// Copyright (c) 2020 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0
//

// Description: Client side of ttRPC comms

use crate::types::{Config, Options};
use crate::utils;
use anyhow::{anyhow, Result};
use byteorder::ByteOrder;
use nix::sys::socket::{connect, socket, AddressFamily, SockAddr, SockFlag, SockType, UnixAddr};
use protocols::agent::*;
use protocols::agent_ttrpc::*;
use protocols::health::*;
use protocols::health_ttrpc::*;
use slog::{debug, info};
use std::io;
use std::io::Write; // XXX: for flush()
use std::os::unix::io::{IntoRawFd, RawFd};
use std::os::unix::net::UnixStream;
use std::thread::sleep;
use std::time::Duration;
use ttrpc;
use ttrpc::context::Context;

// Hack until the actual Context type supports this.
fn clone_context(ctx: &Context) -> Context {
    Context {
        metadata: ctx.metadata.clone(),
        timeout_nano: ctx.timeout_nano,
    }
}

// Agent command handler type
//
// Notes:
//
// - 'cmdline' is the command line (command name and optional space separate
//   arguments).
// - 'options' can be read and written to, allowing commands to pass state to
//   each other via well-known option names.
type AgentCmdFp = fn(
    ctx: &Context,
    client: &AgentServiceClient,
    health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()>;

// Builtin command handler type
type BuiltinCmdFp = fn(args: &str) -> (Result<()>, bool);

enum ServiceType {
    Agent,
    Health,
}

// XXX: Agent command names *MUST* start with an upper-case letter.
struct AgentCmd {
    name: &'static str,
    st: ServiceType,
    fp: AgentCmdFp,
}

// XXX: Builtin command names *MUST* start with a lower-case letter.
struct BuiltinCmd {
    name: &'static str,
    descr: &'static str,
    fp: BuiltinCmdFp,
}

// Command that causes the agent to exit (iff tracing is enabled)
const SHUTDOWN_CMD: &'static str = "DestroySandbox";

// Command that requests this program ends
const CMD_QUIT: &'static str = "quit";
const CMD_REPEAT: &'static str = "repeat";

const DEFAULT_PROC_SIGNAL: &'static str = "SIGKILL";

const ERR_API_FAILED: &str = "API failed";

static AGENT_CMDS: &'static [AgentCmd] = &[
    AgentCmd {
        name: "AddARPNeighbors",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_add_arp_neighbors,
    },
    AgentCmd {
        name: "Check",
        st: ServiceType::Health,
        fp: agent_cmd_health_check,
    },
    AgentCmd {
        name: "Version",
        st: ServiceType::Health,
        fp: agent_cmd_health_version,
    },
    AgentCmd {
        name: "CloseStdin",
        st: ServiceType::Agent,
        fp: agent_cmd_container_close_stdin,
    },
    AgentCmd {
        name: "CopyFile",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_copy_file,
    },
    AgentCmd {
        name: "CreateContainer",
        st: ServiceType::Agent,
        fp: agent_cmd_container_create,
    },
    AgentCmd {
        name: "CreateSandbox",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_create,
    },
    AgentCmd {
        name: "DestroySandbox",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_destroy,
    },
    AgentCmd {
        name: "ExecProcess",
        st: ServiceType::Agent,
        fp: agent_cmd_container_exec,
    },
    AgentCmd {
        name: "GetGuestDetails",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_get_guest_details,
    },
    AgentCmd {
        name: "GetMetrics",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_get_metrics,
    },
    AgentCmd {
        name: "GetOOMEvent",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_get_oom_event,
    },
    AgentCmd {
        name: "ListInterfaces",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_list_interfaces,
    },
    AgentCmd {
        name: "ListRoutes",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_list_routes,
    },
    AgentCmd {
        name: "MemHotplugByProbe",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_mem_hotplug_by_probe,
    },
    AgentCmd {
        name: "OnlineCPUMem",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_online_cpu_mem,
    },
    AgentCmd {
        name: "PauseContainer",
        st: ServiceType::Agent,
        fp: agent_cmd_container_pause,
    },
    AgentCmd {
        name: "ReadStderr",
        st: ServiceType::Agent,
        fp: agent_cmd_container_read_stderr,
    },
    AgentCmd {
        name: "ReadStdout",
        st: ServiceType::Agent,
        fp: agent_cmd_container_read_stdout,
    },
    AgentCmd {
        name: "ReseedRandomDev",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_reseed_random_dev,
    },
    AgentCmd {
        name: "RemoveContainer",
        st: ServiceType::Agent,
        fp: agent_cmd_container_remove,
    },
    AgentCmd {
        name: "ResumeContainer",
        st: ServiceType::Agent,
        fp: agent_cmd_container_resume,
    },
    AgentCmd {
        name: "SetGuestDateTime",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_set_guest_date_time,
    },
    AgentCmd {
        name: "SignalProcess",
        st: ServiceType::Agent,
        fp: agent_cmd_container_signal_process,
    },
    AgentCmd {
        name: "StartContainer",
        st: ServiceType::Agent,
        fp: agent_cmd_container_start,
    },
    AgentCmd {
        name: "StartTracing",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_tracing_start,
    },
    AgentCmd {
        name: "StatsContainer",
        st: ServiceType::Agent,
        fp: agent_cmd_container_stats,
    },
    AgentCmd {
        name: "StopTracing",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_tracing_stop,
    },
    AgentCmd {
        name: "TtyWinResize",
        st: ServiceType::Agent,
        fp: agent_cmd_container_tty_win_resize,
    },
    AgentCmd {
        name: "UpdateContainer",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_update_container,
    },
    AgentCmd {
        name: "UpdateInterface",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_update_interface,
    },
    AgentCmd {
        name: "UpdateRoutes",
        st: ServiceType::Agent,
        fp: agent_cmd_sandbox_update_routes,
    },
    AgentCmd {
        name: "WaitProcess",
        st: ServiceType::Agent,
        fp: agent_cmd_container_wait_process,
    },
    AgentCmd {
        name: "WriteStdin",
        st: ServiceType::Agent,
        fp: agent_cmd_container_write_stdin,
    },
];

static BUILTIN_CMDS: &'static [BuiltinCmd] = &[
    BuiltinCmd {
        name: "echo",
        descr: "Display the arguments",
        fp: builtin_cmd_echo,
    },
    BuiltinCmd {
        name: "help",
        descr: "Alias for 'list'",
        fp: builtin_cmd_list,
    },
    BuiltinCmd {
        name: "list",
        descr: "List all available commands",
        fp: builtin_cmd_list,
    },
    BuiltinCmd {
        name: "repeat",
        descr: "Repeat the next command 'n' times [-1 for forever]",
        fp: builtin_cmd_repeat,
    },
    BuiltinCmd {
        name: "sleep",
        descr:
            "Pause for specified period number of nanoseconds (supports human-readable suffixes [no floating points numbers])",
        fp: builtin_cmd_sleep,
    },
    BuiltinCmd {
        name: CMD_QUIT,
        descr: "Exit this program",
        fp: builtin_cmd_quit,
    },
];

fn get_agent_cmd_names() -> Vec<String> {
    let mut names = Vec::new();

    for cmd in AGENT_CMDS {
        names.push(cmd.name.to_string());
    }

    names
}

fn get_agent_cmd_details() -> Vec<String> {
    let mut cmds = Vec::new();

    for cmd in AGENT_CMDS {
        let service = match cmd.st {
            ServiceType::Agent => "agent",
            ServiceType::Health => "health",
        };

        cmds.push(format!("{} ({} service)", cmd.name, service));
    }

    cmds
}

fn get_agent_cmd_func(name: &str) -> Result<AgentCmdFp> {
    for cmd in AGENT_CMDS {
        if cmd.name == name {
            return Ok(cmd.fp);
        }
    }

    Err(anyhow!("Invalid command: {:?}", name))
}

fn get_builtin_cmd_details() -> Vec<String> {
    let mut cmds = Vec::new();

    for cmd in BUILTIN_CMDS {
        cmds.push(format!("{} ({})", cmd.name, cmd.descr));
    }

    cmds
}

fn get_all_cmd_details() -> Vec<String> {
    let mut cmds = get_builtin_cmd_details();

    cmds.append(&mut get_agent_cmd_names());

    cmds
}

fn get_builtin_cmd_func(name: &str) -> Result<BuiltinCmdFp> {
    for cmd in BUILTIN_CMDS {
        if cmd.name == name {
            return Ok(cmd.fp);
        }
    }

    Err(anyhow!("Invalid command: {:?}", name))
}

fn client_create_vsock_fd(cid: libc::c_uint, port: u32) -> Result<RawFd> {
    let fd = socket(
        AddressFamily::Vsock,
        SockType::Stream,
        SockFlag::SOCK_CLOEXEC,
        None,
    )
    .map_err(|e| anyhow!(e))?;

    let sock_addr = SockAddr::new_vsock(cid, port);

    connect(fd, &sock_addr).map_err(|e| anyhow!(e))?;

    Ok(fd)
}

fn create_ttrpc_client(server_address: String) -> Result<ttrpc::Client> {
    if server_address == "" {
        return Err(anyhow!("server address cannot be blank"));
    }

    let fields: Vec<&str> = server_address.split("://").collect();

    if fields.len() != 2 {
        return Err(anyhow!("invalid server address URI"));
    }

    let scheme = fields[0].to_lowercase();

    let fd: RawFd = match scheme.as_str() {
        // Formats:
        //
        // - "unix://absolute-path" (domain socket)
        //   (example: "unix:///tmp/domain.socket")
        //
        // - "unix://@absolute-path" (abstract socket)
        //   (example: "unix://@/tmp/abstract.socket")
        //
        "unix" => {
            let mut abstract_socket = false;

            let mut path = fields[1].to_string();

            if path.starts_with('@') {
                abstract_socket = true;

                // Remove the magic abstract-socket request character ('@')
                // and crucially add a trailing nul terminator (required to
                // interoperate with the ttrpc crate).
                path = path[1..].to_string() + &"\x00".to_string();
            }

            if abstract_socket {
                let socket_fd = match socket(
                    AddressFamily::Unix,
                    SockType::Stream,
                    SockFlag::empty(),
                    None,
                ) {
                    Ok(s) => s,
                    Err(e) => return Err(anyhow!(e).context("Failed to create Unix Domain socket")),
                };

                let unix_addr = match UnixAddr::new_abstract(path.as_bytes()) {
                    Ok(s) => s,
                    Err(e) => {
                        return Err(
                            anyhow!(e).context("Failed to create Unix Domain abstract socket")
                        )
                    }
                };

                let sock_addr = SockAddr::Unix(unix_addr);

                connect(socket_fd, &sock_addr).map_err(|e| {
                    anyhow!(e).context("Failed to connect to Unix Domain abstract socket")
                })?;

                socket_fd
            } else {
                let stream = match UnixStream::connect(path) {
                    Ok(s) => s,
                    Err(e) => {
                        return Err(
                            anyhow!(e).context("failed to create named UNIX Domain stream socket")
                        )
                    }
                };

                stream.into_raw_fd()
            }
        }
        // Format: "vsock://cid:port"
        "vsock" => {
            let addr: Vec<&str> = fields[1].split(':').collect();

            if addr.len() != 2 {
                return Err(anyhow!("invalid VSOCK server address URI"));
            }

            let cid: u32 = match addr[0] {
                "-1" | "" => libc::VMADDR_CID_ANY,
                _ => match addr[0].parse::<u32>() {
                    Ok(c) => c,
                    Err(e) => return Err(anyhow!(e).context("VSOCK CID is not numeric")),
                },
            };

            let port: u32 = match addr[1].parse::<u32>() {
                Ok(r) => r,
                Err(e) => return Err(anyhow!(e).context("VSOCK port is not numeric")),
            };

            client_create_vsock_fd(cid, port).map_err(|e| {
                anyhow!(e).context("failed to create VSOCK connection (check agent is running)")
            })?
        }
        _ => {
            return Err(anyhow!("invalid server address URI scheme: {:?}", scheme));
        }
    };

    Ok(ttrpc::client::Client::new(fd))
}

fn kata_service_agent(server_address: String) -> Result<AgentServiceClient> {
    let ttrpc_client = create_ttrpc_client(server_address)?;

    Ok(AgentServiceClient::new(ttrpc_client))
}

fn kata_service_health(server_address: String) -> Result<HealthClient> {
    let ttrpc_client = create_ttrpc_client(server_address)?;

    Ok(HealthClient::new(ttrpc_client))
}

fn announce(cfg: &Config) {
    info!(sl!(), "announce"; "config" => format!("{:?}", cfg));
}

pub fn client(cfg: &Config, commands: Vec<&str>) -> Result<()> {
    if commands.len() == 1 && commands[0] == "list" {
        println!("Built-in commands:\n");

        let mut builtin_cmds = get_builtin_cmd_details();
        builtin_cmds.sort();
        builtin_cmds.iter().for_each(|n| println!("  {}", n));

        println!();

        println!("Agent API commands:\n");

        let mut agent_cmds = get_agent_cmd_details();
        agent_cmds.sort();
        agent_cmds.iter().for_each(|n| println!("  {}", n));

        println!();

        return Ok(());
    }

    announce(cfg);

    // Create separate connections for each of the services provided
    // by the agent.
    let client = kata_service_agent(cfg.server_address.clone())?;
    let health = kata_service_health(cfg.server_address.clone())?;

    let mut options = Options::new();

    let ttrpc_ctx = ttrpc::context::with_timeout(cfg.timeout_nano);

    // Special-case loading the OCI config file so it is accessible
    // to all commands.
    let oci_spec_json = utils::get_oci_spec_json(cfg)?;
    options.insert("spec".to_string(), oci_spec_json);

    // Convenience option
    options.insert("bundle-dir".to_string(), cfg.bundle_dir.clone());

    info!(sl!(), "client setup complete";
        "server-address" => cfg.server_address.to_string());

    if cfg.interactive {
        return interactive_client_loop(&cfg, &mut options, &client, &health, &ttrpc_ctx);
    }

    let mut repeat_count = 1;

    for cmd in commands {
        if cmd.starts_with(CMD_REPEAT) {
            repeat_count = get_repeat_count(cmd);
            continue;
        }

        let (result, shutdown) = handle_cmd(
            &cfg,
            &client,
            &health,
            &ttrpc_ctx,
            repeat_count,
            &mut options,
            &cmd,
        );
        if result.is_err() {
            return result;
        }

        if shutdown {
            break;
        }

        // Reset
        repeat_count = 1;
    }

    Ok(())
}

// Handle internal and agent API commands.
fn handle_cmd(
    cfg: &Config,
    client: &AgentServiceClient,
    health: &HealthClient,
    ctx: &Context,
    repeat_count: i64,
    options: &mut Options,
    cmdline: &str,
) -> (Result<()>, bool) {
    let fields: Vec<&str> = cmdline.split_whitespace().collect();

    let cmd = fields[0];

    if cmd == "" {
        // Ignore empty commands
        return (Ok(()), false);
    }

    let first = match cmd.chars().nth(0) {
        Some(c) => c,
        None => return (Err(anyhow!("failed to check command name")), false),
    };

    let args = if fields.len() > 1 {
        fields[1..].join(" ")
    } else {
        String::new()
    };

    let mut count = 0;

    let mut count_msg = String::new();

    if repeat_count < 0 {
        count_msg = "forever".to_string();
    }

    let mut error_count: u64 = 0;
    let mut result: (Result<()>, bool);

    loop {
        if repeat_count > 0 {
            count_msg = format!("{} of {}", count + 1, repeat_count);
        }

        info!(sl!(), "Run command {:} ({})", cmd, count_msg);

        if first.is_lowercase() {
            result = handle_builtin_cmd(cmd, &args);
        } else {
            result = handle_agent_cmd(ctx, client, health, options, cmd, &args);
        }

        if result.0.is_err() {
            if cfg.ignore_errors {
                error_count += 1;
                debug!(sl!(), "ignoring error for command {:}: {:?}", cmd, result.0);
            } else {
                return result;
            }
        }

        info!(
            sl!(),
            "Command {:} ({}) returned {:?}", cmd, count_msg, result
        );

        if repeat_count > 0 {
            count += 1;

            if count == repeat_count {
                break;
            }
        }
    }

    if cfg.ignore_errors {
        debug!(sl!(), "Error count for command {}: {}", cmd, error_count);
        (Ok(()), result.1)
    } else {
        result
    }
}

fn handle_builtin_cmd(cmd: &str, args: &str) -> (Result<()>, bool) {
    let f = match get_builtin_cmd_func(&cmd) {
        Ok(fp) => fp,
        Err(e) => return (Err(e), false),
    };

    f(&args)
}

// Execute the ttRPC specified by the first field of "line". Return a result
// along with a bool which if set means the client should shutdown.
fn handle_agent_cmd(
    ctx: &Context,
    client: &AgentServiceClient,
    health: &HealthClient,
    options: &mut Options,
    cmd: &str,
    args: &str,
) -> (Result<()>, bool) {
    let f = match get_agent_cmd_func(&cmd) {
        Ok(fp) => fp,
        Err(e) => return (Err(e), false),
    };

    let result = f(ctx, client, health, options, &args);
    if result.is_err() {
        return (result, false);
    }

    let shutdown = cmd == SHUTDOWN_CMD;

    (Ok(()), shutdown)
}

fn interactive_client_loop(
    cfg: &Config,
    options: &mut Options,
    client: &AgentServiceClient,
    health: &HealthClient,
    ctx: &Context,
) -> Result<()> {
    let result = builtin_cmd_list("");
    if result.0.is_err() {
        return result.0;
    }

    let mut repeat_count: i64 = 1;

    loop {
        let cmdline =
            readline("Enter command").map_err(|e| anyhow!(e).context("failed to read line"))?;

        if cmdline == "" {
            continue;
        }

        if cmdline.starts_with(CMD_REPEAT) {
            repeat_count = get_repeat_count(&cmdline);
            continue;
        }

        let (result, shutdown) =
            handle_cmd(cfg, client, health, ctx, repeat_count, options, &cmdline);
        if result.is_err() {
            return result;
        }

        if shutdown {
            break;
        }

        // Reset
        repeat_count = 1;
    }

    Ok(())
}

fn readline(prompt: &str) -> std::result::Result<String, String> {
    print!("{}: ", prompt);

    io::stdout()
        .flush()
        .map_err(|e| format!("failed to flush: {:?}", e))?;

    let mut line = String::new();

    std::io::stdin()
        .read_line(&mut line)
        .map_err(|e| format!("failed to read line: {:?}", e))?;

    // Remove NL
    Ok(line.trim_end().to_string())
}

fn agent_cmd_health_check(
    ctx: &Context,
    _client: &AgentServiceClient,
    health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let mut req = CheckRequest::default();

    let ctx = clone_context(ctx);

    // value unused
    req.set_service("".to_string());

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = health
        .check(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_health_version(
    ctx: &Context,
    _client: &AgentServiceClient,
    health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    // XXX: Yes, the API is actually broken!
    let mut req = CheckRequest::default();

    let ctx = clone_context(ctx);

    // value unused
    req.set_service("".to_string());

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = health
        .version(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_create(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = CreateSandboxRequest::default();

    let ctx = clone_context(ctx);

    let sid = utils::get_option("sid", options, args);
    req.set_sandbox_id(sid);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .create_sandbox(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_destroy(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = DestroySandboxRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .destroy_sandbox(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_create(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = CreateContainerRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    // FIXME: container create: add back "spec=file:///" support

    let grpc_spec = utils::get_grpc_spec(options, &cid).map_err(|e| anyhow!(e))?;

    req.set_container_id(cid);
    req.set_exec_id(exec_id);
    req.set_OCI(grpc_spec);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .create_container(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_remove(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = RemoveContainerRequest::default();

    let cid = utils::get_option("cid", options, args);

    let ctx = clone_context(ctx);

    req.set_container_id(cid);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .remove_container(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_exec(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = ExecProcessRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    let grpc_spec = utils::get_grpc_spec(options, &cid).map_err(|e| anyhow!(e))?;

    let bundle_dir = options
        .get("bundle-dir")
        .ok_or("BUG: bundle-dir missing")
        .map_err(|e| anyhow!(e))?;

    let process = grpc_spec
        .Process
        .into_option()
        .ok_or(format!(
            "failed to get process from OCI spec: {}",
            bundle_dir,
        ))
        .map_err(|e| anyhow!(e))?;

    req.set_container_id(cid);
    req.set_exec_id(exec_id);
    req.set_process(process);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .exec_process(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_stats(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = StatsContainerRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);

    req.set_container_id(cid);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .stats_container(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_pause(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = PauseContainerRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);

    req.set_container_id(cid);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .pause_container(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_resume(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = ResumeContainerRequest::default();

    let cid = utils::get_option("cid", options, args);

    let ctx = clone_context(ctx);

    req.set_container_id(cid);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .resume_container(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_start(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = StartContainerRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);

    req.set_container_id(cid);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .start_container(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_get_guest_details(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let mut req = GuestDetailsRequest::default();

    let ctx = clone_context(ctx);

    req.set_mem_block_size(true);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .get_guest_details(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_wait_process(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = WaitProcessRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    req.set_container_id(cid);
    req.set_exec_id(exec_id);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .wait_process(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_signal_process(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = SignalProcessRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    let mut sigstr = utils::get_option("signal", options, args);

    // Convert to a numeric
    if sigstr == "" {
        sigstr = DEFAULT_PROC_SIGNAL.to_string();
    }

    let signum = utils::signame_to_signum(&sigstr).map_err(|e| anyhow!(e))?;

    req.set_container_id(cid);
    req.set_exec_id(exec_id);
    req.set_signal(signum as u32);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .signal_process(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_tracing_start(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = StartTracingRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .start_tracing(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_tracing_stop(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = StopTracingRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .stop_tracing(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_update_interface(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = UpdateInterfaceRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));
    let reply = client
        .update_interface(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    // FIXME: Implement 'UpdateInterface' fully.
    eprintln!("FIXME: 'UpdateInterface' not fully implemented");

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_update_routes(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = UpdateRoutesRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .update_routes(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    // FIXME: Implement 'UpdateRoutes' fully.
    eprintln!("FIXME: 'UpdateRoutes' not fully implemented");

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_list_interfaces(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = ListInterfacesRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .list_interfaces(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_list_routes(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = ListRoutesRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .list_routes(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_tty_win_resize(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = TtyWinResizeRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    req.set_container_id(cid);
    req.set_exec_id(exec_id);

    let rows_str = utils::get_option("row", options, args);

    if rows_str != "" {
        let rows = rows_str
            .parse::<u32>()
            .map_err(|e| anyhow!(e).context("invalid row size"))?;
        req.set_row(rows);
    }

    let cols_str = utils::get_option("column", options, args);

    if cols_str != "" {
        let cols = cols_str
            .parse::<u32>()
            .map_err(|e| anyhow!(e).context("invalid column size"))?;

        req.set_column(cols);
    }

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .tty_win_resize(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_close_stdin(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = CloseStdinRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    req.set_container_id(cid);
    req.set_exec_id(exec_id);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .close_stdin(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_read_stdout(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = ReadStreamRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    req.set_container_id(cid);
    req.set_exec_id(exec_id);

    let length_str = utils::get_option("len", options, args);

    if length_str != "" {
        let length = length_str
            .parse::<u32>()
            .map_err(|e| anyhow!(e).context("invalid length"))?;
        req.set_len(length);
    }

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .read_stdout(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_read_stderr(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = ReadStreamRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    req.set_container_id(cid);
    req.set_exec_id(exec_id);

    let length_str = utils::get_option("len", options, args);

    if length_str != "" {
        let length = length_str
            .parse::<u32>()
            .map_err(|e| anyhow!(e).context("invalid length"))?;
        req.set_len(length);
    }

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .read_stderr(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_container_write_stdin(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = WriteStreamRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);
    let exec_id = utils::get_option("exec_id", options, args);

    let str_data = utils::get_option("data", options, args);
    let data = utils::str_to_bytes(&str_data)?;

    req.set_container_id(cid);
    req.set_exec_id(exec_id);
    req.set_data(data.to_vec());

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .write_stdin(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_get_metrics(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = GetMetricsRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .get_metrics(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_get_oom_event(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = GetOOMEventRequest::default();

    let ctx = clone_context(ctx);

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .get_oom_event(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_copy_file(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = CopyFileRequest::default();

    let ctx = clone_context(ctx);

    let path = utils::get_option("path", options, args);
    if path != "" {
        req.set_path(path);
    }

    let file_size_str = utils::get_option("file_size", options, args);

    if file_size_str != "" {
        let file_size = file_size_str
            .parse::<i64>()
            .map_err(|e| anyhow!(e).context("invalid file_size"))?;

        req.set_file_size(file_size);
    }

    let file_mode_str = utils::get_option("file_mode", options, args);

    if file_mode_str != "" {
        let file_mode = file_mode_str
            .parse::<u32>()
            .map_err(|e| anyhow!(e).context("invalid file_mode"))?;

        req.set_file_mode(file_mode);
    }

    let dir_mode_str = utils::get_option("dir_mode", options, args);

    if dir_mode_str != "" {
        let dir_mode = dir_mode_str
            .parse::<u32>()
            .map_err(|e| anyhow!(e).context("invalid dir_mode"))?;

        req.set_dir_mode(dir_mode);
    }

    let uid_str = utils::get_option("uid", options, args);

    if uid_str != "" {
        let uid = uid_str
            .parse::<i32>()
            .map_err(|e| anyhow!(e).context("invalid uid"))?;

        req.set_uid(uid);
    }

    let gid_str = utils::get_option("gid", options, args);

    if gid_str != "" {
        let gid = gid_str
            .parse::<i32>()
            .map_err(|e| anyhow!(e).context("invalid gid"))?;
        req.set_gid(gid);
    }

    let offset_str = utils::get_option("offset", options, args);

    if offset_str != "" {
        let offset = offset_str
            .parse::<i64>()
            .map_err(|e| anyhow!(e).context("invalid offset"))?;
        req.set_offset(offset);
    }

    let data_str = utils::get_option("data", options, args);
    if data_str != "" {
        let data = utils::str_to_bytes(&data_str)?;
        req.set_data(data.to_vec());
    }

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .copy_file(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_reseed_random_dev(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = ReseedRandomDevRequest::default();

    let ctx = clone_context(ctx);

    let str_data = utils::get_option("data", options, args);
    let data = utils::str_to_bytes(&str_data)?;

    req.set_data(data.to_vec());

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .reseed_random_dev(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_online_cpu_mem(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = OnlineCPUMemRequest::default();

    let ctx = clone_context(ctx);

    let wait_str = utils::get_option("wait", options, args);

    if wait_str != "" {
        let wait = wait_str
            .parse::<bool>()
            .map_err(|e| anyhow!(e).context("invalid wait bool"))?;

        req.set_wait(wait);
    }

    let nb_cpus_str = utils::get_option("nb_cpus", options, args);

    if nb_cpus_str != "" {
        let nb_cpus = nb_cpus_str
            .parse::<u32>()
            .map_err(|e| anyhow!(e).context("invalid nb_cpus value"))?;

        req.set_nb_cpus(nb_cpus);
    }

    let cpu_only_str = utils::get_option("cpu_only", options, args);

    if cpu_only_str != "" {
        let cpu_only = cpu_only_str
            .parse::<bool>()
            .map_err(|e| anyhow!(e).context("invalid cpu_only bool"))?;

        req.set_cpu_only(cpu_only);
    }

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .online_cpu_mem(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_set_guest_date_time(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = SetGuestDateTimeRequest::default();

    let ctx = clone_context(ctx);

    let secs_str = utils::get_option("sec", options, args);

    if secs_str != "" {
        let secs = secs_str
            .parse::<i64>()
            .map_err(|e| anyhow!(e).context("invalid seconds"))?;

        req.set_Sec(secs);
    }

    let usecs_str = utils::get_option("usec", options, args);

    if usecs_str != "" {
        let usecs = usecs_str
            .parse::<i64>()
            .map_err(|e| anyhow!(e).context("invalid useconds"))?;

        req.set_Usec(usecs);
    }

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .set_guest_date_time(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_add_arp_neighbors(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    _options: &mut Options,
    _args: &str,
) -> Result<()> {
    let req = AddARPNeighborsRequest::default();

    let ctx = clone_context(ctx);

    // FIXME: Implement fully.
    eprintln!("FIXME: 'AddARPNeighbors' not fully implemented");

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .add_arp_neighbors(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_update_container(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = UpdateContainerRequest::default();

    let ctx = clone_context(ctx);

    let cid = utils::get_option("cid", options, args);

    req.set_container_id(cid);

    // FIXME: Implement fully
    eprintln!("FIXME: 'UpdateContainer' not fully implemented");

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .update_container(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

fn agent_cmd_sandbox_mem_hotplug_by_probe(
    ctx: &Context,
    client: &AgentServiceClient,
    _health: &HealthClient,
    options: &mut Options,
    args: &str,
) -> Result<()> {
    let mut req = MemHotplugByProbeRequest::default();

    let ctx = clone_context(ctx);

    // Expected to be a comma separated list of hex addresses
    let addr_list = utils::get_option("memHotplugProbeAddr", options, args);

    if addr_list != "" {
        let addrs: Vec<u64> = addr_list
            // Convert into a list of string values.
            .split(",")
            // Convert each string element into a u8 array of bytes, ignoring
            // those elements that fail the conversion.
            .filter_map(|s| hex::decode(s.trim_start_matches("0x")).ok())
            // "Stretch" the u8 byte slice into one of length 8
            // (to allow each 8 byte chunk to be converted into a u64).
            .map(|mut v| -> Vec<u8> {
                v.resize(8, 0x0);
                v
            })
            // Convert the slice of u8 bytes into a u64
            .map(|b| byteorder::LittleEndian::read_u64(&b))
            .collect();

        req.set_memHotplugProbeAddr(addrs);
    }

    debug!(sl!(), "sending request"; "request" => format!("{:?}", req));

    let reply = client
        .mem_hotplug_by_probe(ctx, &req)
        .map_err(|e| anyhow!("{:?}", e).context(ERR_API_FAILED))?;

    info!(sl!(), "response received";
        "response" => format!("{:?}", reply));

    Ok(())
}

#[inline]
fn builtin_cmd_repeat(_args: &str) -> (Result<()>, bool) {
    // XXX: NOP implementation. Due to the way repeat has to work, providing a
    // handler like this is "too late" to be useful. However, a handler
    // is required as "repeat" is a valid command.
    //
    // A cleaner approach would be to make `AgentCmd.fp` an `Option` which for
    // this command would be specified as `None`, but this is the only command
    // which doesn't need an implementation, so this approach is simpler :)

    (Ok(()), false)
}

fn builtin_cmd_sleep(args: &str) -> (Result<()>, bool) {
    let ns = match utils::human_time_to_ns(args) {
        Ok(t) => t,
        Err(e) => return (Err(e), false),
    };

    sleep(Duration::from_nanos(ns as u64));

    (Ok(()), false)
}

fn builtin_cmd_echo(args: &str) -> (Result<()>, bool) {
    println!("{}", args);

    (Ok(()), false)
}

fn builtin_cmd_quit(_args: &str) -> (Result<()>, bool) {
    (Ok(()), true)
}

fn builtin_cmd_list(_args: &str) -> (Result<()>, bool) {
    let cmds = get_all_cmd_details();

    cmds.iter().for_each(|n| println!(" - {}", n));

    println!("");

    (Ok(()), false)
}

fn get_repeat_count(cmdline: &str) -> i64 {
    let default_repeat_count: i64 = 1;

    let fields: Vec<&str> = cmdline.split_whitespace().collect();

    if fields.len() < 2 {
        return default_repeat_count;
    }

    if fields[0] != CMD_REPEAT {
        return default_repeat_count;
    }

    let count = fields[1];

    match count.parse::<i64>() {
        Ok(n) => return n,
        Err(_) => return default_repeat_count,
    }
}