use std::io::Write;

use brush_core::{ExecutionResult, builtins, error, jobs};
use clap::Parser;

/// Manage jobs.
#[derive(Parser)]
pub(crate) struct JobsCommand {
	/// Also show process IDs.
	#[arg(short = 'l')]
	also_show_pids: bool,

	/// List only jobs that have changed status since the last notification.
	#[arg(short = 'n')]
	list_changed_only: bool,

	/// Show only process IDs.
	#[arg(short = 'p')]
	show_pids_only: bool,

	/// Show only running jobs.
	#[arg(short = 'r')]
	running_jobs_only: bool,

	/// Show only stopped jobs.
	#[arg(short = 's')]
	stopped_jobs_only: bool,

	/// Job specs to list.
	// TODO(jobs): Add -x option
	job_specs: Vec<String>,
}

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

	async fn execute<SE: brush_core::ShellExtensions>(
		&self,
		context: brush_core::ExecutionContext<'_, SE>,
	) -> Result<brush_core::ExecutionResult, Self::Error> {
		if self.also_show_pids {
			return error::unimp("jobs -l");
		}
		if self.list_changed_only {
			return error::unimp("jobs -n");
		}

		if self.job_specs.is_empty() {
			for job in &context.shell.jobs().jobs {
				self.display_job(&context, job)?;
			}
		} else {
			return error::unimp("jobs with job specs");
		}

		Ok(ExecutionResult::success())
	}
}

impl JobsCommand {
	fn display_job(
		&self,
		context: &brush_core::ExecutionContext<'_, impl brush_core::ShellExtensions>,
		job: &jobs::Job,
	) -> Result<(), brush_core::Error> {
		if self.running_jobs_only && !matches!(job.state, jobs::JobState::Running) {
			return Ok(());
		}
		if self.stopped_jobs_only && !matches!(job.state, jobs::JobState::Stopped) {
			return Ok(());
		}

		if self.show_pids_only {
			if let Some(pid) = job.representative_pid() {
				writeln!(context.stdout(), "{pid}")?;
			}
		} else {
			writeln!(context.stdout(), "{job}")?;
		}

		Ok(())
	}
}