# See NixOS.md -> List installed packages

# Sources:
# https://www.reddit.com/r/NixOS/comments/fsummx/comment/fm45htj/
# https://www.reddit.com/r/NixOS/comments/fsummx/comment/kt9fb74/
# https://discourse.nixos.org/t/better-why-depends-fill-in-the-gaps/31246/10

# This creates /etc/current-system-packages with list of all packages and their versions.

{ lib, config, options, pkgs, ... }:
{
  environment.etc."system-packages-with-source-v1".text =
    builtins.concatStringsSep "\n\n" (
      map
        (x: x.file + "\n" +
          builtins.concatStringsSep "\n" (map (s: "  " + s) x.value)
        )
        options.environment.systemPackages.definitionsWithLocations
    );

  environment.etc."current-system-packages-v2".text =
    let
      packages = builtins.map (p: "${p.name}") config.environment.systemPackages;
      sortedUnique = builtins.sort builtins.lessThan (pkgs.lib.lists.unique packages);
      formatted = builtins.concatStringsSep "\n" sortedUnique;
    in
      formatted;
}