missing wrappers file

packages/nextlove/src/wrappers.ts

@@ -0,0 +1,379 @@
+// import type { NextRequest as Req } from "next/server"
+/*
+
+Wraps a function in layers of other functions, while preserving the input/output
+type. The output of wrappers will always have the type of it's last parameter
+(the wrapped function)
+
+This function turns this type of composition...
+
+logger.withContext("somecontext")(
+  async (a, b) => {
+    return a
+  }
+)
+
+Into...
+
+wrappers(
+  logger.withContext("somecontext"),
+  async (a, b) => {
+    return a
+  }
+)
+
+Having this as a utility method helps preserve types, which otherwise can get
+messed up by the middlewares. It also can make the code cleaner where there are
+multiple wrappers.
+
+## EXAMPLES
+
+In the context of request middleware you might write something like this...
+
+const withRequestLoggingMiddleware = (next) => async (req, res) => {
+  console.log(`GOT REQUEST ${req.method} ${req.path}`)
+  return next(req, res)
+}
+
+Here's an example of a wrapper that takes some parameters...
+
+const withLoggedArguments =
+    (logPrefix: string) =>
+    (next) =>
+    async (...funcArgs) => {
+      console.log(logPrefix, ...funcArgs)
+      return next(...funcArgs)
+    }
+
+*/
+
+export type Middleware<Req, Res, T, Dep = {}> = (
+  next: (req: Req & Dep & T, res: Res) => any
+) => (req: Req & Dep & T, res: Res) => any
+
+// Safer Middleware requires the use of extendRequest to ensure that the
+// new context (T) was actually added to the request. It's kind of annoying
+// to use in practice, so we don't use it for our Wrappers (yet)
+export type SaferMiddlewareEgde<Req, Res, T, Dep = {}> = (
+  next: (req: Req & Dep & T, res: Res) => any
+) => (req: Req & Dep, res: Res) => any
+
+export const extendRequest = <
+  Req,
+  Res,
+  T extends Req,
+  K extends ArrayLike<unknown>
+>(
+  req: T,
+  merge: K
+): T & K => {
+  for (const [key, v] of Object.entries(merge)) {
+    ;(req as any)[key] = v
+  }
+  return req as any
+}
+
+type Wrappers1 = <Req, Res, Mw1RequestContext, Mw1Dep>(
+  mw1: Middleware<Req, Res, Mw1RequestContext, Mw1Dep>,
+  endpoint: (req: Req & Mw1RequestContext, res: Res) => any
+) => (req: Req, res: Res) => any
+
+type Wrappers2 = <
+  Req,
+  Res,
+  Mw1RequestContext extends Mw2Dep,
+  Mw1Dep,
+  Mw2RequestContext,
+  Mw2Dep
+>(
+  mw1: Middleware<Req, Res, Mw1RequestContext, Mw1Dep>,
+  mw2: Middleware<Req, Res, Mw2RequestContext, Mw2Dep>,
+  endpoint: (req: Req & Mw1RequestContext & Mw2RequestContext, res: Res) => any
+) => (req: Req, res: Res) => any
+
+// TODO figure out how to do a recursive definition, or one that simplifies
+// these redundant Wrappers
+
+type Wrappers3 = <
+  Req,
+  Res,
+  Mw1RequestContext extends Mw2Dep,
+  Mw1Dep,
+  Mw2RequestContext,
+  Mw2Dep,
+  Mw3RequestContext,
+  Mw3Dep
+>(
+  mw1: Middleware<Req, Res, Mw1RequestContext, Mw1Dep>,
+  mw2: Middleware<Req, Res, Mw2RequestContext, Mw2Dep>,
+  mw3: Middleware<
+    Req,
+    Res,
+    Mw3RequestContext,
+    Mw1RequestContext & Mw2RequestContext extends Mw3Dep ? Mw3Dep : never
+  >,
+  endpoint: (
+    req: Req & Mw1RequestContext & Mw2RequestContext & Mw3RequestContext,
+    res: Res
+  ) => any
+) => (req: Req, res: Res) => any
+
+type Wrappers4 = <
+  Req,
+  Res,
+  Mw1RequestContext extends Mw2Dep,
+  Mw1Dep,
+  Mw2RequestContext,
+  Mw2Dep,
+  Mw3RequestContext,
+  Mw3Dep,
+  Mw4RequestContext,
+  Mw4Dep
+>(
+  mw1: Middleware<Req, Res, Mw1RequestContext, Mw1Dep>,
+  mw2: Middleware<Req, Res, Mw2RequestContext, Mw2Dep>,
+  mw3: Middleware<
+    Req,
+    Res,
+    Mw3RequestContext,
+    Mw1RequestContext & Mw2RequestContext extends Mw3Dep ? Mw3Dep : never
+  >,
+  mw4: Middleware<
+    Req,
+    Res,
+    Mw4RequestContext,
+    Mw1RequestContext & Mw2RequestContext & Mw3RequestContext extends Mw4Dep
+      ? Mw4Dep
+      : never
+  >,
+  endpoint: (
+    req: Req &
+      Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext,
+    res: Res
+  ) => any
+) => (req: Req, res: Res) => any
+
+type Wrappers5 = <
+  Req,
+  Res,
+  Mw1RequestContext extends Mw2Dep,
+  Mw1Dep,
+  Mw2RequestContext,
+  Mw2Dep,
+  Mw3RequestContext,
+  Mw3Dep,
+  Mw4RequestContext,
+  Mw4Dep,
+  Mw5RequestContext,
+  Mw5Dep
+>(
+  mw1: Middleware<Req, Res, Mw1RequestContext, Mw1Dep>,
+  mw2: Middleware<Req, Res, Mw2RequestContext, Mw2Dep>,
+  mw3: Middleware<
+    Req,
+    Res,
+    Mw3RequestContext,
+    Mw1RequestContext & Mw2RequestContext extends Mw3Dep ? Mw3Dep : never
+  >,
+  mw4: Middleware<
+    Req,
+    Res,
+    Mw4RequestContext,
+    Mw1RequestContext & Mw2RequestContext & Mw3RequestContext extends Mw4Dep
+      ? Mw4Dep
+      : never
+  >,
+  mw5: Middleware<
+    Req,
+    Res,
+    Mw5RequestContext,
+    Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext extends Mw5Dep
+      ? Mw5Dep
+      : never
+  >,
+  endpoint: (
+    req: Req &
+      Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext &
+      Mw5RequestContext,
+    res: Res
+  ) => any
+) => (req: Req, res: Res) => any
+
+type Wrappers6 = <
+  Req,
+  Res,
+  Mw1RequestContext extends Mw2Dep,
+  Mw1Dep,
+  Mw2RequestContext,
+  Mw2Dep,
+  Mw3RequestContext,
+  Mw3Dep,
+  Mw4RequestContext,
+  Mw4Dep,
+  Mw5RequestContext,
+  Mw5Dep,
+  Mw6RequestContext,
+  Mw6Dep
+>(
+  mw1: Middleware<Req, Res, Mw1RequestContext, Mw1Dep>,
+  mw2: Middleware<Req, Res, Mw2RequestContext, Mw2Dep>,
+  mw3: Middleware<
+    Req,
+    Res,
+    Mw3RequestContext,
+    Mw1RequestContext & Mw2RequestContext extends Mw3Dep ? Mw3Dep : never
+  >,
+  mw4: Middleware<
+    Req,
+    Res,
+    Mw4RequestContext,
+    Mw1RequestContext & Mw2RequestContext & Mw3RequestContext extends Mw4Dep
+      ? Mw4Dep
+      : never
+  >,
+  mw5: Middleware<
+    Req,
+    Res,
+    Mw5RequestContext,
+    Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext extends Mw5Dep
+      ? Mw5Dep
+      : never
+  >,
+  mw6: Middleware<
+    Req,
+    Res,
+    Mw6RequestContext,
+    Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext &
+      Mw5RequestContext extends Mw6Dep
+      ? Mw6Dep
+      : never
+  >,
+  endpoint: (
+    req: Req &
+      Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext &
+      Mw5RequestContext &
+      Mw6RequestContext,
+    res: Res
+  ) => any
+) => (req: Req, res: Res) => any
+
+type Wrappers7 = <
+  Req,
+  Res,
+  Mw1RequestContext extends Mw2Dep,
+  Mw1Dep,
+  Mw2RequestContext,
+  Mw2Dep,
+  Mw3RequestContext,
+  Mw3Dep,
+  Mw4RequestContext,
+  Mw4Dep,
+  Mw5RequestContext,
+  Mw5Dep,
+  Mw6RequestContext,
+  Mw6Dep,
+  Mw7RequestContext,
+  Mw7Dep
+>(
+  mw1: Middleware<Req, Res, Mw1RequestContext, Mw1Dep>,
+  mw2: Middleware<Req, Res, Mw2RequestContext, Mw2Dep>,
+  mw3: Middleware<
+    Req,
+    Res,
+    Mw3RequestContext,
+    Mw1RequestContext & Mw2RequestContext extends Mw3Dep ? Mw3Dep : never
+  >,
+  mw4: Middleware<
+    Req,
+    Res,
+    Mw4RequestContext,
+    Mw1RequestContext & Mw2RequestContext & Mw3RequestContext extends Mw4Dep
+      ? Mw4Dep
+      : never
+  >,
+  mw5: Middleware<
+    Req,
+    Res,
+    Mw5RequestContext,
+    Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext extends Mw5Dep
+      ? Mw5Dep
+      : never
+  >,
+  mw6: Middleware<
+    Req,
+    Res,
+    Mw6RequestContext,
+    Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext &
+      Mw5RequestContext extends Mw6Dep
+      ? Mw6Dep
+      : never
+  >,
+  mw7: Middleware<
+    Req,
+    Res,
+    Mw7RequestContext,
+    Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext &
+      Mw5RequestContext &
+      Mw6RequestContext extends Mw7Dep
+      ? Mw7Dep
+      : never
+  >,
+  endpoint: (
+    req: Req &
+      Mw1RequestContext &
+      Mw2RequestContext &
+      Mw3RequestContext &
+      Mw4RequestContext &
+      Mw5RequestContext &
+      Mw6RequestContext &
+      Mw7RequestContext,
+    res: Res
+  ) => any
+) => (req: Req, res: Res) => any
+
+type Wrappers = Wrappers1 &
+  Wrappers2 &
+  Wrappers3 &
+  Wrappers4 &
+  Wrappers5 &
+  Wrappers6 &
+  Wrappers7
+
+export const wrappers: Wrappers = (...wrappersArgs: any[]) => {
+  const wrappedFunction = wrappersArgs[wrappersArgs.length - 1]
+  const mws = wrappersArgs.slice(0, -1)
+
+  let lastWrappedFunction = wrappedFunction
+  for (let i = mws.length - 1; i >= 0; i--) {
+    lastWrappedFunction = (mws[i] as any)(lastWrappedFunction)
+  }
+
+  return lastWrappedFunction
+}