import { assertValidSchema, lexicographicSortSchema } from "graphql";
import { ListrTask } from "listr";
import { Config } from "../config";
import { GraphQLFileLoader } from "@graphql-tools/graphql-file-loader";
import { fetchSchema } from "../schema/fetchSchema";
import { loadSchema } from "@graphql-tools/load";

export function schemaTask(config: Config): ListrTask {
  const processSchema = (schema) => {
    if (config.sortProperties) {
      return lexicographicSortSchema(schema);
    }
    return schema;
  };

  if (config.endpoint) {
    const endpoint = config.endpoint;
    return {
      title: `fetching schema using ${config.useGet ? "GET" : "POST"} ${endpoint} and headers ${JSON.stringify(
        config.headers
      )}`,
      task: async (ctx) => {
        ctx.schema = processSchema(
          await fetchSchema({
            endpoint,
            usePost: !config.useGet,
            headers: config.headers,
          })
        );
      },
    };
  } else if (config.schema) {
    const schema = config.schema;
    return {
      title: "loading schema",
      task: async (ctx) => {
        // const options = config.options && config.options.schemaBuild
        const document = await loadSchema(schema, {
          loaders: [new GraphQLFileLoader()],
        });
        ctx.schema = processSchema(document);

        try {
          assertValidSchema(ctx.schema);
        } catch (e: any) {
          if (e.message === "Query root type must be provided.") return;
          throw e;
        }
      },
    };
  } else {
    throw new Error("either `endpoint`, `fetcher` or `schema` must be defined in the config");
  }
}