overbrainer 0.2.1

//! What the app does with training runs: listing them, attaching, cancelling, and
//! what quitting and signals do to the training tasks.
//!
//! A training task's token is cancelled only once its job's first status arrived
//! (its watch began), so a start is never cut: asked to detach before, it is
//! marked and detached then. Only a process signal abandons a task at once. A
//! confirmed cancel always runs, quitting included; only a signal drops one not
//! started yet, and says how to run it.
//!
//! A start (`t`) holds the data lock until its job started. Quitting while a
//! Runpod run still provisions offers to abandon it instead of waiting: its pod
//! is deleted and the run fails, as Ctrl-C does on the command line. `c` on such
//! a run offers the same for that run alone, and the TUI stays open.
//!
//! Files are read by tasks, never on the loop's thread nor while drawing.

use std::time::{Duration, SystemTime};

use crossterm::event::KeyCode;

use super::app::{Action, App, Confirm, Effect, Exit, NoteOf, Overlay, Severity, View};
use super::start::{self, Prices, StartPlan};
use super::tasks::{Msg, Task, TaskId, TrainJob};
use super::training::{Detach, Ended, Follow, Job, Listing, RunActivity};
use crate::cli::front::Report;
use crate::events::Event;
use crate::train::TrainMetric;

/// Time between two reads of `runs/` while the Training view is shown.
const REFRESH: Duration = Duration::from_secs(2);

/// What abandoning a Runpod start does, for the dialogs that offer it.
const ABANDONED: &str = "If its pod is still being prepared, it is deleted and the run fails, \
                         as Ctrl-C does on the command line; once its job is being sent, the \
                         run is detached instead.";

impl App {
    /// Reads `runs/` again, in a task; while one reads, once more after it.
    pub(super) fn refresh_runs(&mut self) -> Vec<Effect> {
        self.refreshed = self.now;
        if self.training.listing.is_some() {
            self.training.list_again = true;
            return Vec::new();
        }
        let id = self.task_id();
        self.training.listing = Some(id);
        vec![Effect::Spawn(id, Task::Runs)]
    }

    /// Reads `runs/` again when the Training view is shown and it is time (or
    /// the clock went back).
    pub(super) fn refresh_when_due(&mut self) -> Vec<Effect> {
        let recent = matches!(
            self.now.duration_since(self.refreshed),
            Ok(since) if since < REFRESH
        );
        if self.view == View::Training && !recent {
            return self.refresh_runs();
        }
        Vec::new()
    }

    /// Read `id` of `runs/` found `listing`: shown when it is the latest read,
    /// then the selected run's metrics are read, and a read asked for meanwhile
    /// starts. Each new warning is logged once.
    pub(super) fn listed(&mut self, id: TaskId, listing: Listing) -> Vec<Effect> {
        if self.training.listing != Some(id) {
            return Vec::new();
        }
        self.training.listing = None;
        self.dirty = true;
        for warning in self.training.listed(listing) {
            tracing::warn!("{warning}");
        }
        let mut effects = self.read_selected();
        if std::mem::take(&mut self.training.list_again) {
            effects.extend(self.refresh_runs());
        }
        effects
    }

    /// Reads the local metrics of the selected run, in a task, once, unless a
    /// task follows it.
    fn read_selected(&mut self) -> Vec<Effect> {
        match self.training.to_read() {
            Some(run) => self.read_series(&run),
            None => Vec::new(),
        }
    }

    /// Reads the local metrics of run `run` in a task; an earlier read of it no
    /// longer counts.
    fn read_series(&mut self, run: &str) -> Vec<Effect> {
        let id = self.task_id();
        self.training.reading.insert(run.to_string(), id);
        vec![Effect::Spawn(id, Task::Series(run.to_string()))]
    }

    /// Read `id` of run `run`'s local metrics found `series`: kept when it is
    /// that run's latest read. Read after a task of the run ended, they hold
    /// every metric, late or skipped.
    pub(super) fn series_read(
        &mut self,
        id: TaskId,
        run: String,
        series: Option<Vec<TrainMetric>>,
    ) -> Vec<Effect> {
        if self.training.reading.get(&run) != Some(&id) {
            return Vec::new();
        }
        self.training.reading.remove(&run);
        if let Some(series) = series {
            if let Some(ended) = self.training.ended.get_mut(&run) {
                ended.healed = true;
            }
            self.training.series.insert(run, series);
            self.dirty = true;
        }
        Vec::new()
    }

    /// Read task `id` failed (a panic): it no longer counts.
    pub(super) fn read_failed(&mut self, id: TaskId, error: &str) -> bool {
        if self.training.listing == Some(id) {
            self.training.listing = None;
            self.training.error = Some(format!("cannot list the runs: {error}"));
            return true;
        }
        let before = self.training.reading.len();
        self.training.reading.retain(|_, read| *read != id);
        before != self.training.reading.len()
    }

    /// A key in the Training view.
    pub(super) fn on_training_key(&mut self, code: KeyCode) -> Vec<Effect> {
        let view = &mut self.training;
        match code {
            KeyCode::Up | KeyCode::Char('k') => view.selected = view.selected.saturating_sub(1),
            KeyCode::Down | KeyCode::Char('j') => {
                view.selected = (view.selected + 1).min(view.runs.len().saturating_sub(1));
            },
            KeyCode::Char('a') => return self.attach_selected(),
            KeyCode::Char('c') => {
                self.ask_cancel();
                return Vec::new();
            },
            KeyCode::Char('t') => return self.prepare_start(),
            _ => return Vec::new(),
        }
        self.read_selected()
    }

    /// `a`: follows the selected run again, from its first metric; refused
    /// while the TUI is quitting.
    fn attach_selected(&mut self) -> Vec<Effect> {
        let Some(id) = self
            .training
            .selected_run()
            .map(|row| row.record.id.clone())
        else {
            return Vec::new();
        };
        if self.leaving.is_some() {
            self.say(Severity::Warn, "refused: quitting; nothing new is followed");
            return Vec::new();
        }
        if self.training.cancelling(&id) {
            self.say(Severity::Info, format!("run {id} is being cancelled"));
            return Vec::new();
        }
        if self.training.task_of(&id).is_some() {
            self.say(Severity::Info, format!("run {id} is already followed"));
            return Vec::new();
        }
        self.training.series.remove(&id);
        self.training.ended.remove(&id);
        self.train(Job::Attach, &id)
    }

    /// Refuses a new run while the data is locked (a stage, an edit or another
    /// start runs) or the TUI is quitting; says why.
    fn start_refused(&mut self) -> bool {
        self.refuse_new("one task at a time", "run")
    }

    /// `t`: prepares the confirmation of a new run, in a task.
    fn prepare_start(&mut self) -> Vec<Effect> {
        if self.start_refused() {
            return Vec::new();
        }
        if self.prepare.is_some() {
            self.say(Severity::Info, "already preparing a run");
            return Vec::new();
        }
        let id = self.task_id();
        self.prepare = Some(id);
        vec![Effect::Spawn(id, Task::Prepare)]
    }

    /// The plan of a new run is ready: asks to start it, and looks up the list
    /// prices of a Runpod run meanwhile (an earlier lookup no longer counts).
    /// Dropped once the TUI is quitting, and while a dialog, the help, the menu
    /// or the filter is open (it never replaces what the user is answering):
    /// the status line then says to press `t` again.
    pub(super) fn prepared(&mut self, plan: Result<StartPlan, String>) -> Vec<Effect> {
        self.prepare = None;
        if self.leaving.is_some() {
            return Vec::new();
        }
        let plan = match plan {
            Ok(plan) => plan,
            Err(error) => {
                self.say(Severity::Warn, format!("refused: {error}"));
                return Vec::new();
            },
        };
        if self.overlay.is_some() || self.dataset.input.is_some() {
            self.say(
                Severity::Info,
                "a run is prepared: press t again to start it",
            );
            return Vec::new();
        }
        let gpu_types = plan.runpod.as_ref().map(|runpod| runpod.gpu_types.clone());
        self.overlay = Some(Overlay::Confirm(Confirm {
            title: " Start a training run? ".to_string(),
            text: start::text(&plan, None),
            yes: "start",
            no: "cancel",
            action: Action::Start(Box::new(plan)),
        }));
        self.prices = None;
        let Some(gpu_types) = gpu_types else {
            return Vec::new();
        };
        let id = self.task_id();
        self.prices = Some(id);
        vec![Effect::Spawn(id, Task::Prices(gpu_types))]
    }

    /// The list prices arrived: shown in the start dialog if it is still open;
    /// a type missing from `prices` has an unknown price.
    pub(super) fn priced(&mut self, prices: &Prices) {
        self.prices = None;
        if let Some(Overlay::Confirm(confirm)) = &mut self.overlay
            && let Action::Start(plan) = &confirm.action
        {
            confirm.text = start::text(plan, Some(prices));
        }
    }

    /// Starts the run of `plan`, on `training.target` and without keeping its
    /// pod, unless something started meanwhile.
    pub(super) fn start_run(&mut self, plan: &StartPlan) -> Vec<Effect> {
        if self.start_refused() {
            return Vec::new();
        }
        let runpod = plan.runpod.is_some();
        let effects = self.train(Job::Start { runpod }, "");
        self.say(Severity::Info, format!("starting a run on {}", plan.target));
        effects
    }

    /// Start task `id` was never spawned (the loop ended first): it is
    /// forgotten, and the exit notes say so.
    pub(super) fn start_dropped(&mut self, id: TaskId) {
        self.training.tasks.remove(&id);
        self.exit_notes.push(
            "a new training run was not started: the TUI ended first; start it again with \
             `overbrainer train` or t"
                .to_string(),
        );
        self.leave_when_idle();
    }

    /// Starts a training task doing `job` on run `run_id`. The late messages of
    /// the run's earlier tasks, and a read of its metrics, no longer count.
    fn train(&mut self, job: Job, run_id: &str) -> Vec<Effect> {
        let id = self.task_id();
        let task = match job {
            Job::Start { .. } => TrainJob::Start,
            Job::Attach => TrainJob::Attach(run_id.to_string()),
            Job::Cancel => TrainJob::Cancel(run_id.to_string()),
        };
        if !run_id.is_empty() {
            self.forget_notes(&NoteOf::Run(run_id.to_string()));
        }
        self.training.last.retain(|_, run| run != run_id);
        self.training.reading.remove(run_id);
        self.training.tasks.insert(id, Follow::new(job, run_id));
        vec![Effect::Spawn(id, Task::Train(task))]
    }

    /// `c`: asks to cancel the selected run's job, or to abandon it while it is
    /// a Runpod start still starting; refused after a signal.
    fn ask_cancel(&mut self) {
        let Some(row) = self.training.selected_run() else {
            return;
        };
        let (id, target) = (row.record.id.clone(), row.record.target.clone());
        if self.training.cancelling(&id) {
            self.say(Severity::Info, format!("run {id} is being cancelled"));
            return;
        }
        if self.leaving == Some(Exit::Signal) {
            self.say(Severity::Warn, "refused: interrupted, exiting");
            return;
        }
        let activity = self.training.activity(&id);
        let starting = self
            .training
            .task_of(&id)
            .filter(|_| activity.abandons())
            .map(|(task, _)| (task, matches!(activity, RunActivity::Abandoning { .. })));
        if let Some((task, abandoned)) = starting {
            // A Runpod start has no job to cancel yet: it is abandoned instead.
            if abandoned {
                self.say(Severity::Info, format!("run {id} is being abandoned"));
                return;
            }
            let text = format!(
                "Run {id} is still starting, so it has no job to cancel yet. Abandon it \
                 instead? {ABANDONED}"
            );
            self.overlay = Some(Overlay::Confirm(Confirm {
                title: " Abandon a starting run? ".to_string(),
                text: vec![text],
                yes: "abandon",
                no: "keep it",
                action: Action::AbandonStart(task),
            }));
            return;
        }
        self.overlay = Some(Overlay::Confirm(Confirm {
            title: " Cancel a run? ".to_string(),
            text: vec![format!(
                "Cancel run {id} on {target}? Its job is stopped (its container first), what it \
                 produced is retrieved best effort, and for Runpod the pod is then ended. This \
                 cannot be undone."
            )],
            yes: "cancel the run",
            no: "keep it",
            action: Action::Cancel(id),
        }));
    }

    /// Cancels run `run_id`: a task following it is detached first, and the
    /// cancel starts once it ended, so two flows never end the same pod at once.
    pub(super) fn cancel_run(&mut self, run_id: &str) -> Vec<Effect> {
        if self.training.cancelling(run_id) {
            self.say(Severity::Info, format!("run {run_id} is being cancelled"));
            return Vec::new();
        }
        let Some((task, _)) = self.training.task_of(run_id) else {
            return self.train(Job::Cancel, run_id);
        };
        let Some(follow) = self.training.tasks.get_mut(&task) else {
            return Vec::new();
        };
        follow.cancel_after = true;
        let said = if follow.starting() {
            // Interrupting a start would abandon it: its job is waited for.
            format!("run {run_id} is starting: it is cancelled once its job started")
        } else {
            format!("detaching run {run_id}, then cancelling it")
        };
        self.say(Severity::Info, said);
        self.detach(task)
    }

    /// Detaches task `id`: at once when its watch began, else once its job's
    /// first status arrives.
    fn detach(&mut self, id: TaskId) -> Vec<Effect> {
        let Some(follow) = self.training.tasks.get_mut(&id) else {
            return Vec::new();
        };
        match (follow.detach, follow.watching) {
            (Detach::Done, _) => Vec::new(),
            (_, true) => {
                follow.detach = Detach::Done;
                vec![Effect::Cancel(id)]
            },
            (_, false) => {
                follow.detach = Detach::OnStart;
                Vec::new()
            },
        }
    }

    /// A message of training task `id`, running or ended.
    pub(super) fn on_training_message(&mut self, id: TaskId, message: Msg) -> Vec<Effect> {
        if !self.training.tasks.contains_key(&id) {
            self.late_training_message(id, message);
            return Vec::new();
        }
        match message {
            Msg::Event(_, event) => {
                let started = self.training.event(id, event);
                let waiting = self
                    .training
                    .tasks
                    .get(&id)
                    .is_some_and(|follow| follow.detach == Detach::OnStart);
                if started && waiting {
                    return self.detach(id);
                }
            },
            Msg::Lagged(_, skipped) => {
                if let Some(follow) = self.training.tasks.get_mut(&id) {
                    follow.skipped += skipped;
                }
            },
            Msg::Report(_, Report::Line(line)) => {
                if let Some(follow) = self.training.tasks.get_mut(&id) {
                    follow.lines.push(line);
                }
            },
            Msg::Report(_, Report::RunCreated(run_id)) => {
                if let Some(follow) = self.training.tasks.get_mut(&id) {
                    follow.run_id.clone_from(&run_id);
                }
                self.training.wanted = Some(run_id);
                return self.refresh_runs();
            },
            Msg::EditorExited(_) => {},
        }
        Vec::new()
    }

    /// A message of training task `id` handled after its end: a line joins how
    /// its run ended, and a metric its series, unless the series was read again
    /// from the local file (which holds it).
    fn late_training_message(&mut self, id: TaskId, message: Msg) {
        let Some(run) = self.training.last.get(&id).cloned() else {
            return;
        };
        let healed = self.training.ended.get(&run).is_some_and(|e| e.healed);
        match message {
            Msg::Event(_, Event::Metric(metric)) if !healed => {
                self.training.series.entry(run).or_default().push(metric);
            },
            Msg::Lagged(_, skipped) => {
                if let Some(ended) = self.training.ended.get_mut(&run) {
                    ended.skipped += skipped;
                }
            },
            Msg::Report(_, Report::Line(line)) => {
                if self.leaving.is_some() {
                    // A flow's line (a pod warning) always stays.
                    self.exit_notes.push(line.clone());
                }
                if let Some(ended) = self.training.ended.get_mut(&run) {
                    ended.lines.push(line);
                }
            },
            _ => {},
        }
    }

    /// Training task `id` ended with `result`. A cancel waiting for it starts,
    /// unless a signal came (an exit note then says how to cancel). While the
    /// TUI is leaving, what it reported and its error (a detached run's "keeps
    /// running ... attach") are kept for the exit.
    pub(super) fn trained(&mut self, id: TaskId, result: Result<(), String>) -> Vec<Effect> {
        let Some(follow) = self.training.tasks.remove(&id) else {
            return Vec::new();
        };
        let run = follow.run_id.clone();
        let name = follow.run();
        let error = result.err();
        let cancel = follow.cancel_after && self.leaving != Some(Exit::Signal);
        if self.leaving.is_some() {
            // The flow's lines (pod warnings) always stay.
            self.exit_notes.extend(follow.lines.iter().cloned());
            if !cancel && let Some(error) = &error {
                self.note_leaving(error.clone(), NoteOf::Run(run.clone()));
            }
            if follow.cancel_after && !cancel {
                // A start abandoned may have failed with no job, or detached
                // once its job started (a local or SSH start, a Runpod job
                // already being sent), whose pod then bills until `max_hours`.
                let note = if follow.starting() {
                    format!(
                        "run {run} was not cancelled (a signal came during its start); if it \
                         is running, cancel it with `overbrainer train cancel {run}`"
                    )
                } else {
                    format!(
                        "run {run} was not cancelled: interrupted before its cancel started; \
                         cancel it with `overbrainer train cancel {run}`"
                    )
                };
                self.note_leaving(note, NoteOf::Run(run.clone()));
            }
        }
        match &error {
            Some(error) if !follow.cancel_after => {
                self.say(Severity::Warn, format!("{name}: {error}"));
            },
            Some(_) => {},
            None => self.say(Severity::Info, format!("{name}: done")),
        }
        if run.is_empty() {
            // A start that failed before its run was created: no run to show.
            self.leave_when_idle();
            return Vec::new();
        }
        self.training.ended.insert(
            run.clone(),
            Ended {
                lines: follow.lines,
                error,
                skipped: follow.skipped,
                healed: false,
            },
        );
        self.training.last.insert(id, run.clone());
        let mut effects = Vec::new();
        if self.leaving.is_none() {
            // The local metrics, retrieved with the results, heal any missing
            // point.
            effects.extend(self.read_series(&run));
            effects.extend(self.refresh_runs());
        }
        if cancel {
            effects.extend(self.train(Job::Cancel, &run));
        }
        self.leave_when_idle();
        effects
    }

    /// What quitting does to each training task, for the quit dialog.
    pub(super) fn training_quit_text(&self) -> Vec<String> {
        self.training
            .tasks
            .values()
            .map(|follow| {
                let run = &follow.run_id;
                let pod = match follow.job {
                    Job::Start { runpod: true } => " its pod",
                    _ => "",
                };
                match follow.job {
                    Job::Cancel => format!("Run {run}: cancel in progress, quitting waits for it."),
                    _ if follow.cancel_after => format!(
                        "Run {run}: cancel pending, it starts once the run is detached; \
                         quitting waits for it."
                    ),
                    Job::Start { .. } if follow.starting() => format!(
                        "{} is starting{pod}: quitting waits until its job has started, then \
                         leaves it running.",
                        capitalized(&follow.run())
                    ),
                    Job::Start { .. } | Job::Attach => format!(
                        "Run {run} keeps running{}; attach again from here or with \
                         `overbrainer train attach {run}`.",
                        self.where_it_runs(run)
                    ),
                }
            })
            .collect()
    }

    /// Where run `run` keeps running: its target, or its pod and rate for a Runpod
    /// run with a pod.
    fn where_it_runs(&self, run: &str) -> String {
        let Some(row) = self.training.runs.iter().find(|row| row.record.id == run) else {
            return String::new();
        };
        match row
            .pod
            .as_ref()
            .and_then(|pod| pod.pod_id.as_ref().map(|id| (id, pod)))
        {
            Some((pod_id, pod)) => match pod.cost_per_hour {
                Some(rate) => format!(" on pod {pod_id} (${rate:.2}/h)"),
                None => format!(" on pod {pod_id}"),
            },
            None => format!(" on target `{}`", row.record.target),
        }
    }

    /// Detaches every task that follows a run, each once its watch began;
    /// cancels are waited for.
    pub(super) fn detach_all(&mut self) -> Vec<Effect> {
        let following: Vec<TaskId> = self
            .training
            .tasks
            .iter()
            .filter(|(_, follow)| follow.job != Job::Cancel)
            .map(|(id, _)| *id)
            .collect();
        following
            .into_iter()
            .flat_map(|id| self.detach(id))
            .collect()
    }

    /// Quitting while Runpod runs still provision (and no signal abandoned them
    /// yet): offers to abandon them rather than wait for their jobs.
    pub(super) fn offer_abandon(&mut self) {
        if self.leaving != Some(Exit::Quit) {
            return;
        }
        let starting: Vec<(TaskId, String)> = self
            .training
            .tasks
            .iter()
            .filter(|(_, follow)| {
                follow.job == Job::Start { runpod: true }
                    && follow.starting()
                    && follow.detach != Detach::Done
            })
            .map(|(id, follow)| (*id, follow.run()))
            .collect();
        if starting.is_empty() {
            return;
        }
        let runs: Vec<&str> = starting.iter().map(|(_, run)| run.as_str()).collect();
        let text = format!(
            "Quitting waits until the job of {} has started, which can take minutes. Abandon \
             it instead? {ABANDONED}",
            runs.join(", ")
        );
        self.overlay = Some(Overlay::Confirm(Confirm {
            title: " Abandon a starting run? ".to_string(),
            text: vec![text],
            yes: "abandon",
            no: "wait",
            action: Action::Abandon(starting.into_iter().map(|(id, _)| id).collect()),
        }));
    }

    /// Abandons the start tasks `ids` that still provision, once confirmed: as
    /// a signal would, their pods are deleted and their runs fail. A cancel
    /// asked for meanwhile is dropped: an abandoned run has no job to cancel,
    /// and its flow's error says what became of it.
    pub(super) fn abandon(&mut self, ids: &[TaskId]) -> Vec<Effect> {
        let mut effects = Vec::new();
        for id in ids {
            if let Some(follow) = self.training.tasks.get_mut(id)
                && follow.starting()
                && follow.detach != Detach::Done
            {
                follow.detach = Detach::Done;
                follow.cancel_after = false;
                effects.push(Effect::Abandon(*id));
            }
        }
        effects
    }

    /// Abandons start task `id`, once confirmed after `c`, as [`App::abandon`]
    /// does, and says so, quitting or not. Its job may have started since the
    /// dialog opened: it is then not abandoned, and the status line says how
    /// to cancel it, since its pod keeps billing.
    pub(super) fn abandon_start(&mut self, id: TaskId) -> Vec<Effect> {
        let Some(follow) = self.training.tasks.get(&id) else {
            return Vec::new();
        };
        let run = follow.run();
        if !follow.starting() {
            self.say(
                Severity::Warn,
                format!(
                    "{run}: its job started, so it was not abandoned and its pod keeps billing; \
                     press c to cancel it"
                ),
            );
            return Vec::new();
        }
        if follow.detach == Detach::Done {
            self.say(Severity::Info, format!("{run} is being abandoned"));
            return Vec::new();
        }
        self.say(Severity::Info, format!("abandoning {run}"));
        self.abandon(&[id])
    }

    /// On a process signal: every task that follows a run is abandoned at once,
    /// as Ctrl-C does on the command line (a Runpod run still provisioning
    /// deletes its pod and fails); cancels are waited for. A cancel waiting
    /// for a task never starts after a signal; the exit notes say how to run
    /// it (see [`App::trained`]).
    pub(super) fn abandon_all(&mut self) -> Vec<Effect> {
        self.training
            .tasks
            .iter_mut()
            .filter(|(_, follow)| follow.job != Job::Cancel)
            .map(|(id, follow)| {
                follow.detach = Detach::Done;
                Effect::Abandon(*id)
            })
            .collect()
    }

    /// When quitting is called off: tasks still waiting for their job to detach
    /// keep following, unless a cancel waits for them. Returns how many runs
    /// are detached all the same (their tokens are cancelled), and how many
    /// starts are abandoned all the same.
    pub(super) fn keep_following(&mut self) -> (usize, usize) {
        let (mut detached, mut abandoned) = (0, 0);
        for follow in self.training.tasks.values_mut() {
            if follow.detach == Detach::OnStart && !follow.cancel_after {
                follow.detach = Detach::No;
            }
            if follow.detach != Detach::Done || follow.job == Job::Cancel {
                continue;
            }
            if follow.starting() {
                abandoned += 1;
            } else {
                detached += 1;
            }
        }
        (detached, abandoned)
    }

    /// When the runs were last read: never, for a new app.
    pub(super) fn never() -> SystemTime {
        SystemTime::UNIX_EPOCH
    }
}

/// `text` with its first letter in upper case.
fn capitalized(text: &str) -> String {
    let mut chars = text.chars();
    chars.next().map_or_else(String::new, |first| {
        first.to_uppercase().chain(chars).collect()
    })
}