Now with extra colours and emojis 😮

shell.nix

# On Nixos running this from the project folder with nix-shell will create a shell with all the necessary dependencies
# and run postgresql in an ephemeral mode for development.

{ pkgs ? import <nixpkgs> {} }:
pkgs.mkShell {
  nativeBuildInputs = with pkgs; [
    elixir_1_18
    elixir-ls
    erlang
    rebar3
    nodejs
    yarn
    fish
    gnumake
    postgresql
  ];

  # Environment variables
  MIX_ENV = "dev";
  NIX_ENFORCE_PURITY = "0"; # Without this bcrypt does not compile
  IEX_FILE = "${builtins.getEnv "PWD"}/.iex.exs";
  PROJECT_DIR = "/tmp/indie";
  PGPORT = "5432"; # Use quotes to ensure consistency in shell environments

  shellHook = ''
    # Environment variables that need interpolation
    export PGDATA=$PROJECT_DIR/data
    export PGLOCKDIR=$PROJECT_DIR/lock
    export PGLOG=$PROJECT_DIR/postgress.log  

    alias quit="killall -s KILL postgres && exit"
  
    # Color-coded functions for output
    red() { echo -e "\e[31m🚨 $1\e[0m"; }
    green() { echo -e "\e[32m✅ $1\e[0m"; }
    yellow() { echo -e "\e[33m⚙️  $1\e[0m"; }
    blue() { echo -e "\e[34m🔷 $1\e[0m"; }

    # Step headers
    step_header() { 
      echo -e "\e[35m\n======> $1\e[0m\n"; 
    }

    # Create the .iex.exs file if it doesn't exist
    iexfile() {
      step_header "Setting up .iex.exs file"
      if [ ! -f "$IEX_FILE" ]; then
        red "Creating .iex.exs with common aliases..."
        cat <<EOF > "$IEX_FILE"
          IEx.configure(auto_reload: true)

          alias Indie.Repo
          alias Indie.Accounts.{User, Address}
          alias Indie.Commerce.Order
          alias Indie.Domains.Domain
EOF
        green ".iex.exs created successfully!"
      else
        green ".iex.exs already exists!"
      fi
    }

    # Fetch dependencies
    get_dependencies() {
      step_header "Fetching Dependencies"
      green "Checking dependencies..."
      [ ! -d "deps" ] && yellow "Running mix deps.get" && mix deps.get || green "Dependencies are already fetched."
      [ ! -d "_build" ] && yellow "Running mix deps.compile" && mix deps.compile || green "Dependencies are already compiled."
    }

    # Cleanup and setup directories
    cleanup() {
      step_header "Cleaning up and setting directories"
      yellow "Resetting PostgreSQL data directories..."
      rm -rf $PGDATA
      mkdir -p $PGDATA
      mkdir -p $PGLOCKDIR
      chmod 700 $PGDATA
      chmod 700 $PGLOCKDIR
      green "Directories are ready!"
    }

    # Run PostgreSQL server
    run_postgres() {
      step_header "Starting PostgreSQL server"
      yellow "Initializing PostgreSQL..."
      pg_ctl initdb -o "-U postgres"
      green "PostgreSQL initialized."
      yellow "Starting PostgreSQL server..."
      pg_ctl -D $PGDATA -l $PGLOG -o "-p $PGPORT -h localhost -k $PGLOCKDIR" start
      green "PostgreSQL is running on port $PGPORT!"
    }

    # Populate the database
    populate_db() {
      step_header "Populating the database"
      yellow "Resetting the database..."
      mix ecto.reset
      green "Database populated successfully!"
    }

    # Start the Phoenix development server
    dev() {
      step_header "Starting the Phoenix development server"
      iex -S mix phx.server
    }
    
    # Main execution flow
    iexfile
    get_dependencies
    cleanup
    run_postgres
    populate_db

    # Clean up PostgreSQL process on shell exit
    trap 'killall -s KILL postgres && red "PostgreSQL has been stopped 🥳!"' EXIT
  '';
}