/**
 * What a committed-use deal would have been worth **on the traffic you
 * actually had**.
 *
 * Providers sell committed-use and reserved-capacity contracts, and every team
 * that signs one is doing arithmetic in a spreadsheet against a number they
 * guessed. That is exactly the failure this product exists to end — and it is
 * the highest-stakes instance of it, because the guess is annual and signed.
 *
 * ## An as-if calculation, and the wording never blurs it
 *
 * "On the traffic you actually had, this commitment would have saved $X" is a
 * measurement of the past.
 *
 * "You will save $X" is a claim about the future, and this product has refused
 * that at every scale since 1.27. Nothing here projects, extrapolates, fits a
 * trend or annualises a partial month. Every figure describes months that
 * happened, and the type says so in a field a machine reader can check.
 *
 * ## Both directions, because one direction is the sales pitch
 *
 * A commitment is a **floor** as well as a discount. Below the floor you pay
 * for capacity you did not use, and a saving quoted without that half is not
 * an analysis — it is the vendor's slide.
 *
 * So every month is priced both ways, the months that would have fallen short
 * are counted and named, and what the unused floor would have cost is its own
 * figure rather than netted quietly against the good months.
 *
 * ## The shortfall risk is a count, not a probability
 *
 * "Three of your last twelve months would have fallen short, by $400, $150 and
 * $2,900" is a measurement. "There is a 25% chance of shortfall" is a model of
 * a distribution nobody fitted, presented with the authority of arithmetic.
 * Only the first is available from a log, so only the first is printed.
 */
/** The deal, as the provider states it. */
export interface CommitmentTerms {
    /**
     * What you commit to spending each month, **after** the discount — which is
     * how these contracts are almost always written.
     *
     * If your discounted usage comes in under this, you pay this anyway.
     */
    monthlyFloorUsd: number;
    /** The discount, 0-1. 0.2 is twenty per cent off. */
    discount: number;
    /** How many months the commitment runs. */
    months: number;
}
/** One measured month, as the caller sliced it. */
export interface MeasuredMonth {
    /** `YYYY-MM`. */
    month: string;
    usd: number;
}
export interface MonthReplay {
    month: string;
    /** What was actually paid, with no commitment. */
    listUsd: number;
    /** What the discounted usage would have come to. */
    discountedUsd: number;
    /** What would actually have been paid: the floor, or the discounted usage. */
    paidUsd: number;
    /** Positive means the commitment saved money that month. */
    savingUsd: number;
    /** Whether the floor was the binding number — a month that fell short. */
    shortfall: boolean;
    /** What the unused floor cost, in a month that fell short. Zero otherwise. */
    unusedFloorUsd: number;
}
export type CommitmentUnknown = 'no-history' | 'too-few-months' | 'partial-months-excluded-everything';
export interface CommitmentReplay {
    /**
     * Always `measured-past`. There is no other value, and the field exists so a
     * machine reader cannot mistake this for a projection — the same reason
     * every other document in this product carries its provenance.
     */
    provenance: 'measured-past';
    months: MonthReplay[];
    /** Summed over the months replayed, positive meaning the deal won. */
    netUsd: number;
    /** What the good months saved, before the shortfalls are taken off. */
    savedInGoodMonthsUsd: number;
    /**
     * What the shortfall months cost, kept as its own figure.
     *
     * Netted against the savings it disappears, and the disappearing is the
     * whole trick a vendor's slide relies on.
     */
    lostToUnusedFloorUsd: number;
    /** How many of the measured months would have fallen short. A count, never a rate. */
    shortfallMonths: number;
    /**
     * The monthly spend at which the commitment stops losing money.
     *
     * Equal to the floor: below it you pay the floor for less usage. Above it
     * the saving grows, first as (spend − floor) and then, once discounted usage
     * clears the floor, as spend × discount.
     */
    breakEvenMonthlyUsd: number;
    /**
     * Measured spread across the months replayed — lowest and highest, and how
     * far the range spans as a share of the median.
     *
     * The honest form of "shortfall risk": a reader looking at a range wider than
     * the floor can see the deal is a bet, without anybody modelling a
     * distribution nobody fitted.
     */
    spread: {
        lowUsd: number;
        highUsd: number;
        medianUsd: number;
    } | null;
    /** Set when nothing could be replayed. A refusal never arrives bare. */
    unknown: CommitmentUnknown | null;
    /** How many whole months would settle it, when there are too few. */
    monthsNeeded: number | null;
}
/**
 * The fewest whole months worth replaying a commitment against.
 *
 * Three. Two months cannot show a shortfall pattern and one cannot show
 * anything at all — and a commitment is signed for a year, so an answer from a
 * single month is a year-long decision made on a fortnight of evidence.
 */
export declare const MIN_MONTHS_FOR_REPLAY = 3;
export declare function replayCommitment(history: readonly MeasuredMonth[], terms: CommitmentTerms): CommitmentReplay;
/**
 * Whether the replay covers as long as the commitment runs.
 *
 * Kept separate from the refusals because it does not stop the arithmetic: six
 * months of history against a twelve-month deal is a real answer about six
 * months, and saying so is more useful than refusing. What it must not do is
 * go unsaid — a twelve-month decision read off half a year of evidence, with
 * nothing on the page marking the gap, is the spreadsheet this module was
 * written to replace.
 */
export declare function coversTheTerm(replay: CommitmentReplay, terms: CommitmentTerms): {
    covered: number;
    ofMonths: number;
    short: boolean;
};
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