_middleware.ts

import "buffer";
import P from "parsimmon";
import { NextRequest, NextResponse } from "next/server";

/** State and city tokens are just letters */
const dashToken = P.string("-");
const slashToken = P.string("/");
const zipPrefixToken = P.regex(/zip-/i);
const zipToken = P.regex(/[\d]+/i);
const poiToken = P.string("/p");
const stateToken = P.regex(/[a-z]+/i);
const locationToken = P.regex(/[a-z]+/i);
const refinementsToken = P.regex(/[\w]+/i);

/** The "-apartments" token represents all property types */
const allPropertiesToken = P.string("apartments").map(() => [
  "apartments",
  "condos",
  "houses",
  "townhouses",
]);

/** Other property types map to their defined properties */
const condosToken = P.string("condos").map(() => ["condos"]);
const housesToken = P.string("houses").map(() => ["houses"]);
const townhousesToken = P.string("townhouses").map(() => ["townhouses"]);

/** A valid property type is any of the above tokens */
const propertyTypeToken = P.alt(
  allPropertiesToken,
  condosToken,
  housesToken,
  townhousesToken
);

const propertyTypesAndMaybeRefinementsToken = P.alt(
  P.seq(propertyTypeToken.skip(slashToken), refinementsToken).map(
    ([propertyType, refinements]) => ({
      propertyType,
      refinements: refinements?.split("_"),
    })
  ),
  propertyTypeToken.map((propertyType) => ({
    propertyType,
  }))
);

const zipRouteToken = P.seq(
  slashToken.skip(zipPrefixToken),
  zipToken.skip(dashToken),
  propertyTypesAndMaybeRefinementsToken
).map(([_, zipCode, propertyTypeAndMaybeRefinements]) => ({
  zipCode,
  ...propertyTypeAndMaybeRefinements,
}));

const poiRouteToken = P.seq(
  poiToken.skip(slashToken),
  stateToken.skip(slashToken),
  locationToken.skip(dashToken),
  propertyTypesAndMaybeRefinementsToken
).map(([_, state, location, propertyTypeAndMaybeRefinements]) => ({
  state,
  location,
  ...propertyTypeAndMaybeRefinements,
}));

const cityStateRouteToken = P.seq(
  slashToken,
  stateToken.skip(slashToken),
  locationToken.skip(dashToken),
  propertyTypesAndMaybeRefinementsToken
).map(([_, state, location, propertyTypeAndMaybeRefinements]) => ({
  state,
  location,
  ...propertyTypeAndMaybeRefinements,
}));

const searchParser = P.alt(poiRouteToken, zipRouteToken, cityStateRouteToken);

export function middleware(req: NextRequest) {
  const url: URL = req.nextUrl;
  const result = searchParser.parse(url.pathname);

  if (result.status) {
    console.log(result.value);
    url.pathname = "/search";
    for (const key of Object.keys(result.value)) {
      const value = result.value[key];
      if (Array.isArray(value)) {
        value.forEach((val) => {
          url.searchParams.append(key, val);
        });
      } else {
        url.searchParams.append(key, value);
      }
    }

    return NextResponse.rewrite(url);
  }
}