import type { LearningModule, Lesson, CurriculumNode } from './types.js';
/** Flatten all lessons across modules in curriculum order */
export declare function flattenLessons(modules: LearningModule[], lessons: Lesson[]): Lesson[];
/** Count total lessons across all modules */
export declare function countLessons(modules: LearningModule[], lessons: Lesson[]): number;
/** Calculate total estimated duration in minutes */
export declare function calculateEstimatedDuration(lessons: Lesson[]): number;
/** Format minutes into human-readable duration */
export declare function formatDuration(minutes: number): string;
/** Build a curriculum tree with progress status */
export declare function buildCurriculumTree(modules: LearningModule[], lessons: Lesson[], completedLessonIds?: Set<string>): CurriculumNode[];
/** Reorder items by moving an item from one index to another, updating sortOrders */
export declare function reorderItems<T extends {
    sortOrder: number;
}>(items: T[], fromIndex: number, toIndex: number): T[];
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