import type { PostgresJsDatabase } from "drizzle-orm/postgres-js";
import type { NotificationReminderRule, NotificationReminderRuleStage } from "./schema.js";
import type { ReminderTargetSnapshot } from "./service-sequence.js";
/**
 * Computes the date range a target's `due_date` (or `issue_date`) needs to
 * fall in for any of the rule's stages to be inside their eligibility window
 * today.
 *
 * From `inWindow`: today must satisfy
 *   anchor + windowStartDays ≤ today ≤ anchor + windowEndDays
 * Solving for anchor:
 *   today − windowEndDays ≤ anchor ≤ today − windowStartDays
 *
 * Across all stages with anchor=`due_date`, we union the [start, end] ranges
 * and use the resulting envelope as a SQL `BETWEEN` filter. Returns null when
 * no stage is anchored on the requested column (e.g. all stages anchor on
 * `departure_date`) — caller should skip the pushdown in that case.
 */
export declare function computeAnchorDateEnvelope(stages: NotificationReminderRuleStage[], today: Date, anchor: NotificationReminderRuleStage["anchor"]): {
    from: string;
    to: string;
} | null;
/**
 * Per-rule target fetch that pushes a date envelope into the WHERE when all
 * relevant stages share an anchor we can SQL-filter on (`due_date` for both
 * target types, `invoice_issued_at` for invoices). Other anchors fall through
 * to the unfiltered fetch — they're expected to be rare and the in-app
 * window check still rejects misses.
 */
export declare function fetchTargetsForRule(db: PostgresJsDatabase, rule: NotificationReminderRule, stages?: NotificationReminderRuleStage[], today?: Date): Promise<ReminderTargetSnapshot[]>;