dure 0.2.2

//! Command-line argument parsing for `dure`, built on `clap`.
//!
//! The parser lives in the library so parse behavior can be tested without
//! spawning a subprocess.

use std::num::NonZero;
use std::path::PathBuf;

use clap::error::ErrorKind;
use clap::{Parser, Subcommand};

use crate::constants::SUPERVISOR_COMMAND;
use crate::{AppCommand, Command, Invocation, SessionId};

/// Clap-facing parser for the `dure` binary.
///
/// Translates argv into [`Invocation`] so [`crate::run`] does not depend on clap.
#[derive(Debug, Parser)]
#[command(
    name = "dure",
    about = "Detachable Windows console sessions that outlive the terminal.",
    version
)]
pub struct Cli {
    /// Explain on stderr what each command inspects and decides.
    #[arg(long, global = true)]
    verbose: bool,

    /// Override the session store root.
    ///
    /// Available only through the private test surface.
    #[cfg(any(test, feature = "private-test-util"))]
    #[arg(long, global = true, hide = true)]
    store_root: Option<PathBuf>,

    #[command(subcommand)]
    command: CliCommand,
}

#[derive(Debug, Subcommand)]
enum CliCommand {
    /// Start a new session and attach immediately.
    ///
    /// Always creates a new session, never reconnecting to an existing one. The
    /// command runs directly rather than through a shell, in the current
    /// directory, which also becomes the launch directory `resume` matches on.
    Run {
        /// Command to execute directly, not through a shell.
        ///
        /// A leading `--` is optional and only needed to keep an argument that
        /// starts with a hyphen away from `dure`'s own options.
        #[arg(trailing_var_arg = true, allow_hyphen_values = true, required = true)]
        command: Vec<String>,
    },
    /// Attach to a live session.
    ///
    /// Without an id, attaches to the single live session launched from the
    /// current directory; if that match is not unique, the live sessions are
    /// listed and an id is read from the terminal. Attaching displaces whatever
    /// client held the session before.
    Resume {
        /// Session id to attach to, skipping auto-detect.
        id: Option<NonZero<u32>>,
    },
    /// Print live sessions.
    ///
    /// The ids, attachment state, and launch directories shown here are what an
    /// explicit `resume <id>` or `kill <id>` is chosen from.
    List,
    /// Abruptly terminate the supervisor for a session.
    ///
    /// The app and its ordinary descendants die with the supervisor.
    Kill {
        /// Session id to kill. Required; kill does not auto-detect.
        id: NonZero<u32>,
    },
    /// Hidden supervisor process started by `dure run`.
    #[command(name = SUPERVISOR_COMMAND, hide = true)]
    Supervisor {
        /// One-shot startup pipe created by the client.
        #[arg(long)]
        startup_pipe: String,
        /// Canonical launch directory for the app.
        #[arg(long)]
        launch_directory: PathBuf,
        /// Command argv to execute.
        #[arg(trailing_var_arg = true, allow_hyphen_values = true, required = true)]
        command: Vec<String>,
    },
}

/// A parse outcome that should terminate the program before execution.
#[derive(Debug)]
#[expect(
    clippy::exhaustive_structs,
    reason = "handoff struct read directly by the in-crate binary and tests"
)]
pub struct EarlyExit {
    /// The rendered message (help text or error) to print.
    pub output: String,
    /// `Ok` for help or version text the user asked for, `Err` otherwise.
    pub status: Result<(), ()>,
}

impl EarlyExit {
    fn from_clap(error: &clap::Error) -> Self {
        // Only an explicit request for help or version is work the invocation
        // asked for and got. An invocation that named no command performed no
        // session operation, so a wrapper must not read its usage screen as
        // success.
        let success = matches!(
            error.kind(),
            ErrorKind::DisplayHelp | ErrorKind::DisplayVersion
        );
        Self {
            output: error.to_string(),
            status: if success { Ok(()) } else { Err(()) },
        }
    }

    fn failure(message: &str) -> Self {
        Self {
            output: format!("error: {message}"),
            status: Err(()),
        }
    }
}

impl Cli {
    /// Parses an argument vector into the typed CLI.
    ///
    /// # Errors
    ///
    /// Returns an [`EarlyExit`] when the arguments request help/usage or fail to
    /// parse.
    pub fn from_args(command_name: &[&str], args: &[&str]) -> Result<Self, EarlyExit> {
        let argv: Vec<&str> = command_name.iter().chain(args).copied().collect();
        Self::try_parse_from(argv).map_err(|error| EarlyExit::from_clap(&error))
    }

    /// Translates the parsed arguments into the [`Invocation`] the core logic consumes.
    ///
    /// This is where the argv shape becomes the values the rest of the crate
    /// relies on, so a command that names nothing to run is refused here rather
    /// than travelling as an argv that every later layer has to re-check.
    ///
    /// # Errors
    ///
    /// Returns an [`EarlyExit`] when a subcommand's arguments do not describe
    /// something the tool can act on.
    pub fn into_invocation(self) -> Result<Invocation, EarlyExit> {
        let command = match self.command {
            CliCommand::Run { command } => Command::Run {
                command: app_command(command)?,
            },
            CliCommand::Resume { id } => Command::Resume {
                id: id.map(SessionId::new),
            },
            CliCommand::List => Command::List,
            CliCommand::Kill { id } => Command::Kill {
                id: SessionId::new(id),
            },
            CliCommand::Supervisor {
                startup_pipe,
                launch_directory,
                command,
            } => Command::Supervisor {
                startup_pipe,
                launch_directory,
                command: app_command(command)?,
            },
        };
        Ok(Invocation {
            verbose: self.verbose,
            #[cfg(any(test, feature = "private-test-util"))]
            store_root: self.store_root,
            command,
        })
    }
}

fn app_command(argv: Vec<String>) -> Result<AppCommand, EarlyExit> {
    AppCommand::from_argv(argv)
        .ok_or_else(|| EarlyExit::failure("dure run requires a command to execute"))
}

#[cfg(test)]
#[cfg_attr(coverage_nightly, coverage(off))]
mod tests {
    use super::*;

    fn parse(args: &[&str]) -> Invocation {
        Cli::from_args(&["dure"], args)
            .unwrap()
            .into_invocation()
            .unwrap()
    }

    fn command(argv: &[&str]) -> AppCommand {
        AppCommand::from_argv(argv.iter().map(|arg| (*arg).to_string()).collect()).unwrap()
    }

    #[test]
    fn parse_run_after_double_dash() {
        let input = parse(&["run", "--", "copilot.exe", "--foo"]);
        assert_eq!(
            input.command,
            Command::Run {
                command: command(&["copilot.exe", "--foo"]),
            }
        );
    }

    #[test]
    fn parse_resume_without_id() {
        let input = parse(&["resume"]);
        assert_eq!(input.command, Command::Resume { id: None });
    }

    #[test]
    fn parse_resume_with_positional_id() {
        let input = parse(&["resume", "3"]);
        assert_eq!(
            input.command,
            Command::Resume {
                id: SessionId::from_u32(3),
            }
        );
    }

    #[test]
    fn parse_resume_rejects_id_option() {
        Cli::from_args(&["dure"], &["resume", "--id", "3"]).unwrap_err();
    }

    #[test]
    fn resume_help_shows_positional_id() {
        let err = Cli::from_args(&["dure"], &["resume", "--help"]).unwrap_err();
        assert!(err.status.is_ok());
        assert!(err.output.contains("[ID]"));
        assert!(!err.output.contains("--id"));
    }

    #[test]
    fn parse_list() {
        assert_eq!(parse(&["list"]).command, Command::List);
    }

    #[test]
    fn parse_kill_requires_id() {
        Cli::from_args(&["dure"], &["kill"]).unwrap_err();
        let input = parse(&["kill", "2"]);
        assert_eq!(
            input.command,
            Command::Kill {
                id: SessionId::from_u32(2).unwrap(),
            }
        );
    }

    #[test]
    fn parse_kill_rejects_id_option() {
        Cli::from_args(&["dure"], &["kill", "--id", "2"]).unwrap_err();
    }

    #[test]
    fn kill_help_shows_positional_id() {
        let err = Cli::from_args(&["dure"], &["kill", "--help"]).unwrap_err();
        assert!(err.status.is_ok());
        assert!(err.output.contains("<ID>"));
        assert!(!err.output.contains("--id"));
    }

    #[test]
    fn parse_verbose_and_store_root() {
        let input = parse(&["--verbose", "--store-root", r"C:\tmp", "list"]);
        assert!(input.verbose);
        assert_eq!(
            input.store_root.as_deref(),
            Some(std::path::Path::new(r"C:\tmp"))
        );
    }

    #[test]
    fn help_is_early_exit_success() {
        let err = Cli::from_args(&["dure"], &["--help"]).unwrap_err();
        assert!(err.status.is_ok());
        assert!(err.output.contains("dure"));
    }

    #[test]
    fn version_reports_the_package_release() {
        let err = Cli::from_args(&["dure"], &["--version"]).unwrap_err();
        assert!(err.status.is_ok());
        assert!(err.output.contains(env!("CARGO_PKG_VERSION")));
    }

    #[test]
    fn naming_no_command_is_a_failure() {
        let err = Cli::from_args(&["dure"], &[]).unwrap_err();
        assert!(err.status.is_err());
    }

    #[test]
    fn run_refuses_an_argv_that_names_nothing_to_run() {
        let exit = Cli::from_args(&["dure"], &["run", ""])
            .unwrap()
            .into_invocation()
            .unwrap_err();
        assert!(exit.status.is_err());
    }

    #[test]
    fn run_accepts_a_command_with_or_without_the_separator() {
        let with = parse(&["run", "--", "copilot.exe", "--foo"]);
        let without = parse(&["run", "copilot.exe", "--foo"]);
        assert_eq!(with.command, without.command);
    }

    #[test]
    fn subcommand_help_explains_how_a_session_is_chosen() {
        let err = Cli::from_args(&["dure"], &["resume", "--help"]).unwrap_err();
        assert!(err.output.contains("launched from the current directory"));
        let err = Cli::from_args(&["dure"], &["run", "--help"]).unwrap_err();
        assert!(err.output.contains("Always creates a new session"));
    }
}