use std::convert::TryFrom;
use std::io::Write;

use clap::ArgMatches;

use crate::database::Database;
use crate::error::{Error, Result};
use crate::commands::Command;
use crate::config::Config;

#[derive(Default)]
pub struct Args {
    sheet: Option<String>,
}

impl<'a> TryFrom<&'a ArgMatches<'a>> for Args {
    type Error = Error;

    fn try_from(matches: &'a ArgMatches) -> Result<Self> {
        Ok(Args {
            sheet: matches.value_of("sheet").map(|s| s.into()),
        })
    }
}

pub struct SheetCommand {}

impl<'a> Command<'a> for SheetCommand {
    type Args = Args;

    fn handle<D, O, E>(args: Args, _db: &mut D, _out: &mut O, _err: &mut E, _config: &Config) -> Result<()>
    where
        D: Database,
        O: Write,
        E: Write,
    {
        if let Some(_sheet) = args.sheet {
            // sheet given, switch to it
            unimplemented!()
        } else {
            // call list
            Ok(())
        }
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn switch_to_sheet() {
        assert!(false);
    }

    #[test]
    fn switch_to_sheet_already_in() {
        assert!(false);
    }
}