decompileRoutePath.js

const _ = {
  uniq: require("lodash/uniq"),
  unzip: require("lodash/unzip")
};

module.exports.decompileRoutePath = function decompileRoutePath(paths, ids) {
  const parsedPaths = paths.map(path =>
    path.replace(/^\/+|\/+$/g, "").split("/")
  );
  if (
    !parsedPaths
      .map(({ length }) => length)
      .every((len, index, pathTokensLengthOfPaths) =>
        pathTokensLengthOfPaths.every(_len => _len === len)
      )
  ) {
    throw new Error("path tokens length in each path must be same");
  }
  if (
    !parsedPaths.every(parsedPath => parsedPath.every(pathToken => pathToken))
  ) {
    throw new Error("all the path tokens in each path must be not empty");
  }
  const paramValues = _.unzip(parsedPaths).map(grouped =>
    _.uniq(grouped).length > 1 ? grouped : false
  );
  const paramIdValues = {};
  const routePaths = parsedPaths.map((pathTokens, parsedPathIndex) => {
    const idsConsumer = (function*(ids) {
      let i = -1;
      while (true) yield ids[++i] || ids[(i = 0)];
    })(ids || ["id"]);
    const paramIds = [];
    let modifier = 0;
    const routeTokens = pathTokens.map((pathToken, pathTokenIndex) => {
      if (paramValues[pathTokenIndex][parsedPathIndex]) {
        const currentId = idsConsumer.next().value;
        const paramId = paramIds.includes(currentId)
          ? `${currentId}${++modifier}`
          : currentId;
        paramIds.push(paramId);
        (paramIdValues[paramId] || (paramIdValues[paramId] = [])).push(
          pathToken
        );
        return `:${paramId}`;
      } else {
        return pathToken;
      }
    });
    return `/${routeTokens.join("/")}`;
  });
  return {
    routePath: routePaths[0],
    paramIdValues
  };
}