# Usage

Viv works by ensuring scripts or a given
command are run in an appropriate environment with all specified dependencies.

:::{tip}
`viv` is a single script and available at `viv.dayl.in/viv.py`
meaning every instance of `viv` in these examples could be `python3 <(curl -fsSL viv.dayl.in/viv.py)`
:::

## Run CLI Apps

Run a python app that provides an entrypoint and separate args with `--`:

```sh
viv run frogmouth -- gh daylinmorgan/viv
```

Run a python module use the `-b/--bin` flag and specify `python`:

```sh
viv run rich -b python -- -m rich
```

Make an ephemeral `jupyter` environment with your needed deps:

```sh
viv run jupyter pandas -r requirements-dev.txt -- notebook
```

Generate an executable shell script that will on demand create a vivenv as needed:

```sh
viv shim ruff
```

Output:
```python
#!/usr/bin/env python3
# AUTOGENERATED by viv (v2023.1003)
# see `python3 <(curl -fsSL viv.dayl.in/viv.py) --help`

import subprocess
import sys

if __name__ == "__main__":
    vivenv = __import__("viv").use("ruff") # noqa
    sys.exit(subprocess.run([vivenv / "bin" / "ruff", *sys.argv[1:]]).returncode)
```

## Run Python Scripts

It's possible to use the `viv` CLI to run a python script.
There are several options for invoking a script.

Using the interpreter:
```sh
viv run rich typer -b python -- ./cli.py --help
```

Using `-s/--script`:
```sh
viv run rich typer -s ./cli.py -- --help
# or with a remote script
viv run rich -s https://raw.githubusercontent.com/Textualize/rich/master/examples/fullscreen.py
```

If `viv` is available on your path it's possible to
invoke it with embedded metadata thanks to shebangs:

```python
#!/usr/bin/env -S viv run --keep --script
# /// script
# requires-python = ">3.10"
# dependencies = [
#   "matplotlib",
#   "pandas"
# ]
# ///
```

:::{note}
If using a shebang on a python script `-s/--script` must be the last argument
:::

:::{seealso}
Check out [PEP723](https://peps.python.org/pep-0723/) for more info about inline script metadata.
:::

In any python script with external dependencies you can also add this line prior to imports
to automate `vivenv` creation and installation of dependencies.

```python
__import__("viv").use("click")
```

If your dependencies are sensitive to the version of python
(numpy, cpython-based apps, etc. ) then you can specify `track_exe`.
Which will lead to `viv` creating a unique vivenv based on the detected python executable.

```python
__import__("viv").use("numpy", track_exe=True)
```

If you'd like to pin your dependencies to a resolved environment you
can use the convenience command `viv freeze` to output a list of pinned packages.

Command:
```sh
viv freeze rich typer
```

Output:
```python
__import__("viv").use("rich==13.7.0", "typer==0.9.0", "click==8.1.7", "markdown-it-py==3.0.0", "Pygments==2.17.2", "typing_extensions==4.9.0", "mdurl==0.1.2") # noqa
```

Additionally, you can make this work regardless of `PYTHONPATH` by using `--path`.

Command:
```sh
viv freeze rich typer --path rel
```

Output:
```python
__import__("sys").path.append(__import__("os").path.expanduser("~/.local/share/viv/"))  # noqa
__import__("viv").use("rich==13.7.0", "typer==0.9.0", "click==8.1.7", "markdown-it-py==3.0.0", "Pygments==2.17.2", "typing_extensions==4.9.0", "mdurl==0.1.2") # noqa
```

## Manage Viv

### Interacting with the viv cache

Depending on how you invoke `viv`, it will persist it's virtual environments (vivenvs).
To see all currently existing vivenvs use can use `viv list`.

Viv will attempt to track any usages of the
vivenvs including the scripts that invoke them.

You can remove any existing vivenvs using `viv env remove`:

```sh
viv env remove d4b342b3
```

To get more information about vivenvs you can use `viv list --verbose` or `viv env info <hash>`

:::{note}
For commands that expect a vivenv hash/name you can use as few characters as you
as you like and `viv` will match it against the existing vivenvs in the cache.
:::

You can list vivenvs given a criteria using `--filter` for example:

Created before 2024-01-01:
```sh
viv list --filter "created-before:2024-01-01"
```

Associated with a particular file:
```sh
viv list --filter "files:./script.py"
```

Or no files:
```sh
viv list --filter "files:None"
```

:::{note}
`--filter "files:None"` will also apply to vivenvs
in which the original file is no longer on the disk
:::

The available filtering criteria are `accessed-after`,
`accessed-before`, `created-before`, `created-after`, `spec` and `files`.

To remove all `vivenvs` you can use the below command:

```sh
viv env remove $(viv list -q)
```

To remove `viv` all together you can use the included `purge` command:

```sh
python3 <(curl -fsSL viv.dayl.in/viv.py) manage purge
```

## Bonus: `viv` standalone 

`--standalone` will auto-generate a mini function version of `viv` to accomplish the same basic task as using a local copy of `viv`.
After generating this standalone `shim` you can freely use this script across unix machines which have `python>3.8`.
See [examples/black](https://github.com/daylinmorgan/viv/blob/dev/examples/black) for output of below command.

`viv freeze` also supports `--standalone`

```sh
python3 <(curl -fsSL viv.dayl.in/viv.py) shim black -o ./black --standalone --freeze
```