name: "nix-devshell"
description:
  "Set up Nix, prebuild the devshell and run commands inside the devshell."
inputs:
  prebuild:
    description:
      "Whether to prebuild the devshell (nix develop --command true)."
    required: false
    default: "false"
  commands:
    description:
      "Commands to run inside the devshell (executed with bash -lc)."
    required: false
    default: ""

runs:
  using: "composite"
  steps:
    - name: Install Nix (idempotent)
      shell: bash
      run: |
        set -euo pipefail
        if ! command -v nix >/dev/null 2>&1; then
          curl -L https://nixos.org/nix/install | sh -s -- --no-daemon
        fi
        # source the nix profile if present
        if [ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then
          . "$HOME/.nix-profile/etc/profile.d/nix.sh"
        fi
        nix --version

    - name: Prebuild devshell
      if: ${{ inputs.prebuild == 'true' }}
      shell: bash
      run: |
        set -euo pipefail
        if [ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then
          . "$HOME/.nix-profile/etc/profile.d/nix.sh"
        fi
        nix --extra-experimental-features 'nix-command flakes' develop --command true

    - name: Run commands in devshell
      if: ${{ inputs.commands != '' }}
      shell: bash
      run: |
        set -euo pipefail
        if [ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then
          . "$HOME/.nix-profile/etc/profile.d/nix.sh"
        fi
        nix --extra-experimental-features 'nix-command flakes' develop --command bash -lc "${{ inputs.commands }}"