cpm_planner/

earned_value.rs

//! Pure earned-value engine: PV / EV / AC and the derived SPI / CPI / EAC
//! family, computed from a frozen baseline, the current graph, statuses and
//! actuals. No I/O, no clocks: the caller supplies `as_of`.
//!
//! Costs are in hours multiplied by each deliverable's `metadata.cost_rate`
//! (finite, >= 0, default 1.0). Every division is guarded; an undefined ratio
//! becomes `None` plus an [`Undefined`] entry, never NaN or infinity.
//!
//! `as_of` is the status date of the planned value only: PV is the baseline
//! curve at `as_of`, while EV and AC reflect the progress and actuals
//! recorded up to the moment the call runs (actuals are not versioned in
//! time). A reading with a past `as_of` therefore pairs an old PV with
//! today's EV and AC; a snapshot more than an hour behind its `taken_at` is
//! flagged [`SnapshotSummary::backfilled`] and ignored by [`trend_alerts`].
//!
//! Rows are taken from the baseline only. Deliverables added after the
//! baseline contribute nothing to BAC, PV or EV until re-baseline; they are
//! listed in [`EvReport::excluded_unbaselined`]. Cost rates are frozen in
//! the baseline, so later rate edits do not change budget or AC.
//!
//! Actual cost never disappears: AC sums every actuals row of the plan
//! (reported hours, else leased hours), at the row's baseline cost rate, or
//! 1.0 for an id the baseline does not have (added later, or removed before
//! a re-baseline). So per-row `ac` can sum to less than the total.
//!
//! Removed scope: when a revise removes a baselined deliverable, its earned
//! percent is frozen ([`Actuals::frozen_pct`]: 100 if it was `Complete`,
//! else its rule's percent then). Its row then reports
//! [`EvRowStatus::Removed`] and earns that share of its budget (0 without a
//! frozen percent). Adding the id back clears the freeze and the reported
//! percent, so earning restarts; its hours keep accumulating.
//!
//! Known limitation: selecting variant A, then B, then A again after a
//! revise reopened a carried deliverable can count copied leased hours
//! twice (each select carries the source's leased hours onto the target).

use crate::estimator::EffortEstimator;
pub use crate::plan::EarningRule;
use crate::plan::{
    Deliverable, DeliverableStatus, FINISH_ID, PlanGraph, PlanId, PlannerError, START_ID,
};
use crate::schedule::{compute_cpm, effort_basis};
use crate::task::CriticalPathResult;
use chrono::{DateTime, Datelike, Duration, NaiveDate, Utc, Weekday};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// Working-time calendar for the EV clock. Unknown fields are rejected.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[serde(deny_unknown_fields)]
pub struct Calendar {
    /// Working hours per workday, in (0, 24]. A workday contributes these
    /// hours starting at 00:00 local time.
    #[serde(default = "default_hours_per_day")]
    pub hours_per_day: f32,
    /// Lowercase 3-letter weekday names (`"mon"`..`"sun"`).
    #[serde(default = "default_workdays")]
    pub workdays: Vec<String>,
    /// Local offset from UTC in minutes, in [-1440, 1440].
    #[serde(default)]
    pub utc_offset_minutes: i32,
}

fn default_hours_per_day() -> f32 {
    8.0
}

fn default_workdays() -> Vec<String> {
    ["mon", "tue", "wed", "thu", "fri"]
        .map(String::from)
        .to_vec()
}

impl Default for Calendar {
    fn default() -> Self {
        Self {
            hours_per_day: default_hours_per_day(),
            workdays: default_workdays(),
            utc_offset_minutes: 0,
        }
    }
}

/// One frozen baseline row.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct BaselineRow {
    pub id: String,
    /// Baseline earliest start, hours from plan start.
    pub es: f32,
    /// Baseline earliest finish, hours from plan start.
    pub ef: f32,
    /// Budget = effort basis x cost rate.
    pub budget: f32,
    /// Cost rate captured at baseline time; AC uses this, not the live graph.
    #[serde(default = "one")]
    pub cost_rate: f32,
}

fn one() -> f32 {
    1.0
}

/// A frozen schedule/budget baseline.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct Baseline {
    pub number: u32,
    pub start: DateTime<Utc>,
    /// `None` means wall-clock hours.
    pub calendar: Option<Calendar>,
    pub rows: Vec<BaselineRow>,
    pub bac: f32,
    /// Baseline project finish (`__finish__` earliest finish), in hours.
    pub finish_hours: f32,
    /// True when `start` came from `plan.baseline`'s `backfill_from` rather
    /// than the call time.
    #[serde(default)]
    pub backfilled: bool,
}

/// Reported progress for one deliverable.
#[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
pub struct Actuals {
    pub earned_pct: Option<u8>,
    pub actual_hours: Option<f32>,
    pub leased_hours: f32,
    pub evidence: Vec<String>,
    /// When a revise removed this deliverable from the graph; cleared when a
    /// later revise adds the id back.
    #[serde(default)]
    pub removed_at: Option<DateTime<Utc>>,
    /// Earned percent frozen at removal (100 if it was `Complete`, else its
    /// earned percent under its rule then). A removed baseline row earns
    /// this share of its budget.
    #[serde(default)]
    pub frozen_pct: Option<u8>,
}

/// Status of one EV row: the deliverable's live status, or `removed` for a
/// baseline row whose id is no longer in the graph. Serialised like
/// [`DeliverableStatus`] (`{"status": "..."}`), with the extra value
/// `"removed"`.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(tag = "status", rename_all = "snake_case")]
pub enum EvRowStatus {
    Pending,
    Ready,
    InProgress,
    Complete,
    Failed {
        reason: String,
    },
    /// A revise removed the deliverable after it was baselined; it earns its
    /// frozen percent ([`Actuals::frozen_pct`], 0 if none).
    Removed,
}

impl From<DeliverableStatus> for EvRowStatus {
    fn from(s: DeliverableStatus) -> Self {
        match s {
            DeliverableStatus::Pending => Self::Pending,
            DeliverableStatus::Ready => Self::Ready,
            DeliverableStatus::InProgress => Self::InProgress,
            DeliverableStatus::Complete => Self::Complete,
            DeliverableStatus::Failed { reason } => Self::Failed { reason },
        }
    }
}

impl PartialEq<DeliverableStatus> for EvRowStatus {
    fn eq(&self, other: &DeliverableStatus) -> bool {
        match (self, other) {
            (Self::Pending, DeliverableStatus::Pending)
            | (Self::Ready, DeliverableStatus::Ready)
            | (Self::InProgress, DeliverableStatus::InProgress)
            | (Self::Complete, DeliverableStatus::Complete) => true,
            (Self::Failed { reason: a }, DeliverableStatus::Failed { reason: b }) => a == b,
            _ => false,
        }
    }
}

/// An EV field that could not be computed.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct Undefined {
    pub field: String,
    pub reason: String,
}

/// Per-deliverable EV row.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct EvRow {
    pub id: String,
    pub budget: f32,
    pub pv: f32,
    pub earned_pct: f32,
    pub ev: f32,
    /// This row's spend at its baseline cost rate.
    pub ac: f32,
    /// Live status, or `removed` when the id left the graph after baselining.
    pub status: EvRowStatus,
}

/// The ratios of an earlier snapshot, used for trend alerts.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct EvSummary {
    /// The baseline the snapshot was measured against; alerts only compare
    /// snapshots of the current baseline.
    pub baseline_number: u32,
    pub spi: Option<f32>,
    pub cpi: Option<f32>,
    /// The snapshot was backfilled ([`SnapshotSummary::backfilled`]); alerts
    /// ignore it.
    #[serde(default)]
    pub backfilled: bool,
}

/// Full earned-value report.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct EvReport {
    /// PV status date. EV and AC reflect progress and actuals recorded up
    /// to the moment the report was computed.
    pub as_of: DateTime<Utc>,
    pub baseline_number: u32,
    /// True when the baseline was taken with `backfill_from`.
    #[serde(default)]
    pub backfilled: bool,
    pub bac: f32,
    pub pv: f32,
    pub ev: f32,
    pub ac: f32,
    pub sv: f32,
    pub cv: f32,
    pub spi: Option<f32>,
    pub cpi: Option<f32>,
    pub eac: Option<f32>,
    pub etc: Option<f32>,
    pub vac: Option<f32>,
    pub tcpi: Option<f32>,
    pub undefined: Vec<Undefined>,
    pub rows: Vec<EvRow>,
    pub critical_float_consumed_hours: f32,
    pub alerts: Vec<String>,
    /// Ids in the live graph but absent from the baseline (sorted, synthetic
    /// endpoints excluded). They earn no value and carry no budget until a
    /// re-baseline, but their spend counts in AC at rate 1.0 (their live
    /// `cost_rate` applies only once a baseline row exists).
    pub excluded_unbaselined: Vec<String>,
}

fn weekday_from_name(name: &str) -> Option<Weekday> {
    Some(match name {
        "mon" => Weekday::Mon,
        "tue" => Weekday::Tue,
        "wed" => Weekday::Wed,
        "thu" => Weekday::Thu,
        "fri" => Weekday::Fri,
        "sat" => Weekday::Sat,
        "sun" => Weekday::Sun,
        _ => return None,
    })
}

fn workdays_per_week(days: &[Weekday]) -> usize {
    let mut uniq = days.to_vec();
    uniq.sort_by_key(|d| d.num_days_from_monday());
    uniq.dedup();
    uniq.len()
}

/// `metadata.cost_rate`: finite and >= 0, default 1.0.
fn cost_rate(d: &Deliverable) -> Result<f32, PlannerError> {
    match d.metadata.get("cost_rate") {
        None | Some(serde_json::Value::Null) => Ok(1.0),
        Some(v) => match v.as_f64() {
            Some(x) if x.is_finite() && x >= 0.0 && x <= f64::from(f32::MAX) => Ok(x as f32),
            _ => Err(PlannerError::InvalidGraph {
                reason: format!(
                    "deliverable {:?}: metadata.cost_rate must be a finite number >= 0, got {v}",
                    d.id
                ),
            }),
        },
    }
}

fn budget_of(d: &Deliverable, estimator: &EffortEstimator) -> Result<f32, PlannerError> {
    let budget = effort_basis(d, estimator) * cost_rate(d)?;
    if budget.is_finite() {
        Ok(budget)
    } else {
        Err(PlannerError::InvalidGraph {
            reason: format!("deliverable {:?}: budget is not finite", d.id),
        })
    }
}

/// Project finish in hours: the `__finish__` earliest finish, else the maximum.
fn finish_of(cpm: &CriticalPathResult) -> f32 {
    cpm.tasks
        .iter()
        .find(|t| t.id == FINISH_ID)
        .map(|t| t.earliest_finish)
        .unwrap_or_else(|| {
            cpm.tasks
                .iter()
                .map(|t| t.earliest_finish)
                .fold(0.0, f32::max)
        })
}

/// The percent a deliverable removed from the graph keeps
/// ([`Actuals::frozen_pct`]): 100 if it was `Complete`, else its earned
/// percent under `rule` with the `reported` percent (0 if none).
pub fn frozen_pct(rule: EarningRule, status: &DeliverableStatus, reported: Option<u8>) -> u8 {
    earned_pct(rule, status, reported.map(|p| p.min(100))).clamp(0.0, 100.0) as u8
}

fn earned_pct(rule: EarningRule, status: &DeliverableStatus, reported: Option<u8>) -> f64 {
    if *status == DeliverableStatus::Complete {
        return 100.0;
    }
    match rule {
        EarningRule::ZeroHundred => 0.0,
        EarningRule::FiftyFifty => {
            if *status == DeliverableStatus::InProgress || reported.is_some() {
                50.0
            } else {
                0.0
            }
        }
        EarningRule::Weighted => f64::from(reported.unwrap_or(0)),
    }
}

impl Calendar {
    /// Reject an unusable calendar with a clear reason.
    pub fn validate(&self) -> Result<(), PlannerError> {
        let bad = |reason: String| Err(PlannerError::InvalidGraph { reason });
        if !(self.hours_per_day.is_finite()
            && self.hours_per_day > 0.0
            && self.hours_per_day <= 24.0)
        {
            return bad(format!(
                "calendar.hours_per_day must be in (0, 24], got {}",
                self.hours_per_day
            ));
        }
        if !(-1440..=1440).contains(&self.utc_offset_minutes) {
            return bad(format!(
                "calendar.utc_offset_minutes must be in [-1440, 1440], got {}",
                self.utc_offset_minutes
            ));
        }
        if self.workdays.is_empty() {
            return bad("calendar.workdays must not be empty".to_string());
        }
        for name in &self.workdays {
            if weekday_from_name(name).is_none() {
                return bad(format!(
                    "calendar.workdays entry {name:?} is not a lowercase 3-letter weekday (mon..sun)"
                ));
            }
        }
        Ok(())
    }
}

/// Elapsed EV-clock hours between `start` and `as_of`.
pub fn elapsed_hours(
    start: DateTime<Utc>,
    as_of: DateTime<Utc>,
    calendar: Option<&Calendar>,
) -> Result<f32, PlannerError> {
    if as_of <= start {
        return Ok(0.0);
    }
    let Some(calendar) = calendar else {
        return Ok((as_of - start).num_milliseconds() as f32 / 3_600_000.0);
    };
    calendar.validate()?;
    let off = Duration::minutes(i64::from(calendar.utc_offset_minutes));
    let (ls, le) = (start.naive_utc() + off, as_of.naive_utc() + off);
    let workdays: Vec<Weekday> = calendar
        .workdays
        .iter()
        .filter_map(|n| weekday_from_name(n))
        .collect();
    let hpd = f64::from(calendar.hours_per_day);
    let is_work = |d: NaiveDate| workdays.contains(&d.weekday());
    // Working hours inside [from, to] on local day `d` (window is [00:00, 00:00 + hpd)).
    let partial = |d: NaiveDate, from: chrono::NaiveDateTime, to: chrono::NaiveDateTime| -> f64 {
        if !is_work(d) {
            return 0.0;
        }
        let day0 = d.and_hms_opt(0, 0, 0).unwrap_or(from);
        let lo = (from - day0).num_milliseconds() as f64 / 3_600_000.0;
        let hi = (to - day0).num_milliseconds() as f64 / 3_600_000.0;
        (hi.min(hpd) - lo.max(0.0)).max(0.0)
    };
    let (sd, ed) = (ls.date(), le.date());
    let total = if sd == ed {
        partial(sd, ls, le)
    } else {
        let mut t = partial(sd, ls, le) + partial(ed, ls, le);
        // Interior days (strictly between) are full days; skip whole weeks arithmetically.
        let interior = (ed - sd).num_days() - 1;
        let weeks = interior / 7;
        let per_week = workdays_per_week(&workdays) as f64;
        t += weeks as f64 * per_week * hpd;
        let mut d = sd + Duration::days(1 + weeks * 7);
        while d < ed {
            if is_work(d) {
                t += hpd;
            }
            d += Duration::days(1);
        }
        t
    };
    Ok(total as f32)
}

/// Freeze the current CPM schedule and budgets into a baseline.
pub fn build_baseline(
    graph: &PlanGraph,
    cpm: &CriticalPathResult,
    start: DateTime<Utc>,
    calendar: Option<Calendar>,
    number: u32,
) -> Result<Baseline, PlannerError> {
    if let Some(c) = &calendar {
        c.validate()?;
    }
    let by_id: HashMap<&str, &crate::task::Task> =
        cpm.tasks.iter().map(|t| (t.id.as_str(), t)).collect();
    let estimator = EffortEstimator::new();
    let mut rows = Vec::new();
    for d in &graph.deliverables {
        if d.id == START_ID || d.id == FINISH_ID {
            continue;
        }
        let Some(t) = by_id.get(d.id.as_str()) else {
            return Err(PlannerError::InvalidGraph {
                reason: format!("deliverable {:?} missing from CPM result", d.id),
            });
        };
        rows.push(BaselineRow {
            id: d.id.clone(),
            es: t.earliest_start,
            ef: t.earliest_finish,
            budget: budget_of(d, &estimator)?,
            cost_rate: cost_rate(d)?,
        });
    }
    let bac = rows.iter().map(|r| f64::from(r.budget)).sum::<f64>() as f32;
    if !bac.is_finite() {
        return Err(PlannerError::InvalidGraph {
            reason: "budget at completion (sum of effort x cost_rate) exceeds the f32 range"
                .to_string(),
        });
    }
    Ok(Baseline {
        number,
        start,
        calendar,
        rows,
        bac,
        finish_hours: finish_of(cpm),
        backfilled: false,
    })
}

/// Compute the earned-value report.
///
/// Critical-float consumption is approximated as
/// `max(0, current __finish__ EF - baseline finish)`.
/// Rows are taken from the baseline only. Deliverables added after the baseline
/// contribute nothing to BAC, PV or EV until re-baseline; AC sums every
/// entry of `actuals` (see the module docs). A baseline row whose id is not
/// in `graph` is `removed` and earns its frozen percent.
///
/// `as_of` sets PV only; EV and AC come from `statuses` and `actuals` as
/// given (the progress recorded when the call runs).
///
/// `critical_float_consumed_hours` reflects only graph/estimate changes: it
/// ignores statuses, actuals and `as_of`, so it does not show execution
/// slippage, and it includes scope added after the baseline.
///
/// Reported `actual_hours` that is non-finite or negative is treated as
/// absent (AC falls back to leased hours). TCPI can be negative when AC > BAC.
///
/// Alerts need the two latest entries of `previous_snapshots` (in `as_of`
/// order) taken against this baseline to both have the metric below 0.9
/// (see [`trend_alerts`]).
pub fn compute_ev(
    baseline: &Baseline,
    graph: &PlanGraph,
    statuses: &HashMap<String, DeliverableStatus>,
    rules: &HashMap<String, EarningRule>,
    actuals: &HashMap<String, Actuals>,
    as_of: DateTime<Utc>,
    previous_snapshots: &[EvSummary],
) -> Result<EvReport, PlannerError> {
    let t = f64::from(elapsed_hours(
        baseline.start,
        as_of,
        baseline.calendar.as_ref(),
    )?);
    let (mut pv, mut ev, mut ac) = (0.0_f64, 0.0_f64, 0.0_f64);
    let mut rows = Vec::with_capacity(baseline.rows.len());
    let live: std::collections::HashSet<&str> =
        graph.deliverables.iter().map(|d| d.id.as_str()).collect();
    let valid = |h: f32| h.is_finite() && h >= 0.0;
    // Actual hours, else leased hours; invalid values count as 0.
    let hours_of = |a: &Actuals| -> f32 {
        let h = match a.actual_hours {
            Some(h) if valid(h) => h,
            _ => a.leased_hours,
        };
        if valid(h) { h } else { 0.0 }
    };
    for r in &baseline.rows {
        let budget = f64::from(r.budget);
        let (es, ef) = (f64::from(r.es), f64::from(r.ef));
        let row_pv = if ef <= es {
            if t >= es { budget } else { 0.0 }
        } else {
            budget * ((t - es) / (ef - es)).clamp(0.0, 1.0)
        };
        let act = actuals.get(&r.id);
        let (status, pct) = if live.contains(r.id.as_str()) {
            let status = statuses
                .get(&r.id)
                .cloned()
                .unwrap_or(DeliverableStatus::Pending);
            let rule = rules.get(&r.id).copied().unwrap_or_default();
            let reported = act.and_then(|a| a.earned_pct).map(|p| p.min(100));
            let pct = earned_pct(rule, &status, reported);
            (EvRowStatus::from(status), pct)
        } else {
            let frozen = act.and_then(|a| a.frozen_pct).map_or(0, |p| p.min(100));
            (EvRowStatus::Removed, f64::from(frozen))
        };
        let hours = act.map_or(0.0, hours_of);
        let row_ev = budget * pct / 100.0;
        let row_ac = f64::from(r.cost_rate) * f64::from(hours);
        pv += row_pv;
        ev += row_ev;
        rows.push(EvRow {
            id: r.id.clone(),
            budget: r.budget,
            pv: row_pv as f32,
            earned_pct: pct as f32,
            ev: row_ev as f32,
            ac: row_ac as f32,
            status,
        });
    }
    // AC is every actuals row of the plan (spend never disappears): baseline
    // rows at their frozen cost rate, any other id at rate 1.0.
    let rates: HashMap<&str, f32> = baseline
        .rows
        .iter()
        .map(|r| (r.id.as_str(), r.cost_rate))
        .collect();
    let mut spend: Vec<(&String, &Actuals)> = actuals.iter().collect();
    spend.sort_by(|a, b| a.0.cmp(b.0));
    for (id, a) in spend {
        // Spend with no baseline row (added after the baseline, or descoped by
        // a re-baseline) counts at rate 1.0 until a baseline records its rate.
        let rate = rates.get(id.as_str()).copied().unwrap_or(1.0);
        ac += f64::from(rate) * f64::from(hours_of(a));
    }
    let bac: f64 = baseline.rows.iter().map(|r| f64::from(r.budget)).sum();
    let mut undefined = Vec::new();
    // `None` input = guarded division; a value that overflows f32 is also undefined.
    let mut ratio = |field: &str, v: Option<f64>, reason: &str| -> Option<f64> {
        let out = v.filter(|x| (*x as f32).is_finite());
        if out.is_none() {
            let reason = if v.is_some() {
                "result is not finite as f32"
            } else {
                reason
            };
            undefined.push(Undefined {
                field: field.to_string(),
                reason: reason.to_string(),
            });
        }
        out
    };
    let spi = ratio(
        "spi",
        (pv != 0.0).then(|| ev / pv),
        "PV is 0 before any work was planned",
    );
    let cpi = ratio(
        "cpi",
        (ac != 0.0).then(|| ev / ac),
        "AC is 0, no cost recorded yet",
    );
    let eac_reason = if cpi.is_none() {
        "CPI is undefined"
    } else {
        "CPI is 0, nothing earned for the cost spent"
    };
    let eac = ratio(
        "eac",
        cpi.filter(|c| *c != 0.0).map(|c| bac / c),
        eac_reason,
    );
    let etc = ratio("etc", eac.map(|e| e - ac), "EAC is undefined");
    let vac = ratio("vac", eac.map(|e| bac - e), "EAC is undefined");
    let tcpi = ratio(
        "tcpi",
        ((bac - ac).abs() > 1e-9 * bac.max(1.0)).then(|| (bac - ev) / (bac - ac)),
        "BAC - AC is 0, no budget remains",
    );
    let out = |v: Option<f64>| v.map(|x| x as f32);

    let cpm = compute_cpm(graph)?;
    let critical_float = (finish_of(&cpm) - baseline.finish_hours).max(0.0);

    let alerts = trend_alerts(previous_snapshots, baseline.number);
    for (field, v) in [
        ("pv", pv),
        ("ev", ev),
        ("ac", ac),
        ("sv", ev - pv),
        ("cv", ev - ac),
    ] {
        if !(v as f32).is_finite() {
            return Err(PlannerError::InvalidGraph {
                reason: format!(
                    "earned-value total {field} exceeds the f32 range (check cost_rate and \
                     reported hours)"
                ),
            });
        }
    }

    let report = EvReport {
        as_of,
        baseline_number: baseline.number,
        backfilled: baseline.backfilled,
        bac: baseline.bac,
        pv: pv as f32,
        ev: ev as f32,
        ac: ac as f32,
        sv: (ev - pv) as f32,
        cv: (ev - ac) as f32,
        spi: out(spi),
        cpi: out(cpi),
        eac: out(eac),
        etc: out(etc),
        vac: out(vac),
        tcpi: out(tcpi),
        undefined,
        rows,
        critical_float_consumed_hours: critical_float,
        alerts,
        excluded_unbaselined: {
            let known: std::collections::HashSet<&str> =
                baseline.rows.iter().map(|r| r.id.as_str()).collect();
            let mut v: Vec<String> = graph
                .deliverables
                .iter()
                .filter(|d| d.id != START_ID && d.id != FINISH_ID && !known.contains(d.id.as_str()))
                .map(|d| d.id.clone())
                .collect();
            v.sort();
            v
        },
    };
    Ok(report)
}

/// Longest accepted `plan.baseline` reason, in characters (the evidence
/// limit, [`crate::plan::MAX_EVIDENCE_CHARS`]).
pub const MAX_BASELINE_REASON_CHARS: usize = crate::plan::MAX_EVIDENCE_CHARS;

/// Most snapshots a `plan.snapshot` export lists (the newest ones).
pub const SNAPSHOT_EXPORT_LIMIT: usize = 100;

/// Take a baseline of a plan (`plan.baseline`).
#[derive(Debug, Clone, PartialEq)]
pub struct BaselineRequest {
    pub plan_id: PlanId,
    /// Baseline start; defaults to the planner clock's now.
    pub start: Option<DateTime<Utc>>,
    /// Working-time calendar; `None` counts wall-clock hours.
    pub calendar: Option<Calendar>,
    /// Why the plan is re-baselined. Required (non-blank) when the plan
    /// already has a baseline; at most [`MAX_BASELINE_REASON_CHARS`].
    pub reason: Option<String>,
    /// Retroactive baseline start: the baseline's `start` is this instant
    /// instead of now and the baseline is marked `backfilled`. Must not be
    /// in the future or before the plan's creation time.
    pub backfill_from: Option<DateTime<Utc>>,
}

impl BaselineRequest {
    pub fn new(plan_id: PlanId) -> Self {
        Self {
            plan_id,
            start: None,
            calendar: None,
            reason: None,
            backfill_from: None,
        }
    }

    pub fn with_start(mut self, start: DateTime<Utc>) -> Self {
        self.start = Some(start);
        self
    }

    pub fn with_backfill_from(mut self, backfill_from: DateTime<Utc>) -> Self {
        self.backfill_from = Some(backfill_from);
        self
    }

    pub fn with_calendar(mut self, calendar: Calendar) -> Self {
        self.calendar = Some(calendar);
        self
    }

    pub fn with_reason(mut self, reason: impl Into<String>) -> Self {
        self.reason = Some(reason.into());
        self
    }
}

/// A stored baseline, as `plan.baseline` reports it.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct BaselineOutcome {
    pub plan_id: String,
    pub baseline_number: u32,
    pub start: DateTime<Utc>,
    pub calendar: Option<Calendar>,
    pub bac: f32,
    pub finish_hours: f32,
    pub deliverable_count: usize,
    pub reason: Option<String>,
    /// True when `start` came from `backfill_from`.
    #[serde(default)]
    pub backfilled: bool,
}

/// The reason recorded on a baseline an execution-starting call took
/// automatically because the plan had none.
pub const FIRST_EXECUTION_REASON: &str = "first_execution";

/// How execution treats a plan that has no earned-value baseline yet.
/// Server-configured once at startup with `CPM_BASELINE_MODE`.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub enum BaselineMode {
    /// Execution takes the first baseline itself, from the current graph as
    /// of the call, in the same write transaction (the default).
    #[default]
    Auto,
    /// Execution is refused with `BASELINE_REQUIRED` until the operator
    /// calls `plan.baseline`.
    Refuse,
}

/// A baseline an execution-starting call took automatically. Reported in
/// `baseline_taken` on the call's response; absent when one already existed.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct BaselineTaken {
    /// Number within the plan; `1` for the first baseline.
    pub baseline_number: u32,
    /// The baseline's PV start (the call time).
    pub as_of: DateTime<Utc>,
    /// Always [`FIRST_EXECUTION_REASON`].
    pub reason: String,
}

/// The latest baseline summary `plan.status` reports; `null` before the
/// first baseline.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct PlanBaseline {
    pub baseline_number: u32,
    pub as_of: DateTime<Utc>,
}

/// Export format of `plan.snapshot`.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum SnapshotFormat {
    /// `export` is the list of snapshot summaries, oldest first.
    #[default]
    Json,
    /// `export` is a Markdown table ([`render_snapshots_markdown`]).
    Markdown,
}

/// Append an EV snapshot (`plan.snapshot`).
#[derive(Debug, Clone, PartialEq)]
pub struct SnapshotRequest {
    pub plan_id: PlanId,
    /// Status date of the reading's PV; defaults to the planner clock's now.
    /// EV and AC are always the progress recorded when the snapshot is
    /// taken, so a past `as_of` (over an hour back) marks it
    /// [`SnapshotSummary::backfilled`].
    pub as_of: Option<DateTime<Utc>>,
    pub format: SnapshotFormat,
}

impl SnapshotRequest {
    pub fn new(plan_id: PlanId) -> Self {
        Self {
            plan_id,
            as_of: None,
            format: SnapshotFormat::default(),
        }
    }

    pub fn with_as_of(mut self, as_of: DateTime<Utc>) -> Self {
        self.as_of = Some(as_of);
        self
    }

    pub fn with_format(mut self, format: SnapshotFormat) -> Self {
        self.format = format;
        self
    }
}

/// The snapshot just taken plus the rendered history.
#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct SnapshotOutcome {
    pub summary: SnapshotSummary,
    pub format: SnapshotFormat,
    /// The newest [`SNAPSHOT_EXPORT_LIMIT`] snapshots by `as_of` (ties by
    /// `taken_at`), oldest first: a list of summaries for `json`, a Markdown
    /// table string for `markdown`. A backfilled snapshot sits at its
    /// `as_of` position, and one older than all of those is stored and
    /// counted but not listed.
    pub export: serde_json::Value,
    /// Snapshots stored for the plan, this one included.
    pub snapshot_count: usize,
}

/// Trend alerts over snapshot ratios in `as_of` order: `SPI_BELOW_0_9` /
/// `CPI_BELOW_0_9` when the metric is defined and below 0.9 on both of the
/// two latest snapshots taken against `baseline_number` (snapshots of
/// earlier baselines are ignored). Backfilled snapshots
/// ([`SnapshotSummary::backfilled`]) are ignored too, as the new reading
/// and as the previous one: their EV and AC are today's, not the past
/// date's. Fewer than two remaining snapshots raise nothing.
pub fn trend_alerts(snapshots: &[EvSummary], baseline_number: u32) -> Vec<String> {
    let mut alerts = Vec::new();
    let current: Vec<&EvSummary> = snapshots
        .iter()
        .filter(|s| s.baseline_number == baseline_number && !s.backfilled)
        .collect();
    if let [.., a, b] = current.as_slice() {
        let low = |v: Option<f32>| v.is_some_and(|x| x < 0.9);
        if low(a.spi) && low(b.spi) {
            alerts.push("SPI_BELOW_0_9".to_string());
        }
        if low(a.cpi) && low(b.cpi) {
            alerts.push("CPI_BELOW_0_9".to_string());
        }
    }
    alerts
}

/// The stored summary of one EV snapshot: the report's totals and ratios
/// (an undefined ratio stays `None`, serialised as `null`) and the alerts
/// raised when it was taken.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct SnapshotSummary {
    pub taken_at: DateTime<Utc>,
    pub as_of: DateTime<Utc>,
    pub baseline_number: u32,
    pub bac: f32,
    pub pv: f32,
    pub ev: f32,
    pub ac: f32,
    pub sv: f32,
    pub cv: f32,
    pub spi: Option<f32>,
    pub cpi: Option<f32>,
    pub eac: Option<f32>,
    pub etc: Option<f32>,
    pub vac: Option<f32>,
    pub tcpi: Option<f32>,
    /// Why each `null` ratio is undefined (as in [`EvReport::undefined`]).
    /// Absent in summaries stored before this field existed.
    #[serde(default)]
    pub undefined: Vec<Undefined>,
    pub alerts: Vec<String>,
    /// `as_of` is more than [`BACKFILL_TOLERANCE_HOURS`] before `taken_at`.
    /// EV and AC are measured when the snapshot is taken, so a backfilled
    /// snapshot pairs a past PV with present progress; trend alerts ignore
    /// it. Absent (false) in summaries stored before this field existed.
    #[serde(default)]
    pub backfilled: bool,
}

/// How far `as_of` may lag `taken_at` before a snapshot counts as
/// backfilled ([`SnapshotSummary::backfilled`]).
pub const BACKFILL_TOLERANCE_HOURS: i64 = 1;

/// Whether a reading at `as_of`, taken at `taken_at`, is backfilled.
pub fn is_backfilled(as_of: DateTime<Utc>, taken_at: DateTime<Utc>) -> bool {
    as_of < taken_at - Duration::hours(BACKFILL_TOLERANCE_HOURS)
}

impl SnapshotSummary {
    /// Summarise `report`, taken at `taken_at`.
    pub fn from_report(report: &EvReport, taken_at: DateTime<Utc>) -> Self {
        Self {
            taken_at,
            as_of: report.as_of,
            baseline_number: report.baseline_number,
            bac: report.bac,
            pv: report.pv,
            ev: report.ev,
            ac: report.ac,
            sv: report.sv,
            cv: report.cv,
            spi: report.spi,
            cpi: report.cpi,
            eac: report.eac,
            etc: report.etc,
            vac: report.vac,
            tcpi: report.tcpi,
            undefined: report.undefined.clone(),
            alerts: report.alerts.clone(),
            backfilled: is_backfilled(report.as_of, taken_at),
        }
    }

    /// The ratios trend alerts look at.
    pub fn ratios(&self) -> EvSummary {
        EvSummary {
            baseline_number: self.baseline_number,
            spi: self.spi,
            cpi: self.cpi,
            backfilled: self.backfilled,
        }
    }
}

/// Render snapshots (in the given order) as a Markdown table with columns
/// date (the `as_of` instant, UTC, to the minute), PV, EV, AC, SPI, CPI
/// and EAC. Values have two decimals; an undefined ratio is `n/a`.
pub fn render_snapshots_markdown(snapshots: &[SnapshotSummary]) -> String {
    let ratio = |v: Option<f32>| v.map_or_else(|| "n/a".to_string(), |x| format!("{x:.2}"));
    let mut out = String::from(
        "| date | PV | EV | AC | SPI | CPI | EAC |\n|---|---:|---:|---:|---:|---:|---:|\n",
    );
    for s in snapshots {
        out.push_str(&format!(
            "| {} | {:.2} | {:.2} | {:.2} | {} | {} | {} |\n",
            s.as_of.format("%Y-%m-%dT%H:%MZ"),
            s.pv,
            s.ev,
            s.ac,
            ratio(s.spi),
            ratio(s.cpi),
            ratio(s.eac),
        ));
    }
    out
}

#[cfg(test)]
mod tests {
    use super::*;
    use chrono::{TimeZone, Timelike};

    const EPS: f32 = 1e-3;

    fn at(y: i32, m: u32, d: u32, h: u32) -> DateTime<Utc> {
        Utc.with_ymd_and_hms(y, m, d, h, 0, 0).unwrap()
    }

    fn near(a: f32, b: f32) -> bool {
        (a - b).abs() < EPS
    }

    fn deliverable(id: &str, effort: f32, prereqs: &[&str]) -> Deliverable {
        Deliverable {
            id: id.to_string(),
            owned_files: vec![],
            prerequisites: prereqs
                .iter()
                .map(|p| crate::plan::Prerequisite::Id((*p).to_string()))
                .collect(),
            estimated_effort_hours: Some(effort),
            duration_hours: None,
            estimate: None,
            metadata: serde_json::Value::Null,
            milestone: false,
            earning_rule: None,
        }
    }

    fn graph(ds: Vec<Deliverable>) -> PlanGraph {
        PlanGraph {
            deliverables: ds,
            max_chained_dispatch: None,
        }
    }

    fn row(id: &str, es: f32, ef: f32, budget: f32) -> BaselineRow {
        BaselineRow {
            id: id.to_string(),
            es,
            ef,
            budget,
            cost_rate: 1.0,
        }
    }

    fn baseline(rows: Vec<BaselineRow>) -> Baseline {
        let bac = rows.iter().map(|r| r.budget).sum();
        let finish_hours = rows.iter().map(|r| r.ef).fold(0.0, f32::max);
        Baseline {
            number: 1,
            start: at(2026, 1, 5, 0),
            calendar: None,
            rows,
            bac,
            finish_hours,
            backfilled: false,
        }
    }

    fn statuses(pairs: &[(&str, DeliverableStatus)]) -> HashMap<String, DeliverableStatus> {
        pairs
            .iter()
            .map(|(k, v)| ((*k).to_string(), v.clone()))
            .collect()
    }

    fn report(
        b: &Baseline,
        g: &PlanGraph,
        st: &HashMap<String, DeliverableStatus>,
        rules: &HashMap<String, EarningRule>,
        actuals: &HashMap<String, Actuals>,
        hours: i64,
    ) -> EvReport {
        let as_of = b.start + Duration::hours(hours);
        compute_ev(b, g, st, rules, actuals, as_of, &[]).unwrap()
    }

    fn one(rule: EarningRule, status: DeliverableStatus, pct: Option<u8>) -> EvReport {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let st = statuses(&[("a", status)]);
        let rules = HashMap::from([("a".to_string(), rule)]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                earned_pct: pct,
                ..Actuals::default()
            },
        )]);
        report(&b, &g, &st, &rules, &actuals, 5)
    }

    /// BAC 100 (two rows), PV 50, EV 40, AC 48.
    fn textbook() -> EvReport {
        let b = baseline(vec![row("a", 0.0, 10.0, 50.0), row("b", 10.0, 20.0, 50.0)]);
        let g = graph(vec![
            deliverable("a", 50.0, &[]),
            deliverable("b", 50.0, &["a"]),
        ]);
        let st = statuses(&[("a", DeliverableStatus::InProgress)]);
        let rules = HashMap::from([("a".to_string(), EarningRule::Weighted)]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                earned_pct: Some(80),
                actual_hours: Some(48.0),
                ..Actuals::default()
            },
        )]);
        report(&b, &g, &st, &rules, &actuals, 10)
    }

    #[test]
    fn wall_clock_elapsed_is_plain_hours() {
        let h = elapsed_hours(at(2026, 1, 5, 0), at(2026, 1, 6, 6), None).unwrap();
        assert!(near(h, 30.0));
    }

    #[test]
    fn elapsed_before_start_is_zero() {
        let h = elapsed_hours(at(2026, 1, 5, 0), at(2026, 1, 4, 0), None).unwrap();
        assert!(near(h, 0.0));
    }

    #[test]
    fn calendar_skips_weekends() {
        // Fri 2026-01-09 00:00 to Mon 2026-01-12 00:00: only Friday's 8h.
        let c = Calendar::default();
        let h = elapsed_hours(at(2026, 1, 9, 0), at(2026, 1, 12, 0), Some(&c)).unwrap();
        assert!(near(h, 8.0));
    }

    #[test]
    fn calendar_counts_partial_day() {
        // Monday 03:00 to 05:30 is 2.5 working hours.
        let c = Calendar::default();
        let start = at(2026, 1, 5, 3);
        let h = elapsed_hours(start, start + Duration::minutes(150), Some(&c)).unwrap();
        assert!(near(h, 2.5));
    }

    #[test]
    fn calendar_ignores_hours_after_the_working_window() {
        let c = Calendar::default();
        let h = elapsed_hours(at(2026, 1, 5, 0), at(2026, 1, 5, 20), Some(&c)).unwrap();
        assert!(near(h, 8.0));
    }

    #[test]
    fn calendar_over_many_weeks_counts_whole_weeks() {
        // 10 weeks from a Monday: 10 * 5 * 8 working hours.
        let c = Calendar::default();
        let h = elapsed_hours(at(2026, 1, 5, 0), at(2026, 3, 16, 0), Some(&c)).unwrap();
        assert!(near(h, 400.0));
    }

    #[test]
    fn calendar_utc_offset_shifts_the_local_day() {
        // +120 min: Mon 2026-01-05 22:00 UTC is Tue 00:00 local, so 2h later is 2 work hours.
        let c = Calendar {
            utc_offset_minutes: 120,
            ..Calendar::default()
        };
        let h = elapsed_hours(at(2026, 1, 5, 22), at(2026, 1, 6, 0), Some(&c)).unwrap();
        assert!(near(h, 2.0));
    }

    #[test]
    fn calendar_custom_workdays_count_only_listed_days() {
        let c = Calendar {
            workdays: vec!["sat".into()],
            ..Calendar::default()
        };
        let h = elapsed_hours(at(2026, 1, 5, 0), at(2026, 1, 12, 0), Some(&c)).unwrap();
        assert!(near(h, 8.0));
    }

    fn invalid(c: Calendar) -> bool {
        matches!(c.validate(), Err(PlannerError::InvalidGraph { .. }))
    }

    #[test]
    fn calendar_rejects_zero_hours_per_day() {
        assert!(invalid(Calendar {
            hours_per_day: 0.0,
            ..Calendar::default()
        }));
    }

    #[test]
    fn calendar_rejects_more_than_24_hours_per_day() {
        assert!(invalid(Calendar {
            hours_per_day: 24.5,
            ..Calendar::default()
        }));
    }

    #[test]
    fn calendar_rejects_nan_hours_per_day() {
        assert!(invalid(Calendar {
            hours_per_day: f32::NAN,
            ..Calendar::default()
        }));
    }

    #[test]
    fn calendar_rejects_out_of_range_offset() {
        assert!(invalid(Calendar {
            utc_offset_minutes: 1441,
            ..Calendar::default()
        }));
    }

    #[test]
    fn calendar_rejects_empty_workdays() {
        assert!(invalid(Calendar {
            workdays: vec![],
            ..Calendar::default()
        }));
    }

    #[test]
    fn calendar_rejects_unknown_weekday_name() {
        assert!(invalid(Calendar {
            workdays: vec!["monday".into()],
            ..Calendar::default()
        }));
    }

    #[test]
    fn calendar_accepts_a_24_hour_day() {
        assert!(
            Calendar {
                hours_per_day: 24.0,
                ..Calendar::default()
            }
            .validate()
            .is_ok()
        );
    }

    #[test]
    fn pv_interpolates_linearly_inside_a_task() {
        let b = baseline(vec![row("a", 10.0, 20.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let r = report(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            15,
        );
        assert!(near(r.pv, 50.0));
    }

    #[test]
    fn pv_is_zero_before_task_start() {
        let b = baseline(vec![row("a", 10.0, 20.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 5);
        assert!(near(r.pv, 0.0));
    }

    #[test]
    fn pv_caps_at_budget_after_task_finish() {
        let b = baseline(vec![row("a", 10.0, 20.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let r = report(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            99,
        );
        assert!(near(r.pv, 100.0));
    }

    #[test]
    fn pv_of_zero_length_task_is_zero_before_its_start() {
        let b = baseline(vec![row("m", 10.0, 10.0, 5.0)]);
        let g = graph(vec![deliverable("m", 5.0, &[])]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 9);
        assert!(near(r.pv, 0.0));
    }

    #[test]
    fn pv_of_zero_length_task_steps_to_budget_at_its_start() {
        let b = baseline(vec![row("m", 10.0, 10.0, 5.0)]);
        let g = graph(vec![deliverable("m", 5.0, &[])]);
        let r = report(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            10,
        );
        assert!(near(r.pv, 5.0));
    }

    #[test]
    fn zero_hundred_earns_nothing_while_in_progress() {
        let r = one(
            EarningRule::ZeroHundred,
            DeliverableStatus::InProgress,
            Some(90),
        );
        assert!(near(r.ev, 0.0));
    }

    #[test]
    fn zero_hundred_earns_full_budget_when_complete() {
        let r = one(EarningRule::ZeroHundred, DeliverableStatus::Complete, None);
        assert!(near(r.ev, 100.0));
    }

    #[test]
    fn default_rule_is_zero_hundred_when_unmapped() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let st = statuses(&[("a", DeliverableStatus::InProgress)]);
        let r = report(&b, &g, &st, &HashMap::new(), &HashMap::new(), 5);
        assert!(near(r.ev, 0.0));
    }

    #[test]
    fn fifty_fifty_earns_half_when_in_progress() {
        let r = one(EarningRule::FiftyFifty, DeliverableStatus::InProgress, None);
        assert!(near(r.ev, 50.0));
    }

    #[test]
    fn fifty_fifty_earns_half_when_any_percent_reported() {
        let r = one(EarningRule::FiftyFifty, DeliverableStatus::Ready, Some(10));
        assert!(near(r.ev, 50.0));
    }

    #[test]
    fn fifty_fifty_earns_full_when_complete() {
        let r = one(EarningRule::FiftyFifty, DeliverableStatus::Complete, None);
        assert!(near(r.ev, 100.0));
    }

    #[test]
    fn weighted_earns_the_reported_percent() {
        let r = one(
            EarningRule::Weighted,
            DeliverableStatus::InProgress,
            Some(30),
        );
        assert!(near(r.ev, 30.0));
    }

    #[test]
    fn weighted_earns_nothing_without_a_report() {
        let r = one(EarningRule::Weighted, DeliverableStatus::InProgress, None);
        assert!(near(r.ev, 0.0));
    }

    #[test]
    fn weighted_ignores_reported_percent_once_complete() {
        let r = one(EarningRule::Weighted, DeliverableStatus::Complete, Some(40));
        assert!(near(r.ev, 100.0));
    }

    #[test]
    fn failed_deliverable_earns_nothing_under_zero_hundred() {
        let r = one(
            EarningRule::ZeroHundred,
            DeliverableStatus::Failed { reason: "x".into() },
            None,
        );
        assert!(near(r.ev, 0.0));
    }

    fn ac_for(actual: Option<f32>, leased: f32, rate: Option<f64>) -> f32 {
        let mut br = row("a", 0.0, 10.0, 100.0);
        br.cost_rate = rate.unwrap_or(1.0) as f32;
        let b = baseline(vec![br]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: actual,
                leased_hours: leased,
                ..Actuals::default()
            },
        )]);
        report(&b, &g, &HashMap::new(), &HashMap::new(), &actuals, 5).ac
    }

    #[test]
    fn ac_prefers_reported_hours_over_leased() {
        assert!(near(ac_for(Some(7.0), 3.0, None), 7.0));
    }

    #[test]
    fn ac_falls_back_to_leased_hours() {
        assert!(near(ac_for(None, 3.0, None), 3.0));
    }

    #[test]
    fn ac_is_scaled_by_cost_rate() {
        assert!(near(ac_for(Some(4.0), 0.0, Some(2.5)), 10.0));
    }

    #[test]
    fn baseline_budget_is_effort_times_cost_rate() {
        let mut d = deliverable("a", 10.0, &[]);
        d.metadata = serde_json::json!({ "cost_rate": 3.0 });
        let g = graph(vec![d]);
        let cpm = compute_cpm(&g).unwrap();
        let b = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1).unwrap();
        assert!(near(b.bac, 30.0));
    }

    #[test]
    fn baseline_defaults_cost_rate_to_one() {
        let g = graph(vec![deliverable("a", 10.0, &[])]);
        let cpm = compute_cpm(&g).unwrap();
        let b = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1).unwrap();
        assert!(near(b.bac, 10.0));
    }

    #[test]
    fn baseline_excludes_synthetic_endpoints() {
        let g = graph(vec![deliverable("a", 10.0, &[])]);
        let cpm = compute_cpm(&g).unwrap();
        let b = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1).unwrap();
        assert_eq!(b.rows.len(), 1);
    }

    #[test]
    fn baseline_freezes_cpm_start_and_finish() {
        let g = graph(vec![
            deliverable("a", 10.0, &[]),
            deliverable("b", 5.0, &["a"]),
        ]);
        let cpm = compute_cpm(&g).unwrap();
        let b = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1).unwrap();
        let rb = b.rows.iter().find(|r| r.id == "b").unwrap();
        assert!(near(rb.es, 10.0) && near(rb.ef, 15.0));
    }

    #[test]
    fn baseline_records_finish_hours() {
        let g = graph(vec![
            deliverable("a", 10.0, &[]),
            deliverable("b", 5.0, &["a"]),
        ]);
        let cpm = compute_cpm(&g).unwrap();
        let b = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1).unwrap();
        assert!(near(b.finish_hours, 15.0));
    }

    #[test]
    fn baseline_rejects_negative_cost_rate() {
        let mut d = deliverable("a", 10.0, &[]);
        d.metadata = serde_json::json!({ "cost_rate": -1.0 });
        let g = graph(vec![d]);
        let cpm = compute_cpm(&g).unwrap();
        let e = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1);
        assert!(matches!(e, Err(PlannerError::InvalidGraph { .. })));
    }

    #[test]
    fn baseline_rejects_non_numeric_cost_rate() {
        let mut d = deliverable("a", 10.0, &[]);
        d.metadata = serde_json::json!({ "cost_rate": "free" });
        let g = graph(vec![d]);
        let cpm = compute_cpm(&g).unwrap();
        let e = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1);
        assert!(matches!(e, Err(PlannerError::InvalidGraph { .. })));
    }

    #[test]
    fn baseline_rejects_invalid_calendar() {
        let g = graph(vec![deliverable("a", 10.0, &[])]);
        let cpm = compute_cpm(&g).unwrap();
        let c = Calendar {
            hours_per_day: 0.0,
            ..Calendar::default()
        };
        let e = build_baseline(&g, &cpm, at(2026, 1, 5, 0), Some(c), 1);
        assert!(matches!(e, Err(PlannerError::InvalidGraph { .. })));
    }

    #[test]
    fn budget_in_ev_report_is_baseline_budget() {
        let r = textbook();
        assert!(near(r.bac, 100.0));
    }

    #[test]
    fn textbook_pv() {
        assert!(near(textbook().pv, 50.0));
    }

    #[test]
    fn textbook_ev() {
        assert!(near(textbook().ev, 40.0));
    }

    #[test]
    fn textbook_ac() {
        assert!(near(textbook().ac, 48.0));
    }

    #[test]
    fn textbook_sv() {
        assert!(near(textbook().sv, -10.0));
    }

    #[test]
    fn textbook_cv() {
        assert!(near(textbook().cv, -8.0));
    }

    #[test]
    fn textbook_spi() {
        assert!(near(textbook().spi.unwrap(), 0.8));
    }

    #[test]
    fn textbook_cpi() {
        assert!(near(textbook().cpi.unwrap(), 0.8333));
    }

    #[test]
    fn textbook_eac() {
        assert!(near(textbook().eac.unwrap(), 120.0));
    }

    #[test]
    fn textbook_etc() {
        assert!(near(textbook().etc.unwrap(), 72.0));
    }

    #[test]
    fn textbook_vac() {
        assert!(near(textbook().vac.unwrap(), -20.0));
    }

    #[test]
    fn textbook_tcpi() {
        assert!(near(textbook().tcpi.unwrap(), 60.0 / 52.0));
    }

    #[test]
    fn textbook_has_no_undefined_fields() {
        assert!(textbook().undefined.is_empty());
    }

    fn undefined_reason(r: &EvReport, field: &str) -> Option<String> {
        r.undefined
            .iter()
            .find(|u| u.field == field)
            .map(|u| u.reason.clone())
    }

    #[test]
    fn spi_is_null_when_pv_is_zero() {
        let b = baseline(vec![row("a", 10.0, 20.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 0);
        assert!(r.spi.is_none());
    }

    #[test]
    fn spi_zero_pv_reason_is_explained() {
        let b = baseline(vec![row("a", 10.0, 20.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 0);
        assert_eq!(
            undefined_reason(&r, "spi").as_deref(),
            Some("PV is 0 before any work was planned")
        );
    }

    #[test]
    fn cpi_is_null_when_ac_is_zero() {
        let r = one(EarningRule::ZeroHundred, DeliverableStatus::Complete, None);
        assert!(r.cpi.is_none());
    }

    #[test]
    fn cpi_zero_ac_reason_is_explained() {
        let r = one(EarningRule::ZeroHundred, DeliverableStatus::Complete, None);
        assert_eq!(
            undefined_reason(&r, "cpi").as_deref(),
            Some("AC is 0, no cost recorded yet")
        );
    }

    #[test]
    fn eac_is_null_when_cpi_is_null() {
        let r = one(EarningRule::ZeroHundred, DeliverableStatus::Complete, None);
        assert!(r.eac.is_none());
    }

    #[test]
    fn dependents_of_eac_are_null_and_explained() {
        let r = one(EarningRule::ZeroHundred, DeliverableStatus::Complete, None);
        assert!(r.etc.is_none() && r.vac.is_none());
        assert!(undefined_reason(&r, "etc").is_some() && undefined_reason(&r, "vac").is_some());
    }

    #[test]
    fn eac_is_null_when_cpi_is_zero() {
        // Spent 10h, earned nothing: CPI = 0, EAC would divide by zero.
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: Some(10.0),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &actuals, 5);
        assert!(r.eac.is_none());
    }

    #[test]
    fn tcpi_is_null_when_bac_equals_ac() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: Some(100.0),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &actuals, 5);
        assert!(r.tcpi.is_none());
    }

    #[test]
    fn tcpi_zero_denominator_reason_is_explained() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: Some(100.0),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &actuals, 5);
        assert_eq!(
            undefined_reason(&r, "tcpi").as_deref(),
            Some("BAC - AC is 0, no budget remains")
        );
    }

    #[test]
    fn empty_baseline_yields_all_finite_values() {
        let b = baseline(vec![]);
        let g = graph(vec![]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 5);
        assert!(r.pv.is_finite() && r.ev.is_finite() && r.ac.is_finite());
    }

    #[test]
    fn rows_report_per_deliverable_ev() {
        let r = textbook();
        let a = r.rows.iter().find(|x| x.id == "a").unwrap();
        assert!(near(a.ev, 40.0));
    }

    #[test]
    fn rows_report_status() {
        let r = textbook();
        let a = r.rows.iter().find(|x| x.id == "a").unwrap();
        assert_eq!(a.status, DeliverableStatus::InProgress);
    }

    #[test]
    fn missing_status_defaults_to_pending() {
        let r = textbook();
        let b = r.rows.iter().find(|x| x.id == "b").unwrap();
        assert_eq!(b.status, DeliverableStatus::Pending);
    }

    #[test]
    fn critical_float_consumed_is_forecast_overrun() {
        // Baseline finish 5h, current CPM finish 12h.
        let mut b = baseline(vec![row("a", 0.0, 5.0, 12.0)]);
        b.finish_hours = 5.0;
        let g = graph(vec![deliverable("a", 12.0, &[])]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 1);
        assert!(near(r.critical_float_consumed_hours, 7.0));
    }

    #[test]
    fn critical_float_consumed_never_negative() {
        let mut b = baseline(vec![row("a", 0.0, 20.0, 12.0)]);
        b.finish_hours = 20.0;
        let g = graph(vec![deliverable("a", 12.0, &[])]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 1);
        assert!(near(r.critical_float_consumed_hours, 0.0));
    }

    fn snap(spi: f32, cpi: f32) -> EvSummary {
        EvSummary {
            baseline_number: 1,
            spi: Some(spi),
            cpi: Some(cpi),
            backfilled: false,
        }
    }

    fn alerts_with(prev: &[EvSummary]) -> Vec<String> {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let as_of = b.start + Duration::hours(5);
        compute_ev(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            as_of,
            prev,
        )
        .unwrap()
        .alerts
    }

    #[test]
    fn spi_alert_fires_when_two_latest_snapshots_are_below_threshold() {
        let a = alerts_with(&[snap(0.95, 1.0), snap(0.8, 1.0), snap(0.85, 1.0)]);
        assert_eq!(a, vec!["SPI_BELOW_0_9".to_string()]);
    }

    #[test]
    fn alert_does_not_fire_on_a_single_low_snapshot() {
        assert!(alerts_with(&[snap(0.95, 1.0), snap(0.8, 1.0)]).is_empty());
    }

    #[test]
    fn alert_does_not_fire_with_one_snapshot() {
        assert!(alerts_with(&[snap(0.5, 0.5)]).is_empty());
    }

    #[test]
    fn cpi_alert_fires_when_two_latest_snapshots_are_below_threshold() {
        let a = alerts_with(&[snap(1.0, 0.7), snap(1.0, 0.89)]);
        assert_eq!(a, vec!["CPI_BELOW_0_9".to_string()]);
    }

    #[test]
    fn alert_ignores_snapshots_with_undefined_metric() {
        let none = EvSummary {
            baseline_number: 1,
            spi: None,
            cpi: None,
            backfilled: false,
        };
        assert!(alerts_with(&[snap(0.5, 0.5), none]).is_empty());
    }

    #[test]
    fn report_is_independent_of_map_insertion_order() {
        let b = baseline(vec![row("a", 0.0, 10.0, 50.0), row("b", 0.0, 10.0, 50.0)]);
        let g = graph(vec![
            deliverable("a", 50.0, &[]),
            deliverable("b", 50.0, &[]),
        ]);
        let act = |h: f32| Actuals {
            actual_hours: Some(h),
            ..Actuals::default()
        };
        let fwd = HashMap::from([("a".to_string(), act(3.0)), ("b".to_string(), act(4.0))]);
        let mut rev = HashMap::new();
        rev.insert("b".to_string(), act(4.0));
        rev.insert("a".to_string(), act(3.0));
        let e = HashMap::new();
        assert_eq!(
            report(&b, &g, &e, &e2(), &fwd, 5),
            report(&b, &g, &e, &e2(), &rev, 5)
        );
    }

    fn e2() -> HashMap<String, EarningRule> {
        HashMap::new()
    }

    #[test]
    fn removed_deliverable_keeps_baselined_cost_rate() {
        let mut br = row("a", 0.0, 10.0, 100.0);
        br.cost_rate = 2.0;
        let b = baseline(vec![br]);
        let g = graph(vec![]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: Some(5.0),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &actuals, 5);
        assert!(near(r.ac, 10.0));
    }

    #[test]
    fn rate_edit_after_baseline_does_not_change_ac() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let mut d = deliverable("a", 100.0, &[]);
        d.metadata = serde_json::json!({ "cost_rate": 9.0 });
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: Some(5.0),
                ..Actuals::default()
            },
        )]);
        let r = report(
            &b,
            &graph(vec![d]),
            &HashMap::new(),
            &HashMap::new(),
            &actuals,
            5,
        );
        assert!(near(r.ac, 5.0));
    }

    #[test]
    fn invalid_rate_added_after_baseline_does_not_fail_compute() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let mut d = deliverable("a", 100.0, &[]);
        d.metadata = serde_json::json!({ "cost_rate": -4.0 });
        let r = compute_ev(
            &b,
            &graph(vec![d]),
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            b.start,
            &[],
        );
        assert!(r.is_ok());
    }

    #[test]
    fn baseline_captures_cost_rate_per_row() {
        let mut d = deliverable("a", 10.0, &[]);
        d.metadata = serde_json::json!({ "cost_rate": 3.0 });
        let g = graph(vec![d]);
        let cpm = compute_cpm(&g).unwrap();
        let b = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1).unwrap();
        assert!(near(b.rows[0].cost_rate, 3.0));
    }

    #[test]
    fn deliverable_added_after_baseline_is_excluded_and_listed() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![
            deliverable("z", 40.0, &[]),
            deliverable("a", 100.0, &[]),
            deliverable("m", 40.0, &[]),
        ]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 5);
        assert_eq!(
            r.excluded_unbaselined,
            vec!["m".to_string(), "z".to_string()]
        );
    }

    #[test]
    fn unbaselined_deliverable_adds_nothing_to_bac() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![
            deliverable("a", 100.0, &[]),
            deliverable("z", 40.0, &[]),
        ]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &HashMap::new(), 5);
        assert!(near(r.bac, 100.0));
    }

    #[test]
    fn negative_reported_hours_fall_back_to_leased() {
        assert!(near(ac_for(Some(-2.0), 3.0, None), 3.0));
    }

    #[test]
    fn non_finite_reported_hours_fall_back_to_leased() {
        assert!(near(ac_for(Some(f32::NAN), 3.0, None), 3.0));
    }

    #[test]
    fn as_of_before_start_gives_zero_pv() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let r = report(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            -5,
        );
        assert!(near(r.pv, 0.0));
    }

    #[test]
    fn as_of_before_start_leaves_spi_null_with_reason() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let r = report(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            -5,
        );
        assert!(r.spi.is_none() && undefined_reason(&r, "spi").is_some());
    }

    #[test]
    fn pv_is_flat_over_a_weekend_on_a_working_calendar() {
        // Task spans 40 working hours (a full work week); Fri 2026-01-09 00:00 + 8h = 40h elapsed.
        let mut b = baseline(vec![row("a", 0.0, 80.0, 100.0)]);
        b.calendar = Some(Calendar::default());
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let at_fri_end = compute_ev(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            at(2026, 1, 9, 12),
            &[],
        )
        .unwrap();
        let mon = compute_ev(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &HashMap::new(),
            at(2026, 1, 12, 0),
            &[],
        )
        .unwrap();
        assert!(near(at_fri_end.pv, mon.pv));
    }

    #[test]
    fn eac_reason_when_cpi_is_zero_is_explained() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: Some(10.0),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &g, &HashMap::new(), &HashMap::new(), &actuals, 5);
        assert_eq!(
            undefined_reason(&r, "eac").as_deref(),
            Some("CPI is 0, nothing earned for the cost spent")
        );
    }

    #[test]
    fn tcpi_is_negative_when_ac_exceeds_bac() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let st = statuses(&[("a", DeliverableStatus::InProgress)]);
        let rules = HashMap::from([("a".to_string(), EarningRule::Weighted)]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                earned_pct: Some(50),
                actual_hours: Some(150.0),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &g, &st, &rules, &actuals, 5);
        assert!(near(r.tcpi.unwrap(), -1.0));
    }

    #[test]
    fn f32_overflow_in_a_ratio_becomes_undefined() {
        let b = baseline(vec![
            row("a", 0.0, 10.0, 3.0e38),
            row("b", 0.0, 10.0, 3.0e38),
        ]);
        let g = graph(vec![deliverable("a", 1.0, &[]), deliverable("b", 1.0, &[])]);
        let st = statuses(&[("a", DeliverableStatus::Complete)]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: Some(1.0e-30),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &g, &st, &HashMap::new(), &actuals, 5);
        assert!(r.cpi.is_none() && undefined_reason(&r, "cpi").is_some());
    }

    #[test]
    fn alert_needs_both_of_the_two_previous_snapshots() {
        // Oldest is low, but the latest two are (low, healthy): no alert.
        assert!(alerts_with(&[snap(0.5, 1.0), snap(0.5, 1.0), snap(1.0, 1.0)]).is_empty());
    }

    #[test]
    fn elapsed_matches_naive_minute_loop_over_random_spans() {
        let mut seed: u64 = 0x5eed_1234_abcd_ef01;
        let mut next = move |n: u64| {
            seed = seed
                .wrapping_mul(6364136223846793005)
                .wrapping_add(1442695040888963407);
            (seed >> 33) % n
        };
        let names = ["mon", "tue", "wed", "thu", "fri", "sat", "sun"];
        let mut mismatches = Vec::new();
        for case in 0..60 {
            let start = at(2026, 1, 3, 0) + Duration::minutes(next(60 * 24 * 14) as i64);
            let span = Duration::minutes(next(60 * 24 * 40) as i64 + 1);
            let off = next(2881) as i32 - 1440;
            let n_days = 1 + next(7) as usize;
            let first = next(7) as usize;
            let workdays: Vec<String> = (0..n_days)
                .map(|i| names[(first + i) % 7].to_string())
                .collect();
            let hpd = [8.0_f32, 6.5, 24.0][next(3) as usize];
            let c = Calendar {
                hours_per_day: hpd,
                workdays: workdays.clone(),
                utc_offset_minutes: off,
            };
            let got = elapsed_hours(start, start + span, Some(&c)).unwrap();
            let mut naive = 0u64;
            let window = (f64::from(hpd) * 60.0) as i64;
            let mut m = start;
            let end = start + span;
            while m < end {
                let local = m + Duration::minutes(i64::from(off));
                let name = names[local.weekday().num_days_from_monday() as usize];
                let mins = i64::from(local.hour()) * 60 + i64::from(local.minute());
                if workdays.iter().any(|w| w == name) && mins < window {
                    naive += 1;
                }
                m += Duration::minutes(1);
            }
            let want = naive as f32 / 60.0;
            if (got - want).abs() > 1e-2 {
                mismatches.push((case, got, want));
            }
        }
        assert!(mismatches.is_empty(), "{mismatches:?}");
    }

    // ── P5 Task 3: snapshot support ─────────────────────────────────────

    #[test]
    fn trend_alerts_fire_spi_when_two_latest_are_low() {
        let a = trend_alerts(&[snap(0.8, 1.0), snap(0.85, 1.0)], 1);
        assert_eq!(a, vec!["SPI_BELOW_0_9".to_string()]);
    }

    #[test]
    fn baseline_rejects_budget_total_beyond_f32() {
        let heavy = |id: &str| {
            let mut d = deliverable(id, 1.0, &[]);
            d.metadata = serde_json::json!({ "cost_rate": 3.0e38 });
            d
        };
        let g = graph(vec![heavy("a"), heavy("b")]);
        let cpm = compute_cpm(&g).unwrap();
        let e = build_baseline(&g, &cpm, at(2026, 1, 5, 0), None, 1);
        assert!(matches!(e, Err(PlannerError::InvalidGraph { .. })));
    }

    #[test]
    fn ev_rejects_actual_cost_beyond_f32() {
        let mut br = row("a", 0.0, 10.0, 100.0);
        br.cost_rate = 3.0e38;
        let b = baseline(vec![br]);
        let g = graph(vec![deliverable("a", 100.0, &[])]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                actual_hours: Some(1.0e6),
                ..Actuals::default()
            },
        )]);
        let as_of = b.start + Duration::hours(5);
        let e = compute_ev(
            &b,
            &g,
            &HashMap::new(),
            &HashMap::new(),
            &actuals,
            as_of,
            &[],
        );
        assert!(matches!(e, Err(PlannerError::InvalidGraph { .. })));
    }

    #[test]
    fn calendar_rejects_unknown_fields() {
        let c = serde_json::from_value::<Calendar>(serde_json::json!({ "hours": 8 }));
        assert!(c.is_err());
    }

    fn summary_of(r: &EvReport) -> SnapshotSummary {
        SnapshotSummary::from_report(r, r.as_of)
    }

    #[test]
    fn snapshot_summary_carries_report_spi() {
        let r = textbook();
        assert_eq!(summary_of(&r).spi, r.spi);
    }

    #[test]
    fn snapshot_markdown_starts_with_header_row() {
        let md = render_snapshots_markdown(&[summary_of(&textbook())]);
        assert!(md.starts_with("| date | PV | EV | AC | SPI | CPI | EAC |\n"));
    }

    #[test]
    fn snapshot_markdown_renders_one_row_per_snapshot() {
        let s = summary_of(&textbook());
        let md = render_snapshots_markdown(&[s.clone(), s]);
        assert_eq!(md.lines().count(), 4);
    }

    #[test]
    fn snapshot_markdown_row_shows_textbook_values() {
        let md = render_snapshots_markdown(&[summary_of(&textbook())]);
        assert_eq!(
            md.lines().nth(2),
            Some("| 2026-01-05T10:00Z | 50.00 | 40.00 | 48.00 | 0.80 | 0.83 | 120.00 |")
        );
    }

    #[test]
    fn snapshot_markdown_renders_undefined_ratio_as_na() {
        let r = one(EarningRule::ZeroHundred, DeliverableStatus::Pending, None);
        let md = render_snapshots_markdown(&[summary_of(&r)]);
        assert!(
            md.lines()
                .nth(2)
                .is_some_and(|l| l.ends_with("| n/a | n/a |"))
        );
    }

    #[test]
    fn alerts_ignore_a_backfilled_new_reading() {
        let mut backfilled = snap(0.5, 1.0);
        backfilled.backfilled = true;
        assert!(trend_alerts(&[snap(0.5, 1.0), backfilled], 1).is_empty());
    }

    #[test]
    fn snapshot_more_than_an_hour_behind_its_taken_at_is_backfilled() {
        let r = textbook();
        assert!(SnapshotSummary::from_report(&r, r.as_of + Duration::minutes(61)).backfilled);
    }

    #[test]
    fn snapshot_within_an_hour_of_its_taken_at_is_not_backfilled() {
        let r = textbook();
        assert!(!SnapshotSummary::from_report(&r, r.as_of + Duration::minutes(60)).backfilled);
    }

    #[test]
    fn removed_row_earns_its_frozen_percent() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let actuals = HashMap::from([(
            "a".to_string(),
            Actuals {
                frozen_pct: Some(40),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &graph(vec![]), &HashMap::new(), &e2(), &actuals, 5);
        assert!(near(r.ev, 40.0));
    }

    #[test]
    fn removed_row_without_frozen_percent_earns_nothing() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let st = statuses(&[("a", DeliverableStatus::Complete)]);
        let r = report(&b, &graph(vec![]), &st, &e2(), &HashMap::new(), 5);
        assert!(near(r.ev, 0.0));
    }

    #[test]
    fn unbaselined_actuals_count_in_ac_at_rate_one() {
        let b = baseline(vec![row("a", 0.0, 10.0, 100.0)]);
        let g = graph(vec![
            deliverable("a", 100.0, &[]),
            deliverable("n", 5.0, &[]),
        ]);
        let actuals = HashMap::from([(
            "n".to_string(),
            Actuals {
                actual_hours: Some(3.0),
                ..Actuals::default()
            },
        )]);
        let r = report(&b, &g, &HashMap::new(), &e2(), &actuals, 5);
        assert!(near(r.ac, 3.0));
    }

    #[test]
    fn frozen_pct_of_a_complete_deliverable_is_100() {
        let pct = frozen_pct(EarningRule::ZeroHundred, &DeliverableStatus::Complete, None);
        assert_eq!(pct, 100);
    }

    #[test]
    fn alerts_ignore_snapshots_from_previous_baseline() {
        assert!(trend_alerts(&[snap(0.5, 0.5), snap(0.5, 0.5)], 2).is_empty());
    }

    #[test]
    fn alerts_use_the_two_latest_snapshots_of_the_current_baseline() {
        let mut current = snap(0.5, 1.0);
        current.baseline_number = 2;
        let a = trend_alerts(&[current.clone(), snap(1.0, 1.0), current], 2);
        assert_eq!(a, vec!["SPI_BELOW_0_9".to_string()]);
    }

    #[test]
    fn snapshot_summary_explains_undefined_ratios() {
        let r = one(EarningRule::ZeroHundred, DeliverableStatus::Pending, None);
        assert_eq!(summary_of(&r).undefined, r.undefined);
    }

    #[test]
    fn summary_without_undefined_field_decodes() {
        let mut v = serde_json::to_value(summary_of(&textbook())).unwrap();
        v.as_object_mut().unwrap().remove("undefined");
        assert!(serde_json::from_value::<SnapshotSummary>(v).is_ok());
    }
}