flake.nix

{
  description = "singularity_workflow - Elixir implementation of Singularity.Workflow";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = {
    nixpkgs,
    flake-utils,
  }:
    flake-utils.lib.eachDefaultSystem (system: let
      pkgs = nixpkgs.legacyPackages.${system};
      beamPackages = pkgs.beam.packages.erlang;
      # Use Elixir 1.19.x (latest)
      elixir = beamPackages.elixir_1_19;

      # PostgreSQL with pgmq extension
      # Note: Using PostgreSQL 18 (uuid_generate_v7() is built-in, no extension needed)
      postgresqlWithExtensions = pkgs.postgresql_18.withPackages (ps: [
        ps.pgmq # In-database message queue
      ]);
    in {
      devShells.default = pkgs.mkShell {
        buildInputs = [
          beamPackages.erlang
          elixir # Elixir 1.19.x
          postgresqlWithExtensions
          pkgs.nodejs # For moon installation
          pkgs.yarn # Alternative package manager
          pkgs.gh # GitHub CLI for repository management
        ];

        shellHook = ''
          # Clear PATH and rebuild with nix packages FIRST (before system paths)
          export PATH="${beamPackages.erlang}/bin:${elixir}/bin:${postgresqlWithExtensions}/bin:${pkgs.nodejs}/bin:${pkgs.yarn}/bin:${pkgs.gh}/bin:$PATH"
          export DATABASE_URL="postgresql://postgres:postgres@localhost:5432/singularity_workflow"
          echo "ShellHook PATH: $PATH"
          echo "Elixir location: $(which elixir 2>/dev/null || echo 'not found')"
          echo "Mix location: $(which mix 2>/dev/null || echo 'not found')"
          echo "GitHub CLI location: $(which gh 2>/dev/null || echo 'not found')"

          # Install moon if not present
          if ! command -v moon >/dev/null 2>&1; then
            echo "Moon task runner not available - using mix commands directly"
          fi

          # Function to cleanup PostgreSQL on exit
          cleanup_postgres() {
            if [ -f ".postgres_pid" ] && kill -0 $(cat .postgres_pid) 2>/dev/null; then
              echo "Stopping PostgreSQL..."
              pg_ctl -D .postgres_data stop
              rm -f .postgres_pid
            fi
          }

          # Set trap to cleanup on shell exit
          trap cleanup_postgres EXIT

          # Start PostgreSQL if not already running
          if ! pg_isready -h localhost -p 5432 >/dev/null 2>&1; then
            echo "Starting PostgreSQL..."

            # Create data directory if it doesn't exist
            if [ ! -d ".postgres_data" ]; then
              echo "Initializing PostgreSQL data directory..."
              initdb -D .postgres_data --no-locale --encoding=UTF8
            fi

            # Start PostgreSQL
            pg_ctl -D .postgres_data -l .postgres.log -o "-p 5432" start
            echo $! > .postgres_pid

            # Wait for PostgreSQL to be ready
            sleep 3

            # Create postgres role if it doesn't exist
            if ! psql -p 5432 -d postgres -tAc "SELECT 1 FROM pg_roles WHERE rolname='postgres'" | grep -q 1; then
              echo "Creating postgres role..."
              psql -p 5432 -d postgres -c "CREATE ROLE postgres WITH SUPERUSER LOGIN PASSWORD 'postgres';"
            fi

            # Create database and install extensions if they don't exist
            if ! psql -lqt | cut -d \| -f 1 | grep -qw singularity_workflow; then
              echo "Creating singularity_workflow database..."
              createdb -p 5432 singularity_workflow
              psql -p 5432 -d singularity_workflow -c "CREATE EXTENSION IF NOT EXISTS pgmq;"
              echo "Database and extensions ready"
            else
              echo "Database already exists"
            fi

            echo "PostgreSQL started with pgmq extension"
          else
            echo "PostgreSQL already running"
          fi

          echo "singularity_workflow development environment ready!"
          echo "Database: singularity_workflow on localhost:5432 with pgmq extension"
          echo "Run 'mix test' to run tests"
          echo "PostgreSQL will auto-stop when you exit this shell"
        '';
      };
    });
}