# Instructions on building the athena detector geometry

Instructions on how to setup your environment and run the full simulation.

## Step 1: Setup a sandbox directory

Create a local directory that you want to work in, e.g., `~/eic`
```bash
mkdir ~/eic
cd ~/eic
```

## Step 2: Deploy the containerized environment and launc a shell

Execute the following line in your temrinal to setup your environment in your sandbox
directory. This will install the latest stable container and place a script called
`eic-shell` in the top-level directory. This script will load the environment for you.
```bash
curl https://eicweb.phy.anl.gov/containers/eic_container/-/raw/master/install.sh | bash
```

Now you can launch a shell in our development environment:
```bash
./eic-shell
```

Note that this will also set the `$ATHENA_PREFIX` environment variable, and the related
environment variables. You should install all local software to this `$ATHENA_PREFIX`
(which is the `./local` subdirectory of your sandbox working directory).

## Step 3: Clone the repos

Right now there are 2 repos you need:
* IP6 (IP-specific components)
* Athena detector

```bash
git clone https://eicweb.phy.anl.gov/EIC/detectors/athena.git
git clone https://eicweb.phy.anl.gov/EIC/detectors/ip6.git
```

## Step 4: Build/install the detector plugins

We need to build detector plugins for both the Athena and for the IP.

### Building IP6
```bash
cd ip6
mkdir build && cd build
cmake -DCMAKE_INSTALL_PREFIX=$ATHENA_PREFIX ..
make install
cd ../..
```

### Building the athena detector
```bash
cd athena
mkdir build && cd build
cmake -DCMAKE_INSTALL_PREFIX=$ATHENA_PREFIX ..
make install -j8
cd ../..
```

## Step 5: Link the compact files for IP6 
```bash
cd athena
ln -s ../ip6/ip6
```

## Final Step 
That's all, you are now fully setup. Let's try a simple geometry overlap check
to make sure everything works properly.

```bash
checkOverlaps -c athena.xml
```

In order to run the simulation with our datamodel, you should use the `npsim` executable.
You can exectute
```bash
npsim -h
```
to get help on how to do this. 

Here is an example command for npsim with from a Hepmc3 file:
```bash
npsim --runType batch \
      --part.minimalKineticEnergy 100 \
      -v WARNING \
      --numberOfEvents 100 \
      --compactFile athena.xml \
      --inputFiles YOUR_FILES.hepmc \
      --outputFile YOUR_FILENAME.root
```