"""GraphQL-core based schema parser.

Uses graphql-core's parse() to extract queries, mutations, and object types from SDL strings.
"""

from graphql import parse
from graphql.language.ast import (
    ObjectTypeDefinitionNode,
    ObjectTypeExtensionNode,
)

SKIP_TYPES = {'Subscription'}


def parse_sdl(sdl: str) -> tuple[set[str], set[str], dict[str, set[str]]]:
    """Parse an SDL string and extract queries, mutations, and object types.

    Returns:
        queries:   set of field names on type Query
        mutations: set of field names on type Mutation
        objects:   {typeName: set(fieldNames)} for object types (excluding Query/Mutation/interfaces)
    """
    queries: set[str] = set()
    mutations: set[str] = set()
    objects: dict[str, set[str]] = {}

    document = parse(sdl)

    for definition in document.definitions:
        if not isinstance(definition, (ObjectTypeDefinitionNode, ObjectTypeExtensionNode)):
            continue

        type_name = definition.name.value
        if type_name.startswith('_') or type_name in SKIP_TYPES:
            continue

        field_names = set()
        for field in definition.fields or []:
            name = field.name.value
            if not name.startswith('_'):
                field_names.add(name)

        if type_name == 'Query':
            queries.update(field_names)
        elif type_name == 'Mutation':
            mutations.update(field_names)
        else:
            if type_name not in objects:
                objects[type_name] = set()
            objects[type_name].update(field_names)

    return queries, mutations, objects