graphql.ts

import * as Http from "@effect/platform/HttpClient"
import { Context, Effect, Layer, pipe } from "effect"

const headers = {
  Accept:
    "application/graphql-response+json; charset=utf-8, application/json; charset=utf-8",
  "Content-Type": "application/json",
}

export class GraphQLClient extends Context.Tag("graphql-codegen/GraphQLClient")<
  GraphQLClient,
  Http.client.Client<
    never,
    Http.error.HttpClientError | "missing",
    {
      readonly headers: Http.headers.Headers
      readonly body: any
    }
  >
>() {
  static fromDefaultClient(
    client: Http.client.Client.Default,
  ): Layer.Layer<GraphQLClient> {
    return Layer.succeed(
      GraphQLClient,
      pipe(
        client,
        Http.client.mapRequest(Http.request.setHeaders(headers)),
        Http.client.filterStatusOk,
        Http.client.mapEffectScoped((res) =>
          Effect.flatMap(res.json, (_) => {
            const body = _ as any
            return body.data
              ? Effect.succeed(body.data)
              : Effect.fail("missing" as const)
          }),
        ),
      ),
    )
  }

  static Live: Layer.Layer<GraphQLClient, never, Http.client.Client.Default> =
    Layer.unwrapEffect(
      Effect.map(Http.client.Client, GraphQLClient.fromDefaultClient),
    )

  static fromEndpoint(
    endpoint: string,
  ): Layer.Layer<GraphQLClient, never, Http.client.Client.Default> {
    return Layer.unwrapEffect(
      Effect.map(Http.client.Client, (client) =>
        GraphQLClient.fromDefaultClient(
          Http.client.mapRequest(client, Http.request.prependUrl(endpoint)),
        ),
      ),
    )
  }
}

const endpoint = ({ query, operationName, variables }: any) =>
  Effect.flatMap(GraphQLClient, (client) =>
    pipe(
      Http.request.post(""),
      Http.request.jsonBody({
        query,
        operationName,
        variables,
      }),
      Effect.flatMap(client),
    ),
  )

endpoint({}).pipe(
  Effect.provide(
    GraphQLClient.fromEndpoint("https://api.github.com/graphql").pipe(
      Layer.provide(Http.client.layer),
    ),
  ),
)