"""Markdown filters with mistune

Used from markdown.py
"""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.


import base64
import mimetypes
import os
import re
from functools import partial
from html import escape

import bs4
from mistune import PLUGINS, BlockParser, HTMLRenderer, InlineParser, Markdown  # type:ignore
from pygments import highlight
from pygments.formatters import HtmlFormatter
from pygments.lexers import get_lexer_by_name
from pygments.util import ClassNotFound

from nbconvert.filters.strings import add_anchor

html_escape = partial(escape, quote=False)


class InvalidNotebook(Exception):  # noqa
    """An invalid notebook model."""

    pass


class MathBlockParser(BlockParser):
    """This acts as a pass-through to the MathInlineParser. It is needed in
    order to avoid other block level rules splitting math sections apart.
    """

    MULTILINE_MATH = re.compile(
        r"(?<!\\)[$]{2}.*?(?<!\\)[$]{2}|"
        r"\\\\\[.*?\\\\\]|"
        r"\\begin\{([a-z]*\*?)\}.*?\\end\{\1\}",
        re.DOTALL,
    )

    RULE_NAMES = ("multiline_math",) + BlockParser.RULE_NAMES

    # Regex for header that doesn't require space after '#'
    AXT_HEADING = re.compile(r" {0,3}(#{1,6})(?!#+)(?: *\n+|([^\n]*?)(?:\n+|\s+?#+\s*\n+))")

    def parse_multiline_math(self, m, state):
        """Pass token through mutiline math."""
        return {"type": "multiline_math", "text": m.group(0)}


def _dotall(pattern):
    """Make the '.' special character match any character inside the pattern, including a newline.

    This is implemented with the inline flag `(?s:...)` and is equivalent to using `re.DOTALL` when
    it is the only pattern used. It is necessary since `mistune>=2.0.0`, where the pattern is passed
    to the undocumented `re.Scanner`.
    """
    return f"(?s:{pattern})"


class MathInlineParser(InlineParser):
    r"""This interprets the content of LaTeX style math objects.

    In particular this grabs ``$$...$$``, ``\\[...\\]``, ``\\(...\\)``, ``$...$``,
    and ``\begin{foo}...\end{foo}`` styles for declaring mathematics. It strips
    delimiters from all these varieties, and extracts the type of environment
    in the last case (``foo`` in this example).
    """
    BLOCK_MATH_TEX = _dotall(r"(?<!\\)\$\$(.*?)(?<!\\)\$\$")
    BLOCK_MATH_LATEX = _dotall(r"(?<!\\)\\\\\[(.*?)(?<!\\)\\\\\]")
    INLINE_MATH_TEX = _dotall(r"(?<![$\\])\$(.+?)(?<![$\\])\$")
    INLINE_MATH_LATEX = _dotall(r"(?<!\\)\\\\\((.*?)(?<!\\)\\\\\)")
    LATEX_ENVIRONMENT = _dotall(r"\\begin\{([a-z]*\*?)\}(.*?)\\end\{\1\}")

    # The order is important here
    RULE_NAMES = (
        "block_math_tex",
        "block_math_latex",
        "inline_math_tex",
        "inline_math_latex",
        "latex_environment",
    ) + InlineParser.RULE_NAMES

    def parse_block_math_tex(self, m, state):
        """Parse block text math."""
        # sometimes the Scanner keeps the final '$$', so we use the
        # full matched string and remove the math markers
        text = m.group(0)[2:-2]
        return "block_math", text

    def parse_block_math_latex(self, m, state):
        """Parse block latex math ."""
        text = m.group(1)
        return "block_math", text

    def parse_inline_math_tex(self, m, state):
        """Parse inline tex math."""
        text = m.group(1)
        return "inline_math", text

    def parse_inline_math_latex(self, m, state):
        """Parse inline latex math."""
        text = m.group(1)
        return "inline_math", text

    def parse_latex_environment(self, m, state):
        """Parse a latex environment."""
        name, text = m.group(1), m.group(2)
        return "latex_environment", name, text


class MarkdownWithMath(Markdown):
    """Markdown text with math enabled."""

    def __init__(self, renderer, block=None, inline=None, plugins=None):
        """Initialize the parser."""
        if block is None:
            block = MathBlockParser()
        if inline is None:
            inline = MathInlineParser(renderer, hard_wrap=False)
        if plugins is None:
            plugins = [
                # "abbr",
                # 'footnotes',
                "strikethrough",
                "table",
                "url",
                "task_lists",
                "def_list",
            ]
            _plugins = []
            for p in plugins:
                if isinstance(p, str):
                    _plugins.append(PLUGINS[p])
                else:
                    _plugins.append(p)
            plugins = _plugins
        super().__init__(renderer, block, inline, plugins)

    def render(self, s):
        """Compatibility method with `mistune==0.8.4`."""
        return self.parse(s)


class IPythonRenderer(HTMLRenderer):
    """An ipython html renderer."""

    def __init__(
        self,
        escape=True,
        allow_harmful_protocols=True,
        embed_images=False,
        exclude_anchor_links=False,
        anchor_link_text="¶",
        path="",
        attachments=None,
    ):
        """Initialize the renderer."""
        super().__init__(escape, allow_harmful_protocols)
        self.embed_images = embed_images
        self.exclude_anchor_links = exclude_anchor_links
        self.anchor_link_text = anchor_link_text
        self.path = path
        if attachments is not None:
            self.attachments = attachments
        else:
            self.attachments = {}

    def block_code(self, code, info=None):
        """Handle block code."""
        lang = ""
        lexer = None
        if info:
            try:
                lang = info.strip().split(None, 1)[0]
                lexer = get_lexer_by_name(lang, stripall=True)
            except ClassNotFound:
                code = lang + "\n" + code
                lang = None  # type:ignore

        if not lang:
            return super().block_code(code)

        formatter = HtmlFormatter()
        return highlight(code, lexer, formatter)

    def block_html(self, html):
        """Handle block html."""
        if self.embed_images:
            html = self._html_embed_images(html)

        return super().block_html(html)

    def inline_html(self, html):
        """Handle inline html."""
        if self.embed_images:
            html = self._html_embed_images(html)

        return super().inline_html(html)

    def heading(self, text, level):
        """Handle a heading."""
        html = super().heading(text, level)
        if self.exclude_anchor_links:
            return html
        return add_anchor(html, anchor_link_text=self.anchor_link_text)

    def escape_html(self, text):
        """Escape html content."""
        return html_escape(text)

    def multiline_math(self, text):
        """Handle mulitline math."""
        return text

    def block_math(self, text):
        """Handle block math."""
        return f"$${self.escape_html(text)}$$"

    def latex_environment(self, name, text):
        """Handle a latex environment."""
        name, text = self.escape_html(name), self.escape_html(text)
        return f"\\begin{{{name}}}{text}\\end{{{name}}}"

    def inline_math(self, text):
        """Handle inline math."""
        return f"${self.escape_html(text)}$"

    def image(self, src, text, title):
        """Rendering a image with title and text.

        :param src: source link of the image.
        :param text: alt text of the image.
        :param title: title text of the image.
        """
        attachment_prefix = "attachment:"

        if src.startswith(attachment_prefix):
            name = src[len(attachment_prefix) :]

            if name not in self.attachments:
                raise InvalidNotebook(f"missing attachment: {name}")

            attachment = self.attachments[name]
            # we choose vector over raster, and lossless over lossy
            preferred_mime_types = ["image/svg+xml", "image/png", "image/jpeg"]
            for preferred_mime_type in preferred_mime_types:
                if preferred_mime_type in attachment:
                    break
            else:  # otherwise we choose the first mimetype we can find
                preferred_mime_type = list(attachment.keys())[0]
            mime_type = preferred_mime_type
            data = attachment[mime_type]
            src = "data:" + mime_type + ";base64," + data

        elif self.embed_images:
            base64_url = self._src_to_base64(src)

            if base64_url is not None:
                src = base64_url

        return super().image(src, text, title)

    def _src_to_base64(self, src):
        """Turn the source file into a base64 url.

        :param src: source link of the file.
        :return: the base64 url or None if the file was not found.
        """
        src_path = os.path.join(self.path, src)

        if not os.path.exists(src_path):
            return None

        with open(src_path, "rb") as fobj:
            mime_type = mimetypes.guess_type(src_path)[0]

            base64_data = base64.b64encode(fobj.read())
            base64_str = base64_data.replace(b"\n", b"").decode("ascii")

            return f"data:{mime_type};base64,{base64_str}"

    def _html_embed_images(self, html):
        parsed_html = bs4.BeautifulSoup(html, features="html.parser")
        imgs = parsed_html.find_all("img")

        # Replace img tags's sources by base64 dataurls
        for img in imgs:
            if "src" not in img.attrs:
                continue

            base64_url = self._src_to_base64(img.attrs["src"])

            if base64_url is not None:
                img.attrs["src"] = base64_url

        return str(parsed_html)


def markdown2html_mistune(source):
    """Convert a markdown string to HTML using mistune"""
    return MarkdownWithMath(renderer=IPythonRenderer(escape=False)).render(source)
