from datetime import datetime
from math import ceil
import os
from os.path import isfile, dirname
import traceback

class AppError(Exception):
  pass
  
def open_file(fn):
  d = dirname(fn)
  os.makedirs(d, exist_ok=True)
  if isfile(fn):
    return open(fn, 'rb+')
  else:
    return open(fn, 'ab+')

def must_get(d, k):
  if type(k) == str:
    k = k.split('.')
  part = k.pop(0)
  if type(d) != dict or part not in d:
    raise ValueError(part + ' not found')
  val = d[part]
  if len(k) == 0:
    return val
  else:
    return must_get(val, k)

mg = must_get

def should_get(d, k, default=None):
  try:
    return must_get(d, k)
  except ValueError:
    return default

sg = should_get

def find_where_eq(l, k, v):
  for i in l:
    if k in i and i[k] == v:
      return i
  return None

def all_subclasses(cls):
  return set(cls.__subclasses__()).union(
    [s for c in cls.__subclasses__() for s in all_subclasses(c)])

def pprint(d, detail=2):
  print(pretty(d, detail=detail))
  
def pretty(d, ident=0, detail=2):
  if type(d) in [int, str, float, bool]:
    return str(d)
  if hasattr(d, 'f'):
    return d.f(detail)
  r = ''
  idt = ' ' * ident
  if type(d) in [list, set]:
    r += 'lst'
    for i in d:
      r += '\n' + idt + pretty(i, ident + 1, detail)
  elif type(d) == dict:
    r += 'map'
    for k,v in d.items():
      r += '\n' + idt + k + ': ' + pretty(v, ident + 1, detail)
  return r

def trim(s, l):
  s = s[:l]
  s += ' ' * (l-len(s))
  return s

def total_pages(meta):
  total = mg(meta, 'total')
  limit = mg(meta, 'limit')
  pages = ceil(total / limit)
  return pages
  
# >>> parse_timestamp('2023-06-02T20:34:48.293Z')
# 1685738088
def parse_timestamp(ts):
  return int(datetime.strptime(ts, '%Y-%m-%dT%H:%M:%S.%f%z').timestamp())

def render_timestamp(ts):
  return datetime.utcfromtimestamp(ts).isoformat()
  
def fmtex(e):
  return ''.join(traceback.TracebackException.from_exception(e).format())