# vim:fileencoding=utf-8
# License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
from __python__ import hash_literals

UNDEFINED_DATE_ISO = '0101-01-01T00:00:00+00:00'
UNDEFINED_DATE = Date(UNDEFINED_DATE_ISO)

def is_date_undefined(date):
    dy, uy = date.getUTCFullYear(), UNDEFINED_DATE.getUTCFullYear()
    return dy < uy or (
            dy is uy and
            date.getUTCMonth() is UNDEFINED_DATE.getUTCMonth() and
            date.getUTCDate() <= UNDEFINED_DATE.getUTCDate() + 1)

# format_date() {{{

lcdata = {
    'abday': ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
    'abmon': ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
    'day'  : ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
    'mon'  : ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
}

supports_locales = False
try:
    Date().toLocaleString('dfkjghdfkgj')
except RangeError:
    supports_locales = True
except:
    pass


def fmt_date_pat():
    ans = fmt_date_pat.ans
    if not ans?:
        ans = fmt_date_pat.ans = /(s{1,2})|(m{1,2})|(h{1,2})|(H{1,2})|(zzz)|(z)|(ap)|(AP)|(a)|(A)|(t)|(d{1,4}|M{1,4}|(?:yyyy|yy))/g
    return ans


def fd_format_hour(dt, ampm, hr, as_utc):
    h = dt.getUTCHours() if as_utc else dt.getHours()
    if ampm:
        h = h % 12
    return h.toString() if hr.length is 1 else str.format('{:02d}', h)


def fd_format_hour24(dt, ampm, hr, as_utc):
    return fd_format_hour(dt, False, hr, as_utc)


def fd_format_minute(dt, ampm, min, as_utc):
    m = dt.getUTCMinutes() if as_utc else dt.getMinutes()
    return m.toString() if min.length is 1 else str.format('{:02d}', m)

def fd_format_second(dt, ampm, min, as_utc):
    s = dt.getUTCSeconds() if as_utc else dt.getSeconds()
    return s.toString() if min.length is 1 else str.format('{:02d}', s)

def fd_format_ms(dt, ampm, min, as_utc):
    s = dt.getUTCMilliseconds() if as_utc else dt.getSeconds()
    return s.toString() if min.length is 1 else str.format('{:03d}', s)



def fd_format_timezone(dt, ampm, t, as_utc):
    short = dt.toLocaleTimeString()
    full = dt.toLocaleTimeString(v'[]', {'timeZoneName': 'long'})
    idx = full.indexOf(short)
    if idx > -1:
        return full[idx + short.length:].strip()
    return window.Intl.DateTimeFormat().resolvedOptions().timeZone


def fd_format_ampm(dt, ampm, ap, as_utc):
    h = dt.getUTCHours() if as_utc else dt.getHours()
    ans = 'am' if h < 12 else 'pm'
    return ans if (ap is 'ap' or ap is 'a') else ans.toUpperCase()


def fd_format_day(dt, ampm, dy, as_utc):
    d = dt.getUTCDate() if as_utc else dt.getDate()
    if dy.length is 1:
        return d.toString()
    if dy.length is 2:
        return str.format('{:02d}', d)
    if supports_locales:
        options = {'weekday': ('short' if dy.length is 3 else 'long')}
        if as_utc:
            options['timeZone'] = 'UTC'
        return dt.toLocaleString(window.navigator.language, options)
    w = dt.getUTCDay() if as_utc else dt.getDay()
    return lcdata['abday' if dy.length is 3 else 'day'][(w + 1) % 7]

def fd_format_month(dt, ampm, mo, as_utc):
    m = dt.getUTCMonth() if as_utc else dt.getMonth()
    if mo.length is 1:
        return (m + 1).toString()
    if mo.length is 2:
        return str.format('{:02d}', m + 1)
    if supports_locales:
        options = {'month': {1:'numeric', 2:'2-digit', 3:'short', 4:'long'}[mo.length] or 'long'}
        if as_utc:
            options['timeZone'] = 'UTC'
        return dt.toLocaleString(window.navigator.language, options)
    return lcdata['abmon' if mo.length is 3 else 'mon'][m]

def fd_format_year(dt, ampm, yr, as_utc):
    y = dt.getUTCFullYear() if as_utc else dt.getFullYear()
    if yr.length is 2:
        return str.format('{:02d}', y % 100)
    return str.format('{:04d}', y)

fd_function_index = {
    'd': fd_format_day,
    'M': fd_format_month,
    'y': fd_format_year,
    'h': fd_format_hour,
    'H': fd_format_hour24,
    'm': fd_format_minute,
    's': fd_format_second,
    'a': fd_format_ampm,
    'A': fd_format_ampm,
    'z': fd_format_ms,
    't': fd_format_timezone,
}


def am_pm_pat():
    ans = am_pm_pat.ans
    if not ans?:
        ans = am_pm_pat.ans = /(ap)|(a)/
    return ans


def format_date(date=None, fmt='dd MMM yyyy', as_utc=False):
    fmt = fmt or 'dd MMM yyyy'
    ampm = am_pm_pat().test(fmt)
    if jstype(date) is 'string':
        date = Date(date)
    date = date or Date()
    if is_date_undefined(date):
        return ''
    return fmt.replace(fmt_date_pat(), def(match):
        if not match:
            return ''
        try:
            return fd_function_index[match[0]](date, ampm, match, as_utc)
        except Exception:
            print(str.format('Failed to format date with format: {} and match: {}', fmt, match))
            return ''
    )
# }}}