Replace common functionality with rust implementation

mgr/src/bin/client.rs

@@ -0,0 +1,87 @@
+#![expect(
+    clippy::print_stderr,
+    clippy::print_stdout,
+    reason = "output is fine for cli"
+)]
+
+use std::{
+    env,
+    io::{self, Read as _},
+    net,
+    os::unix::net::UnixStream,
+    process, str,
+};
+
+use thiserror::Error;
+
+use mgr::{
+    Action,
+    cli::{self, CliCommand as _, ParseError},
+    wire::{client, socket},
+};
+
+#[derive(Debug, Error)]
+enum Error {
+    #[error(transparent)]
+    Io(#[from] io::Error),
+    #[error(transparent)]
+    Socket(#[from] socket::Error),
+    #[error(transparent)]
+    Send(#[from] client::SendError),
+    #[error(transparent)]
+    CliParse(#[from] cli::ParseError),
+    #[error("response is not valid utf8: {0}")]
+    ResponseNonUtf8(#[from] str::Utf8Error),
+}
+
+enum MainResult {
+    Success,
+    Failure(Error),
+}
+
+impl process::Termination for MainResult {
+    fn report(self) -> process::ExitCode {
+        match self {
+            Self::Success => process::ExitCode::SUCCESS,
+            Self::Failure(e) => {
+                eprintln!("Error: {e}");
+                process::ExitCode::FAILURE
+            }
+        }
+    }
+}
+
+fn main() -> MainResult {
+    fn inner() -> Result<(), Error> {
+        let mut args = env::args().skip(1);
+
+        let socket = socket::get_socket_path()?;
+        let mut stream = UnixStream::connect(socket)?;
+
+        let action =
+            Action::parse_str(args.next().ok_or(ParseError::MissingAction)?.as_str(), args)?;
+
+        action.send(&mut stream)?;
+
+        stream.shutdown(net::Shutdown::Write)?;
+
+        let response = {
+            let mut buf = Vec::new();
+            stream.read_to_end(&mut buf)?;
+            let response = str::from_utf8(&buf)?.to_owned();
+            drop(stream);
+            response
+        };
+
+        if !response.is_empty() {
+            println!("{response}");
+        }
+
+        Ok(())
+    }
+
+    match inner() {
+        Ok(()) => MainResult::Success,
+        Err(e) => MainResult::Failure(e),
+    }
+}

mgr/src/bin/main.rs

@@ -0,0 +1,105 @@
+#![expect(
+    clippy::print_stderr,
+    clippy::print_stdout,
+    reason = "output is fine for cli"
+)]
+
+use std::{env, process};
+
+use thiserror::Error;
+use tracing::Level;
+
+use mgr::{
+    self, Action, Exec as _,
+    cli::{CliCommand as _, ParseError},
+};
+
+#[derive(Debug, Error)]
+enum Error {
+    #[error(transparent)]
+    Power(#[from] mgr::power::Error),
+    #[error(transparent)]
+    Dmenu(#[from] mgr::dmenu::Error),
+    #[error(transparent)]
+    Server(#[from] mgr::wire::server::Error),
+    #[error(transparent)]
+    Presentation(#[from] mgr::present::Error),
+    #[error(transparent)]
+    Exec(#[from] mgr::ExecError),
+    #[error(transparent)]
+    ParseParse(#[from] ParseError),
+    #[error(transparent)]
+    Tracing(#[from] tracing::dispatcher::SetGlobalDefaultError),
+}
+
+enum MainResult {
+    Success,
+    Failure(Error),
+}
+
+impl process::Termination for MainResult {
+    fn report(self) -> process::ExitCode {
+        match self {
+            Self::Success => process::ExitCode::SUCCESS,
+            Self::Failure(e) => {
+                eprintln!("Error: {e}");
+                process::ExitCode::FAILURE
+            }
+        }
+    }
+}
+
+impl From<Error> for MainResult {
+    fn from(value: Error) -> Self {
+        Self::Failure(value)
+    }
+}
+
+fn init_tracing() -> Result<(), Error> {
+    tracing::subscriber::set_global_default(
+        tracing_subscriber::fmt()
+            .with_max_level(Level::DEBUG)
+            .event_format(
+                tracing_subscriber::fmt::format()
+                    .with_ansi(false)
+                    .with_target(false)
+                    .compact(),
+            )
+            .finish(),
+    )?;
+    Ok(())
+}
+
+fn main() -> MainResult {
+    fn inner() -> Result<(), Error> {
+        init_tracing()?;
+
+        let mut args = env::args().skip(1);
+
+        match args.next().ok_or(ParseError::MissingAction)?.as_str() {
+            "serve" => {
+                mgr::wire::server::run()?;
+                Ok(())
+            }
+            "run" => {
+                let action = Action::parse_str(
+                    args.next().ok_or(ParseError::MissingAction)?.as_str(),
+                    args,
+                )?;
+                if let Some(output) = action.execute()? {
+                    println!("{output}");
+                }
+                Ok(())
+            }
+            input => Err(ParseError::UnknownAction {
+                action: input.to_owned(),
+            }
+            .into()),
+        }
+    }
+
+    match inner() {
+        Ok(()) => MainResult::Success,
+        Err(e) => MainResult::Failure(e),
+    }
+}

mgr/src/brightness.rs

@@ -0,0 +1,77 @@
+use thiserror::Error;
+
+use super::{
+    Exec,
+    cli::{self, CliCommand},
+    cmd,
+    wire::{WireCommand, server},
+};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Cli(#[from] cli::ParseError),
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Action {
+    Inc,
+    Dec,
+}
+
+impl WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError> {
+        match input.next().ok_or(server::ParseError::Eof)? {
+            0x01 => Ok(Self::Inc),
+            0x02 => Ok(Self::Dec),
+            byte => Err(server::ParseError::Unknown(byte)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::Inc => vec![0x01],
+            Self::Dec => vec![0x02],
+        }
+    }
+}
+
+impl CliCommand for Action {
+    type ExecErr = Error;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        let result = match input {
+            "inc" => Self::Inc,
+            "dec" => Self::Dec,
+            s => {
+                return Err(cli::ParseError::UnknownAction {
+                    action: s.to_owned(),
+                });
+            }
+        };
+
+        let rest = rest.collect::<Vec<String>>();
+        if rest.is_empty() {
+            Ok(result)
+        } else {
+            Err(cli::ParseError::UnexpectedInput { rest })
+        }
+    }
+}
+
+impl Exec for Action {
+    type ExecErr = Error;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::Inc => cmd::command("brightnessctl", &["set", "8%+"])?,
+            Self::Dec => cmd::command("brightnessctl", &["set", "8%-"])?,
+        }
+        Ok(None)
+    }
+}

mgr/src/cli.rs

@@ -0,0 +1,19 @@
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum ParseError {
+    #[error("no action given")]
+    MissingAction,
+    #[error("unknown action: {action}")]
+    UnknownAction { action: String },
+    #[error("unexpected input: {rest:?}")]
+    UnexpectedInput { rest: Vec<String> },
+}
+
+pub trait CliCommand {
+    type ExecErr: From<ParseError>;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, ParseError>
+    where
+        Self: Sized;
+}

mgr/src/cmd.rs

@@ -0,0 +1,183 @@
+use std::{io, panic, process, str, thread};
+
+use thiserror::Error;
+use tracing::{Level, event};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error("command \"{command}\" failed: {error}")]
+    CommandInvocation {
+        command: &'static str,
+        error: io::Error,
+    },
+    #[error("command \"{command}\" was terminated by signal")]
+    CommandTerminatedBySignal { command: &'static str },
+    #[error(
+        "command \"{command}\" failed [{code}]: {stderr}",
+        code = match *.code {
+            Some(code) => &.code.to_string(),
+            _ => "unknown exit code",
+        },
+        stderr = if .stderr.is_empty() {
+            "[stderr empty]"
+        } else {
+            .stderr
+    })]
+    CommandFailed {
+        command: &'static str,
+        code: Option<i32>,
+        stderr: String,
+    },
+    #[error("{command} produced non-utf8 output: {error}")]
+    CommandOutputNonUtf8 {
+        command: &'static str,
+        error: str::Utf8Error,
+    },
+    #[error("failed writing to stdin of command \"{command}\": {error}")]
+    StdinWriteFailed {
+        command: &'static str,
+        error: io::Error,
+    },
+}
+
+pub(crate) fn command(command: &'static str, args: &[&str]) -> Result<(), Error> {
+    let _: FinishedProcess = run_command_checked(command, args)?;
+    Ok(())
+}
+
+pub(crate) fn run_command(command: &'static str, args: &[&str]) -> Result<FinishedProcess, Error> {
+    event!(Level::DEBUG, "running {command} {args:?}");
+    let proc = process::Command::new(command)
+        .args(args)
+        .output()
+        .map_err(|error| Error::CommandInvocation { command, error })?;
+
+    Ok(FinishedProcess {
+        exit_code: proc
+            .status
+            .code()
+            .ok_or(Error::CommandTerminatedBySignal { command })?,
+        stdout: str::from_utf8(&proc.stdout)
+            .map_err(|error| Error::CommandOutputNonUtf8 { command, error })?
+            .to_owned(),
+        stderr: str::from_utf8(&proc.stderr)
+            .map_err(|error| Error::CommandOutputNonUtf8 { command, error })?
+            .to_owned(),
+    })
+}
+
+pub(crate) fn run_command_checked(
+    command: &'static str,
+    args: &[&str],
+) -> Result<FinishedProcess, Error> {
+    let output = run_command(command, args)?;
+
+    if output.exit_code != 0_i32 {
+        event!(Level::DEBUG, "{command} {args:?} failed");
+        return Err(Error::CommandFailed {
+            command,
+            code: Some(output.exit_code),
+            stderr: output.stderr,
+        });
+    }
+
+    Ok(output)
+}
+
+pub(crate) fn command_output(command: &'static str, args: &[&str]) -> Result<String, Error> {
+    let output = run_command_checked(command, args)?;
+    Ok(output.stdout)
+}
+
+#[derive(Debug)]
+pub(crate) struct FinishedProcess {
+    pub exit_code: i32,
+    pub stdout: String,
+    pub stderr: String,
+}
+
+pub(crate) fn command_output_with_stdin_write(
+    command: &'static str,
+    args: &[&str],
+    input: &[u8],
+) -> Result<FinishedProcess, Error> {
+    use io::Write as _;
+
+    let process = process::Command::new(command)
+        .args(args)
+        .stdin(process::Stdio::piped())
+        .stdout(process::Stdio::piped())
+        .stderr(process::Stdio::null())
+        .spawn()
+        .map_err(|error| Error::CommandInvocation { command, error })?;
+
+    let mut stdin = process
+        .stdin
+        .as_ref()
+        .expect("stdin handle must be present");
+
+    stdin
+        .write_all(input)
+        .map_err(|error| Error::StdinWriteFailed { command, error })?;
+
+    let output = process
+        .wait_with_output()
+        .map_err(|error| Error::CommandInvocation { command, error })?;
+
+    let exit_code = output
+        .status
+        .code()
+        .ok_or(Error::CommandTerminatedBySignal { command })?;
+
+    let stdout = str::from_utf8(&output.stdout)
+        .map_err(|error| Error::CommandOutputNonUtf8 { command, error })?
+        .to_owned();
+
+    let stderr = str::from_utf8(&output.stderr)
+        .map_err(|error| Error::CommandOutputNonUtf8 { command, error })?
+        .to_owned();
+
+    Ok(FinishedProcess {
+        exit_code,
+        stdout,
+        stderr,
+    })
+}
+
+pub(crate) struct RunningProcess {
+    command: &'static str,
+    join_handle: thread::JoinHandle<Result<FinishedProcess, Error>>,
+}
+
+impl RunningProcess {
+    pub fn with<F: Fn() -> Result<(), E>, E: From<Error>>(
+        self,
+        f: F,
+    ) -> Result<FinishedProcess, E> {
+        f()?;
+        event!(
+            Level::DEBUG,
+            "waiting for process {} to finish",
+            self.command
+        );
+        let ret = match self.join_handle.join() {
+            Ok(ret) => ret?,
+            Err(e) => panic::resume_unwind(e),
+        };
+        event!(Level::DEBUG, "process {} finished", self.command);
+        Ok(ret)
+    }
+}
+
+pub(crate) fn start_command(
+    command: &'static str,
+    args: &'static [&'static str],
+) -> RunningProcess {
+    event!(Level::DEBUG, "starting {command} {args:?}");
+    let join_handle = thread::spawn(move || run_command_checked(command, args));
+
+    RunningProcess {
+        command,
+        join_handle,
+    }
+}

mgr/src/dirs.rs

@@ -0,0 +1,29 @@
+use std::path::PathBuf;
+
+use thiserror::Error;
+
+use super::env;
+
+const ENV_XDG_RUNTIME_DIR: &str = "XDG_RUNTIME_DIR";
+const ENV_XDG_CACHE_DIR: &str = "XDG_CACHE_HOME";
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error(transparent)]
+    Env(#[from] env::Error),
+}
+
+pub(crate) fn xdg_runtime_dir() -> Result<Option<PathBuf>, Error> {
+    Ok(env::get(ENV_XDG_RUNTIME_DIR)?.map(PathBuf::from))
+}
+
+pub(crate) fn require_xdg_runtime_dir() -> Result<PathBuf, Error> {
+    Ok(PathBuf::from(env::require(ENV_XDG_RUNTIME_DIR)?))
+}
+
+pub(crate) fn xdg_cache_dir() -> Result<PathBuf, Error> {
+    Ok(match env::get(ENV_XDG_CACHE_DIR)? {
+        Some(value) => PathBuf::from(value),
+        None => PathBuf::from(env::require("HOME")?).join(".cache"),
+    })
+}

mgr/src/dmenu.rs

@@ -0,0 +1,66 @@
+use std::{fmt::Write as _, num};
+
+use thiserror::Error;
+use tracing::{Level, event};
+
+use super::cmd;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("rofi did not return an integer: {error}")]
+    RofiNonIntOutput { error: num::ParseIntError },
+    #[error("rofi returned an invalid indexx: {index}")]
+    RofiInvalidIndex { index: usize },
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+}
+
+pub(crate) fn get_choice(actions: &[&'static str]) -> Result<Option<&'static str>, Error> {
+    const ROFI: &str = "rofi";
+
+    event!(Level::DEBUG, "starting rofi");
+
+    let process = cmd::command_output_with_stdin_write(
+        ROFI,
+        &[
+            "-dmenu",
+            "-p",
+            "action",
+            "-l",
+            &actions.len().to_string(),
+            "-no-custom",
+            "-sync",
+            "-format",
+            "i",
+        ],
+        actions
+            .iter()
+            .enumerate()
+            .fold(String::new(), |mut output, (i, action)| {
+                writeln!(
+                    output,
+                    "({i}) {action}",
+                    i = i.checked_add(1).expect("too many action")
+                )
+                .expect("writing to string cannot fail");
+                output
+            })
+            .as_bytes(),
+    )?;
+
+    if process.exit_code == 1 {
+        Ok(None)
+    } else {
+        let choice = process
+            .stdout
+            .trim()
+            .parse::<usize>()
+            .map_err(|error| Error::RofiNonIntOutput { error })?;
+
+        Ok(Some(
+            actions
+                .get(choice)
+                .ok_or(Error::RofiInvalidIndex { index: choice })?,
+        ))
+    }
+}

mgr/src/dunst.rs

@@ -0,0 +1,40 @@
+use thiserror::Error;
+
+use super::cmd;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+    #[error("dunstctl is-paused returned unknown output: {output}")]
+    DunstctlIsPausedUnknownOutput { output: String },
+}
+
+#[derive(Clone, Copy)]
+pub(crate) enum Status {
+    Paused,
+    Unpaused,
+}
+
+pub(crate) fn set_status(status: Status) -> Result<(), Error> {
+    Ok(cmd::command(
+        "dunstctl",
+        &[
+            "set-paused",
+            match status {
+                Status::Paused => "true",
+                Status::Unpaused => "false",
+            },
+        ],
+    )?)
+}
+
+pub(crate) fn is_paused() -> Result<bool, Error> {
+    let output = cmd::command_output("dunstctl", &["is-paused"])?;
+
+    match output.trim() {
+        "true" => Ok(true),
+        "false" => Ok(false),
+        _ => Err(Error::DunstctlIsPausedUnknownOutput { output }),
+    }
+}

mgr/src/env.rs

@@ -0,0 +1,28 @@
+use std::{env, ffi::OsString};
+
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error(
+        "env variable \"{name}\" is not valid unicode: \"{value}\"",
+        value = value.to_string_lossy()
+    )]
+    EnvNotUnicode { name: &'static str, value: OsString },
+    #[error("env variable \"{name}\" not found")]
+    EnvNotFound { name: &'static str },
+}
+
+pub(crate) fn get(var: &'static str) -> Result<Option<String>, Error> {
+    match env::var(var) {
+        Ok(value) => Ok(Some(value)),
+        Err(e) => match e {
+            env::VarError::NotPresent => Ok(None),
+            env::VarError::NotUnicode(value) => Err(Error::EnvNotUnicode { name: var, value }),
+        },
+    }
+}
+
+pub(crate) fn require(var: &'static str) -> Result<String, Error> {
+    get(var)?.ok_or(Error::EnvNotFound { name: var })
+}

mgr/src/lib.rs

@@ -0,0 +1,190 @@
+use thiserror::Error;
+
+pub(crate) mod brightness;
+pub mod cli;
+pub(crate) mod cmd;
+pub(crate) mod dirs;
+pub mod dmenu;
+pub(crate) mod dunst;
+pub(crate) mod env;
+pub mod power;
+pub mod present;
+pub(crate) mod pulseaudio;
+pub(crate) mod redshift;
+pub(crate) mod spotify;
+pub(crate) mod systemd;
+pub(crate) mod theme;
+pub(crate) mod weather;
+pub mod wire;
+
+#[derive(Debug, Error)]
+pub enum ExecError {
+    #[error(transparent)]
+    Power(#[from] power::Error),
+    #[error(transparent)]
+    Presentation(#[from] present::Error),
+    #[error(transparent)]
+    Pulseaudio(#[from] pulseaudio::Error),
+    #[error(transparent)]
+    Theme(#[from] theme::Error),
+    #[error(transparent)]
+    Spotify(#[from] spotify::Error),
+    #[error(transparent)]
+    Redshift(#[from] redshift::Error),
+    #[error(transparent)]
+    Weather(#[from] weather::Error),
+    #[error(transparent)]
+    Brightness(#[from] brightness::Error),
+    #[error(transparent)]
+    Parse(#[from] cli::ParseError),
+}
+
+#[derive(Debug)]
+pub enum Action {
+    Power(power::Action),
+    Present(present::Action),
+    Pulseaudio(pulseaudio::Action),
+    Theme(theme::Action),
+    Spotify(spotify::Action),
+    Redshift(redshift::Action),
+    Weather(weather::Action),
+    Brightness(brightness::Action),
+}
+
+impl wire::WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, wire::server::ParseError> {
+        match input.next().ok_or(wire::server::ParseError::Eof)? {
+            0x01 => Ok(Self::Power(power::Action::parse_wire(input)?)),
+            0x02 => Ok(Self::Present(present::Action::parse_wire(input)?)),
+            0x03 => Ok(Self::Pulseaudio(pulseaudio::Action::parse_wire(input)?)),
+            0x04 => Ok(Self::Theme(theme::Action::parse_wire(input)?)),
+            0x05 => Ok(Self::Spotify(spotify::Action::parse_wire(input)?)),
+            0x06 => Ok(Self::Redshift(redshift::Action::parse_wire(input)?)),
+            0x07 => Ok(Self::Weather(weather::Action::parse_wire(input)?)),
+            0x08 => Ok(Self::Brightness(brightness::Action::parse_wire(input)?)),
+            other => Err(wire::server::ParseError::Unknown(other)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::Power(action) => {
+                let mut v = vec![0x01];
+                v.extend_from_slice(&action.to_wire());
+                v
+            }
+            Self::Present(action) => {
+                let mut v = vec![0x02];
+                v.extend_from_slice(&action.to_wire());
+                v
+            }
+            Self::Pulseaudio(action) => {
+                let mut v = vec![0x03];
+                v.extend_from_slice(&action.to_wire());
+                v
+            }
+            Self::Theme(action) => {
+                let mut v = vec![0x04];
+                v.extend_from_slice(&action.to_wire());
+                v
+            }
+            Self::Spotify(action) => {
+                let mut v = vec![0x05];
+                v.extend_from_slice(&action.to_wire());
+                v
+            }
+            Self::Redshift(action) => {
+                let mut v = vec![0x06];
+                v.extend_from_slice(&action.to_wire());
+                v
+            }
+            Self::Weather(action) => {
+                let mut v = vec![0x07];
+                v.extend_from_slice(&action.to_wire());
+                v
+            }
+            Self::Brightness(action) => {
+                let mut v = vec![0x08];
+                v.extend_from_slice(&action.to_wire());
+                v
+            }
+        }
+    }
+}
+
+impl cli::CliCommand for Action {
+    type ExecErr = ExecError;
+
+    fn parse_str(
+        input: &str,
+        mut rest: impl Iterator<Item = String>,
+    ) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        match input {
+            "power" => {
+                let choice = rest.next().ok_or(cli::ParseError::MissingAction)?;
+                Ok(Self::Power(power::Action::parse_str(&choice, rest)?))
+            }
+            "present" => {
+                let choice = rest.next().ok_or(cli::ParseError::MissingAction)?;
+                Ok(Self::Present(present::Action::parse_str(&choice, rest)?))
+            }
+            "pulseaudio" => {
+                let choice = rest.next().ok_or(cli::ParseError::MissingAction)?;
+                Ok(Self::Pulseaudio(pulseaudio::Action::parse_str(
+                    &choice, rest,
+                )?))
+            }
+            "theme" => {
+                let choice = rest.next().ok_or(cli::ParseError::MissingAction)?;
+                Ok(Self::Theme(theme::Action::parse_str(&choice, rest)?))
+            }
+            "spotify" => {
+                let choice = rest.next().ok_or(cli::ParseError::MissingAction)?;
+                Ok(Self::Spotify(spotify::Action::parse_str(&choice, rest)?))
+            }
+            "redshift" => {
+                let choice = rest.next().ok_or(cli::ParseError::MissingAction)?;
+                Ok(Self::Redshift(redshift::Action::parse_str(&choice, rest)?))
+            }
+            "weather" => {
+                let choice = rest.next().ok_or(cli::ParseError::MissingAction)?;
+                Ok(Self::Weather(weather::Action::parse_str(&choice, rest)?))
+            }
+            "brightness" => {
+                let choice = rest.next().ok_or(cli::ParseError::MissingAction)?;
+                Ok(Self::Brightness(brightness::Action::parse_str(
+                    &choice, rest,
+                )?))
+            }
+            s => Err(cli::ParseError::UnknownAction {
+                action: s.to_owned(),
+            }),
+        }
+    }
+}
+
+pub trait Exec {
+    type ExecErr: Into<ExecError>;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr>;
+}
+
+impl Exec for Action {
+    type ExecErr = ExecError;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::Power(action) => Ok(action.execute()?),
+            Self::Present(action) => Ok(action.execute()?),
+            Self::Pulseaudio(action) => Ok(action.execute()?),
+            Self::Theme(action) => Ok(action.execute()?),
+            Self::Spotify(action) => Ok(action.execute()?),
+            Self::Redshift(action) => Ok(action.execute()?),
+            Self::Weather(action) => Ok(action.execute()?),
+            Self::Brightness(action) => Ok(action.execute()?),
+        }
+    }
+}

mgr/src/power.rs

@@ -0,0 +1,223 @@
+use thiserror::Error;
+use tracing::{Level, event};
+
+use super::{
+    Exec,
+    cli::{self, CliCommand},
+    cmd, dmenu, dunst, spotify,
+    wire::{WireCommand, server},
+};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Dunst(#[from] dunst::Error),
+    #[error("unknown action: {action}")]
+    UnknownAction { action: String },
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+    #[error(transparent)]
+    Dmenu(#[from] dmenu::Error),
+    #[error(transparent)]
+    Cli(#[from] cli::ParseError),
+    #[error(transparent)]
+    Spotify(#[from] spotify::Error),
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Action {
+    Menu,
+    Lock,
+    Suspend,
+    Hibernate,
+    Reboot,
+    Poweroff,
+}
+
+impl Action {
+    fn as_str(self) -> &'static str {
+        match self {
+            Self::Menu => "menu",
+            Self::Lock => "lock",
+            Self::Suspend => "suspend",
+            Self::Hibernate => "hibernate",
+            Self::Reboot => "reboot",
+            Self::Poweroff => "poweroff",
+        }
+    }
+}
+
+impl WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError> {
+        match input.next().ok_or(server::ParseError::Eof)? {
+            0x01 => Ok(Self::Menu),
+            0x02 => Ok(Self::Lock),
+            0x03 => Ok(Self::Suspend),
+            0x04 => Ok(Self::Hibernate),
+            0x05 => Ok(Self::Reboot),
+            0x06 => Ok(Self::Poweroff),
+            byte => Err(server::ParseError::Unknown(byte)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::Menu => vec![0x01],
+            Self::Lock => vec![0x02],
+            Self::Suspend => vec![0x03],
+            Self::Hibernate => vec![0x04],
+            Self::Reboot => vec![0x05],
+            Self::Poweroff => vec![0x06],
+        }
+    }
+}
+
+impl Exec for Action {
+    type ExecErr = Error;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::Menu => menu()?,
+            Self::Lock => lock_and_screen_off()?,
+            Self::Suspend => lock_and_suspend()?,
+            Self::Hibernate => hibernate()?,
+            Self::Reboot => reboot()?,
+            Self::Poweroff => poweroff()?,
+        }
+        Ok(None)
+    }
+}
+
+impl CliCommand for Action {
+    type ExecErr = Error;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        let result = match input {
+            "menu" => Self::Menu,
+            "lock" => Self::Lock,
+            "suspend" => Self::Suspend,
+            "hibernate" => Self::Hibernate,
+            "reboot" => Self::Reboot,
+            "shutdown" => Self::Poweroff,
+            s => {
+                return Err(cli::ParseError::UnknownAction {
+                    action: s.to_owned(),
+                });
+            }
+        };
+
+        let rest = rest.collect::<Vec<String>>();
+        if rest.is_empty() {
+            Ok(result)
+        } else {
+            Err(cli::ParseError::UnexpectedInput { rest })
+        }
+    }
+}
+
+const MENU_ACTIONS: &[Action] = &[
+    Action::Lock,
+    Action::Suspend,
+    Action::Hibernate,
+    Action::Reboot,
+    Action::Poweroff,
+];
+
+fn menu() -> Result<(), Error> {
+    let choice = dmenu::get_choice(
+        &MENU_ACTIONS
+            .iter()
+            .map(|action| action.as_str())
+            .collect::<Vec<&str>>(),
+    )?;
+
+    if let Some(choice) = choice {
+        MENU_ACTIONS
+            .iter()
+            .find(|action| action.as_str() == choice)
+            .copied()
+            .expect("choice must be one of the valid values")
+            .execute()?;
+    } else {
+        event!(Level::DEBUG, "rofi was cancelled");
+    }
+
+    Ok(())
+}
+
+fn screen_off() -> Result<(), Error> {
+    Ok(cmd::command("xset", &["dpms", "force", "off"])?)
+}
+
+fn lock() -> Result<cmd::RunningProcess, Error> {
+    spotify::pause()?;
+
+    let lock_handle = cmd::start_command(
+        "i3lock",
+        &[
+            "--nofork",
+            "--show-failed-attempts",
+            "--ignore-empty-password",
+            "--color",
+            "000000",
+        ],
+    );
+
+    Ok(lock_handle)
+}
+
+fn reset_screen() -> Result<(), Error> {
+    Ok(cmd::command(
+        "systemctl",
+        &["--user", "restart", "dpms.service"],
+    )?)
+}
+
+fn lock_and_screen_off() -> Result<(), Error> {
+    let dunst_paused = dunst::is_paused()?;
+    if dunst_paused {
+        dunst::set_status(dunst::Status::Paused)?;
+    }
+
+    lock()?.with(|| -> Result<(), Error> {
+        screen_off()?;
+        Ok(())
+    })?;
+
+    if dunst_paused {
+        dunst::set_status(dunst::Status::Unpaused)?;
+    }
+
+    reset_screen()?;
+
+    Ok(())
+}
+
+fn suspend() -> Result<(), Error> {
+    Ok(cmd::command("systemctl", &["suspend"])?)
+}
+
+fn hibernate() -> Result<(), Error> {
+    Ok(cmd::command("systemctl", &["hibernate"])?)
+}
+
+fn reboot() -> Result<(), Error> {
+    Ok(cmd::command("systemctl", &["reboot"])?)
+}
+
+fn poweroff() -> Result<(), Error> {
+    Ok(cmd::command("systemctl", &["poweroff"])?)
+}
+
+fn lock_and_suspend() -> Result<(), Error> {
+    lock()?.with(|| -> Result<(), Error> {
+        screen_off()?;
+        suspend()?;
+        Ok(())
+    })?;
+
+    Ok(())
+}

mgr/src/present.rs

@@ -0,0 +1,154 @@
+use std::{fs, io, path::PathBuf};
+
+use thiserror::Error;
+
+use super::{
+    Exec,
+    cli::{self, CliCommand},
+    cmd, dirs, dunst, redshift, spotify,
+    wire::{WireCommand, server},
+};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Io(#[from] io::Error),
+    #[error("unknown action: {action}")]
+    UnknownAction { action: String },
+    #[error(transparent)]
+    Cli(#[from] cli::ParseError),
+    #[error(transparent)]
+    Dirs(#[from] dirs::Error),
+    #[error(transparent)]
+    Dunst(#[from] dunst::Error),
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+    #[error(transparent)]
+    Redshift(#[from] redshift::Error),
+    #[error(transparent)]
+    Spotify(#[from] spotify::Error),
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Action {
+    On,
+    Off,
+    Toggle,
+    Status,
+}
+
+impl WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError> {
+        match input.next().ok_or(server::ParseError::Eof)? {
+            0x01 => Ok(Self::On),
+            0x02 => Ok(Self::Off),
+            0x03 => Ok(Self::Toggle),
+            0x04 => Ok(Self::Status),
+            byte => Err(server::ParseError::Unknown(byte)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::On => vec![0x01],
+            Self::Off => vec![0x02],
+            Self::Toggle => vec![0x03],
+            Self::Status => vec![0x04],
+        }
+    }
+}
+
+fn status_file() -> Result<PathBuf, Error> {
+    Ok(dirs::require_xdg_runtime_dir()?.join("presentation-mode-on"))
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Status {
+    On,
+    Off,
+}
+
+fn status() -> Result<Status, Error> {
+    Ok(if status_file()?.exists() {
+        Status::On
+    } else {
+        Status::Off
+    })
+}
+
+fn on() -> Result<(), Error> {
+    drop(fs::File::create(status_file()?)?);
+    dunst::set_status(dunst::Status::Paused)?;
+    redshift::set(redshift::Status::Off)?;
+    spotify::set(spotify::Status::Off)?;
+    Ok(())
+}
+
+fn off() -> Result<(), Error> {
+    fs::remove_file(status_file()?)?;
+    dunst::set_status(dunst::Status::Unpaused)?;
+    redshift::set(redshift::Status::On)?;
+    spotify::set(spotify::Status::On)?;
+    Ok(())
+}
+
+fn toggle() -> Result<(), Error> {
+    match status()? {
+        Status::On => off()?,
+        Status::Off => on()?,
+    }
+    Ok(())
+}
+
+impl Exec for Action {
+    type ExecErr = Error;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::On => {
+                on()?;
+                Ok(None)
+            }
+            Self::Off => {
+                off()?;
+                Ok(None)
+            }
+            Self::Toggle => {
+                toggle()?;
+                Ok(None)
+            }
+            Self::Status => Ok(match status()? {
+                Status::On => Some("on".to_owned()),
+                Status::Off => Some("off".to_owned()),
+            }),
+        }
+    }
+}
+
+impl CliCommand for Action {
+    type ExecErr = Error;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        let result = match input {
+            "on" => Self::On,
+            "off" => Self::Off,
+            "toggle" => Self::Toggle,
+            "status" => Self::Status,
+            s => {
+                return Err(cli::ParseError::UnknownAction {
+                    action: s.to_owned(),
+                });
+            }
+        };
+
+        let rest = rest.collect::<Vec<String>>();
+        if rest.is_empty() {
+            Ok(result)
+        } else {
+            Err(cli::ParseError::UnexpectedInput { rest })
+        }
+    }
+}

mgr/src/pulseaudio.rs

@@ -0,0 +1,112 @@
+use thiserror::Error;
+
+use super::{
+    Exec,
+    cli::{self, CliCommand},
+    cmd,
+    wire::{WireCommand, server},
+};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Cli(#[from] cli::ParseError),
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Action {
+    InputToggle,
+    OutputToggle,
+    OutputInc,
+    OutputDec,
+}
+
+impl WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError> {
+        match input.next().ok_or(server::ParseError::Eof)? {
+            0x01 => Ok(Self::InputToggle),
+            0x02 => Ok(Self::OutputToggle),
+            0x03 => Ok(Self::OutputInc),
+            0x04 => Ok(Self::OutputDec),
+            byte => Err(server::ParseError::Unknown(byte)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::InputToggle => vec![0x01],
+            Self::OutputToggle => vec![0x02],
+            Self::OutputInc => vec![0x03],
+            Self::OutputDec => vec![0x04],
+        }
+    }
+}
+
+impl CliCommand for Action {
+    type ExecErr = Error;
+
+    fn parse_str(
+        input: &str,
+        mut rest: impl Iterator<Item = String>,
+    ) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        let result = match input {
+            "input" => match rest.next().ok_or(cli::ParseError::MissingAction)?.as_str() {
+                "toggle" => Self::InputToggle,
+                s => {
+                    return Err(cli::ParseError::UnknownAction {
+                        action: s.to_owned(),
+                    });
+                }
+            },
+            "output" => match rest.next().ok_or(cli::ParseError::MissingAction)?.as_str() {
+                "toggle" => Self::OutputToggle,
+                "inc" => Self::OutputInc,
+                "dec" => Self::OutputDec,
+                s => {
+                    return Err(cli::ParseError::UnknownAction {
+                        action: s.to_owned(),
+                    });
+                }
+            },
+            s => {
+                return Err(cli::ParseError::UnknownAction {
+                    action: s.to_owned(),
+                });
+            }
+        };
+
+        let rest = rest.collect::<Vec<String>>();
+        if rest.is_empty() {
+            Ok(result)
+        } else {
+            Err(cli::ParseError::UnexpectedInput { rest })
+        }
+    }
+}
+
+impl Exec for Action {
+    type ExecErr = Error;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::InputToggle => {
+                cmd::command("pactl", &["set-source-mute", "@DEFAULT_SOURCE@", "toggle"])?;
+            }
+            Self::OutputToggle => {
+                cmd::command("pactl", &["set-sink-mute", "@DEFAULT_SINK@", "toggle"])?;
+            }
+            Self::OutputInc => {
+                cmd::command("pactl", &["set-sink-volume", "@DEFAULT_SINK@", "+5%"])?;
+            }
+            Self::OutputDec => {
+                cmd::command("pactl", &["set-sink-volume", "@DEFAULT_SINK@", "-5%"])?;
+            }
+        }
+        Ok(None)
+    }
+}

mgr/src/redshift.rs

@@ -0,0 +1,116 @@
+use thiserror::Error;
+
+use super::{
+    Exec,
+    cli::{self, CliCommand},
+    cmd, systemd,
+    wire::{WireCommand, server},
+};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+    #[error(transparent)]
+    Cli(#[from] cli::ParseError),
+    #[error(transparent)]
+    Systemd(#[from] systemd::Error),
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Action {
+    Start,
+    Stop,
+    Status,
+}
+
+impl WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError> {
+        match input.next().ok_or(server::ParseError::Eof)? {
+            0x01 => Ok(Self::Start),
+            0x02 => Ok(Self::Stop),
+            0x03 => Ok(Self::Status),
+            byte => Err(server::ParseError::Unknown(byte)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::Start => vec![0x01],
+            Self::Stop => vec![0x02],
+            Self::Status => vec![0x03],
+        }
+    }
+}
+
+impl Exec for Action {
+    type ExecErr = Error;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::Start => {
+                set(Status::On)?;
+                Ok(None)
+            }
+            Self::Stop => {
+                set(Status::Off)?;
+                Ok(None)
+            }
+            Self::Status => Ok(
+                if systemd::user::unit_status("redshift.service")?.is_active() {
+                    Some("active".to_owned())
+                } else {
+                    Some("inactive".to_owned())
+                },
+            ),
+        }
+    }
+}
+
+impl CliCommand for Action {
+    type ExecErr = Error;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        let result = match input {
+            "start" => Self::Start,
+            "stop" => Self::Stop,
+            "status" => Self::Status,
+            s => {
+                return Err(cli::ParseError::UnknownAction {
+                    action: s.to_owned(),
+                });
+            }
+        };
+
+        let rest = rest.collect::<Vec<String>>();
+        if rest.is_empty() {
+            Ok(result)
+        } else {
+            Err(cli::ParseError::UnexpectedInput { rest })
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub(crate) enum Status {
+    On,
+    Off,
+}
+
+pub(crate) fn set(status: Status) -> Result<(), Error> {
+    Ok(cmd::command(
+        "systemctl",
+        &[
+            "--user",
+            "--no-block",
+            match status {
+                Status::On => "start",
+                Status::Off => "stop",
+            },
+            "redshift.service",
+        ],
+    )?)
+}

mgr/src/spotify.rs

@@ -0,0 +1,164 @@
+use thiserror::Error;
+
+use super::{
+    Exec,
+    cli::{self, CliCommand},
+    cmd, systemd,
+    wire::{WireCommand, server},
+};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+    #[error(transparent)]
+    Cli(#[from] cli::ParseError),
+    #[error(transparent)]
+    Systemd(#[from] systemd::Error),
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Action {
+    Start,
+    Stop,
+    Status,
+    Play,
+    Pause,
+    Toggle,
+    Previous,
+    Next,
+}
+
+impl WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError> {
+        match input.next().ok_or(server::ParseError::Eof)? {
+            0x01 => Ok(Self::Start),
+            0x02 => Ok(Self::Stop),
+            0x03 => Ok(Self::Status),
+            0x04 => Ok(Self::Play),
+            0x05 => Ok(Self::Pause),
+            0x06 => Ok(Self::Toggle),
+            0x07 => Ok(Self::Previous),
+            0x08 => Ok(Self::Next),
+            byte => Err(server::ParseError::Unknown(byte)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::Start => vec![0x01],
+            Self::Stop => vec![0x02],
+            Self::Status => vec![0x03],
+            Self::Play => vec![0x04],
+            Self::Pause => vec![0x05],
+            Self::Toggle => vec![0x06],
+            Self::Previous => vec![0x07],
+            Self::Next => vec![0x08],
+        }
+    }
+}
+
+impl Exec for Action {
+    type ExecErr = Error;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::Start => {
+                set(Status::On)?;
+                Ok(None)
+            }
+            Self::Stop => {
+                set(Status::Off)?;
+                Ok(None)
+            }
+            Self::Status => Ok(
+                if systemd::user::unit_status("spotify.service")?.is_active() {
+                    Some("active".to_owned())
+                } else {
+                    Some("inactive".to_owned())
+                },
+            ),
+            Self::Play => {
+                playerctl("play")?;
+                Ok(None)
+            }
+            Self::Pause => {
+                playerctl("pause")?;
+                Ok(None)
+            }
+            Self::Toggle => {
+                playerctl("play-pause")?;
+                Ok(None)
+            }
+            Self::Previous => {
+                playerctl("previous")?;
+                Ok(None)
+            }
+            Self::Next => {
+                playerctl("next")?;
+                Ok(None)
+            }
+        }
+    }
+}
+
+impl CliCommand for Action {
+    type ExecErr = Error;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        let result = match input {
+            "start" => Self::Start,
+            "stop" => Self::Stop,
+            "status" => Self::Status,
+            "play" => Self::Play,
+            "pause" => Self::Pause,
+            "toggle" => Self::Toggle,
+            "previous" => Self::Previous,
+            "next" => Self::Next,
+            s => {
+                return Err(cli::ParseError::UnknownAction {
+                    action: s.to_owned(),
+                });
+            }
+        };
+
+        let rest = rest.collect::<Vec<String>>();
+        if rest.is_empty() {
+            Ok(result)
+        } else {
+            Err(cli::ParseError::UnexpectedInput { rest })
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub(crate) enum Status {
+    On,
+    Off,
+}
+
+pub(crate) fn set(status: Status) -> Result<(), Error> {
+    Ok(cmd::command(
+        "systemctl",
+        &[
+            "--user",
+            "--no-block",
+            match status {
+                Status::On => "start",
+                Status::Off => "stop",
+            },
+            "spotify.service",
+        ],
+    )?)
+}
+
+fn playerctl(cmd: &str) -> Result<(), Error> {
+    Ok(cmd::command("playerctl", &["-p", "spotify", cmd])?)
+}
+
+pub(crate) fn pause() -> Result<(), Error> {
+    playerctl("pause")
+}

mgr/src/systemd.rs

@@ -0,0 +1,38 @@
+use thiserror::Error;
+
+use super::cmd;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+    #[error("unknown status output: \"{output}\"")]
+    UnknownStatusOutput { output: String },
+}
+
+#[derive(Debug, Clone, Copy)]
+pub(crate) enum UnitStatus {
+    Active,
+    Inactive,
+}
+
+impl UnitStatus {
+    pub(crate) fn is_active(self) -> bool {
+        matches!(self, Self::Active)
+    }
+}
+
+pub(crate) mod user {
+    use super::{super::cmd, Error, UnitStatus};
+
+    pub(crate) fn unit_status(unit: &str) -> Result<UnitStatus, Error> {
+        let output = cmd::run_command("systemctl", &["--user", "is-active", unit])?;
+        match output.stdout.as_str().trim() {
+            "active" => Ok(UnitStatus::Active),
+            "inactive" => Ok(UnitStatus::Inactive),
+            other => Err(Error::UnknownStatusOutput {
+                output: other.to_owned(),
+            }),
+        }
+    }
+}

mgr/src/theme.rs

@@ -0,0 +1,101 @@
+use thiserror::Error;
+
+use super::{
+    Exec,
+    cli::{self, CliCommand},
+    cmd, systemd,
+    wire::{WireCommand, server},
+};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Cli(#[from] cli::ParseError),
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+    #[error(transparent)]
+    Systemd(#[from] systemd::Error),
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Action {
+    Dark = 0x01,
+    Light = 0x02,
+    Status = 0x03,
+}
+
+impl WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError> {
+        match input.next().ok_or(server::ParseError::Eof)? {
+            0x01 => Ok(Self::Dark),
+            0x02 => Ok(Self::Light),
+            0x03 => Ok(Self::Status),
+            byte => Err(server::ParseError::Unknown(byte)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::Dark => vec![0x01],
+            Self::Light => vec![0x02],
+            Self::Status => vec![0x03],
+        }
+    }
+}
+
+impl CliCommand for Action {
+    type ExecErr = Error;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        let result = match input {
+            "dark" => Self::Dark,
+            "light" => Self::Light,
+            "status" => Self::Status,
+            s => {
+                return Err(cli::ParseError::UnknownAction {
+                    action: s.to_owned(),
+                });
+            }
+        };
+
+        let rest = rest.collect::<Vec<String>>();
+        if rest.is_empty() {
+            Ok(result)
+        } else {
+            Err(cli::ParseError::UnexpectedInput { rest })
+        }
+    }
+}
+
+impl Exec for Action {
+    type ExecErr = Error;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::Dark => {
+                cmd::command(
+                    "systemctl",
+                    &["--user", "--no-block", "start", "color-theme-dark.service"],
+                )?;
+                Ok(None)
+            }
+            Self::Light => {
+                cmd::command(
+                    "systemctl",
+                    &["--user", "--no-block", "start", "color-theme-light.service"],
+                )?;
+                Ok(None)
+            }
+            Self::Status => Ok(
+                if systemd::user::unit_status("color-theme-light.service")?.is_active() {
+                    Some("light".to_owned())
+                } else {
+                    Some("dark".to_owned())
+                },
+            ),
+        }
+    }
+}

mgr/src/weather.rs

@@ -0,0 +1,198 @@
+use std::{
+    fs, io,
+    ops::Sub as _,
+    path::{Path, PathBuf},
+};
+
+use thiserror::Error;
+use time::format_description::well_known::Iso8601;
+use tracing::{Level, event};
+
+const CACHE_AGE: time::Duration = time::Duration::hours(1);
+const CACHE_DELIMITER: char = '|';
+
+use super::{
+    Exec,
+    cli::{self, CliCommand},
+    cmd, dirs, systemd,
+    wire::{WireCommand, server},
+};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+    #[error(transparent)]
+    Cli(#[from] cli::ParseError),
+    #[error(transparent)]
+    Systemd(#[from] systemd::Error),
+    #[error(transparent)]
+    Http(#[from] ureq::Error),
+    #[error(transparent)]
+    Dirs(#[from] dirs::Error),
+    #[error(transparent)]
+    Io(#[from] io::Error),
+    #[error("delimiter not found in cache file")]
+    CacheDelimitedNotFound,
+    #[error("invalid timestamp \"{input}\" in cache file: {error}")]
+    CacheTimestampParse {
+        input: String,
+        error: time::error::Parse,
+    },
+    #[error("cache timestamp ({cache_timestamp}) is from the future (now: {now})")]
+    CacheTimestampOverflow {
+        now: time::UtcDateTime,
+        cache_timestamp: time::UtcDateTime,
+    },
+    #[error("formatting cache timestamp failed: {error}")]
+    CacheTimestampFormat { error: time::error::Format },
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Action {
+    Get,
+}
+
+impl WireCommand for Action {
+    fn parse_wire(mut input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError> {
+        match input.next().ok_or(server::ParseError::Eof)? {
+            0x01 => Ok(Self::Get),
+            byte => Err(server::ParseError::Unknown(byte)),
+        }
+    }
+
+    fn to_wire(&self) -> Vec<u8> {
+        match *self {
+            Self::Get => vec![0x01],
+        }
+    }
+}
+
+impl Exec for Action {
+    type ExecErr = Error;
+
+    fn execute(&self) -> Result<Option<String>, Self::ExecErr> {
+        match *self {
+            Self::Get => Ok(Some(get()?)),
+        }
+    }
+}
+
+impl CliCommand for Action {
+    type ExecErr = Error;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, cli::ParseError>
+    where
+        Self: Sized,
+    {
+        let result = match input {
+            "get" => Self::Get,
+            s => {
+                return Err(cli::ParseError::UnknownAction {
+                    action: s.to_owned(),
+                });
+            }
+        };
+
+        let rest = rest.collect::<Vec<String>>();
+        if rest.is_empty() {
+            Ok(result)
+        } else {
+            Err(cli::ParseError::UnexpectedInput { rest })
+        }
+    }
+}
+
+#[derive(Debug)]
+struct Cache {
+    timestamp: time::UtcDateTime,
+    value: String,
+}
+
+fn cache_file() -> Result<PathBuf, Error> {
+    Ok(dirs::xdg_cache_dir()?.join("workstation-mgr.wttr.cache"))
+}
+
+fn store_cache(path: &Path, timestamp: &time::UtcDateTime, value: &str) -> Result<(), Error> {
+    event!(Level::DEBUG, "storing in cache: {timestamp} {value}");
+    Ok(fs::write(
+        path,
+        format!(
+            "{timestamp}{CACHE_DELIMITER}{value}",
+            timestamp = timestamp
+                .format(&Iso8601::DEFAULT)
+                .map_err(|error| Error::CacheTimestampFormat { error })?,
+        ),
+    )?)
+}
+
+fn get_cache(path: &Path) -> Result<Option<Cache>, Error> {
+    match fs::read_to_string(path) {
+        Ok(content) => {
+            let (timestamp, value) = content
+                .split_once(CACHE_DELIMITER)
+                .ok_or(Error::CacheDelimitedNotFound)?;
+
+            let cache_timestamp =
+                time::UtcDateTime::parse(timestamp, &Iso8601::DEFAULT).map_err(|error| {
+                    Error::CacheTimestampParse {
+                        input: timestamp.to_owned(),
+                        error,
+                    }
+                })?;
+
+            Ok(Some(Cache {
+                timestamp: cache_timestamp,
+                value: value.to_owned(),
+            }))
+        }
+        Err(e) if e.kind() == io::ErrorKind::NotFound => Ok(None),
+        Err(e) => Err(e.into()),
+    }
+}
+
+fn request() -> Result<String, Error> {
+    Ok(ureq::get("https://wttr.in/Ansbach?m&T&format=%c%t")
+        .call()?
+        .body_mut()
+        .read_to_string()?)
+}
+
+fn get_and_update_cache(cache_file: &Path, now: &time::UtcDateTime) -> Result<String, Error> {
+    event!(Level::DEBUG, "refreshing cache");
+    let value = request()?;
+    store_cache(cache_file, now, &value)?;
+    Ok(value)
+}
+
+fn get() -> Result<String, Error> {
+    let cache_file = cache_file()?;
+    event!(Level::DEBUG, "using cache file {cache_file:?}");
+
+    let cache = get_cache(&cache_file)?;
+    event!(Level::DEBUG, "read from cache: {cache:?}");
+
+    let now = time::UtcDateTime::now();
+
+    match cache {
+        Some(cache) => {
+            let cache_age = now.sub(cache.timestamp);
+            event!(Level::DEBUG, "cache age: {cache_age}");
+
+            if cache_age.is_negative() {
+                return Err(Error::CacheTimestampOverflow {
+                    now,
+                    cache_timestamp: cache.timestamp,
+                });
+            }
+
+            if cache_age <= CACHE_AGE {
+                event!(Level::DEBUG, "reusing cache");
+                Ok(cache.value)
+            } else {
+                get_and_update_cache(&cache_file, &now)
+            }
+        }
+        None => get_and_update_cache(&cache_file, &now),
+    }
+}

mgr/src/wire/client.rs

@@ -0,0 +1,20 @@
+use std::{
+    io::{self, Write as _},
+    os::unix::net::UnixStream,
+};
+
+use thiserror::Error;
+
+use super::{super::Action, WireCommand as _};
+
+#[derive(Debug, Error)]
+pub enum SendError {
+    #[error(transparent)]
+    Io(#[from] io::Error),
+}
+
+impl Action {
+    pub fn send(&self, stream: &mut UnixStream) -> Result<(), SendError> {
+        Ok(stream.write_all(&self.to_wire())?)
+    }
+}

mgr/src/wire/mod.rs

@@ -0,0 +1,11 @@
+pub mod client;
+pub mod server;
+pub mod socket;
+
+pub(crate) trait WireCommand {
+    fn parse_wire(input: impl Iterator<Item = u8>) -> Result<Self, server::ParseError>
+    where
+        Self: Sized;
+
+    fn to_wire(&self) -> Vec<u8>;
+}

mgr/src/wire/server.rs

@@ -0,0 +1,88 @@
+use std::{
+    io::{self, Read, Write},
+    os::unix::net::{SocketAddr, UnixListener, UnixStream},
+    thread,
+};
+
+use thiserror::Error;
+use tracing::{Level, event};
+
+use super::{
+    super::{Action, Exec as _},
+    WireCommand, socket,
+};
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error(transparent)]
+    Io(#[from] io::Error),
+    #[error(transparent)]
+    Parse(#[from] ParseError),
+    #[error(transparent)]
+    Socket(#[from] socket::Error),
+    #[error(transparent)]
+    Exec(#[from] crate::ExecError),
+}
+
+#[derive(Debug, Error)]
+pub enum ParseError {
+    #[error("received unexpected eof")]
+    Eof,
+    #[error("received unknown byte: {0:#X}")]
+    Unknown(u8),
+    #[error("received surplus input: {0:?}")]
+    Surplus(Vec<u8>),
+}
+
+fn handle_client(stream: &mut UnixStream) -> Result<(), Error> {
+    let input = {
+        let mut buf = Vec::new();
+        stream.read_to_end(&mut buf)?;
+        buf
+    };
+
+    event!(Level::DEBUG, "request data: {input:?}");
+
+    let action = Action::parse_wire(input.into_iter())?;
+
+    event!(Level::DEBUG, "parsed request: {action:?}");
+
+    if let Some(output) = action.execute()? {
+        stream.write_all(output.as_bytes())?;
+    }
+
+    Ok(())
+}
+
+pub fn run() -> Result<(), Error> {
+    event!(Level::DEBUG, "starting server");
+
+    let socket_path = socket::get_socket_path()?;
+
+    socket::try_remove_socket(&socket_path)?;
+
+    let socket_addr = SocketAddr::from_pathname(socket_path)?;
+
+    event!(Level::DEBUG, "socket address {socket_addr:?}");
+
+    let listener = UnixListener::bind_addr(&socket_addr)?;
+
+    for stream in listener.incoming() {
+        let mut stream = stream?;
+        thread::spawn(move || {
+            event!(Level::DEBUG, "received request");
+            let result = handle_client(&mut stream);
+            if let Err(e) = result {
+                let msg = e.to_string();
+                event!(Level::ERROR, "action failed: {msg}");
+                if let Err(e) = stream.write_all(msg.as_bytes()) {
+                    event!(Level::ERROR, "sending \"{msg}\" failed: {e}");
+                }
+            }
+            event!(Level::DEBUG, "closing stream");
+            drop(stream);
+        });
+    }
+
+    unreachable!()
+}

mgr/src/wire/socket.rs

@@ -0,0 +1,35 @@
+use std::{
+    fs, io,
+    path::{Path, PathBuf},
+};
+
+use thiserror::Error;
+
+use super::super::dirs;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("could not find a suitable socket path")]
+    NoSocketPathFound,
+    #[error(transparent)]
+    Io(#[from] io::Error),
+    #[error(transparent)]
+    Dirs(#[from] dirs::Error),
+}
+
+pub fn get_socket_path() -> Result<PathBuf, Error> {
+    if let Some(mut dir) = dirs::xdg_runtime_dir()? {
+        dir.push("workstation-mgr.sock");
+        return Ok(dir);
+    }
+
+    Err(Error::NoSocketPathFound)
+}
+
+pub(crate) fn try_remove_socket(path: &Path) -> Result<(), Error> {
+    match fs::remove_file(path) {
+        Ok(()) => Ok(()),
+        Err(e) if e.kind() == io::ErrorKind::NotFound => Ok(()),
+        Err(e) => Err(e.into()),
+    }
+}