# schema_utils.py
from typing import Dict, Set
from schema_map import schema

def fieldset_for(collection: str) -> Set[str]:
    col = schema.get(collection, {})
    fields = {k for k in col.keys() if not k.startswith("$")}
    # expand nested alias target names too
    aliases = col.get("$aliases", {}) or {}
    fields |= set(aliases.values())
    return fields

def alias_map_for(collection: str) -> Dict[str, str]:
    col = schema.get(collection, {})
    return col.get("$aliases", {}) or {}

def resolve_field(collection: str, field: str) -> str:
    """Return the canonical field name (apply alias if present)."""
    aliases = alias_map_for(collection)
    return aliases.get(field, field)

def has_field(collection: str, field: str) -> bool:
    return resolve_field(collection, field) in fieldset_for(collection)