Return today's date in the resolved local timezone."""
    return get_local_now(env, employee).date()


def get_local_day_boundaries(env, date_val, employee=None):
    """
    Return (start_utc, end_utc) as **naive** UTC datetimes representing
    midnight-to-midnight of *date_val* in the local timezone.

    Suitable for Odoo domain filters like:
        ('check_in', '>=', start_utc),
        ('check_in', '<',  end_utc),
    """
    tz = _resolve_tz(env, employee)
    local_start = tz.localize(datetime.combine(date_val, datetime.min.time()))
    local_end = tz.localize(datetime.combine(date_val + timedelta(days=1), datetime.min.time()))
    return (
        local_start.astimezone(pytz.UTC).replace(tzinfo=None),
        local_end.astimezone(pytz.UTC).replace(tzinfo=None),
    )


def utc_to_local_str(dt_utc, env, employee=None, fmt='%I:%M %p'):
    """
    Convert a naive-UTC datetime to a formatted string in local timezone.
    Returns '' if dt_utc is falsy.
    """
    if not dt_utc:
        return ''
    tz = _resolve_tz(env, employee)
    aware = pytz.UTC.localize(dt_utc)
    return aware.astimezone(tz).strftime(fmt)