import dataclasses
import datetime
import os
import logging
import pathlib
import glob
import typing
import markdown
import yaml
import markupsafe
import subprocess

logger = logging.getLogger(__name__)


# Known exceptions, these are raised when generating on program exiting error, and are displayed to the user nicely
class ArticleHandlerException(Exception):
    pass


class ArticleMetaDataMalformed(ArticleHandlerException):
    pass


class ArticleNoMetaData(ArticleHandlerException):
    pass


@dataclasses.dataclass
class WebPage:
    url: str
    name: str


@dataclasses.dataclass
class MetaData():
    description: str
    created: datetime.date

    @property
    def pretty_print(self) -> str:
        return f'''
    Description: {self.description}
    Created: {self.created}'''


def truncate(text: str, max_length: int = 50):
    if len(text) < max_length:
        return text
    else:
        return text[0:max_length - 1]


@dataclasses.dataclass
class Article(WebPage):
    metadata: MetaData  # date, description
    web_dir: tuple  # Url path of the article, folder agnostic, removes .md
    source_path: str  # Path to the markdown source file
    git_path: str  # This is the top most path e.g. /article.md for single file articles, and /Article folder for folder
    source: str    # Source markdown, without the metadata
    html: str      # The generated HTML output
    modified: datetime.datetime  # Article last modification date
    thumbnail_path: typing.Union[None, str] = None  # Path to the thumbnail image to display in folder view, e.g. /
    folder_path: typing.Union[None, str] = None  # Path to the folder path to the article folder, if applicable

    @property
    def pretty_print(self) -> str:
        return f'''
Name:           {self.name}
Metadata:       {self.metadata.pretty_print}
Web dir:        {self.web_dir}
URL:            {self.url}
Source path:    {self.source_path}
Git path:       {self.git_path}
Thumbnail path: {self.thumbnail_path}
Folder path:    {self.folder_path}
Modified:       {self.modified}
HTML:           {truncate(self.html)}
Source:         {truncate(self.source)}'''


@dataclasses.dataclass
class Folder(WebPage):
    articles: typing.List[Article] = dataclasses.field(default_factory=list)
    sub_folders: typing.Dict[str, object] = dataclasses.field(default_factory=dict)


class ArticleGenerator:
    def __init__(self, articles_path: str):
        self.articles_path = articles_path

    def get_web_dir(self, path, name) -> tuple[str, ...]:
        dir = path.split(name)[0]  # Get dir for one file articles and folder articles
        web_path = pathlib.Path(dir).relative_to(pathlib.Path(self.articles_path))
        return web_path.parts

    def parse_article_meta_data(self, source: str) -> typing.Tuple[str, MetaData]:
        if source.startswith('---'):
            meta_data_yml_end_char_index = source.find('---', 3)
            meta_data_yml = source[3:meta_data_yml_end_char_index]
            # Strip metadata text from source, before feeding it to the markdown reader
            source = source[meta_data_yml_end_char_index + 3:]
            meta_data = yaml.safe_load(meta_data_yml)
            meta_data['description'] = markupsafe.Markup(markdown.markdown(meta_data['description']))

            try:
                meta_data = MetaData(**meta_data)
            except TypeError as type_error_exception:
                raise ArticleMetaDataMalformed(str(type_error_exception))
            return source, meta_data
        else:
            raise ArticleNoMetaData(f'No metadata found')

    def get_article(self, path: str) -> Article:
        logger.info(path)
        article_args = {}
        filename, file_extension = os.path.splitext(path)

        basename = os.path.basename(filename)
        if basename == 'index':
            # Article type is folder
            article_folder_name = os.path.dirname(path)
            article_args['folder_path'] = article_folder_name
            dir_basename = os.path.basename(article_folder_name)
            article_args['name'] = dir_basename

            # Look for a thumbnail (file extension agnostic)
            thumbnail_paths = glob.glob(f'{article_args["folder_path"]}/Thumbnail*')

            if len(thumbnail_paths) > 1:
                logger.warning(f"More than one thumbnail found, using: {thumbnail_paths[0]}")

            if len(thumbnail_paths) == 0:
                logger.warning("No thumbnail image")
            else:
                article_args['thumbnail_path'] = '/'.join(pathlib.Path(thumbnail_paths[0]).parts[-2:])
            article_args['git_path'] = article_args['folder_path']
        else:
            # Article is one file
            article_args['name'] = os.path.basename(filename)
            article_args['git_path'] = path
        article_args['web_dir'] = self.get_web_dir(path, article_args['name'])
        article_args['source_path'] = path

        article_args[
            'url'] = f'{"/" if article_args["web_dir"] else ""}{"/".join(article_args["web_dir"])}/{article_args["name"]}'

        try:
            git_date = subprocess.run(['git', 'log', '-1', '--pretty=format:%ci', pathlib.Path(article_args['git_path']) \
                    .relative_to(self.articles_path)], cwd=self.articles_path, capture_output=True, text=True).stdout
        except FileNotFoundError:
            logger.warning('"git" isn\'t installed, modified dates will use file system (worse data)')
            git_date = ''
        if git_date == '':
            logger.warning("Article folder is not a git directory, modified dates will use file system (worse data)")
            # Get article modified date time from file system
            article_args['modified'] = datetime.datetime.utcfromtimestamp(os.path.getmtime(path)) \
                    .replace(tzinfo=datetime.datetime.now().astimezone().tzinfo)
        else:
            # Get article modified date time from git commit
            article_args['modified'] = datetime.datetime.fromisoformat(git_date)


        with open(path, 'r') as file:
            source = file.read()
        article_args['source'], article_args['metadata'] = self.parse_article_meta_data(source)
        article_args['html'] = markdown.markdown(article_args['source'], extensions=
        [
            'fenced_code',
            'codehilite',
            'tables',
            'toc'  # Automatically generates unique IDs for headers allowing for ID URL referral (Anchor)
        ])

        article = Article(**article_args)
        return article

    def discover_folder_structure(self, article: Article, articles: Folder):
        previous_folder = articles
        for folder_name in article.web_dir:
            logger.debug(folder_name)

            if folder_name not in previous_folder.sub_folders:
                logger.debug('new')
                current_folder = Folder(url=f'{previous_folder.url}{folder_name}/', name=folder_name)
                previous_folder.sub_folders[folder_name] = current_folder
            else:
                logger.debug('reuse')
                current_folder = previous_folder.sub_folders[folder_name]
            previous_folder = current_folder
            logger.debug('')

        previous_folder.articles.append(article)

    def sort_articles(self, folder: Folder):
        folder.articles = sorted(folder.articles,
                                 key=lambda
                                     x: x.metadata.created if x.metadata.created is not None else datetime.date.min,
                                 reverse=True)
        for folder in folder.sub_folders.values():
            self.sort_articles(folder)

    def discover_articles(self):
        articles_paths = glob.glob(f'{self.articles_path}/**/*.md', recursive=True)  # Equivalent to ls ./**.md
        articles = Folder(url='/', name='index')
        for article_path in articles_paths:
            article = self.get_article(article_path)
            logger.debug(article.pretty_print)
            self.discover_folder_structure(article=article, articles=articles)
        self.sort_articles(articles)
        return articles