import sys
import warnings

from ... import mistune
from ...conversion import Converter


class Style:
    def __init__(self, display_name=None):
        if display_name:
            self.display_name = display_name
        else:
            self.display_name = ''

    def __repr__(self):
        s = ''
        for attribute in vars(self):
            if getattr(self, attribute) and attribute != 'display_name':
                s += f'{self.display_name}.{attribute}: {getattr(self, attribute)}\n'
        return s.replace('\n\n', '\n')


class FontStyle(Style):
    def __init__(self, display_name=None, color=None, size=None, bold=None, italic=None, name=None):
        super().__init__(display_name=display_name)
        self.color = color
        self.size = size
        self.bold = bold
        self.italic = italic
        self.name = name


class MarkdownStyle:
    """
    ``MarkdownStyle`` defines how ``Markdown`` objects are being rendered in Excel cells or shapes.
    Start by instantiating a ``MarkdownStyle`` object. Printing it will show you the current (default)
    style:

    >>> style = MarkdownStyle()
    >>> style
    <MarkdownStyle>
    h1.font: .bold: True
    h1.blank_lines_after: 1
    paragraph.blank_lines_after: 1
    unordered_list.bullet_character: •
    unordered_list.blank_lines_after: 1
    strong.bold: True
    emphasis.italic: True

    You can override the defaults, e.g., to make ``**strong**`` text red instead of bold, do this:

    >>> style.strong.bold = False
    >>> style.strong.color = (255, 0, 0)
    >>> style.strong
    strong.color: (255, 0, 0)

    .. versionadded:: 0.23.0
    """
    class __Heading1(Style):
        def __init__(self):
            super().__init__(display_name='h1')
            self.font = FontStyle(bold=True)
            self.blank_lines_after = 1

    class __Paragraph(Style):
        def __init__(self):
            super().__init__(display_name='paragraph')
            self.blank_lines_after = 1

    class __UnorderedList(Style):
        def __init__(self):
            super().__init__(display_name='unordered_list')
            self.bullet_character = '\u2022'
            self.blank_lines_after = 1

    def __init__(self):
        self.h1 = self.__Heading1()
        self.paragraph = self.__Paragraph()
        self.unordered_list = self.__UnorderedList()
        self.strong = FontStyle(display_name='strong', bold=True)
        self.emphasis = FontStyle(display_name='emphasis', italic=True)

    def __repr__(self):
        s = '<MarkdownStyle>\n'
        for attribute in vars(self):
            s += f'{getattr(self, attribute)}'
        return s


class Markdown:
    """
    Markdown objects can be assigned to a single cell or shape via ``myrange.value`` or ``myshape.text``.
    They accept a string in Markdown format which will cause the text in the cell to be formatted accordingly.
    They can also be used in ``mysheet.render_template()``.

    .. note:: On macOS, formatting is currently not supported, but things like bullet points will still work.

    Arguments
    ---------
    text : str
        The text in Markdown syntax

    style : MarkdownStyle object, optional
        The MarkdownStyle object defines how the text will be formatted.

    Examples
    --------

    >>> mysheet['A1'].value = Markdown("A text with *emphasis* and **strong** style.")
    >>> myshape.text = Markdown("A text with *emphasis* and **strong** style.")

    .. versionadded:: 0.23.0
    """
    def __init__(self, text, style=MarkdownStyle()):
        self.text = text
        self.style = style


class MarkdownConverter(Converter):

    @classmethod
    def write_value(cls, value, options):
        return render_text(value.text, value.style)


def traverse_ast_node(tree, data=None, level=0):
    data = {'length': [], 'type': [], 'parent_type': [],
            'text': [], 'parents': [], 'level': []} if data is None else data
    for element in tree:
        data['parents'] = data['parents'][:level]
        if 'children' in element:
            data['parents'].append(element)
            traverse_ast_node(element['children'], data, level=level + 1)
        else:
            data['level'].append(level)
            data['parent_type'].append([parent['type'] for parent in data['parents']])
            data['type'].append(element['type'])
            if element['type'] == 'text':
                data['length'].append(len(element['text']))
                data['text'].append(element['text'])
            elif element['type'] == 'linebreak':
                data['length'].append(1)
                data['text'].append('\n')
    return data


def flatten_ast(value):
    parse_ast = mistune.create_markdown(renderer=mistune.AstRenderer())
    ast = parse_ast(value)
    flat_ast = []
    for node in ast:
        rv = traverse_ast_node([node])
        del rv['parents']
        flat_ast.append(rv)
    return flat_ast


def render_text(text, style):
    flat_ast = flatten_ast(text)
    output = ''
    for node in flat_ast:
        # heading/list currently don't respect the level
        if 'heading' in node['parent_type'][0]:
            output += ''.join(node['text'])
            output += '\n' + style.h1.blank_lines_after * '\n'
        elif 'paragraph' in node['parent_type'][0]:
            output += ''.join(node['text'])
            output += '\n' + style.paragraph.blank_lines_after * '\n'
        elif 'list' in node['parent_type'][0]:
            for j in node['text']:
                output += f'{style.unordered_list.bullet_character} {j}\n'
            output += style.unordered_list.blank_lines_after * '\n'
    return output.rstrip('\n')


def format_text(parent, text, style):
    if sys.platform.startswith('darwin'):
        # Characters formatting is broken because of a bug in AppleScript/Excel 2016
        warnings.warn('Markdown formatting is currently ignored on macOS.')
        return
    flat_ast = flatten_ast(text)
    position = 0
    for node in flat_ast:
        if 'heading' in node['parent_type'][0]:
            node_length = sum(node['length']) + style.h1.blank_lines_after + 1
            apply_style_to_font(style.h1.font,
                                parent.characters[position:position + node_length].font)
        elif 'paragraph' in node['parent_type'][0]:
            node_length = sum(node['length']) + style.paragraph.blank_lines_after + 1
            intra_node_position = position
            for ix, j in enumerate(node['parent_type']):
                selection = slice(intra_node_position, intra_node_position + node['length'][ix])
                if 'strong' in j:
                    apply_style_to_font(style.strong, parent.characters[selection].font)
                elif 'emphasis' in j:
                    apply_style_to_font(style.emphasis, parent.characters[selection].font)
                intra_node_position += node['length'][ix]
        elif 'list' in node['parent_type'][0]:
            node_length = sum(node['length']) + style.unordered_list.blank_lines_after
            for _ in node['text']:
                # TODO: check ast level to allow nested **strong** etc.
                node_length += 3  # bullet, space and new line
        position += node_length


def apply_style_to_font(style_object, font_object):
    for attribute in vars(style_object):
        if getattr(style_object, attribute):
            setattr(font_object, attribute, getattr(style_object, attribute))
