"""Configured public email links, independent of request Host/forwarded headers."""
from urllib.parse import urlsplit
from ..runtime import get_runtime_settings
from ..installation_origin import managed_runtime


def valid_public_url(value):
    value = str(value or '').strip().rstrip('/')
    try:
        parsed = urlsplit(value)
        if (parsed.scheme in {'http', 'https'} and parsed.hostname
                and not (parsed.username or parsed.password or parsed.query or parsed.fragment)
                and (parsed.port is None or parsed.port > 0)
                and not any(c.isspace() or ord(c) < 33 or c in '<>"\\' for c in value)):
            return value
    except ValueError:
        pass
    return ''


def magent_public_url(legacy_url=''):
    runtime = get_runtime_settings()
    proxy = getattr(runtime, 'magent_proxy_base_url', None)
    application = getattr(runtime, 'magent_application_url', None)
    if managed_runtime():
        return valid_public_url(application)
    if getattr(runtime, 'magent_proxy_enabled', False) and str(proxy or '').strip():
        return valid_public_url(proxy)
    if str(application or '').strip():
        return valid_public_url(application)
    # Preserve pre-existing installations until Hosting & proxy has been configured.
    return valid_public_url(legacy_url)