2021-12-10-advent-calendar-2021-sample3.ts

// .msw/handler.ts
import { rest } from "msw";
import parsePreferHeader from "parse-prefer-header";
import { endpoints, OpenAPISpec } from "./openAPISpec";
import { OpenAPISpecTools } from "./openAPIUtils";

export function getHandlers(openAPISpec: OpenAPISpec) {
  const openAPISpecTools = new OpenAPISpecTools(openAPISpec);
  return endpoints
    .map((endpoint) => {
      return openAPISpecTools.getMethodsBy(endpoint).map((method) => {
        // mswとopenapiでpath parameterの指定方法が違うため置換している
        const requestPath = endpoint
          .replace(/{.*}/g, ":$&")
          .replace(/[{,}]/g, "");
        return rest.get(`${requestPath}`, (_req, res, ctx) => {
          const exampleNames =
            openAPISpecTools.getExampleNamesBy(endpoint)(method)("200");
          const exampleKind = exampleNames[0];
          if (exampleKind === undefined) {
            throw new Error("could not get example names");
          }

          const preference = _req.headers.get("Prefer")
            ? parsePreferHeader(_req.headers.get("Prefer"))
            : {
                code: "200",
                example: exampleKind,
              };

          if (preference.code === undefined) {
            preference.code = "200";
          }

          if (preference.code === "200") {
            if (typeof preference.example === "string") {
              if (
                openAPISpecTools.isValidExampleNameBy(endpoint)(method)(
                  preference.code
                )(preference.example)
              ) {
                return res(
                  ctx.json(
                    openAPISpecTools.getExampleBy(endpoint)(method)(
                      preference.code
                    )(preference.example)
                  )
                );
              }

              return res(
                ctx.json(
                  openAPISpecTools.getExampleBy(endpoint)(method)(
                    preference.code
                  )(exampleKind)
                )
              );
            }
          }

          // 以降、エラーハンドリングなどを記述

        });
      });
    })
    .flat();
}