"""
Alignment module.
"""
from __future__ import print_function, division, absolute_import

import sys

from cutadapt._align import Aligner, compare_prefixes, locate

# flags for global alignment

# The interpretation of the first flag is:
# An initial portion of seq1 may be skipped at no cost.
# This is equivalent to saying that in the alignment,
# gaps in the beginning of seq2 are free.
#
# The other flags have an equivalent meaning.
START_WITHIN_SEQ1 = 1
START_WITHIN_SEQ2 = 2
STOP_WITHIN_SEQ1 = 4
STOP_WITHIN_SEQ2 = 8
ALLOW_WILDCARD_SEQ1 = 1
ALLOW_WILDCARD_SEQ2 = 2

# Use this to get regular semiglobal alignment
# (all gaps in the beginning or end are free)
SEMIGLOBAL = START_WITHIN_SEQ1 | START_WITHIN_SEQ2 | STOP_WITHIN_SEQ1 | STOP_WITHIN_SEQ2


def compare_suffixes(s1, s2, degenerate=0):
	"""
	Find out whether one string is the suffix of the other one, allowing
	mismatches. Used to find an anchored 3' adapter when no indels are allowed.
	"""
	s1 = s1[::-1]
	s2 = s2[::-1]
	_, length, _, _, matches, errors = compare_prefixes(s1, s2, degenerate)
	return (len(s1) - length, len(s1), len(s2) - length, len(s2), matches, errors)