/**
 * What is new or changed in agent memory since the user last looked.
 *
 * Derived from the entry's own timestamps against a per-scope "last viewed"
 * mark, so the store carries no review state and the user is never asked to
 * confirm anything. Looking at the tab is the acknowledgement.
 *
 * The two badges are worth separating: a memory the agent has just invented
 * and one it has quietly rewritten need different attention, and lumping them
 * together as "new" would hide every correction.
 */

import type { AgentMemoryEntry, AgentMemoryScope } from './agentMemoryApi';

export type MemoryBadge = 'new' | 'changed' | null;

/**
 * The key a scope's mark is stored under. Project marks are keyed by path
 * because each project has its own store — one shared mark would let opening
 * one project silently clear another's badges.
 */
export const memoryViewKey = (scope: AgentMemoryScope, projectPath: string | null): string => (
  scope === 'global' ? 'global' : `project:${projectPath ?? ''}`
);

/**
 * `viewedAt` of 0 means the user has never opened this scope. Everything stored
 * is then genuinely new to them, which is what a first look should show.
 */
export const classifyMemory = (entry: AgentMemoryEntry, viewedAt: number): MemoryBadge => {
  if (entry.createdAt > viewedAt) {
    return 'new';
  }
  // Only a change the user has not seen counts. An entry rewritten before their
  // last look was already accounted for by that look.
  if (entry.updatedAt > viewedAt) {
    return 'changed';
  }
  return null;
};

export const countHighlightedMemories = (entries: AgentMemoryEntry[], viewedAt: number): number => (
  entries.reduce((total, entry) => (classifyMemory(entry, viewedAt) ? total + 1 : total), 0)
);