import { randomBytes } from 'node:crypto';
import { buildHealthTimeline, summarizeTimelineForAssess } from './health-timeline.mjs';

export function createHealthShareService({ observationService, eventEngine, baselineEngine } = {}) {
  if (!observationService) throw new Error('createHealthShareService requires observationService');

  const tokens = new Map();

  return {
    async createReadonlySnapshot(userId, { ttlMs = 7 * 24 * 60 * 60 * 1000, now = Date.now() } = {}) {
      const observations = await observationService.list(userId, { limit: 500 });
      const baselines = baselineEngine?.computeHealthBaselines
        ? baselineEngine.computeHealthBaselines(observations, { now })
        : [];
      const events = eventEngine?.evaluateHealthEvents
        ? eventEngine.evaluateHealthEvents(observations, baselines, { now, mode: 'active' })
        : [];
      const timeline = buildHealthTimeline(observations);
      const token = randomBytes(16).toString('hex');
      const snapshot = {
        userId: String(userId),
        createdAt: now,
        expiresAt: now + ttlMs,
        summary: summarizeTimelineForAssess(timeline),
        timeline: timeline.slice(0, 14),
        openEvents: events.filter((e) => e.severity === 'watch' || e.severity === 'alert').slice(0, 10),
        baselines: baselines.filter((b) => b.windowDays === 30 && b.sampleCount >= 7).slice(0, 12),
      };
      tokens.set(token, snapshot);
      return { token, expiresAt: snapshot.expiresAt };
    },
    getSnapshot(token) {
      const snapshot = tokens.get(String(token));
      if (!snapshot) return null;
      if (Date.now() > snapshot.expiresAt) {
        tokens.delete(String(token));
        return null;
      }
      return snapshot;
    },
    revoke(token) {
      return tokens.delete(String(token));
    },
  };
}

export function buildMedicationTimelineHint() {
  return '用药 Timeline 将在 P3 与 schedule-assistant 整合；当前请先在提醒助手中管理用药计划。';
}