# -*- coding: utf-8 -*-

# Copyright 2015, 2016 Mike Fährmann
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.

"""Collection of functions that work in strings/text"""

import sys
import re
import os.path
import html
import urllib.parse

def remove_html(text):
    """Remove html-tags from a string"""
    return " ".join(re.sub("<[^>]+?>", " ", text).split())

def filename_from_url(url):
    """Extract the last part of an url to use as a filename"""
    try:
        path = urllib.parse.urlparse(url).path
        pos = path.rindex("/")
        return path[pos+1:]
    except ValueError:
        return url

def nameext_from_url(url, data=None):
    """Extract the last part of an url and fill keywords of 'data' accordingly"""
    if data is None:
        data = {}
    data["filename"] = unquote(filename_from_url(url))
    data["name"], ext = os.path.splitext(data["filename"])
    data["extension"] = ext[1:].lower()
    return data

def clean_path_windows(path):
    """Remove illegal characters from a path-segment (Windows)"""
    try:
        return re.sub(r'[<>:"\\/|?*]', "_", path)
    except TypeError:
        return path

def clean_path_posix(path):
    """Remove illegal characters from a path-segment (Posix)"""
    try:
        return path.replace("/", "_")
    except AttributeError:
        return path

def shorten_path(path, limit=255, encoding=sys.getfilesystemencoding()):
    """Shorten a path segment to at most 'limit' bytes"""
    return (path.encode(encoding)[:limit]).decode(encoding, "ignore")

def shorten_filename(filename, limit=255, encoding=sys.getfilesystemencoding()):
    """Shorten a filename to at most 'limit' bytes while preserving extension"""
    name, extension = os.path.splitext(filename)
    bext = extension.encode(encoding)
    bname = name.encode(encoding)[:limit-len(bext)]
    return bname.decode(encoding, "ignore") + extension

def extract(txt, begin, end, pos=0):
    """Extract the text between 'begin' and 'end' from 'txt'

    Args:
        txt: String to search in
        begin: First string to be searched for
        end: Second string to be searched for after 'begin'
        pos: Starting position for searches in 'txt'

    Returns:
        The string between the two search-strings 'begin' and 'end' beginning
        with position 'pos' in 'txt' as well as the position after 'end'.

        If at least one of 'begin' or 'end' is not found, None and the original
        value of 'pos' is returned

    Examples:
        extract("abcde", "b", "d")    -> "c" , 4
        extract("abcde", "b", "d", 3) -> None, 3
    """
    try:
        first = txt.index(begin, pos) + len(begin)
        last = txt.index(end, first)
        return txt[first:last], last+len(end)
    except ValueError:
        return None, pos

def extract_all(txt, rules, pos=0, values=None):
    """Calls extract for each rule and returns the result in a dict"""
    if values is None:
        values = {}
    for key, begin, end in rules:
        result, pos = extract(txt, begin, end, pos)
        if key:
            values[key] = result
    return values, pos

def extract_iter(txt, begin, end, pos=0):
    """Yield all values obtained by repeated calls to text.extract"""
    while True:
        value, pos = extract(txt, begin, end, pos)
        if value is None:
            return
        yield value

if os.name == "nt":
    clean_path = clean_path_windows
else:
    clean_path = clean_path_posix

unquote = urllib.parse.unquote

unescape = html.unescape
