import type { UsageFilter, UsageRepository } from '../db/repositories/usage-repository.js';
/**
 * Spend against a target, and where it is heading.
 *
 * Nothing in the tool surface accepted a budget number, so extrapolating
 * month-end spend meant reading the active days out of `daily` and picking a
 * denominator -- calendar days? active days? -- by hand. That is a modelling
 * choice, and the two answers differ by a factor of two on a machine used on
 * weekdays only. This reports BOTH, labelled, and never blends them into one
 * "projected" figure.
 *
 * The prior question the issue raises -- which cost figure a Pro/Max subscriber
 * should budget from -- is answered the same way `--fail-over` answers it: the
 * caller names the basis. There is no default. Reported and estimated cost are
 * separate figures that are never summed, so a budget with no stated basis is a
 * budget against nothing in particular.
 */
export type BudgetBasis = 'reported' | 'estimated';
export declare const BUDGET_BASES: BudgetBasis[];
/** A calendar period has an end to project towards; a rolling window does not. */
export type BudgetPeriod = 'month' | 'week';
export declare const BUDGET_PERIODS: BudgetPeriod[];
export interface Projection {
    /** Spend per day on this denominator. */
    ratePerDay: number;
    /** Where the period ends up at this rate. */
    projected: number;
    /** Positive when the projection exceeds the budget; absent when it does not. */
    overBy?: number;
    /** The denominator used, so the figure can be checked by hand. */
    days: number;
}
export interface BudgetReport {
    period: {
        since: string;
        until: string;
        label: string;
    };
    basis: BudgetBasis;
    amount: number;
    /** Spend so far on the chosen basis only. Never a blend of the two. */
    spent: number;
    remaining: number;
    /** Spend as a fraction of the budget. May exceed 1. */
    fractionUsed: number;
    /** Whole and partial days elapsed, and the period's full length. */
    elapsed: {
        days: number;
        totalDays: number;
        fraction: number;
    };
    /** Elapsed days with any recorded activity. The second denominator. */
    activeDays: number;
    /** Deliberately two, because the choice of denominator changes the answer. */
    projections: {
        perCalendarDay: Projection;
        perActiveDay: Projection;
    };
    /** True when SPENT already exceeds the budget. A fact, not a forecast. */
    overBudget: boolean;
    /** Things that would make the figures misleading if unsaid. Never empty. */
    caveats: string[];
}
export declare function budgetWindow(period: BudgetPeriod, now?: Date): {
    since: Date;
    until: Date;
    label: string;
};
export declare class BudgetService {
    private readonly repo;
    constructor(repo: UsageRepository);
    budget(options: {
        amount: number;
        basis: BudgetBasis;
        period: BudgetPeriod;
        filter?: UsageFilter;
        now?: Date;
    }): BudgetReport;
    private caveats;
}