import re
from typing import Iterable, List, Match, NamedTuple, Optional, Tuple, Union

from .errors import MarkupError
from .style import Style
from .text import Span, Text
from ._emoji_replace import _emoji_replace


RE_TAGS = re.compile(
    r"""((\\*)\[([a-z#\/].*?)\])""",
    re.VERBOSE,
)


class Tag(NamedTuple):
    """A tag in console markup."""

    name: str
    """The tag name. e.g. 'bold'."""
    parameters: Optional[str]
    """Any additional parameters after the name."""

    def __str__(self) -> str:
        return (
            self.name if self.parameters is None else f"{self.name} {self.parameters}"
        )

    @property
    def markup(self) -> str:
        """Get the string representation of this tag."""
        return (
            f"[{self.name}]"
            if self.parameters is None
            else f"[{self.name}={self.parameters}]"
        )


def escape(markup: str, _escape=re.compile(r"(\\*)(\[[a-z#\/].*?\])").sub) -> str:
    """Escapes text so that it won't be interpreted as markup.

    Args:
        markup (str): Content to be inserted in to markup.

    Returns:
        str: Markup with square brackets escaped.
    """

    def escape_backslashes(match: Match[str]) -> str:
        """Called by re.sub replace matches."""
        backslashes, text = match.groups()
        return f"{backslashes}{backslashes}\\{text}"

    markup = _escape(escape_backslashes, markup)
    return markup


def _parse(markup: str) -> Iterable[Tuple[int, Optional[str], Optional[Tag]]]:
    """Parse markup in to an iterable of tuples of (position, text, tag).

    Args:
        markup (str): A string containing console markup

    """
    position = 0
    _divmod = divmod
    _Tag = Tag
    for match in RE_TAGS.finditer(markup):
        full_text, escapes, tag_text = match.groups()
        start, end = match.span()
        if start > position:
            yield start, markup[position:start], None
        if escapes:
            backslashes, escaped = _divmod(len(escapes), 2)
            if backslashes:
                # Literal backslashes
                yield start, "\\" * backslashes, None
                start += backslashes * 2
            if escaped:
                # Escape of tag
                yield start, full_text[len(escapes) :], None
                position = end
                continue
        text, equals, parameters = tag_text.partition("=")
        yield start, None, _Tag(text, parameters if equals else None)
        position = end
    if position < len(markup):
        yield position, markup[position:], None


def render(markup: str, style: Union[str, Style] = "", emoji: bool = True) -> Text:
    """Render console markup in to a Text instance.

    Args:
        markup (str): A string containing console markup.
        emoji (bool, optional): Also render emoji code. Defaults to True.

    Raises:
        MarkupError: If there is a syntax error in the markup.

    Returns:
        Text: A test instance.
    """
    emoji_replace = _emoji_replace
    if "[" not in markup:
        return Text(emoji_replace(markup) if emoji else markup, style=style)
    text = Text(style=style)
    append = text.append
    normalize = Style.normalize

    style_stack: List[Tuple[int, Tag]] = []
    pop = style_stack.pop

    spans: List[Span] = []
    append_span = spans.append

    _Span = Span
    _Tag = Tag

    def pop_style(style_name: str) -> Tuple[int, Tag]:
        """Pop tag matching given style name."""
        for index, (_, tag) in enumerate(reversed(style_stack), 1):
            if tag.name == style_name:
                return pop(-index)
        raise KeyError(style_name)

    for position, plain_text, tag in _parse(markup):
        if plain_text is not None:
            append(emoji_replace(plain_text) if emoji else plain_text)
        elif tag is not None:
            if tag.name.startswith("/"):  # Closing tag
                style_name = tag.name[1:].strip()
                if style_name:  # explicit close
                    style_name = normalize(style_name)
                    try:
                        start, open_tag = pop_style(style_name)
                    except KeyError:
                        raise MarkupError(
                            f"closing tag '{tag.markup}' at position {position} doesn't match any open tag"
                        ) from None
                else:  # implicit close
                    try:
                        start, open_tag = pop()
                    except IndexError:
                        raise MarkupError(
                            f"closing tag '[/]' at position {position} has nothing to close"
                        ) from None

                append_span(_Span(start, len(text), str(open_tag)))
            else:  # Opening tag
                normalized_tag = _Tag(normalize(tag.name), tag.parameters)
                style_stack.append((len(text), normalized_tag))

    text_length = len(text)
    while style_stack:
        start, tag = style_stack.pop()
        style = str(tag)
        if style:
            append_span(_Span(start, text_length, style))

    text.spans = sorted(spans)
    return text


if __name__ == "__main__":  # pragma: no cover

    from rich.console import Console
    from rich.text import Text

    console = Console(highlight=False)

    console.print("Hello [1], [1,2,3] ['hello']")
    console.print("foo")
    console.print("Hello [link=https://www.willmcgugan.com]W[b red]o[/]rld[/]!")

    from rich import print

    print(escape("[red]"))
    print(escape(r"\[red]"))
    print(escape(r"\\[red]"))
    print(escape(r"\\\[red]"))