# envkit

`envkit` is a small Rust crate for reading environment variables and converting them into typed values.

It keeps the API minimal:

- `EnvLoader::get` reads a required variable.
- `EnvLoader::get_or` reads a variable with a fallback.
- `EnvLoader::get_opt` returns `Option<T>`.
- `with_prefix` lets you build loaders for namespaced variables like `APP_PORT` or `DB_HOST`.

## Supported types

`envkit` currently supports:

- `String`
- `bool`
- numeric types: `i8`, `i16`, `i32`, `i64`, `i128`, `isize`, `u8`, `u16`, `u32`, `u64`, `u128`, `usize`, `f32`, `f64`

Boolean parsing accepts:

- `true` / `false`
- `1` / `0`
- `t` / `f`

## Quick start

```rust
use envkit::EnvLoader;

fn main() -> Result<(), envkit::error::EnvError> {
    let loader = EnvLoader;

    let port: u16 = loader.get("PORT")?;
    let debug: bool = loader.get_or("DEBUG", false);
    let app_name: String = loader.get_opt("APP_NAME").unwrap_or_else(|| "envkit".to_string());

    println!("port={port}, debug={debug}, app_name={app_name}");
    Ok(())
}
```

## Prefixed variables

```rust
use envkit::EnvLoader;

fn main() -> Result<(), envkit::error::EnvError> {
    let loader = EnvLoader;
    let app = loader.with_prefix("APP_");

    let host: String = app.get("HOST")?;
    let port: u16 = app.get_or("PORT", 8080);

    println!("host={host}, port={port}");
    Ok(())
}
```

If you use the prefixed loader above, it reads `APP_HOST` and `APP_PORT`.

## Errors

`envkit` returns `EnvError` for two cases:

- `MissingVar` when the environment variable is not present
- `Invalid` when parsing fails

## Examples

See the `examples/` folder for runnable usage samples.

## Development

Run the test suite with:

```bash
cargo test
```