#!/bin/bash

export N=$HOME/nix  # real install to ~/nix
#export N=/dev/shm/nix     # temp install to RAM

{
oops() { echo "$0:" "$@" >&2; exit 1; }
title() { echo "$*"; sleep 0.5; printf "\033]0;%s\007" "$*"; }

USER=$(id -u -n)

if [ -d "$N" ]; then
    echo "Nix already installed. Entering environment."
    echo "In future enter nix by running:"
    echo
    echo "  $N/enter"
    echo
    exec "$N/enter"
fi

mkdir "$N" "$N/root-nix" "$N/home" "$N/home/.config" "$N/home/.config/nix" "$N/home/.config/home-manager" || oops "Unable to create directories"
ln -s "$HOME" "$N/home/$USER" || oops "unable to create $USER symlink"

title "Downloading nix-user-chroot"
wget -O "$N/nix-user-chroot" https://github.com/nix-community/nix-user-chroot/releases/download/1.2.2/nix-user-chroot-bin-1.2.2-x86_64-unknown-linux-musl || oops "Failed to download nix-user-chroot"
chmod u+x "$N/nix-user-chroot" || oops "Unable to make $N/nix-user-chroot executable"

title "Downloading nixos.org/nix/install"
wget -O "$N/nix.install" https://nixos.org/nix/install || oops "Failed to download nixos.org/nix/install"

title "Downloading pinokio package files"
wget -O "$N/home/.config/home-manager/pinokio.nix" https://raw.githubusercontent.com/ThomasEricB/pinokio-with-user-nix/refs/heads/main/pinokio.nix || oops "Failed to download pinokio.nix"
wget -O "$N/home/.config/home-manager/pinokio-flake.nix" https://raw.githubusercontent.com/ThomasEricB/pinokio-with-user-nix/refs/heads/main/pinokio-flake.nix || oops "Failed to download pinokio-flake.nix"

title "Creating files"
cat <<EOF > "$N/home/README"
Q1. How do I enter the nix environment? Run:

  $N/enter

Q2. How do I run a program without installing it?

  nix run nixpkgs#ncdu
  nix run nixpkgs#vlc

or

  nix shell nixpkgs#ncdu
  ncdu

Q3. How do I find a program to run?

  nix search nixpkgs ncdu

Q4. How do I install a program? Add the name of the program to home.nix's home.packages line. For example:

  home.packages = (with pkgs; [
    nix nettools bashInteractive
    ncdu vlc
  ]);

Then rebuild with:

  home-manager switch

Q5. Where is the home.nix and flake.nix?

  $N/home/.config/home-manager/home.nix
  $N/home/.config/home-manager/flake.nix

Q6. How do I rebuild after editing home.nix or flake.nix? Run:

   home-manager switch

Note: After initial setup, always use "home-manager switch" to rebuild.
The bootstrap activation script is only used during first install.

Q7. How do I update the programs?

  nix flake update --flake ~/.config/home-manager
  home-manager switch

Note: The flake.lock file pins exact package versions. "nix flake update"
bumps all inputs (nixpkgs, home-manager) to their latest commits.

Q8. How do I reclaim disk space?

  nix-collect-garbage -d
  nix-store --optimise

The first command removes old generations and unreferenced packages.
The second deduplicates identical files in the store (can save 25-35%).
Run both periodically, especially on limited storage.

Q9. What is the layout of this install?

  dir          $N
  enter script $N/enter
  pinokio      $N/pinokio.sh
  home         $N/home
  README       $N/home/README
  pinokio pkg  $N/home/.config/home-manager/pinokio.nix
  nix store    $N/root-nix/store

Q10. How do I remove everything, including the nix home directory?

  chmod -R u+w '$N'
  rm '$N' -r

WARNING: Never run "nix profile install" or "nix profile remove" commands.
These permanently corrupt the profile format used by home-manager and nix-env.
If you accidentally ran one, delete ~/.nix-profile and rebuild:

  rm -f ~/.nix-profile
  home-manager switch

Q11. Where are these instructions stored?

  $N/home/README

Q12. How do I enter the nix environment again? Run:

  $N/enter

Q13. How do I launch Pinokio?

  $N/pinokio.sh

This runs the installed Pinokio through the nix-user-chroot.
You can also launch it from inside the nix environment with:

  pinokio

EOF

cat <<EOF > "$N/home/.config/nix/nix.conf"
experimental-features = nix-command flakes
max-jobs = auto
auto-optimise-store = true
warn-dirty = false
EOF

cat <<EOF > "$N/home/.config/home-manager/flake.nix"
{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
    hm = {
      url = "github:nix-community/home-manager/release-25.11";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };
  outputs = { self, nixpkgs, hm }: {
    homeConfigurations.$USER = hm.lib.homeManagerConfiguration {
      pkgs = nixpkgs.legacyPackages.x86_64-linux;
      modules = [
        ./home.nix
      ];
    };
  };
}
EOF

cat <<EOF > "$N/home/.config/home-manager/home.nix"
# After editing this file, run:
#
#   home-manager switch
#
{ config, pkgs, ... }:

let
  pinokio = pkgs.callPackage ./pinokio.nix {};
in
{
  home.username = "$USER";
  home.homeDirectory = "$N/home";
  # DO NOT CHANGE. This must stay at the version you first installed.
  # Changing it can break your configuration. See:
  # https://nix-community.github.io/home-manager/release-notes.xhtml
  home.stateVersion = "22.05";

  home.packages = (with pkgs; [
    nix nettools bashInteractive glibcLocales
    # To find more packages, use:
    #
    #   nix search nixpkgs NAME
    #
  ]) ++ [ pinokio ];

  # Required for locale support inside the nix-user-chroot.
  # Without this, bash warns about missing pt_BR.UTF-8 (or your locale).
  home.sessionVariables = {
    LOCALE_ARCHIVE = "\${pkgs.glibcLocales}/lib/locale/locale-archive";
  };

  #To find more home-manager programs use:
  #
  #  man home-configuration.nix
  #
  programs.home-manager.enable = true;

  programs.bash = {
    enable = true;
    profileExtra = ''
      . "\${config.home.profileDirectory}/etc/profile.d/nix.sh"
    '';
  };
}
EOF

cat <<EOF > "$N/enter"
#!/bin/bash
export HOME=$N/home
cd ~/
du -hs $N
echo "home:" \$HOME
export LOCALE_ARCHIVE=\$HOME/.nix-profile/lib/locale/locale-archive
exec $N/nix-user-chroot $N/root-nix ~/.nix-profile/bin/bash -l
EOF

chmod u+x "$N/enter" || oops "Unable to make $N/enter executable"

cat <<EOF > "$N/pinokio.sh"
#!/bin/bash
export HOME=$N/home
export LOCALE_ARCHIVE=\$HOME/.nix-profile/lib/locale/locale-archive
exec $N/nix-user-chroot $N/root-nix \$HOME/.nix-profile/bin/pinokio "\$@"
EOF

chmod u+x "$N/pinokio.sh" || oops "Unable to make $N/pinokio.sh executable"

cat <<EOF > "$N/home-manager-flake.install"
oops() { echo "$0:" "$@" >&2; exit 1; }
title() { printf "\033]0;%s\007" "$*"; }

title "Loading ~/.nix-profile/etc/profile.d/nix.sh"
. ~/.nix-profile/etc/profile.d/nix.sh || oops "failed to source ~/.nix-profile/etc/profile.d/nix.sh"

title "nix registry pin nixpkgs"
nix registry pin nixpkgs || oops "failed to: nix registry pin nixpkgs"

title "Building home-manager configuration"
nix-env --set-flag priority 10 nix || oops "failed to: nix-env --set-flag priority 10 nix"
nix build --no-link ~/.config/home-manager#homeConfigurations.$USER.activationPackage || oops "failed to build ~/.config/home-manager#homeConfigurations.$USER.activationPackage"

title "Activating home-manager configuration"
"\$(nix path-info ~/.config/home-manager#homeConfigurations.$USER.activationPackage)"/activate || oops "failed to activate home-manager config"

title "Removing nix-env's nix command"
nix-env -e nix || oops "failed to remove nix-env's version of the nix command"

title "nix-collect-garbage -d"
nix-collect-garbage -d || oops "failed to nix-collect-garbage -d"
EOF

title "Running nixos.org/nix/install"
HOME="$N/home" "$N/nix-user-chroot" "$N/root-nix" /bin/bash "$N/nix.install" || oops "nixos.org/nix/install failed"

title "Installing home-manager"
HOME="$N/home" "$N/nix-user-chroot" "$N/root-nix" /bin/bash "$N/home-manager-flake.install" || oops "home-manager-flake.install failed"

echo
du -hs "$N"
echo
cat "$N/home/README"

"$N/enter"
}