tix-tracker 0.10.0

//! One-pass WIP aggregates: what each column holds, where that stands against its
//! limit, and why a total is unknown when it is (mission
//! `configurable-wip-limits-01M3C6WX`, WP02).
//!
//! # One snapshot, derived once
//!
//! Every surface that wants to show or decide a limit asks *this* module, and the
//! module asks the issue slice once (T007). Counting per column by scanning the
//! issue set again would be `columns × issues` — and, worse, two surfaces counting
//! separately is how `tix status` and the board start disagreeing about how full a
//! column is. The snapshot is derived state: it is built from issues a caller
//! already holds, it reads no file, and it writes nothing.
//!
//! # Never a wrong number
//!
//! An issue whose `estimate` cannot be counted (not `<number><unit>`,
//! `malformed_estimate`; a unit the board does not declare, `missing_conversion`;
//! a conversion that does not divide exactly, `ambiguous_conversion`) makes the
//! column's estimate total **unknown**, not zero and not the sum of the others
//! (C-003). The diagnostic names the issue, so the reader can fix it; the state
//! stays [`LimitState::Unknown`], which is never read as "within the limit".

use crate::config::BoardConfiguration;
use crate::model::Issue;

use super::config::{ColumnLimit, Estimate, LimitPolicy, WipDiagnostic};

/// Where a column stands against its limit.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum LimitState {
    /// Within every configured ceiling.
    Within,
    /// Over at least one configured ceiling.
    Over,
    /// At least one aggregate could not be computed, so nothing is claimed. This
    /// is never "within": an uncountable estimate must not pass a limit silently.
    Unknown,
}

impl LimitState {
    /// The stable spelling every surface prints.
    pub const fn as_str(self) -> &'static str {
        match self {
            Self::Within => "within",
            Self::Over => "over",
            Self::Unknown => "unknown",
        }
    }

    /// Whether anything is actually wrong: `Over`, or a total nobody can trust.
    pub const fn is_violation(self) -> bool {
        matches!(self, Self::Over)
    }

    /// The worse of two states, for a column that has two ceilings.
    pub const fn worse(self, other: Self) -> Self {
        match (self, other) {
            (Self::Over, _) | (_, Self::Over) => Self::Over,
            (Self::Unknown, _) | (_, Self::Unknown) => Self::Unknown,
            _ => Self::Within,
        }
    }
}

/// One column's usage, and the limit it is measured against.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ColumnUsage {
    /// The column's name, as the board declares it.
    pub column: String,
    /// How many issues the column holds.
    pub items: u32,
    /// The estimate total in the limit's unit.
    ///
    /// `None` when the board states no estimate ceiling for the column (there is no
    /// unit to count in) **or** when at least one issue's estimate could not be
    /// counted — the snapshot's diagnostics say which issue, and
    /// [`ColumnUsage::state`] is then [`LimitState::Unknown`].
    pub estimate: Option<u32>,
    /// The enabled limit in force for the column, if any.
    pub limit: Option<ColumnLimit>,
}

impl ColumnUsage {
    /// The item ceiling, when the column has one.
    pub fn max_items(&self) -> Option<u32> {
        self.limit.as_ref().and_then(|limit| limit.max_items)
    }

    /// The estimate ceiling, when the column has one.
    pub fn max_estimate(&self) -> Option<u32> {
        self.limit.as_ref().and_then(|limit| limit.max_estimate)
    }

    /// The unit the estimate ceiling counts in, when there is one.
    pub fn unit(&self) -> Option<&str> {
        self.limit.as_ref().and_then(|limit| limit.unit.as_deref())
    }

    /// The policy the column enforces, when it enforces one.
    pub fn policy(&self) -> Option<LimitPolicy> {
        self.limit.as_ref().and_then(ColumnLimit::resolved_policy)
    }

    /// Where the column stands on its own item ceiling.
    pub fn item_state(&self) -> LimitState {
        match self.max_items() {
            Some(max) => match self.items.cmp(&max) {
                std::cmp::Ordering::Greater => LimitState::Over,
                _ => LimitState::Within,
            },
            None => LimitState::Within,
        }
    }

    /// Where the column stands on its own estimate ceiling.
    pub fn estimate_state(&self) -> LimitState {
        match (self.max_estimate(), self.estimate) {
            // A ceiling nobody can measure is `Unknown`, never `Within`.
            (Some(_), None) => LimitState::Unknown,
            (Some(max), Some(total)) => match total.cmp(&max) {
                std::cmp::Ordering::Greater => LimitState::Over,
                _ => LimitState::Within,
            },
            (None, _) => LimitState::Within,
        }
    }

    /// Where the column stands overall: the worse of its two ceilings.
    pub fn state(&self) -> LimitState {
        self.item_state().worse(self.estimate_state())
    }

    /// The state the column **would** be in after `add_items` more cards and
    /// `add_estimate` more of its unit (T009).
    ///
    /// This is the before/after shape a move is judged with: the caller passes what
    /// the move would add, and reads the answer without touching a file. A move that
    /// adds nothing reproduces [`state`](ColumnUsage::state) exactly.
    pub fn prospective(&self, add_items: u32, add_estimate: u32) -> LimitState {
        let items = self.items.saturating_add(add_items);
        let item_state = match self.max_items() {
            Some(max) if items > max => LimitState::Over,
            _ => LimitState::Within,
        };
        let estimate_state = match (self.max_estimate(), self.estimate) {
            (Some(_), None) => LimitState::Unknown,
            (Some(max), Some(total)) => match total.saturating_add(add_estimate).cmp(&max) {
                std::cmp::Ordering::Greater => LimitState::Over,
                _ => LimitState::Within,
            },
            (None, _) => LimitState::Within,
        };
        item_state.worse(estimate_state)
    }

    /// The usage as one short cell: `4/5`, or `4` when the column has no item
    /// ceiling, with the estimate ceiling beside it in its unit (`12/20d`) when the
    /// board states one. A trailing `!` means something is over, or unknown.
    ///
    /// It is deliberately the *usage*, not a verdict: the verdict is the policy
    /// layer's, and a cell that said "block" would be a claim this module is not
    /// entitled to make.
    pub fn cell(&self) -> String {
        let mut cell = match self.max_items() {
            Some(max) => format!("{}/{max}", self.items),
            None => self.items.to_string(),
        };
        if let Some(max) = self.max_estimate() {
            let unit = self.unit().unwrap_or("");
            match self.estimate {
                Some(total) => cell.push_str(&format!(" {total}/{max}{unit}")),
                // No number to print: the diagnostics name the issue that made this
                // unmeasurable, and a `?` here is the honest cell.
                None => cell.push_str(&format!(" ?/{max}{unit}")),
            }
        }
        if !matches!(self.state(), LimitState::Within) {
            cell.push('!');
        }
        cell
    }
}

/// The board's WIP state: one derived snapshot of every configured column (T008).
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct WipSnapshot {
    columns: Vec<ColumnUsage>,
    diagnostics: Vec<WipDiagnostic>,
    configured: bool,
}

impl WipSnapshot {
    /// Derive the snapshot from `issues`, in the board's column order.
    ///
    /// **One pass over the issues** and no I/O: the columns are indexed once, and
    /// every issue is examined once and added to its own column's slot. An issue
    /// whose `status` is not a configured column is not counted anywhere — the board
    /// does not render it, so a limit on some other column is not its business
    /// (`tix status`'s own `mismatch` reporting is where such an issue is surfaced).
    pub fn build(board: &BoardConfiguration, issues: &[Issue]) -> Self {
        let mut columns: Vec<ColumnUsage> = board
            .columns
            .iter()
            .map(|column| ColumnUsage {
                column: column.clone(),
                items: 0,
                estimate: None,
                limit: board.wip.effective_limit(column).cloned(),
            })
            .collect();
        // A column that has an estimate ceiling starts its total at zero and grows
        // it; a column without one keeps `None`, because there is no unit to count
        // in and a raw sum would be a number with no meaning.
        let mut totals: Vec<Option<u32>> = columns
            .iter()
            .map(|usage| usage.max_estimate().map(|_| 0))
            .collect();
        let mut diagnostics: Vec<WipDiagnostic> = Vec::new();
        let index: std::collections::HashMap<&str, usize> = board
            .columns
            .iter()
            .enumerate()
            .map(|(slot, column)| (column.as_str(), slot))
            .collect();

        for issue in issues {
            let Some(&slot) = index.get(issue.status.display()) else {
                continue;
            };
            columns[slot].items = columns[slot].items.saturating_add(1);
            let Some(total) = totals[slot].as_mut() else {
                continue;
            };
            let Some(raw) = issue
                .estimate
                .as_deref()
                .map(str::trim)
                .filter(|raw| !raw.is_empty())
            else {
                // No estimate is zero estimate: the card is work, and it states no
                // size. That is not an error and produces no diagnostic.
                continue;
            };
            let unit = columns[slot].unit().unwrap_or_default().to_string();
            match Estimate::parse(raw).and_then(|estimate| board.wip.convert(&estimate, &unit)) {
                Ok(value) => *total = total.saturating_add(value),
                Err(error) => {
                    let diagnostic = error.first();
                    diagnostics.push(
                        WipDiagnostic::new(
                            diagnostic.kind,
                            format!(
                                "issue #{} in `{}` states `{raw}`, which this board cannot count \
                                 in `{unit}`: {}",
                                issue.number, columns[slot].column, diagnostic.message
                            ),
                        )
                        .because(
                            "the column's estimate total is unknown until this is fixed, and an \
                             unknown total never passes a limit (C-003)",
                        ),
                    );
                    // The total is now untrustworthy: `None` is the only honest value.
                    totals[slot] = None;
                    columns[slot].estimate = None;
                }
            }
        }

        for (slot, total) in totals.into_iter().enumerate() {
            columns[slot].estimate = total;
        }
        let configured = columns.iter().any(|usage| usage.limit.is_some());
        Self {
            columns,
            diagnostics,
            configured,
        }
    }

    /// Every configured column, in board order.
    pub fn columns(&self) -> &[ColumnUsage] {
        &self.columns
    }

    /// One column's usage, by name.
    pub fn column(&self, column: &str) -> Option<&ColumnUsage> {
        self.columns.iter().find(|usage| usage.column == column)
    }

    /// The findings that made a total unknown.
    pub fn diagnostics(&self) -> &[WipDiagnostic] {
        &self.diagnostics
    }

    /// Whether any column enforces a limit at all.
    ///
    /// A surface that shows limits should ask this first: a board with no limits must
    /// render exactly what it rendered before this mission, byte for byte.
    pub fn is_configured(&self) -> bool {
        self.configured
    }

    /// Where `column` stands, or [`LimitState::Within`] for a column with no limit.
    pub fn state(&self, column: &str) -> LimitState {
        self.column(column)
            .map_or(LimitState::Within, ColumnUsage::state)
    }

    /// Every column that is over a ceiling, in board order.
    pub fn violations(&self) -> impl Iterator<Item = &ColumnUsage> {
        self.columns
            .iter()
            .filter(|usage| usage.state().is_violation())
    }
}

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

    use crate::config::BoardConfiguration;
    use crate::wip::WipConfig;
    use crate::wip::config::WipDiagnosticKind;

    fn board(limits: &[(&str, ColumnLimit)]) -> BoardConfiguration {
        BoardConfiguration {
            columns: ["todo", "in progress", "in review", "done"]
                .into_iter()
                .map(String::from)
                .collect(),
            wip: WipConfig {
                units: [("d", 1), ("w", 5)]
                    .into_iter()
                    .map(|(name, factor)| (name.to_string(), factor))
                    .collect::<IndexMap<_, _>>(),
                limits: limits
                    .iter()
                    .map(|(column, limit)| ((*column).to_string(), limit.clone()))
                    .collect(),
            },
            ..BoardConfiguration::default()
        }
    }

    /// An issue through the **real** parser: the `estimate:` key is frontmatter, so
    /// the fixture is the file format rather than a hand-built struct.
    fn issue(number: u32, status: &str, estimate: Option<&str>) -> Issue {
        let estimate = estimate
            .map(|value| format!("estimate: \"{value}\"\n"))
            .unwrap_or_default();
        let contents = format!(
            "---\nnumber: {number}\ntitle: \"Issue {number}\"\nstatus: \"{status}\"\n\
             created: \"2026-01-01\"\nupdated: \"2026-01-01\"\n{estimate}---\n\nBody.\n"
        );
        let mut issue = Issue::parse(&contents).expect("the fixture parses");
        issue.filename = format!("issue-{number}.md");
        issue
    }

    #[test]
    fn wip_aggregate_counts_every_column_in_one_pass() {
        let board = board(&[("in progress", ColumnLimit::items(2, LimitPolicy::Warn))]);
        let issues = vec![
            issue(1, "todo", None),
            issue(2, "in progress", None),
            issue(3, "in progress", None),
            issue(4, "done", None),
            issue(5, "shipped", None), // not a configured column
        ];
        let snapshot = WipSnapshot::build(&board, &issues);
        assert_eq!(
            snapshot
                .columns()
                .iter()
                .map(|usage| (usage.column.as_str(), usage.items))
                .collect::<Vec<_>>(),
            vec![
                ("todo", 1),
                ("in progress", 2),
                ("in review", 0),
                ("done", 1)
            ],
            "every configured column appears, in board order"
        );
        assert_eq!(
            snapshot.column("in progress").expect("usage").state(),
            LimitState::Within
        );
        assert_eq!(
            snapshot.state("todo"),
            LimitState::Within,
            "no limit is within"
        );
        assert!(snapshot.is_configured());
    }

    #[test]
    fn wip_aggregate_state_is_over_only_past_the_ceiling() {
        let board = board(&[("in progress", ColumnLimit::items(2, LimitPolicy::Block))]);
        let at_limit = WipSnapshot::build(
            &board,
            &[issue(1, "in progress", None), issue(2, "in progress", None)],
        );
        let usage = at_limit.column("in progress").expect("usage");
        assert_eq!(
            usage.state(),
            LimitState::Within,
            "exactly at the limit is within"
        );
        assert_eq!(usage.prospective(1, 0), LimitState::Over);
        assert_eq!(
            usage.prospective(0, 0),
            LimitState::Within,
            "a no-op move is within"
        );

        let over = WipSnapshot::build(
            &board,
            &[
                issue(1, "in progress", None),
                issue(2, "in progress", None),
                issue(3, "in progress", None),
            ],
        );
        assert_eq!(
            over.column("in progress").expect("usage").state(),
            LimitState::Over
        );
        assert_eq!(over.violations().count(), 1);
        assert_eq!(over.column("in progress").expect("usage").cell(), "3/2!");
    }

    #[test]
    fn wip_aggregate_totals_estimates_in_the_limit_unit() {
        let board = board(&[(
            "in progress",
            ColumnLimit::estimate(10, "d", LimitPolicy::Warn),
        )]);
        let issues = vec![
            issue(1, "in progress", Some("3")),
            issue(2, "in progress", Some("1w")),
            issue(3, "in progress", None),
            issue(4, "in progress", Some("  ")),
            issue(5, "todo", Some("9w")),
        ];
        let snapshot = WipSnapshot::build(&board, &issues);
        let usage = snapshot.column("in progress").expect("usage");
        assert_eq!(usage.items, 4, "an unestimated card is still work");
        assert_eq!(
            usage.estimate,
            Some(8),
            "3 + 5d; the empty ones add nothing"
        );
        assert_eq!(usage.state(), LimitState::Within);
        assert_eq!(usage.cell(), "4 8/10d");
        assert_eq!(
            snapshot.column("todo").expect("usage").estimate,
            None,
            "no estimate ceiling means no unit, so no total"
        );
        assert_eq!(snapshot.diagnostics(), []);
    }

    #[test]
    fn wip_aggregate_unknown_total_is_never_within() {
        let board = board(&[(
            "in progress",
            ColumnLimit::estimate(10, "d", LimitPolicy::Block),
        )]);
        for (raw, kind) in [
            ("three", WipDiagnosticKind::MalformedEstimate),
            ("3q", WipDiagnosticKind::MissingConversion),
        ] {
            let snapshot = WipSnapshot::build(
                &board,
                &[
                    issue(1, "in progress", Some("2")),
                    issue(2, "in progress", Some(raw)),
                ],
            );
            let usage = snapshot.column("in progress").expect("usage");
            assert_eq!(usage.estimate, None, "`{raw}`: no total is claimed");
            assert_eq!(usage.estimate_state(), LimitState::Unknown, "`{raw}`");
            assert_eq!(usage.prospective(0, 0), LimitState::Unknown, "`{raw}`");
            assert_eq!(
                usage.cell(),
                "2 ?/10d!",
                "the cell says unknown with a `!`, never a number"
            );
            let diagnostic = &snapshot.diagnostics()[0];
            assert_eq!(diagnostic.kind, kind, "`{raw}`");
            assert!(
                diagnostic.message.contains("issue #2") && diagnostic.message.contains(raw),
                "{}",
                diagnostic.message
            );
        }
    }

    #[test]
    fn wip_aggregate_fractional_conversion_makes_the_total_unknown() {
        let mut board = board(&[(
            "in progress",
            ColumnLimit::estimate(10, "w", LimitPolicy::Warn),
        )]);
        board.wip.units.insert("h".to_string(), 1);
        board.wip.units.insert("d".to_string(), 8);
        let snapshot = WipSnapshot::build(&board, &[issue(1, "in progress", Some("3d"))]);
        let usage = snapshot.column("in progress").expect("usage");
        assert_eq!(usage.estimate_state(), LimitState::Unknown);
        assert_eq!(
            snapshot.diagnostics()[0].kind,
            WipDiagnosticKind::AmbiguousConversion
        );
    }

    #[test]
    fn wip_aggregate_without_limits_is_inert() {
        let board = BoardConfiguration::default();
        let issues = vec![issue(1, "todo", Some("3d")), issue(2, "todo", Some("nope"))];
        let snapshot = WipSnapshot::build(&board, &issues);
        assert!(!snapshot.is_configured(), "nothing is configured");
        assert!(snapshot.violations().next().is_none());
        assert_eq!(snapshot.column("todo").expect("usage").items, 2);
        assert!(
            snapshot.diagnostics().is_empty(),
            "with no limit there is nothing to measure, so nothing is broken"
        );
    }
}