import hashlib
import os

from flask import request



def get_file_hash(filepath: str) -> str:
    with open(filepath, 'rb') as file_handle:
        return hashlib.md5(file_handle.read()).hexdigest()[:8]



def register_asset_helpers(app):
    @app.context_processor
    def inject_static_hash():
        def static_hash(filename: str) -> str:
            filepath = os.path.join(app.static_folder, filename)
            file_hash = get_file_hash(filepath)
            return f'/static/{filename}?v={file_hash}'
        return dict(static_hash=static_hash)

    @app.after_request
    def add_header(response):
        if request.path.startswith('/static/'):
            response.cache_control.no_cache = None
            response.cache_control.no_store = None
            response.cache_control.max_age = 31536000
            response.cache_control.public = True
            response.headers.pop('Content-Disposition', None)
        else:
            response.cache_control.no_cache = True
            response.cache_control.no_store = True
        return response

    @app.context_processor
    def inject_config():
        def get_base_url() -> str:
            scheme = request.headers.get('X-Forwarded-Proto', request.scheme)
            host = request.headers.get('X-Forwarded-Host', request.host)
            return f'{scheme}://{host}'
        return dict(base_url=get_base_url, request=request)