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feat(stats): make milestone computation pluggable via strategy #308

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Merged
Amund211 merged 1 commit into from
Jun 30, 2026
Merged

feat(stats): make milestone computation pluggable via strategy #308

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86 changes: 66 additions & 20 deletions src/stats/progression.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -91,11 +91,12 @@ export const findSmallestPositiveCubicRoot = (
};

/*
* Next round-number index milestone above (or below) `value`, scaled to the
* value's order of magnitude. Going down at exactly a power of 10 drops one
* order of magnitude (e.g. 100 -> 90, not 100 -> 0).
* Next round number above (or below) `value`, scaled to the value's order of
* magnitude. Going down at exactly a power of 10 drops one order of magnitude
* (e.g. 100 -> 90, not 100 -> 0). Shared by the index and generic-counter
* milestone defaults.
*/
const nextIndexMilestone = (value: number, trendingUpward: boolean): number => {
const nextRoundNumberMilestone = (value: number, trendingUpward: boolean): number => {
if (value <= 0) {
return 1;
}
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Expand All @@ -108,6 +109,47 @@ const nextIndexMilestone = (value: number, trendingUpward: boolean): number => {
return Math.floor(adjusted / magnitude) * magnitude;
};

/**
* Picks the next milestone target for `stat` at its current `value`, given the
* direction it is trending.
*
* CONTRACT: the returned value MUST be strictly greater than `value` when
* `trendingUpward`, and strictly less than `value` when `!trendingUpward`. The
* time-to-reach solvers rely on this to keep `daysUntilMilestone` non-negative
* and correctly signed; a value on the wrong side produces a negative or
* nonsensical projection, and the renderer has no defense against it.
*/
export type MilestoneStrategy = (
value: number,
trendingUpward: boolean,
stat: StatKey,
) => number;

/*
* The built-in milestone strategy: the next "natural" threshold for each stat
* family — the next prestige for stars, the next whole number for ratios, and
* the next round number (scaled to order of magnitude) for everything else.
*/
export const nextNaturalMilestone: MilestoneStrategy = (
value,
trendingUpward,
stat,
) => {
switch (stat) {
case "stars": {
// Next prestige (multiple of 100).
return (Math.floor(value / 100) + 1) * 100;
}
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case "fkdr":
case "kdr": {
return trendingUpward ? Math.floor(value) + 1 : Math.ceil(value) - 1;
}
default: {
return nextRoundNumberMilestone(value, trendingUpward);
}
}
};

interface BaseStatProgression {
trackingDataTimeInterval: TimeInterval;
stat: StatKey;
Expand Down Expand Up @@ -146,6 +188,9 @@ const computeQuotientProgression = (
dividendStat: Exclude<StatKey, "winstreak">,
divisorStat: Exclude<StatKey, "winstreak">,
gamemode: GamemodeKey,
// Required (no default) so the public `computeStatProgression` boundary is
// the single place the default strategy is applied.
milestoneStrategy: MilestoneStrategy,
): QuotientProgression | { error: true; reason: string } => {
const [start, end] = trackingHistory;
const startDate = start.queriedAt;
Expand Down Expand Up @@ -177,6 +222,7 @@ const computeQuotientProgression = (
trackingEnd,
dividendStat,
gamemode,
milestoneStrategy,
);
if (dividendProgression.error) {
return dividendProgression;
Expand All @@ -199,10 +245,7 @@ const computeQuotientProgression = (
const trendingUpward =
sessionQuotient >= endQuotient || noSessionProgress || infiniteSessionQuotient;

// TODO: Smaller steps for smaller quotients
const nextMilestoneValue = trendingUpward
? Math.floor(endQuotient) + 1
: Math.ceil(endQuotient) - 1;
const nextMilestoneValue = milestoneStrategy(endQuotient, trendingUpward, stat);

if (
// Will make no progress since the quotients are equal (as long as the session quotient is not infinite)
Expand Down Expand Up @@ -299,6 +342,7 @@ export const computeStatProgression = (
trackingEnd: Date,
stat: StatKey,
gamemode: GamemodeKey,
milestoneStrategy: MilestoneStrategy = nextNaturalMilestone,
): StatProgression | { error: true; reason: string } => {
if (trackingHistory === undefined || trackingHistory.length === 0) {
return { error: true, reason: ERR_NO_DATA };
Expand Down Expand Up @@ -329,16 +373,19 @@ export const computeStatProgression = (
// NOTE: Slightly inaccurate over short distances as it does not account for the different exp requirements for different levels
const starsPerDay = expPerDay / (PRESTIGE_EXP / 100);

const nextPrestige = Math.floor(endStars / 100) + 1;
const nextPrestigeExp = nextPrestige * PRESTIGE_EXP;
const expToNextPrestige = nextPrestigeExp - endExp;
const daysToNextPrestige = expToNextPrestige / expPerDay;
// Stars only ever trend upward. Convert the star milestone back to
// exp via the same linear "average exp per star" model used above;
// grouped as `(M * PRESTIGE_EXP) / 100` so the default
// (M = next prestige * 100) is bit-identical to `nextPrestige * PRESTIGE_EXP`.
const nextMilestoneValue = milestoneStrategy(endStars, true, stat);
const expAtMilestone = (nextMilestoneValue * PRESTIGE_EXP) / 100;
const daysUntilMilestone = (expAtMilestone - endExp) / expPerDay;
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return {
stat,
trackingDataTimeInterval: { start: startDate, end: endDate },
endValue: endStars,
nextMilestoneValue: nextPrestige * 100,
daysUntilMilestone: daysToNextPrestige,
nextMilestoneValue,
daysUntilMilestone,
progressPerDay: starsPerDay,
trendingUpward: true,
};
Expand All @@ -351,6 +398,7 @@ export const computeStatProgression = (
"finalKills",
"finalDeaths",
gamemode,
milestoneStrategy,
);
}
case "kdr": {
Expand All @@ -361,6 +409,7 @@ export const computeStatProgression = (
"kills",
"deaths",
gamemode,
milestoneStrategy,
);
}
case "index": {
Expand Down Expand Up @@ -394,7 +443,7 @@ export const computeStatProgression = (
: s * k0 * k0 * d0 + 2 * s0 * k0 * k * d0 - 2 * s0 * k0 * k0 * d;
const trendingUpward = trendNumerator >= 0;

const M = nextIndexMilestone(endIndex, trendingUpward);
const M = milestoneStrategy(endIndex, trendingUpward, stat);

const a = s * k * k;
const b = isFkdrAsKills
Expand Down Expand Up @@ -450,11 +499,8 @@ export const computeStatProgression = (
};
}

const endMagnitude = 10 ** Math.floor(Math.log10(endValue));
// TODO: More meaningful milestones (e.g. 100, 250, 500, 1000, 2500, 5000, 10000, 20000, 30000, ...)
// TODO: Pick your own milestone
const nextMilestoneValue =
(Math.floor(endValue / endMagnitude) + 1) * endMagnitude;
// Linear counters only ever trend upward.
const nextMilestoneValue = milestoneStrategy(endValue, true, stat);

const daysUntilMilestone = (nextMilestoneValue - endValue) / increasePerDay;

Expand Down
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