kanbrain-core 0.6.0

//! Entries (tasks, notes and decisions), their links, status history, time-tracking sessions, comments and activity.
//!
//! - [`markdown`]: reading and writing the task file format.
//! - [`text`]: tags, file-name slugs and heading rules for user text.
//! - [`time`]: timestamps, ages and durations.

mod markdown;
mod text;
mod time;

pub(crate) use markdown::MISSING_ID;
pub use markdown::{not_a_link, parse_links};
pub use text::{counted, one_line, parse_tags, sanitize_comment, sanitize_description, slugify};
#[cfg(test)]
pub use time::parse_ts;
pub use time::{covered, fmt_age, fmt_clock, fmt_dur, fmt_ts, now};

use crate::enums::named_enum;
use chrono::{DateTime, Duration, Local};
use std::path::PathBuf;

named_enum! {
    /// Where a task stands. Declared in the order the task list shows them, so
    /// `position()` is the sort key; the names are what task files contain.
    #[derive(Clone, Copy, Debug, PartialEq, Eq)]
    pub enum Status {
        /// Being worked on.
        Doing => "doing",
        /// Not started yet.
        Todo => "todo",
        /// Started, then set aside for now.
        Parked => "parked",
        /// Finished; hidden from the list by default.
        Done => "done",
    }
}

named_enum! {
    /// Who made a change: the user, or a coding agent working through `kb`. Comments and status changes
    /// record it, so the board tells them apart, and so a question an agent asked waits for a person.
    #[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
    pub enum Author {
        /// The user: in the kanban app, or `kb` typed at a terminal.
        #[default]
        Human => "human",
        /// A coding agent, as `kb` finds from its environment.
        Agent => "agent",
    }
}

named_enum! {
    /// Where a decision stands. An agent records the decisions within its task as accepted, and proposes
    /// those it shouldn't take alone (architecture, dependencies, storage) for a person to accept or reject.
    #[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
    pub enum DecisionState {
        /// In force.
        #[default]
        Accepted => "accepted",
        /// Waiting for a person to accept or reject it.
        Proposed => "proposed",
        /// Turned down: kept so the same approach isn't proposed again.
        Rejected => "rejected",
    }
}

named_enum! {
    /// What an entry is. Only tasks have a status, history and sessions; notes and decisions are
    /// documents that tasks and each other link to. Declared in the order `tab` cycles the list.
    #[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
    pub enum Kind {
        /// Something to do.
        #[default]
        Task => "task",
        /// Something to remember: a finding, how something works, a snippet.
        Note => "note",
        /// Something decided, with its context and consequences (an ADR).
        Decision => "decision",
    }
}

/// One status change, as kept in the task's history.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub struct StatusChange {
    /// When the status changed.
    pub at: DateTime<Local>,
    /// The status before.
    pub from: Status,
    /// The status after.
    pub to: Status,
    /// Who moved it.
    pub by: Author,
}

/// One continuous stretch of tracked work on a task.
#[derive(Clone, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub struct Session {
    /// When the session started.
    pub start: DateTime<Local>,
    /// `None` while the session is still running.
    pub end: Option<DateTime<Local>>,
}

impl Session {
    /// How long the session lasted, or has lasted so far if it's running.
    pub fn duration(&self, now: DateTime<Local>) -> Duration {
        (self.end.unwrap_or(now) - self.start).max(Duration::zero())
    }

    /// Part of this session that falls inside `[from, to)`.
    pub fn overlap(&self, from: DateTime<Local>, to: DateTime<Local>, now: DateTime<Local>) -> Duration {
        let (start, end) = self.span(from, to, now);
        (end - start).max(Duration::zero())
    }

    /// Where this session starts and ends within `[from, to)`, a running one ending `now`; the end is
    /// before the start when it falls outside.
    pub fn span(
        &self,
        from: DateTime<Local>,
        to: DateTime<Local>,
        now: DateTime<Local>,
    ) -> (DateTime<Local>, DateTime<Local>) {
        (self.start.max(from), self.end.unwrap_or(now).min(to))
    }
}

/// A timestamped comment on a task, like on a GitHub/GitLab issue.
#[derive(Clone, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub struct Comment {
    /// When the comment was written.
    pub created: DateTime<Local>,
    /// Set when the body was changed after posting.
    pub edited: Option<DateTime<Local>>,
    /// The comment text (markdown).
    pub body: String,
    /// Who wrote it.
    pub author: Author,
    /// A question to the user: the task waits for a person's answer (see [`Task::asked`]).
    pub question: bool,
    /// The answer to the question before it, whoever wrote it: a verdict on the decision it asked about, which an
    /// agent may give on the user's word.
    pub answer: bool,
    /// Words of the header's parentheses this version doesn't know, written back as they were.
    pub unknown: Vec<String>,
}

impl Comment {
    /// A plain comment by `author`.
    pub fn new(created: DateTime<Local>, body: String, author: Author) -> Self {
        Self { created, edited: None, body, author, question: false, answer: false, unknown: Vec::new() }
    }
}

/// Where a question an agent asked on a task stands, while the task is parked waiting on it.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Asked<'a> {
    /// Nobody has answered the question yet.
    Waiting(&'a Comment),
    /// A person answered (the latest answer): the task can be picked up again.
    Answered(&'a Comment),
}

impl Asked<'_> {
    /// Where it stands, as the command line's text and JSON say it.
    pub fn label(self) -> &'static str {
        match self {
            Self::Waiting(_) => "waiting for an answer",
            Self::Answered(_) => "answered",
        }
    }
}

/// An entry in another repository of the same project, written `shop-api#3`: ids repeat across
/// repositories, so the repository's name goes with it.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct RepoLink {
    /// The repository's name in the project, as `kb init` registered it.
    pub repo: String,
    /// The entry's id there.
    pub id: u32,
}

impl std::fmt::Display for RepoLink {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}#{}", self.repo, self.id)
    }
}

/// An entry: a task, note or decision. What it is, how it's tagged and linked, and for tasks,
/// where it stands and how it got there.
#[derive(Clone, Debug)]
#[non_exhaustive]
pub struct Task {
    /// Unique number across all kinds, also the start of the file name.
    pub id: u32,
    /// Task, note or decision.
    pub kind: Kind,
    /// One-line title.
    pub title: String,
    /// Lowercase, without the leading `#`.
    pub tags: Vec<String>,
    /// Ids of related entries, in the order they were added. Deleting an entry removes the links to it.
    pub links: Vec<u32>,
    /// Related entries in the project's other repositories, in the order they were added. Nothing checks
    /// them once written: the other repository may be elsewhere, or the entry deleted there since.
    pub repo_links: Vec<RepoLink>,
    /// Where the task stands.
    pub status: Status,
    /// Decisions only: whether it's in force, proposed or rejected.
    pub decision: DecisionState,
    /// When the task was created.
    pub created: DateTime<Local>,
    /// Free text describing the task.
    pub description: String,
    /// Oldest first.
    pub comments: Vec<Comment>,
    /// Every status change, oldest first.
    pub history: Vec<StatusChange>,
    /// Every change to the title, tags, related entries or description, oldest first.
    pub activity: Vec<Activity>,
    /// Tracked work, oldest first; only the last one can be open, and only while the task is `doing`.
    pub sessions: Vec<Session>,
    /// File this task was loaded from / saved to.
    pub path: Option<PathBuf>,
    /// What the file holds that this version doesn't understand, written back as it was.
    pub unknown: Unknown,
}

/// Fields, link forms and sections a newer version wrote, kept as written: otherwise an older `kb` or app
/// saving the entry, for a comment or a status change, would drop them from the file.
#[derive(Clone, Debug, Default)]
#[non_exhaustive]
pub struct Unknown {
    /// `- key: value` lines before the first section, in file order.
    pub meta: Vec<String>,
    /// Words of `- links:` that are neither an id nor `REPO#ID`.
    pub links: Vec<String>,
    /// Other `##` sections, each from its heading line, in file order.
    pub sections: Vec<String>,
    /// `## Activity` items this version can't read (a newer version's kind of change), each with its lines.
    pub activity: Vec<String>,
}

/// One change to an entry's title, tags, related entries or description, as kept in its activity: the thread shows
/// them among the comments, like an issue's on GitHub or GitLab.
#[derive(Clone, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub struct Activity {
    /// When it was made.
    pub at: DateTime<Local>,
    /// Who made it.
    pub by: Author,
    /// What it changed.
    pub change: Changed,
}

impl Activity {
    /// A change `by` someone `at` a time.
    pub fn new(at: DateTime<Local>, by: Author, change: Changed) -> Self {
        Self { at, by, change }
    }
}

/// What a change to an entry changed. Lists say what was added and removed rather than what was there before and
/// after, so a change reads the same on each side of a relation, and a tag renamed in every entry says so in each.
#[derive(Clone, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub enum Changed {
    /// The title.
    Title {
        /// What it was.
        from: String,
        /// What it became.
        to: String,
    },
    /// The tags.
    Tags {
        /// Tags it got.
        added: Vec<String>,
        /// Tags it lost.
        removed: Vec<String>,
    },
    /// The related entries, whichever side keeps the link: `5` names an entry of the same brain, `shop-api#3` one of
    /// the project's other repositories, as `- links:` writes them.
    Related {
        /// Entries it was related to.
        added: Vec<String>,
        /// Entries it was unrelated from.
        removed: Vec<String>,
    },
    /// The description: only that it changed, since one can be long.
    Description,
}

impl Changed {
    /// What it did, said after who did it: `changed the title from "A" to "B"`, `added the tag #ux and removed the
    /// tag #bug`, `related it to #5 and unrelated it from shop-api#3`, `changed the description`.
    pub fn said(&self) -> String {
        type Name = fn(&String) -> String;
        let (added, removed, verbs, name): (&[String], &[String], _, Name) = match self {
            Self::Title { from, to } => return format!("changed the title from \"{from}\" to \"{to}\""),
            Self::Description => return "changed the description".to_string(),
            Self::Tags { added, removed } => (added, removed, ["added", "removed"], |tag| format!("#{tag}")),
            // An entry of this brain is `#5`, one of another repository `shop-api#3`, as links are typed.
            Self::Related { added, removed } => (added, removed, ["related it to", "unrelated it from"], |word| {
                if word.contains('#') { word.clone() } else { format!("#{word}") }
            }),
        };
        let noun = |words: &[String]| match self {
            Self::Tags { .. } if words.len() == 1 => " the tag",
            Self::Tags { .. } => " the tags",
            _ => "",
        };
        [(verbs[0], added), (verbs[1], removed)]
            .into_iter()
            .filter(|(_, words)| !words.is_empty())
            .map(|(verb, words)| {
                format!("{verb}{} {}", noun(words), words.iter().map(name).collect::<Vec<_>>().join(", "))
            })
            .collect::<Vec<_>>()
            .join(" and ")
    }

    /// Whether it changes nothing: a list with nothing added or removed, or a title back to what it was.
    fn is_empty(&self) -> bool {
        match self {
            Self::Title { from, to } => from == to,
            Self::Tags { added, removed } | Self::Related { added, removed } => added.is_empty() && removed.is_empty(),
            Self::Description => false,
        }
    }

    /// Takes in `next`, a later change of the same kind, as one change; `next` back when it's another kind.
    fn absorb(&mut self, next: Changed) -> Result<(), Changed> {
        match (self, next) {
            (Self::Title { to, .. }, Self::Title { to: next, .. }) => *to = next,
            (Self::Tags { added, removed }, Self::Tags { added: more, removed: fewer })
            | (Self::Related { added, removed }, Self::Related { added: more, removed: fewer }) => {
                combine(added, removed, more, fewer);
            }
            (Self::Description, Self::Description) => {}
            (_, next) => return Err(next),
        }
        Ok(())
    }
}

/// One item of an entry's thread, as the app and `kb show` list it: a comment, with its index among the comments, or a
/// change.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum ThreadItem<'a> {
    /// A comment, and where it is in [`Task::comments`].
    Comment(usize, &'a Comment),
    /// A change to the title, tags, related entries or description.
    Change(&'a Activity),
}

/// Adds `more` and `fewer` to what was `added` and `removed`: a word added and then removed, or the other way round,
/// is neither.
fn combine(added: &mut Vec<String>, removed: &mut Vec<String>, more: Vec<String>, fewer: Vec<String>) {
    for word in more {
        match removed.iter().position(|w| *w == word) {
            Some(at) => drop(removed.remove(at)),
            None if !added.contains(&word) => added.push(word),
            None => {}
        }
    }
    for word in fewer {
        match added.iter().position(|w| *w == word) {
            Some(at) => drop(added.remove(at)),
            None if !removed.contains(&word) => removed.push(word),
            None => {}
        }
    }
}

impl Task {
    /// A new `todo` task.
    pub fn new(id: u32, title: String, now: DateTime<Local>) -> Self {
        Self {
            id,
            kind: Kind::Task,
            title,
            tags: Vec::new(),
            links: Vec::new(),
            repo_links: Vec::new(),
            unknown: Unknown::default(),
            status: Status::Todo,
            decision: DecisionState::Accepted,
            created: now,
            description: String::new(),
            comments: Vec::new(),
            history: Vec::new(),
            activity: Vec::new(),
            sessions: Vec::new(),
            path: None,
        }
    }

    /// Records `change`, made `by` someone `at` a time, in the activity, in time order (another computer's clock
    /// may be behind). The latest change, when the same author made it in the same second to the same thing, takes it
    /// in (the app saves a form's related entries one at a time), and one that ends up changing nothing goes; any
    /// other change between them keeps them apart, so the activity still says what came first.
    pub fn log(&mut self, at: DateTime<Local>, by: Author, change: Changed) {
        let place = self.activity.partition_point(|a| a.at <= at);
        let mut change = change;
        if let Some(latest) = place.checked_sub(1).filter(|&i| self.activity[i].at == at && self.activity[i].by == by) {
            match self.activity[latest].change.absorb(change) {
                Ok(()) => {
                    if self.activity[latest].change.is_empty() {
                        self.activity.remove(latest);
                    }
                    return;
                }
                Err(other) => change = other,
            }
        }
        if !change.is_empty() {
            self.activity.insert(place, Activity::new(at, by, change));
        }
    }

    /// Gives the entry `title`, made `by` someone `at` a time, and logs it; returns whether it changed.
    pub fn set_title(&mut self, title: String, at: DateTime<Local>, by: Author) -> bool {
        if title == self.title {
            return false;
        }
        let from = std::mem::replace(&mut self.title, title);
        self.log(at, by, Changed::Title { from, to: self.title.clone() });
        true
    }

    /// Gives the entry `tags`, made `by` someone `at` a time, and logs which it got and lost; returns whether they
    /// changed, the order included.
    pub fn set_tags(&mut self, tags: Vec<String>, at: DateTime<Local>, by: Author) -> bool {
        if tags == self.tags {
            return false;
        }
        let added = tags.iter().filter(|t| !self.tags.contains(t)).cloned().collect();
        let removed = self.tags.iter().filter(|t| !tags.contains(t)).cloned().collect();
        self.tags = tags;
        self.log(at, by, Changed::Tags { added, removed });
        true
    }

    /// Gives the entry `description`, made `by` someone `at` a time, and logs that it changed; returns whether it did.
    pub fn set_description(&mut self, description: String, at: DateTime<Local>, by: Author) -> bool {
        if description == self.description {
            return false;
        }
        self.description = description;
        self.log(at, by, Changed::Description);
        true
    }

    /// Logs that the entry was related to the entries `added` names and unrelated from those `removed` names (see
    /// [`Changed::Related`]), by someone `at` a time. Whichever side keeps the link, both entries log it.
    pub fn relate(&mut self, at: DateTime<Local>, by: Author, added: &[String], removed: &[String]) {
        self.log(at, by, Changed::Related { added: added.to_vec(), removed: removed.to_vec() });
    }

    /// Moves the task to `status` and records the change, made `by` someone. Returns false if it already
    /// was there. Leaving `doing` closes the open session, so a clock never keeps running on a task that
    /// isn't being worked on.
    pub fn set_status(&mut self, status: Status, now: DateTime<Local>, by: Author) -> bool {
        if self.status == status {
            return false;
        }
        if status != Status::Doing {
            self.stop_session(now);
        }
        self.history.push(StatusChange { at: now, from: self.status, to: status, by });
        self.status = status;
        true
    }

    /// Whether the last session is still open.
    pub fn is_running(&self) -> bool {
        self.sessions.last().is_some_and(|s| s.end.is_none())
    }

    /// How long the open session has been running, if any.
    pub fn running_for(&self, now: DateTime<Local>) -> Option<Duration> {
        self.sessions.last().filter(|s| s.end.is_none()).map(|s| s.duration(now))
    }

    /// Opens a session now, unless one is already running. The caller moves the task to `doing`.
    pub fn start_session(&mut self, now: DateTime<Local>) {
        if !self.is_running() {
            self.sessions.push(Session { start: now, end: None });
        }
    }

    /// Closes the open session, if any.
    pub fn stop_session(&mut self, now: DateTime<Local>) {
        if let Some(session) = self.sessions.last_mut().filter(|s| s.end.is_none()) {
            session.end = Some(now.max(session.start));
        }
    }

    /// Time tracked in all sessions.
    pub fn total(&self, now: DateTime<Local>) -> Duration {
        self.sessions.iter().map(|s| s.duration(now)).sum()
    }

    /// Time tracked inside `[from, to)`: sessions are clipped to the range. For several tasks, see [`worked`].
    pub fn time_between(&self, from: DateTime<Local>, to: DateTime<Local>, now: DateTime<Local>) -> Duration {
        self.sessions.iter().map(|s| s.overlap(from, to, now)).sum()
    }

    /// Who last moved the task to `doing`: a person or an agent. A task in `doing` with no such change (from
    /// an older version, or edited by hand) counts as a person's.
    pub fn started_by(&self) -> Author {
        self.history.iter().rev().find(|c| c.to == Status::Doing).map_or(Author::Human, |c| c.by)
    }

    /// When the status last changed (or the task was created, if never); used for sorting.
    pub fn status_since(&self) -> DateTime<Local> {
        self.history.last().map_or(self.created, |c| c.at)
    }

    /// The question this parked task waits on, or its answer. A question is the latest comment marked as
    /// one; a person's comment after it answers it, as does a verdict on the decision it asked about. Starting the
    /// task after either means it was picked up, so it's neither once the task is parked again for another reason.
    pub fn asked(&self) -> Option<Asked<'_>> {
        if !self.is_task() || self.status != Status::Parked {
            return None;
        }
        let at = self.comments.iter().rposition(|c| c.question)?;
        let question = &self.comments[at];
        let answer = self.comments[at + 1..].iter().rev().find(|c| c.author == Author::Human || c.answer);
        // Strictly after: times are whole seconds, and an agent that starts a task and asks at once does
        // both in the same second, which isn't picking it up again.
        let picked_up = self.history.iter().any(|c| c.to == Status::Doing && c.at > question.created);
        match answer {
            _ if picked_up => None,
            Some(answer) => Some(Asked::Answered(answer)),
            None => Some(Asked::Waiting(question)),
        }
    }

    /// The comments and the activity together, oldest first, each in its own order. A change and a comment in the
    /// same second go change first: the app's **Save and tell** writes the comment that tells of a change after it.
    pub fn thread(&self) -> Vec<ThreadItem<'_>> {
        let mut thread = Vec::with_capacity(self.comments.len() + self.activity.len());
        let mut changes = self.activity.iter().peekable();
        for (index, comment) in self.comments.iter().enumerate() {
            while let Some(change) = changes.next_if(|change| change.at <= comment.created) {
                thread.push(ThreadItem::Change(change));
            }
            thread.push(ThreadItem::Comment(index, comment));
        }
        thread.extend(changes.map(ThreadItem::Change));
        thread
    }

    /// Whether this entry has a status, history and sessions (only tasks do).
    pub fn is_task(&self) -> bool {
        self.kind == Kind::Task
    }

    /// Search: every whitespace-separated term must match. `#term` matches a tag prefix;
    /// anything else matches the title or a tag. Case-insensitive.
    pub fn matches(&self, query: &str) -> bool {
        query.split_whitespace().all(|term| self.has_term(&term.to_lowercase(), false))
    }

    /// Whether the entry has `term`, already lowercase: `#tag` (written as a tag is typed anywhere) a tag that
    /// starts with it; anything else the title or a tag, and with `everywhere`, the description or a comment too.
    pub(crate) fn has_term(&self, term: &str, everywhere: bool) -> bool {
        match term.strip_prefix('#') {
            Some("") => true,
            Some(tag) => text::parse_tags(tag).first().is_some_and(|tag| self.tags.iter().any(|t| t.starts_with(tag))),
            None => {
                self.title.to_lowercase().contains(term)
                    || self.tags.iter().any(|t| t.contains(term))
                    || everywhere
                        && (self.description.to_lowercase().contains(term)
                            || self.comments.iter().any(|c| c.body.to_lowercase().contains(term)))
            }
        }
    }
}

/// Time worked on any of `tasks` inside `[from, to)`: time two of them ran at once counts once (see
/// [`covered`]), so agents' tasks running in parallel don't make a day longer than it was.
pub fn worked<'a>(
    tasks: impl IntoIterator<Item = &'a Task>,
    from: DateTime<Local>,
    to: DateTime<Local>,
    now: DateTime<Local>,
) -> Duration {
    covered(tasks.into_iter().flat_map(|t| &t.sessions).map(|s| s.span(from, to, now)))
}

#[cfg(test)]
#[path = "../../tests/model.rs"]
mod tests;