"""
Common helpers and adaptations for Py2/3.
To be used in tests.
"""

# Slows down test runs by factors. Enable to debug proxy handling issues.
DEBUG_PROXY_ISSUES = False  # True

import gc
import os
import os.path
import re
import sys
import tempfile
import unittest

from contextlib import contextmanager
from io import StringIO, BytesIO
import urllib.parse as urlparse
from urllib.request import pathname2url

from lxml import etree, html

def make_version_tuple(version_string):
    return tuple(
        int(part) if part.isdigit() else part
        for part in re.findall('([0-9]+|[^0-9.]+)', version_string)
    )

IS_PYPY = (getattr(sys, 'implementation', None) == 'pypy' or
           getattr(sys, 'pypy_version_info', None) is not None)

from xml.etree import ElementTree

if hasattr(ElementTree, 'VERSION'):
    ET_VERSION = make_version_tuple(ElementTree.VERSION)
else:
    ET_VERSION = (0,0,0)

DOC_DIR = os.path.join(os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(__file__)))), 'doc')


def filter_by_version(test_class, version_dict, current_version):
    """Remove test methods that do not work with the current lib version.
    """
    find_required_version = version_dict.get
    def dummy_test_method(self):
        pass
    for name in dir(test_class):
        expected_version = find_required_version(name, (0,0,0))
        if expected_version > current_version:
            setattr(test_class, name, dummy_test_method)


def needs_libxml(*version):
    return unittest.skipIf(
        etree.LIBXML_VERSION < version,
        "needs libxml2 >= %s.%s.%s" % (version + (0, 0, 0))[:3])


def needs_feature(feature_name):
    assert feature_name in [
        'catalog', 'ftp', 'html', 'http', 'iconv', 'icu',
        'lzma', 'regexp', 'schematron', 'xmlschema', 'xpath', 'zlib',
    ], feature_name
    features = ', '.join(sorted(etree.LIBXML_FEATURES))
    return unittest.skipIf(
        feature_name not in etree.LIBXML_FEATURES,
        f"needs libxml2 with feature {feature_name}, found [{features}]"
    )


import doctest

try:
    import pytest
except ImportError:
    class skipif:
        "Using a class because a function would bind into a method when used in classes"
        def __init__(self, *args): pass
        def __call__(self, func, *args): return func
else:
    skipif = pytest.mark.skipif


unichr_escape = re.compile(r'\\u[0-9a-fA-F]{4}|\\U[0-9a-fA-F]{8}')


# Python 3
from codecs import unicode_escape_decode
def _str(s, encoding="UTF-8"):
    return unichr_escape.sub(lambda x: unicode_escape_decode(x.group(0))[0], s)
def _bytes(s, encoding="UTF-8"):
    return s.encode(encoding)

from io import BytesIO as _BytesIO

def BytesIO(*args):
    if args and isinstance(args[0], str):
        args = (args[0].encode("UTF-8"),)
    return _BytesIO(*args)

doctest_parser = doctest.DocTestParser()

def make_doctest(filename):
    file_path = os.path.join(DOC_DIR, filename)
    return doctest.DocFileSuite(file_path, module_relative=False, encoding='utf-8', optionflags=doctest.ELLIPSIS)


class HelperTestCase(unittest.TestCase):
    def tearDown(self):
        if DEBUG_PROXY_ISSUES:
            gc.collect()

    def parse(self, text, parser=None):
        f = BytesIO(text) if isinstance(text, bytes) else StringIO(text)
        return etree.parse(f, parser=parser)

    def _rootstring(self, tree):
        return etree.tostring(tree.getroot()).replace(
            b' ', b'').replace(b'\n', b'')

    try:
        unittest.TestCase.assertRegex
    except AttributeError:
        def assertRegex(self, *args, **kwargs):
            return self.assertRegex(*args, **kwargs)


class SillyFileLike:
    def __init__(self, xml_data=b'<foo><bar/></foo>'):
        self.xml_data = xml_data

    def read(self, amount=None):
        if self.xml_data:
            if amount:
                data = self.xml_data[:amount]
                self.xml_data = self.xml_data[amount:]
            else:
                data = self.xml_data
                self.xml_data = b''
            return data
        return b''


class LargeFileLike:
    def __init__(self, charlen=100, depth=4, children=5):
        self.data = BytesIO()
        self.chars  = b'a' * charlen
        self.children = range(children)
        self.more = self.iterelements(depth)

    def iterelements(self, depth):
        yield b'<root>'
        depth -= 1
        if depth > 0:
            for child in self.children:
                yield from self.iterelements(depth)
                yield self.chars
        else:
            yield self.chars
        yield b'</root>'

    def read(self, amount=None):
        data = self.data
        append = data.write
        if amount:
            for element in self.more:
                append(element)
                if data.tell() >= amount:
                    break
        else:
            for element in self.more:
                append(element)
        result = data.getvalue()
        data.seek(0)
        data.truncate()
        if amount:
            append(result[amount:])
            result = result[:amount]
        return result


class LargeFileLikeUnicode(LargeFileLike):
    def __init__(self, charlen=100, depth=4, children=5):
        LargeFileLike.__init__(self, charlen, depth, children)
        self.data = StringIO()
        self.chars  = 'a' * charlen
        self.more = self.iterelements(depth)

    def iterelements(self, depth):
        yield '<root>'
        depth -= 1
        if depth > 0:
            for child in self.children:
                yield from self.iterelements(depth)
                yield self.chars
        else:
            yield self.chars
        yield '</root>'


class SimpleFSPath:
    def __init__(self, path):
        self.path = path
    def __fspath__(self):
        return self.path


def fileInTestDir(name):
    _testdir = os.path.dirname(__file__)
    return os.path.join(_testdir, name)


def path2url(path):
    return urlparse.urljoin(
        'file://', pathname2url(path))


def fileUrlInTestDir(name):
    return path2url(fileInTestDir(name))


def read_file(name, mode='r'):
    with open(name, mode) as f:
        data = f.read()
    return data


def write_to_file(name, data, mode='w'):
    with open(name, mode) as f:
        f.write(data)


def readFileInTestDir(name, mode='r'):
    return read_file(fileInTestDir(name), mode)


def canonicalize(xml):
    tree = etree.parse(BytesIO(xml) if isinstance(xml, bytes) else StringIO(xml))
    f = BytesIO()
    tree.write_c14n(f)
    return f.getvalue()


@contextmanager
def tmpfile(**kwargs):
    handle, filename = tempfile.mkstemp(**kwargs)
    try:
        yield filename
    finally:
        os.close(handle)
        os.remove(filename)
