"""Parse the slot v2 the Orchestrator writes to Redis (contract C1, SIENTIAPDE-1974).

Each server carries its connection (`url`, `subscription_period_ms`), its OPC security
(`security`: mode + policy) and its client certificate (`certificate`: certificate_id,
application_uri and the MinIO objects of the cert and the private key; None = connect
without security, D5). Each tag carries `names`: one entry per collection / tag name /
model the reading is written to.
"""

SERVER_FIELDS = ('server_id', 'url', 'subscription_period_ms', 'security', 'certificate')
# What a connection/subscription needs (the pool keys clients by server_id itself).
CONNECTION_FIELDS = tuple(f for f in SERVER_FIELDS if f != 'server_id')
NAME_FIELDS = ('collection', 'tag_name', 'model_id')


def _parse_names(address: str, tag: dict) -> list[dict]:
    names = tag.get('names')
    if not names:
        raise ValueError(f'tag {address!r} has no names')
    for name in names:
        missing = [field for field in NAME_FIELDS if field not in name]
        if missing:
            raise ValueError(f'tag {address!r} has a name without {missing}')
    return names


def _parse_tag(address: str, tag: dict) -> dict:
    return {
        'frequency': tag['frequency'],
        'names': _parse_names(address, tag),
        'active_read': tag.get('active_read', {'enabled': False}),
    }


def _parse_server(name: str, server: dict) -> dict:
    if not isinstance(server.get('security'), dict):
        raise ValueError(f'server {name!r} has no security')
    parsed = {field: server.get(field) for field in SERVER_FIELDS}
    parsed['name'] = server.get('name', name)
    parsed['tags'] = {addr: _parse_tag(addr, tag) for addr, tag in server['tags'].items()}
    return parsed


def parse_slot(raw: dict) -> dict:
    """Normalize a raw slot v2 into `{server_name: {..., tags: {addr: tag}}}`.

    Raises:
        KeyError | TypeError | ValueError: When the slot is not a valid slot v2 (e.g. a
            slot v1 with `topics`).
    """
    return {name: _parse_server(name, server) for name, server in raw.items()}