from llm_server import opts
from llm_server.cluster.redis_config_cache import RedisClusterStore
from llm_server.cluster.redis_cycle import add_backend_cycler, redis_cycle
from llm_server.cluster.stores import redis_running_models
from llm_server.routes.helpers.model import estimate_model_size

cluster_config = RedisClusterStore('cluster_config')


def get_backends():
    backends = cluster_config.all()
    result = {}
    for k, v in backends.items():
        b = cluster_config.get_backend(k)
        status = b.get('online', False)
        priority = b['priority']
        result[k] = {'status': status, 'priority': priority}

    if not opts.prioritize_by_size:
        online_backends = sorted(
            ((url, info) for url, info in backends.items() if info['online']),
            key=lambda kv: -kv[1]['priority'],
            reverse=True
        )
    else:
        online_backends = sorted(
            ((url, info) for url, info in backends.items() if info['online']),
            key=lambda kv: estimate_model_size(kv[1]['model_config']),
            reverse=True
        )
    offline_backends = sorted(
        ((url, info) for url, info in backends.items() if not info['online']),
        key=lambda kv: -kv[1]['priority'],
        reverse=True
    )
    return [url for url, info in online_backends], [url for url, info in offline_backends]


def get_a_cluster_backend(model=None):
    """
    Get a backend from Redis. If there are no online backends, return None.
    If `model` is not supplied, we will pick one ourself.
    """
    if model:
        # First, determine if there are multiple backends hosting the same model.
        backends_hosting_model = [i.decode('utf-8') for i in redis_running_models.smembers(model)]

        # If so, create an iterator for those backends
        if len(backends_hosting_model):
            add_backend_cycler(model, backends_hosting_model)
            cycled = redis_cycle(model)
            if len(cycled):
                return cycled[0]
        else:
            # No backend hosting that model
            return None
    else:
        online, _ = get_backends()
        if len(online):
            return online[0]