import Maybe from "../tsutils/Maybe";
import { GraphQLObjectType } from "./definition";
import { GraphQLType, GraphQLNamedType, GraphQLAbstractType } from "./definition";
import { SchemaDefinitionNode, SchemaExtensionNode } from "../language/ast";
import { GraphQLDirective } from "./directives";

/**
 * Test if the given value is a GraphQL schema.
 */
export function isSchema(schema: any): schema is GraphQLSchema;

/**
 * Schema Definition
 *
 * A Schema is created by supplying the root types of each type of operation,
 * query and mutation (optional). A schema definition is then supplied to the
 * validator and executor.
 *
 * Example:
 *
 *     const MyAppSchema = new GraphQLSchema({
 *       query: MyAppQueryRootType,
 *       mutation: MyAppMutationRootType,
 *     })
 *
 * Note: If an array of `directives` are provided to GraphQLSchema, that will be
 * the exact list of directives represented and allowed. If `directives` is not
 * provided then a default set of the specified directives (e.g. @include and
 * @skip) will be used. If you wish to provide *additional* directives to these
 * specified directives, you must explicitly declare them. Example:
 *
 *     const MyAppSchema = new GraphQLSchema({
 *       ...
 *       directives: specifiedDirectives.concat([ myCustomDirective ]),
 *     })
 *
 */
export class GraphQLSchema {
    astNode: Maybe<SchemaDefinitionNode>;
    extensionASTNodes: Maybe<ReadonlyArray<SchemaExtensionNode>>;

    constructor(config: GraphQLSchemaConfig);

    getQueryType(): Maybe<GraphQLObjectType>;
    getMutationType(): Maybe<GraphQLObjectType>;
    getSubscriptionType(): Maybe<GraphQLObjectType>;
    getTypeMap(): TypeMap;
    getType(name: string): Maybe<GraphQLNamedType>;
    getPossibleTypes(abstractType: GraphQLAbstractType): ReadonlyArray<GraphQLObjectType>;

    isPossibleType(abstractType: GraphQLAbstractType, possibleType: GraphQLObjectType): boolean;

    getDirectives(): ReadonlyArray<GraphQLDirective>;
    getDirective(name: string): Maybe<GraphQLDirective>;
}

type TypeMap = { [key: string]: GraphQLNamedType };

export interface GraphQLSchemaValidationOptions {
    /**
     * When building a schema from a GraphQL service's introspection result, it
     * might be safe to assume the schema is valid. Set to true to assume the
     * produced schema is valid.
     *
     * Default: false
     */
    assumeValid?: boolean;

    /**
     * If provided, the schema will consider fields or types with names included
     * in this list valid, even if they do not adhere to the specification's
     * schema validation rules.
     *
     * This option is provided to ease adoption and will be removed in v15.
     */
    allowedLegacyNames?: Maybe<ReadonlyArray<string>>;
}

export interface GraphQLSchemaConfig extends GraphQLSchemaValidationOptions {
    query: Maybe<GraphQLObjectType>;
    mutation?: Maybe<GraphQLObjectType>;
    subscription?: Maybe<GraphQLObjectType>;
    types?: Maybe<GraphQLNamedType[]>;
    directives?: Maybe<GraphQLDirective[]>;
    astNode?: Maybe<SchemaDefinitionNode>;
    extensionASTNodes?: Maybe<ReadonlyArray<SchemaExtensionNode>>;
}