{ versionsPath }:

{
  channelSources =
    let
      # channelVersions = (import ((builtins.getEnv "PWD")+"/${dir}/versions.nix"));
      channelVersions = (import versionsPath);
      mkChannelSource = channel: builtins.fetchGit {
        # Descriptive name to make the store path easier to identify
        url = "https://github.com/NixOS/nixpkgs-channels/";
        # Commit hash for nixos-unstable as of 2018-09-12
        # `git ls-remote https://github.com/nixos/nixpkgs-channels nixos-unstable`
        rev = (builtins.getAttr channel channelVersions);
        name = "nixpkgs-channels-${channel}";
      };
      nix_path = builtins.foldl' (sum: elem: sum +":" + builtins.concatStringsSep "=" elem) "" [
        [ "nixpkgs" (mkChannelSource "channelsNixosStable") ]
        [ "nixos" (mkChannelSource "channelsNixosStable") ]
        [ "channels-nixos-stable" (mkChannelSource "channelsNixosStable") ]
        [ "channels-nixos-unstable" (mkChannelSource "channelsNixosUnstable") ]
      ];
    in (import (mkChannelSource "channelsNixosStable") {}).writeText "channels.rc" ''
      export NIX_PATH=${nix_path}
    '';
  }