fundaia 0.5.0

//! "There is a newer one" — and then there is not, because it installed it.
//!
//! Four properties are what make this worth having at all, and every one of
//! them is a constraint on when it may act rather than on what it does:
//!
//! - **It never delays the command.** The look at crates.io is started before
//!   the command runs and collected after it, so it overlaps the work instead
//!   of being added to it. Whatever has not answered by then is dropped.
//! - **It goes to stderr.** `deploy` is meant to be chained and its output is
//!   read by scripts; a notice on stdout is a notice that ends up in a variable.
//! - **A failure is silent.** No network, a captive portal, crates.io down, a
//!   read-only home directory: none of that is the person's problem right now,
//!   and a CLI that explains why it could not check its own version is worse
//!   than one that never checks.
//! - **It only replaces itself in front of a person.** With stderr on a
//!   terminal this is somebody's laptop, and the next command should be the new
//!   version. Through a pipe it is a script or a CI job, where a binary that
//!   changes underneath a running pipeline is a bug nobody will find; there it
//!   says the sentence and stops, which is all it ever used to do.
//!
//! The answer is cached for a day in the directory that already holds the
//! profiles. The stamp records the *attempt*, not the success — otherwise a
//! machine with no route to crates.io asks again on every single invocation,
//! and an update that cannot be installed is retried by every command all day.

mod install;
mod registry;
mod version;

use std::io::IsTerminal;
use std::path::{Path, PathBuf};
use std::time::{Duration, SystemTime, UNIX_EPOCH};

use anyhow::{bail, Result};
use owo_colors::OwoColorize;
use serde::{Deserialize, Serialize};
use tokio::task::JoinHandle;

use crate::config::config_path;
use crate::render::theme;

use install::{Progress, SelfInstaller};

/// Where each of the two callers wants the running commentary.
///
/// The automatic check writes to stderr, because nobody asked for it and
/// `deploy` is meant to be chained; `upgrade` writes to stdout, because there
/// it is the answer to what was typed.
struct OnStderr;
struct OnStdout;

impl Progress for OnStderr {
    fn say(&self, message: &str) {
        eprintln!("  {}", message.style(theme::muted()));
    }
}

impl Progress for OnStdout {
    fn say(&self, message: &str) {
        println!("  {}", message.style(theme::muted()));
    }
}

/// How long one look at the registry is good for.
const CACHE_LIFETIME: Duration = Duration::from_secs(24 * 60 * 60);

/// The whole network budget of the automatic check. Deliberately below any
/// human patience threshold: this is a courtesy, and a courtesy that hangs is a
/// bug.
const FETCH_TIMEOUT: Duration = Duration::from_secs(2);

/// What `upgrade` waits, which is longer because somebody asked for that one
/// and is watching it.
const ASKED_TIMEOUT: Duration = Duration::from_secs(15);

/// What the process is willing to wait for the answer *after* the command is
/// done. Nearly always zero — every command talks to a server first, and the
/// check finishes during that — so this is a backstop, not a budget.
const TAIL_WAIT: Duration = Duration::from_millis(400);

const OPT_OUT: &str = "FUNDAIA_NO_UPDATE_CHECK";

/// Keeps the notice and drops the installing, for somebody who would rather
/// their package manager owned this binary.
const NO_SELF_UPDATE: &str = "FUNDAIA_NO_SELF_UPDATE";

/// A check in flight, or nothing at all.
///
/// Owned by `main` and collected there, rather than a background task that
/// prints whenever it happens to finish: a line that lands in the middle of a
/// table is worse than no line.
pub struct UpdateCheck {
    current: &'static str,
    /// Set when the cache already knew, so the fetch does not say it twice.
    announced: bool,
    /// Absent when the check was switched off, or answered from disk.
    pending: Option<Pending>,
}

struct Pending {
    /// What the stale cache said, kept so a failed look does not forget it.
    known: String,
    fetch: JoinHandle<Option<String>>,
}

impl UpdateCheck {
    /// Reads what is already known and, if it is stale, starts asking.
    ///
    /// Anything on disk is used immediately: the common case is a person who
    /// ran the tool yesterday, and there is no reason to make them wait for a
    /// round trip to be told what a file already says.
    pub fn start(current: &'static str) -> Self {
        let mut check = Self {
            current,
            announced: false,
            pending: None,
        };

        if switched_off(OPT_OUT) {
            return check;
        }

        let Some(path) = cache_path() else {
            return check;
        };

        let cached = Cache::read(&path);

        if let Some(newer) = version::newer(current, &cached.latest) {
            announce(current, newer);
            check.announced = true;
        }

        if is_fresh(cached.checked_at, now_seconds()) {
            return check;
        }

        check.pending = Some(Pending {
            known: cached.latest,
            fetch: tokio::spawn(registry::latest_version(FETCH_TIMEOUT)),
        });

        check
    }

    /// Collects the answer if it is there, and acts on it.
    ///
    /// The stamp is written either way, and that is the point of writing it
    /// here rather than where the answer is. It records *that the tool asked*,
    /// so a machine with no route to crates.io asks once a day like everybody
    /// else — and an update that failed to install is not attempted again by
    /// the very next command.
    pub async fn finish(self) {
        let Some(pending) = self.pending else {
            return;
        };

        let found = match tokio::time::timeout(TAIL_WAIT, pending.fetch).await {
            Ok(Ok(Some(latest))) => Some(latest),
            // A refusal, a timeout, no network, a panic: all the same answer.
            _ => None,
        };

        let latest = found.unwrap_or(pending.known);
        remember(&latest);

        let Some(newer) = version::newer(self.current, &latest) else {
            return;
        };

        // Anything the cache already knew was said before the command ran.
        if !self.announced {
            announce(self.current, newer);
        }

        replace_this_binary(newer).await;
    }
}

/// `fundaia upgrade`, which is the same work asked for on purpose.
///
/// Three things differ from the automatic path, all of them because somebody
/// typed this. The cache is ignored, since the point of asking is to get
/// today's answer rather than yesterday's. It speaks on stdout, because here
/// the version *is* what was asked. And it fails loudly instead of shrugging: a
/// person who asked to be updated and was not is owed the reason.
pub async fn upgrade(current: &'static str, check_only: bool) -> Result<()> {
    let Some(latest) = registry::latest_version(ASKED_TIMEOUT).await else {
        bail!("no se ha podido consultar crates.io");
    };

    remember(&latest);

    let Some(newer) = version::newer(current, &latest) else {
        println!(
            "  {} fundaia {current} ya es la versión más reciente.",
            theme::CHECK.style(theme::success()),
        );
        return Ok(());
    };

    println!(
        "  Hay una versión nueva: {current} {} {}",
        theme::ARROW,
        newer.style(theme::strong()),
    );

    if check_only {
        return Ok(());
    }

    let installer = SelfInstaller::prepare(newer)?;
    installer.install(&OnStdout).await?;

    println!(
        "  {} Instalada en {}",
        theme::CHECK.style(theme::success()),
        installer.destination().display().style(theme::muted()),
    );

    Ok(())
}

/// Updates in place, or explains once why it left the binary alone.
///
/// Every failure here is reported and swallowed. This runs after a command that
/// already did what it was asked, and a deploy that worked must not exit
/// non-zero because the tool could not upgrade itself afterwards.
async fn replace_this_binary(version: &str) {
    if switched_off(NO_SELF_UPDATE) || !std::io::stderr().is_terminal() {
        eprintln!("  {}", manual_route().style(theme::muted()));
        return;
    }

    let installed = match SelfInstaller::prepare(version) {
        Ok(installer) => installer.install(&OnStderr).await,
        Err(error) => Err(error),
    };

    match installed {
        Ok(()) => eprintln!(
            "  {} {}",
            theme::CHECK.style(theme::success()),
            format!("Actualizado. La siguiente orden ya usa {version}.").style(theme::muted()),
        ),
        Err(error) => {
            eprintln!(
                "  {}",
                format!("no se ha podido actualizar: {error}").style(theme::muted())
            );
            eprintln!("  {}", manual_route().style(theme::muted()));
        }
    }
}

/// What to do by hand when this cannot do it. `cargo install` rather than
/// `install.sh`, because a person who has the tool at all has one of the two
/// and only one of them is a single line worth printing.
fn manual_route() -> &'static str {
    "Actualiza con `cargo install fundaia`."
}

/// The headline, on stderr, in the muted style the rest of the tool uses for
/// anything that is not the answer to what was asked.
fn announce(current: &str, latest: &str) {
    eprintln!(
        "  {} Hay una versión nueva de fundaia: {current} {} {latest}",
        "!".style(theme::warning()),
        theme::ARROW,
    );
}

/// Records that the registry was asked, and what it said.
fn remember(latest: &str) {
    let Some(path) = cache_path() else {
        return;
    };

    let _ = Cache::write(
        &path,
        &Cache {
            checked_at: now_seconds(),
            latest: latest.to_owned(),
        },
    );
}

/// The last answer, and when it was last asked for.
#[derive(Debug, Default, Serialize, Deserialize)]
struct Cache {
    /// Unix seconds of the last attempt, whether or not it worked.
    #[serde(default)]
    checked_at: u64,
    /// Empty until one succeeds.
    #[serde(default)]
    latest: String,
}

impl Cache {
    /// Anything unreadable is treated as absent: this file is a convenience
    /// the tool wrote itself, and refusing to run over it would be absurd.
    fn read(path: &Path) -> Self {
        std::fs::read_to_string(path)
            .ok()
            .and_then(|text| toml::from_str(&text).ok())
            .unwrap_or_default()
    }

    fn write(path: &Path, cache: &Self) -> Option<()> {
        let directory = path.parent()?;
        std::fs::create_dir_all(directory).ok()?;
        std::fs::write(path, toml::to_string(cache).ok()?).ok()
    }
}

/// Beside the profiles, so `FUNDAIA_CONFIG` moves both together.
fn cache_path() -> Option<PathBuf> {
    Some(beside(&config_path().ok()?))
}

fn beside(config: &Path) -> PathBuf {
    config.with_file_name("update-check.toml")
}

fn now_seconds() -> u64 {
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .map(|since| since.as_secs())
        .unwrap_or(0)
}

/// A clock that moved backwards leaves the stamp in the future, and
/// `saturating_sub` reads that as fresh — which is the safe direction. The
/// alternative is a machine whose clock is wrong asking on every invocation.
fn is_fresh(checked_at: u64, now: u64) -> bool {
    checked_at != 0 && now.saturating_sub(checked_at) < CACHE_LIFETIME.as_secs()
}

fn switched_off(variable: &str) -> bool {
    std::env::var(variable).is_ok_and(|value| silences(&value))
}

/// `=1` switches it off; `=0` and an empty value do not.
///
/// Unset and set-to-nothing are the same intent, and a shell that exports an
/// empty variable did not mean "yes".
fn silences(value: &str) -> bool {
    let value = value.trim();
    !value.is_empty() && value != "0"
}

#[cfg(test)]
mod tests {
    use super::*;

    fn scratch(name: &str) -> PathBuf {
        std::env::temp_dir().join(format!("fundaia-update-{name}.toml"))
    }

    #[test]
    fn it_should_treat_a_stamp_from_a_minute_ago_as_fresh() {
        assert!(is_fresh(1_000_000, 1_000_060));
    }

    #[test]
    fn it_should_treat_a_stamp_from_two_days_ago_as_stale() {
        assert!(!is_fresh(1_000_000, 1_000_000 + 2 * 24 * 60 * 60));
    }

    #[test]
    fn it_should_treat_a_missing_stamp_as_stale() {
        assert!(!is_fresh(0, 1_000_000));
    }

    #[test]
    fn it_should_treat_a_stamp_from_the_future_as_fresh() {
        assert!(is_fresh(2_000_000, 1_000_000));
    }

    #[test]
    fn it_should_remember_the_version_it_last_found() {
        let path = scratch("remembers");
        Cache::write(
            &path,
            &Cache {
                checked_at: 42,
                latest: "9.9.9".to_owned(),
            },
        )
        .expect("the temporary directory is writable");

        let read = Cache::read(&path);
        let _ = std::fs::remove_file(&path);

        assert_eq!(read.latest, "9.9.9");
    }

    #[test]
    fn it_should_remember_when_it_last_asked() {
        let path = scratch("stamps");
        Cache::write(
            &path,
            &Cache {
                checked_at: 42,
                latest: String::new(),
            },
        )
        .expect("the temporary directory is writable");

        let read = Cache::read(&path);
        let _ = std::fs::remove_file(&path);

        assert_eq!(read.checked_at, 42);
    }

    #[test]
    fn it_should_treat_a_cache_that_is_not_there_as_empty() {
        assert_eq!(Cache::read(&scratch("never-written")).checked_at, 0);
    }

    #[test]
    fn it_should_treat_a_corrupt_cache_as_empty() {
        let path = scratch("corrupt");
        std::fs::write(&path, "this is not toml {{").expect("the temporary directory is writable");

        let read = Cache::read(&path);
        let _ = std::fs::remove_file(&path);

        assert_eq!(read.checked_at, 0);
    }

    #[test]
    fn it_should_be_silenced_by_the_environment_variable() {
        assert!(silences("1"));
    }

    #[test]
    fn it_should_not_be_silenced_by_an_empty_value() {
        assert!(!silences(""));
    }

    #[test]
    fn it_should_not_be_silenced_by_a_zero() {
        assert!(!silences("0"));
    }

    #[test]
    fn it_should_keep_the_cache_beside_the_profiles() {
        assert_eq!(
            beside(Path::new("/somewhere/fundaia/config.toml")),
            PathBuf::from("/somewhere/fundaia/update-check.toml"),
        );
    }
}