Sets up a basic CLI interface

[stuartlynn]

• Installs clap
• Defines a new module for the CLI
• Implements some placeholder commands with Arg structs

TODO

• [x] Figure out validation for things like bounding boxes
• [x] Implement a struct to represent Data Requests more generally and implement a From trait for it from the CLI parser. This will let us potentially reuse that same struct for a config file version of invoking the app.
• [x] Figure out an ergonomic way to map commands to executors.
• • Just a big match statement?
• • Trait and impl on the Args object for each Command with dynamic dispatch?
• • enum dispatch like pattern on the Commands object?

[stuartlynn]

Example command to run

cargo run -- data --bbox 12,5,3,4 -m E0034,E444,E343

Gives the result

You selected the Data command DataArgs {
    bbox: Some(
        BBox(
            [
                12.0,
                5.0,
                3.0,
                4.0,
            ],
        ),
    ),
    metrics: Some(
        "E0034,E444,E343",
    ),
}

[stuartlynn]

Last push added a pattern for running command more ergonomically.

Now we declare a trait RunCommand:

#[enum_dispatch]
pub trait RunCommand{
    fn run(&self)->Result<()>;
} 

which each Command needs to implement. We then just invoke command.run() in the main.rs entrypoint to run the command. For example

impl RunCommand for DataCommand{
    fn run(&self)->Result<()> {
        println!("Running Data Command");
        println!("{self:#?}");
        Ok(())
    }
}

In addition I stubbed out a lib struct to start to represent a data request. We have implemented From<DataCommand> for DataRequestSpec. This will probably grow and change in time but is a good starting point for now.

impl From<DataCommand> for DataRequestSpec{
        fn from(value: DataCommand) -> Self {
            let region = if let Some(bbox) = value.bbox{
                vec![RegionSpec::BoundingBox(bbox)] 
            }
            else{
                vec![]
            };
            let metrics = vec![];
            DataRequestSpec{
                region,
                metrics
            }

    }
}

[stuartlynn]

Thanks @yongrenjie accepted those changes.

Also, presumably when it's all fleshed out we might want to eventually separate the commands out into their own modules?

I think this makes sense but seems a bit premature just now. I am hoping most of them will end up being simple calls to the library functions so we can capture most of the complexity in there.

I feel like the spurious FromStr warning should be reported upstream if it isn't already

Yeah this is a weird one. Not sure who to report it (probably rust-analyser?) to or even how to describe the bug .

[yongrenjie]

Macros are too magic :)

[yongrenjie]

I think it's this issue here: https://github.com/rust-lang/rust-analyzer/issues/15501