/*** IMPORT ------------------------------------------- ***/

import type { GraphQLArgs, GraphQLSchema } from "graphql";

/*** UTILITY ------------------------------------------ ***/

import type { RenderPageOptions } from "../graphiql/render.ts";

interface MutationParams {
  mutation: string;
  operationName?: string;
  query?: never;
  variables?: Record<string, unknown>;
}

interface QueryParams {
  mutation?: never;
  operationName?: string;
  query: string;
  variables?: Record<string, unknown>;
}

/*** EXPORT ------------------------------------------- ***/

/**
 * Configuration accepted by `GraphQLHTTP` and `runHttpQuery`.
 *
 * Extends `GraphQLArgs` from `graphql-js` minus `source` (supplied per request).
 */
export interface GQLOptions<Context, Req extends GQLRequest = GQLRequest> extends Omit<GraphQLArgs, "source"> {
  /** Builds the context value passed to resolvers. Runs per request. */
  context?: (val: Req) => Context | Promise<Context>;
  /** Serve the GraphQL Playground on `GET` + `Accept: text/html`. */
  graphiql?: boolean;
  /** Extra headers merged into every response. */
  headers?: HeadersInit;
  /** Passthrough options for the Playground renderer (minus `endpoint`). */
  playgroundOptions?: Omit<RenderPageOptions, "endpoint">;
  /** The executable schema to query against. */
  schema: GraphQLSchema;
}

/** A single GraphQL operation — either a `query` or a `mutation`, never both. */
export type GraphQLParams = QueryParams | MutationParams;

/** Minimal Fetch-shaped request accepted by the HTTP handler. */
export type GQLRequest = {
  headers: Headers;
  json: () => Promise<GraphQLParams>;
  method: string;
  url: string;
};