"""General page functionality."""
import datetime
import logging
import os

import markdown
from flask import Blueprint, Markup, abort
from flask import current_app as app
from flask import render_template
from tzlocal import get_localzone

logger = logging.getLogger(__name__)

bp = Blueprint('pages', __name__, url_prefix='/')
md = markdown.Markdown(extensions=['meta', 'tables'])


@bp.route('/', defaults={'path': 'index'})
@bp.route('/<path:path>')
def display_page(path):
    """Get the file contents of the requested path and render the file."""
    resolved_path = resolve_page_file(path)
    logger.debug("received request for path '%s', resolved to '%s'", path, resolved_path)
    try:
        with app.open_instance_resource(resolved_path, 'r') as entry_file:
            logger.debug("file '%s' found", resolved_path)
            parent_navs = generate_parent_navs(path)
            mtime = datetime.datetime.fromtimestamp(os.path.getmtime(entry_file.name), get_localzone())
            entry = entry_file.read()
    except FileNotFoundError:
        logger.warning("requested path '%s' (resolved path '%s') not found!", path, resolved_path)
        abort(404)
    else:
        content = Markup(md.convert(entry))
        logger.debug("file metadata: %s", md.Meta)
        title = " ".join(md.Meta.get('title')) if md.Meta.get('title') else ""
        return render_template('base.html', title=title, content=content, navs=parent_navs,
                               mtime=mtime.strftime('%Y-%m-%d %H:%M:%S %Z'))


def resolve_page_file(path):
    """Manipulate the request path to find appropriate page file.

    * convert dir requests to index files

    Worth noting, Flask already does stuff like convert '/foo/../../../bar' to
    '/bar', so we don't need to take care around file access here.
    """
    if path.endswith('/'):
        path = f'{path}index'
    path = f'pages/{path}.md'
    return path


def generate_parent_navs(path):
    """Create a series of paths/links to navigate up from the given path."""
    # derive additional path/location stuff based on path
    resolved_path = resolve_page_file(path)
    parent_dir = os.path.dirname(resolved_path)
    parent_path = '/'.join(path[:-1].split('/')[:-1]) + '/'

    logger.debug("path: '%s'; parent path: '%s'; resolved path: '%s'; parent dir: '%s'",
                 path, parent_path, resolved_path, parent_dir)

    if path in ('index', '/'):
        return [(app.config['TITLE_SUFFIX'], '/')]
    else:
        with app.open_instance_resource(resolved_path, 'r') as entry_file:
            entry = entry_file.read()
        _ = Markup(md.convert(entry))
        page_name = " ".join(md.Meta.get('title')) if md.Meta.get('title') else f'/{path}'
        return generate_parent_navs(parent_path) + [(page_name, f'/{path}')]