from article import Article, Site
from dataclasses import dataclass
from io import TextIOWrapper
from jinja2 import Environment, Template, FileSystemLoader, select_autoescape
from json import loads
from os.path import join

TEMPLATE_VERSIONS = [1]

@dataclass
class TemplateConfig:
    version: int
    name: str
    articles_per_page: int

    @staticmethod
    def from_open_file(file: TextIOWrapper) -> "TemplateConfig":
        content = file.read()
        data = loads(content)

        if data['version'] not in TEMPLATE_VERSIONS: 
            raise ValueError('Template version' + data['version'] + ' is not compatible. ' + # TODO right exception?
                             'Supported versions: ' + ', '.join(str(i) for i in TEMPLATE_VERSIONS))

        return TemplateConfig(**data)

class TemplateEnvironment:
    environment: Environment
    config: TemplateConfig
    site: Site
    article_template: Template
    index_template: Template
    
    def __init__(self, template_directory: str, site: Site):
        self.environment = Environment(
            loader = FileSystemLoader(template_directory, followlinks=True),
            autoescape = select_autoescape()
        )
        
        self.site = site
        self.article_template = self.environment.get_template('article_template.html')
        self.index_template = self.environment.get_template('index.html')

        self.__load_config(template_directory)

    def __load_config(self, template_directory: str):
        fn = join(template_directory, 'template.json')
        file = open(fn)
        self.config = TemplateConfig.from_open_file(file)
        file.close()

    def process_article(self, article: Article) -> str:
        return self.article_template.render(
            site = self.site,
            article = article
        )
    
    def process_index(self, *articles: Article) -> str:
        return self.index_template.render(
                site = self.site,
                articles = articles
            )