shell.nix

{
  pkgs ? import <nixpkgs> {},
  fenix ? import <fenix> {},
}: let
  # Helpful nix function
  getLibFolder = pkg: "${pkg}/lib";

  # Rust Toolchain via fenix
  toolchain = fenix.packages.${pkgs.system}.fromToolchainFile {
    file = ./rust-toolchain.toml;

    # Don't worry, if you need sha256 of your toolchain,
    # just run `nix build` and copy paste correct sha256.
    sha256 = "sha256-Hn2uaQzRLidAWpfmRwSRdImifGUCAb9HeAqTYFXWeQk=";
  };

  # Manifest via Cargo.toml
  manifest = (pkgs.lib.importTOML ./Cargo.toml).package;
in
  pkgs.stdenv.mkDerivation {
    name = "${manifest.name}-dev";

    # Compile time dependencies
    nativeBuildInputs = with pkgs; [
      # GCC toolchain
      gcc
      gnumake
      pkg-config

      # LLVM toolchain
      cmake
      llvmPackages.llvm
      llvmPackages.clang

      # Hail the Nix
      nixd
      statix
      deadnix
      alejandra

      # Rust
      toolchain
      cargo-watch

      # Other compile time dependencies
      openssl
      # libressl
    ];

    # Runtime dependencies which will be shipped
    # with nix package
    buildInputs = with pkgs; [
      openssl
      # libressl
    ];

    # Set Environment Variables
    RUST_BACKTRACE = "full";

    # Compiler LD variables
    # > Make sure packages have /lib or /include path'es
    NIX_LDFLAGS = "-L${(getLibFolder pkgs.libiconv)}";
    LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath [
      pkgs.gcc
      pkgs.libiconv
      pkgs.llvmPackages.llvm
    ];

    # Touch only if you know what you're doing
    # (bash skill issues are not welcomed here)
    shellHook = ''
      # Check for .env file
      if [ ! -f .env ]; then
      read -r -p "Please enter your telegram bot token: " TELOXIDE_TOKEN;
        echo "export TELOXIDE_TOKEN=$TELOXIDE_TOKEN" > .env;
        echo "export WATCH_MODE=false" >> .env;
      fi

      # Load everything from .env
      source .env;

      # Lesss goooo...
      if [ $WATCH_MODE == true ]; then
        echo "Watchmode in background is enabled!"
        echo "Starting cargo watch session on backround..."
        echo

        start() {
          # Start watching for changes in the background
          cargo watch -x "run --bin ${manifest.name} -- env" &
          echo
          echo
          echo ===========================================================================
          echo "Press enter to continue on your terminal"
          echo "\> Don't close this terminal as bot is running on watch mode and see log"
          echo "\> Just open your editor from this terminal to make your editor read PATH"
          echo ===========================================================================

          # Store the PID of the background process to file & env
          CARGO_WATCH_PID=$!
          echo "$CARGO_WATCH_PID" > .daemon

          # Function to clean up the background process on exit
          cleanup() {
            kill $CARGO_WATCH_PID || true
            rm -rf ./.daemon
          }

          # Trap EXIT signal to run cleanup function
          trap cleanup EXIT INT TERM
        }

        # Check if there's already session running
        if [ -e ".daemon" ]; then
            echo "There's a session already running..."
            read -p "would you like to stop running instance? (y/n): " answer

            case "$answer" in
                [Yy]*)
                  # Read old session file
                  _pid=$(<.daemon)

                  # Kill & remove old session
                  kill $_pid || true

                  # Cleanup daemon
                  rm -rf ./.daemon

                  # Cleanup the pid variable
                  unset _pid

                  # Start the damn bot
                  start
                  ;;
                [Nn]*)
                  echo "Aight, no problem bro. I got you..."
                  ;;
                *)
                  echo "Invalid input, ignoring running instance and not running anything"
                  ;;
            esac
        else
          # Start the damn bot
          start
        fi
      else
        echo "You disabled the watch mode on background."
        echo "Feel free to enable it back again at .env file!"
      fi
    '';
  }