"""
General utilities.

MIT license.

Copyright (c) 2017 Isaac Muse <isaacmuse@gmail.com>
"""
from markdown.inlinepatterns import InlineProcessor
import xml.etree.ElementTree as etree
from collections import namedtuple
import sys
import copy
import re
import html
from urllib.request import pathname2url, url2pathname
from urllib.parse import urlparse
from functools import wraps
import warnings

RE_WIN_DRIVE_LETTER = re.compile(r"^[A-Za-z]$")
RE_WIN_DRIVE_PATH = re.compile(r"^[A-Za-z]:(?:\\.*)?$")
RE_URL = re.compile('(http|ftp)s?|data|mailto|tel|news')
RE_WIN_DEFAULT_PROTOCOL = re.compile(r"^///[A-Za-z]:(?:/.*)?$")

if sys.platform.startswith('win'):
    _PLATFORM = "windows"
elif sys.platform == "darwin":  # pragma: no cover
    _PLATFORM = "osx"
else:
    _PLATFORM = "linux"

PY39 = (3, 9) <= sys.version_info


def is_win():  # pragma: no cover
    """Is Windows."""

    return _PLATFORM == "windows"


def is_linux():  # pragma: no cover
    """Is Linux."""

    return _PLATFORM == "linux"


def is_mac():  # pragma: no cover
    """Is macOS."""

    return _PLATFORM == "osx"


def url2path(path):
    """Path to URL."""

    return url2pathname(path)


def path2url(url):
    """URL to path."""

    path = pathname2url(url)
    # If on windows, replace the notation to use a default protocol `///` with nothing.
    if is_win() and RE_WIN_DEFAULT_PROTOCOL.match(path):
        path = path.replace('///', '', 1)
    return path


def get_code_points(s):
    """Get the Unicode code points."""

    return [c for c in s]


def get_ord(c):
    """Get Unicode ord."""

    return ord(c)


def get_char(value):
    """Get the Unicode char."""

    return chr(value)


def escape_chars(md, echrs):
    """
    Add chars to the escape list.

    Don't just append as it modifies the global list permanently.
    Make a copy and extend **that** copy so that only this Markdown
    instance gets modified.
    """

    escaped = copy.copy(md.ESCAPED_CHARS)
    for ec in echrs:
        if ec not in escaped:
            escaped.append(ec)
    md.ESCAPED_CHARS = escaped


def parse_url(url):
    """
    Parse the URL.

    Try to determine if the following is a file path or
    (as we will call anything else) a URL.

    We return it slightly modified and combine the path parts.

    We also assume if we see something like c:/ it is a Windows path.
    We don't bother checking if this **is** a Windows system, but
    'nix users really shouldn't be creating weird names like c: for their folder.
    """

    is_url = False
    is_absolute = False
    scheme, netloc, path, params, query, fragment = urlparse(html.unescape(url))

    if RE_URL.match(scheme):
        # Clearly a URL
        is_url = True
    elif scheme == '' and netloc == '' and path == '':
        # Maybe just a URL fragment
        is_url = True
    elif scheme == 'file' and (RE_WIN_DRIVE_PATH.match(netloc)):
        # file://c:/path or file://c:\path
        path = '/' + (netloc + path).replace('\\', '/')
        netloc = ''
        is_absolute = True
    elif scheme == 'file' and netloc.startswith('\\'):
        # file://\c:\path or file://\\path
        path = (netloc + path).replace('\\', '/')
        netloc = ''
        is_absolute = True
    elif scheme == 'file':
        # file:///path
        is_absolute = True
    elif RE_WIN_DRIVE_LETTER.match(scheme):
        # c:/path
        path = '/%s:%s' % (scheme, path.replace('\\', '/'))
        scheme = 'file'
        netloc = ''
        is_absolute = True
    elif scheme == '' and netloc != '' and url.startswith('//'):
        # //file/path
        path = '//' + netloc + path
        scheme = 'file'
        netloc = ''
        is_absolute = True
    elif scheme != '' and netloc != '':
        # A non-file path or strange URL
        is_url = True
    elif path.startswith(('/', '\\')):
        # /root path
        is_absolute = True

    return (scheme, netloc, path, params, query, fragment, is_url, is_absolute)


class PatSeqItem(namedtuple('PatSeqItem', ['pattern', 'builder', 'tags'])):
    """Pattern sequence item item."""


class PatternSequenceProcessor(InlineProcessor):
    """Processor for handling complex nested patterns such as strong and em matches."""

    PATTERNS = []

    def build_single(self, m, tag, idx):
        """Return single tag."""
        el1 = etree.Element(tag)
        text = m.group(2)
        self.parse_sub_patterns(text, el1, None, idx)
        return el1

    def build_double(self, m, tags, idx):
        """Return double tag."""

        tag1, tag2 = tags.split(",")
        el1 = etree.Element(tag1)
        el2 = etree.Element(tag2)
        text = m.group(2)
        self.parse_sub_patterns(text, el2, None, idx)
        el1.append(el2)
        if len(m.groups()) == 3:
            text = m.group(3)
            self.parse_sub_patterns(text, el1, el2, idx)
        return el1

    def build_double2(self, m, tags, idx):
        """Return double tags (variant 2): `<strong>text <em>text</em></strong>`."""

        tag1, tag2 = tags.split(",")
        el1 = etree.Element(tag1)
        el2 = etree.Element(tag2)
        text = m.group(2)
        self.parse_sub_patterns(text, el1, None, idx)
        text = m.group(3)
        el1.append(el2)
        self.parse_sub_patterns(text, el2, None, idx)
        return el1

    def parse_sub_patterns(self, data, parent, last, idx):
        """
        Parses sub patterns.

        `data` (`str`):
            text to evaluate.

        `parent` (`etree.Element`):
            Parent to attach text and sub elements to.

        `last` (`etree.Element`):
            Last appended child to parent. Can also be None if parent has no children.

        `idx` (`int`):
            Current pattern index that was used to evaluate the parent.

        """

        offset = 0
        pos = 0

        length = len(data)
        while pos < length:
            # Find the start of potential emphasis or strong tokens
            if self.compiled_re.match(data, pos):
                matched = False
                # See if the we can match an emphasis/strong pattern
                for index, item in enumerate(self.PATTERNS):
                    # Only evaluate patterns that are after what was used on the parent
                    if index <= idx:
                        continue
                    m = item.pattern.match(data, pos)
                    if m:
                        # Append child nodes to parent
                        # Text nodes should be appended to the last
                        # child if present, and if not, it should
                        # be added as the parent's text node.
                        text = data[offset:m.start(0)]
                        if text:
                            if last is not None:
                                last.tail = text
                            else:
                                parent.text = text
                        el = self.build_element(m, item.builder, item.tags, index)
                        parent.append(el)
                        last = el
                        # Move our position past the matched hunk
                        offset = pos = m.end(0)
                        matched = True
                if not matched:
                    # We matched nothing, move on to the next character
                    pos += 1
            else:
                # Increment position as no potential emphasis start was found.
                pos += 1

        # Append any leftover text as a text node.
        text = data[offset:]
        if text:
            if last is not None:
                last.tail = text
            else:
                parent.text = text

    def build_element(self, m, builder, tags, index):
        """Element builder."""

        if builder == 'double2':
            return self.build_double2(m, tags, index)
        elif builder == 'double':
            return self.build_double(m, tags, index)
        else:
            return self.build_single(m, tags, index)

    def handleMatch(self, m, data):
        """Parse patterns."""

        el = None
        start = None
        end = None

        for index, item in enumerate(self.PATTERNS):
            m1 = item.pattern.match(data, m.start(0))
            if m1:
                start = m1.start(0)
                end = m1.end(0)
                el = self.build_element(m1, item.builder, item.tags, index)
                break
        return el, start, end


def deprecated(message, stacklevel=2):  # pragma: no cover
    """
    Raise a `DeprecationWarning` when wrapped function/method is called.

    Usage:

        @deprecated("This method will be removed in version X; use Y instead.")
        def some_method()"
            pass
    """

    def _wrapper(func):
        @wraps(func)
        def _deprecated_func(*args, **kwargs):
            warnings.warn(
                f"'{func.__name__}' is deprecated. {message}",
                category=DeprecationWarning,
                stacklevel=stacklevel
            )
            return func(*args, **kwargs)
        return _deprecated_func
    return _wrapper


def warn_deprecated(message, stacklevel=2):  # pragma: no cover
    """Warn deprecated."""

    warnings.warn(
        message,
        category=DeprecationWarning,
        stacklevel=stacklevel
    )
