config.py

# app/config.py
import json
import os
from functools import lru_cache
from urllib.parse import quote

APPSETTINGS_PATH = os.environ.get("APPSETTINGS_JSON", "appsettings.json")

def _load_json(path):
    if not os.path.exists(path):
        return {}
    with open(path, "r", encoding="utf-8") as f:
        return json.load(f)

def _resolve_env_placeholders(data):
    """
    Recursively replace values that are ".env" with the matching environment variable.
    """
    if isinstance(data, dict):
        return {k: _resolve_env_placeholders(v) for k, v in data.items()}
    elif isinstance(data, list):
        return [_resolve_env_placeholders(v) for v in data]
    elif isinstance(data, str) and data.strip() == ".env":
        # Use the key name uppercased from parent call if available
        # This requires that parent dict was processed with context
        return None  # will be handled by the parent context
    return data

def _replace_env_vars(d, parent_key=None):
    """
    Same as _resolve_env_placeholders but knows the parent key for .env resolution.
    """
    if isinstance(d, dict):
        result = {}
        for k, v in d.items():
            result[k] = _replace_env_vars(v, k)
        return result
    elif isinstance(d, str) and d.strip() == ".env":
        env_key = parent_key.upper()
        return os.environ.get(env_key)
    else:
        return d

def build_amqp_url(cfg):
    local = cfg.get("LocalSystemUrl")
    if not local:
        return None
    scheme = "amqps" if local.get("UseTls", True) else "amqp"
    host = local.get("RabbitHostName")
    port = local.get("RabbitPort") or (5671 if scheme == "amqps" else 5672)
    user = local.get("RabbitUserName")
    pwd = local.get("RabbitPassword") or os.environ.get("RABBIT_PASSWORD")
    vhost = local.get("RabbitVHost") or "/"
    vhost_enc = quote(vhost, safe="")
    if not (host and user and pwd):
        return None
    return f"{scheme}://{user}:{pwd}@{host}:{port}/{vhost_enc}?heartbeat=30"

@lru_cache
def get_settings():
    cfg = _load_json(APPSETTINGS_PATH)
    cfg = _replace_env_vars(cfg)
    # If AMQP_URL is not directly set, build it
    if not cfg.get("AMQP_URL"):
        amqp_url = build_amqp_url(cfg)
        if amqp_url:
            cfg["AMQP_URL"] = amqp_url
    return cfg

settings = get_settings()