"""
Useful functions to be used in Python scripts.

Usage:

::

    from grass.script import utils as gutils

(C) 2014-2016 by the GRASS Development Team
This program is free software under the GNU General Public
License (>=v2). Read the file COPYING that comes with GRASS
for details.

.. sectionauthor:: Glynn Clements
.. sectionauthor:: Martin Landa <landa.martin gmail.com>
.. sectionauthor:: Anna Petrasova <kratochanna gmail.com>
"""

import os
import sys
import shutil
import locale
import shlex
import re

def float_or_dms(s):
    """Convert DMS to float.

    >>> round(float_or_dms('26:45:30'), 5)
    26.75833
    >>> round(float_or_dms('26:0:0.1'), 5)
    26.00003

    :param s: DMS value

    :return: float value
    """
    return sum(float(x) / 60 ** n for (n, x) in enumerate(s.split(':')))


def separator(sep):
    """Returns separator from G_OPT_F_SEP appropriately converted
    to character.

    >>> separator('pipe')
    '|'
    >>> separator('comma')
    ','

    If the string does not match any of the separator keywords,
    it is returned as is:

    >>> separator(', ')
    ', '

    :param str separator: character or separator keyword

    :return: separator character
    """
    if sep == "pipe":
        return "|"
    elif sep == "comma":
        return ","
    elif sep == "space":
        return " "
    elif sep == "tab" or sep == "\\t":
        return "\t"
    elif sep == "newline" or sep == "\\n":
        return "\n"
    return sep


def diff_files(filename_a, filename_b):
    """Diffs two text files and returns difference.

    :param str filename_a: first file path
    :param str filename_b: second file path

    :return: list of strings
    """
    import difflib
    differ = difflib.Differ()
    fh_a = open(filename_a, 'r')
    fh_b = open(filename_b, 'r')
    result = list(differ.compare(fh_a.readlines(),
                                 fh_b.readlines()))
    return result


def try_remove(path):
    """Attempt to remove a file; no exception is generated if the
    attempt fails.

    :param str path: path to file to remove
    """
    try:
        os.remove(path)
    except:
        pass


def try_rmdir(path):
    """Attempt to remove a directory; no exception is generated if the
    attempt fails.

    :param str path: path to directory to remove
    """
    try:
        os.rmdir(path)
    except:
        shutil.rmtree(path, ignore_errors=True)


def basename(path, ext=None):
    """Remove leading directory components and an optional extension
    from the specified path

    :param str path: path
    :param str ext: extension
    """
    name = os.path.basename(path)
    if not ext:
        return name
    fs = name.rsplit('.', 1)
    if len(fs) > 1 and fs[1].lower() == ext:
        name = fs[0]
    return name


class KeyValue(dict):
    """A general-purpose key-value store.

    KeyValue is a subclass of dict, but also allows entries to be read and
    written using attribute syntax. Example:

    >>> reg = KeyValue()
    >>> reg['north'] = 489
    >>> reg.north
    489
    >>> reg.south = 205
    >>> reg['south']
    205
    """

    def __getattr__(self, key):
        return self[key]

    def __setattr__(self, key, value):
        self[key] = value


def decode(bytes_):
    """Decode bytes with default locale and return (unicode) string

    No-op if parameter is not bytes (assumed unicode string).

    :param bytes bytes_: the bytes to decode
    """
    if isinstance(bytes_, bytes):
        enc = locale.getdefaultlocale()[1]
        return bytes_.decode(enc) if enc else bytes_.decode()
    return bytes_


def encode(string):
    """Encode string with default locale and return bytes with that encoding

    No-op if parameter is bytes (assumed already encoded).
    This ensures garbage in, garbage out.

    :param str string: the string to encode
    """
    if isinstance(string, bytes):
        return string
    enc = locale.getdefaultlocale()[1]
    return string.encode(enc) if enc else string.encode()


def parse_key_val(s, sep='=', dflt=None, val_type=None, vsep=None):
    """Parse a string into a dictionary, where entries are separated
    by newlines and the key and value are separated by `sep` (default: `=`)

    >>> parse_key_val('min=20\\nmax=50') == {'min': '20', 'max': '50'}
    True
    >>> parse_key_val('min=20\\nmax=50',
    ...     val_type=float) == {'min': 20, 'max': 50}
    True

    :param str s: string to be parsed
    :param str sep: key/value separator
    :param dflt: default value to be used
    :param val_type: value type (None for no cast)
    :param vsep: vertical separator (default is Python 'universal newlines' approach)

    :return: parsed input (dictionary of keys/values)
    """
    result = KeyValue()

    if not s:
        return result

    if isinstance(s, bytes):
        sep = encode(sep)
        vsep = encode(vsep) if vsep else vsep

    if vsep:
        lines = s.split(vsep)
        try:
            lines.remove('\n')
        except ValueError:
            pass
    else:
        lines = s.splitlines()

    for line in lines:
        kv = line.split(sep, 1)
        k = decode(kv[0].strip())
        if len(kv) > 1:
            v = decode(kv[1].strip())
        else:
            v = dflt

        if val_type:
            result[k] = val_type(v)
        else:
            result[k] = v

    return result


def get_num_suffix(number, max_number):
    """Returns formatted number with number of padding zeros
    depending on maximum number, used for creating suffix for data series.
    Does not include the suffix separator.

    :param number: number to be formatted as map suffix
    :param max_number: maximum number of the series to get number of digits

    >>> get_num_suffix(10, 1000)
    '0010'
    >>> get_num_suffix(10, 10)
    '10'
    """
    return '{number:0{width}d}'.format(width=len(str(max_number)),
                                       number=number)

def split(s):
    """!Platform specific shlex.split"""
    if sys.version_info >= (2, 6):
        return shlex.split(s, posix = (sys.platform != "win32"))
    elif sys.platform == "win32":
        return shlex.split(s.replace('\\', r'\\'))
    else:
        return shlex.split(s)


# source:
#    http://stackoverflow.com/questions/4836710/
#    does-python-have-a-built-in-function-for-string-natural-sort/4836734#4836734
def natural_sort(l):
    """Returns sorted strings using natural sort
    """
    convert = lambda text: int(text) if text.isdigit() else text.lower()
    alphanum_key = lambda key: [convert(c) for c in re.split('([0-9]+)', key)]
    return sorted(l, key=alphanum_key)


def get_lib_path(modname, libname=None):
    """Return the path of the libname contained in the module.
    """
    from os.path import isdir, join, sep
    from os import getenv

    if isdir(join(getenv('GISBASE'), 'etc', modname)):
        path = join(os.getenv('GISBASE'), 'etc', modname)
    elif getenv('GRASS_ADDON_BASE') and libname and \
            isdir(join(getenv('GRASS_ADDON_BASE'), 'etc', modname, libname)):
        path = join(getenv('GRASS_ADDON_BASE'), 'etc', modname)
    elif getenv('GRASS_ADDON_BASE') and \
            isdir(join(getenv('GRASS_ADDON_BASE'), 'etc', modname)):
        path = join(getenv('GRASS_ADDON_BASE'), 'etc', modname)
    elif getenv('GRASS_ADDON_BASE') and \
            isdir(join(getenv('GRASS_ADDON_BASE'), modname, modname)):
        path = join(os.getenv('GRASS_ADDON_BASE'), modname, modname)
    else:
        # used by g.extension compilation process
        cwd = os.getcwd()
        idx = cwd.find(modname)
        if idx < 0:
            return None
        path = '{cwd}{sep}etc{sep}{modname}'.format(cwd=cwd[:idx+len(modname)],
                                                    sep=sep,
                                                    modname=modname)
        if libname:
            path += '{pathsep}{cwd}{sep}etc{sep}{modname}{sep}{libname}'.format(
                cwd=cwd[:idx+len(modname)],
                sep=sep,
                modname=modname, libname=libname,
                pathsep=os.pathsep
            )

    return path


def set_path(modulename, dirname=None, path='.'):
    """Set sys.path looking in the the local directory GRASS directories.

    :param modulename: string with the name of the GRASS module
    :param dirname: string with the directory name containing the python
                    libraries, default None
    :param path: string with the path to reach the dirname locally.

    Example
    --------

    "set_path" example working locally with the source code of a module
    (r.green) calling the function with all the parameters. Below it is
    reported the directory structure on the r.green module.

    ::

        grass_prompt> pwd
        ~/Download/r.green/r.green.hydro/r.green.hydro.financial

        grass_prompt> tree ../../../r.green
        ../../../r.green
        |-- ...
        |-- libgreen
        |   |-- pyfile1.py
        |   +-- pyfile2.py
        +-- r.green.hydro
           |-- Makefile
           |-- libhydro
           |   |-- pyfile1.py
           |   +-- pyfile2.py
           |-- r.green.hydro.*
           +-- r.green.hydro.financial
               |-- Makefile
               |-- ...
               +-- r.green.hydro.financial.py

        21 directories, 125 files

    in the source code the function is called with the following parameters: ::

        set_path('r.green', 'libhydro', '..')
        set_path('r.green', 'libgreen', os.path.join('..', '..'))

    when we are executing the module: r.green.hydro.financial locally from
    the command line:  ::

        grass_prompt> python r.green.hydro.financial.py --ui

    In this way we are executing the local code even if the module was already
    installed as grass-addons and it is available in GRASS standards path.

    The function is cheching if the dirname is provided and if the
    directory exists and it is available using the path
    provided as third parameter, if yes add the path to sys.path to be
    importable, otherwise it will check on GRASS GIS standard paths.

    """
    import sys
    # TODO: why dirname is checked first - the logic should be revised
    pathlib = None
    if dirname:
        pathlib = os.path.join(path, dirname)
    if pathlib and os.path.exists(pathlib):
        # we are running the script from the script directory, therefore
        # we add the path to sys.path to reach the directory (dirname)
        sys.path.append(os.path.abspath(path))
    else:
        # running from GRASS GIS session
        path = get_lib_path(modulename, dirname)
        if path is None:
            pathname = os.path.join(modulename, dirname) if dirname else modulename
            raise ImportError("Not able to find the path '%s' directory "
                              "(current dir '%s')." % (pathname, os.getcwd()))

        sys.path.insert(0, path)
