#! /usr/bin/env python3
# encoding: utf-8

# ----------------------------------------------------------------

def flatten_dict(root, glue=" ", prefix=[]):
	lines = []
	
	for k, v in root.items():
		new_prefix = prefix + [k]
		
		if type(v) == dict:
			lines.extend(flatten_dict(v, glue, new_prefix))
		else:
			lines.append((glue.join(new_prefix), v))
	
	return lines

# ----------------------------------------------------------------

def clamp(A, low, high):
	"""
	Clamps integer A to <low; high>
	"""
	
	if A < low:
		return low
	elif A > high:
		return high
	else:
		return A

# ----------------------------------------------------------------

import random

PASSPHRASE_VOWELS = "aeiuAEU"
PASSPHRASE_CONSONANTS = "bcdfghjkmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ23456789"

def random_bytes(length):
	return open("/dev/urandom", "rb").read(length)

def random_syllable():
	return random.choice(PASSPHRASE_CONSONANTS) + random.choice(PASSPHRASE_VOWELS) + random.choice(PASSPHRASE_CONSONANTS)

def random_word(syllables=3):
	parts = []
	
	for _ in range(syllables):
		parts.append(random_syllable())
	
	return "".join(parts)

# ----------------------------------------------------------------

import hashlib

def hash_password(p, hexdigest=True):
	h = hashlib.blake2b()
	
	h.update(p.encode("utf-8"))
	
	return h.hexdigest() if hexdigest else h.digest()

# ----------------------------------------------------------------

class DeleteOverlay:
	pass

def overlay_tree(base, overlay):
	"""
	For every key path in `overlay`, sets the leaf value of the same
	key path in `base`. Any missing non-leaf keys will be created.
	
	To delete a key, set its overlay value to DeleteOverlay.
	"""
	
	stack = [(base, overlay)]
	
	while stack:
		base_p, over_p = stack.pop()
		
		for k, v in over_p.items():
			if v is DeleteOverlay:
				del base_p[k]
			else:
				if type(v) is dict:
					if k not in base_p or type(base_p[k]) is not dict:
						base_p[k] = {}
					
					stack.append((base_p[k], over_p[k]))
				
				else:
					base_p[k] = v