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

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

logger = logging.getLogger(__name__)

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


@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)
    parent_navs = generate_parent_navs(resolved_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)
            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."""
    parent_dir = os.path.dirname(path)
    if parent_dir == 'pages':
        return [(app.config['TITLE_SUFFIX'], '/')]
    elif path.endswith('index.md'):
        # if we're on an index.md, don't link to ourselves as we're our own parent
        return generate_parent_navs(parent_dir)
    else:
        parent_path = f'{parent_dir}/'.replace('pages/', '/', 1)
        resolved_parent_path = resolve_page_file(parent_path)
        with app.open_instance_resource(resolved_parent_path, 'r') as entry_file:
            entry = entry_file.read()
        _ = Markup(md.convert(entry))
        parent_name = " ".join(md.Meta.get('title')) if md.Meta.get('title') else os.path.basename(parent_dir)
        return generate_parent_navs(parent_dir) + [(parent_name, parent_path)]