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

"""
This file contains compatibility code to stay compatible with
as many python versions as possible.
"""

import sys

import vim  # pylint:disable=import-error

def _vim_dec(string):
    """Decode 'string' using &encoding."""
    try:
        return string.decode(vim.eval("&encoding"))
    except UnicodeDecodeError:
        # At least we tried. There might be some problems down the road now
        return string

def _vim_enc(string):
    """Encode 'string' using &encoding."""
    try:
        return string.encode(vim.eval("&encoding"))
    except UnicodeEncodeError:
        return string

if sys.version_info >= (3, 0):
    def col2byte(line, col):
        """
        Convert a valid column index into a byte index inside
        of vims buffer.
        """
        pre_chars = vim.current.buffer[line-1][:col]
        return len(_vim_enc(pre_chars))

    def byte2col(line, nbyte):
        """
        Convert a column into a byteidx suitable for a mark or cursor
        position inside of vim
        """
        line = vim.current.buffer[line-1]
        raw_bytes = _vim_enc(line)[:nbyte]
        return len(_vim_dec(raw_bytes))

    def as_unicode(string):
        """Return 'string' as unicode instance."""
        if isinstance(string, bytes):
            return _vim_dec(string)
        return str(string)

    def as_vimencoding(string):
        """Return 'string' as Vim internal encoding."""
        return string
else:
    import warnings
    warnings.filterwarnings("ignore", category=DeprecationWarning)

    def col2byte(line, col):
        """
        Convert a valid column index into a byte index inside
        of vims buffer.
        """
        pre_chars = _vim_dec(vim.current.buffer[line-1])[:col]
        return len(_vim_enc(pre_chars))

    def byte2col(line, nbyte):
        """
        Convert a column into a byteidx suitable for a mark or cursor
        position inside of vim
        """
        line = vim.current.buffer[line-1]
        if nbyte >= len(line): # This is beyond end of line
            return nbyte
        return len(_vim_dec(line[:nbyte]))

    def as_unicode(string):
        """Return 'string' as unicode instance."""
        if isinstance(string, str):
            return _vim_dec(string)
        return unicode(string)

    def as_vimencoding(string):
        """Return 'string' as unicode instance."""
        return _vim_enc(string)