holochain_scaffolding_cli 0.601.0

use build_fs_tree::file;
use dirs::home_dir;
use std::fs::{self, OpenOptions};
use std::io::Write;
use std::path::Path;
use std::process::{Command, Stdio};

use crate::error::{ScaffoldError, ScaffoldResult};
use crate::file_tree::*;

use super::git::is_inside_git_repo;

pub fn flake_nix() -> FileTree {
    file!(
        r#"{
  description = "Flake for Holochain app development";

  inputs = {
    holonix.url = "github:holochain/holonix?ref=main-0.6";

    nixpkgs.follows = "holonix/nixpkgs";
    flake-parts.follows = "holonix/flake-parts";
  };

  outputs = inputs@{ flake-parts, ... }: flake-parts.lib.mkFlake { inherit inputs; } {
    systems = builtins.attrNames inputs.holonix.devShells;
    perSystem = { inputs', pkgs, ... }: {
      formatter = pkgs.nixpkgs-fmt;

      devShells.default = pkgs.mkShell {
        inputsFrom = [ inputs'.holonix.devShells.default ];

        packages = (with pkgs; [
          nodejs_22
          binaryen
        ]);

        shellHook = ''
          export PS1='\[\033[1;34m\][holonix:\w]\$\[\033[0m\] '
        '';
      };
    };
  };
}"#
    )
}

pub fn setup_nix_developer_environment(
    command_root_dir: &Path,
    app_dir: &Path,
) -> ScaffoldResult<()> {
    if cfg!(target_os = "windows") {
        return Err(ScaffoldError::NixSetupError(
            "Windows doesn't support nix".to_string(),
        ));
    }

    // This is here to catch the issue from this thread https://discourse.nixos.org/t/nix-flakes-nix-store-source-no-such-file-or-directory/17836
    // If you run Scaffolding inside a Git repository when the `nix flake update` will fail. At some point Nix should report this so we don't need
    // to worry about it but for now this helps solve a strange error message.
    if is_inside_git_repo(command_root_dir) {
        return Err(ScaffoldError::NixSetupError("- detected that Scaffolding is running inside an existing Git repository. Nix cannot be set up in an existing Git repository. Please choose a different location to scaffold or use --setup-nix=false".to_string()));
    }

    println!("Setting up nix development environment...");

    add_extra_experimental_features()?;

    let output = Command::new("nix")
        .stdout(Stdio::inherit())
        .stderr(Stdio::inherit())
        .current_dir(app_dir)
        .args(["flake", "update"])
        .output()?;

    if !output.status.success() {
        Err(ScaffoldError::NixSetupError("".to_string()))?
    }

    Ok(())
}

const EXTRA_EXPERIMENTAL_FEATURES_LINE: &str = "extra-experimental-features = flakes nix-command";

pub fn add_extra_experimental_features() -> ScaffoldResult<()> {
    let config_path = home_dir().ok_or(ScaffoldError::NixSetupError(
        "Config dir doesn't exist".to_string(),
    ))?;

    let nix_conf_dir = config_path.join(".config").join("nix");
    fs::create_dir_all(&nix_conf_dir)?;

    let nix_conf_path = nix_conf_dir.join("nix.conf");
    if let Ok(contents) = fs::read_to_string(&nix_conf_path) {
        if contents.contains(EXTRA_EXPERIMENTAL_FEATURES_LINE) {
            return Ok(());
        }
    }

    if let Ok(mut file) = OpenOptions::new()
        .read(true)
        .append(true)
        .create(true)
        .open(nix_conf_path)
    {
        file.write_all(EXTRA_EXPERIMENTAL_FEATURES_LINE.as_bytes())?;
    } else {
        println!("Warning: could not write extra-experimental-features to nix.conf");
    }
    Ok(())
}