use brush_core::{ExecutionExitCode, ExecutionResult, builtins};
use clap::Parser;

/// Shift positional arguments.
#[derive(Parser)]
pub(crate) struct ShiftCommand {
	/// Number of positions to shift the arguments by (defaults to 1).
	n: Option<i32>,
}

impl builtins::Command for ShiftCommand {
	type Error = brush_core::Error;

	async fn execute<SE: brush_core::ShellExtensions>(
		&self,
		context: brush_core::ExecutionContext<'_, SE>,
	) -> Result<brush_core::ExecutionResult, Self::Error> {
		let n = self.n.unwrap_or(1);

		if n < 0 {
			return Ok(ExecutionExitCode::InvalidUsage.into());
		}

		#[expect(clippy::cast_sign_loss)]
		let n = n as usize;

		let args = context.shell.current_shell_args_mut();

		if n > args.len() {
			return Ok(ExecutionExitCode::InvalidUsage.into());
		}

		args.drain(0..n);

		Ok(ExecutionResult::success())
	}
}