// Investor Flow — Conviction tier unlock alert producer.
//
// conviction_unlock: fires when a user earns a new sizing unlock (tier_a,
// tier_a_star, etc.) from accumulated trading history. Watermark = last
// earned_at per user, so re-reading the same unlock stays silent.
//
// ADR-0007: an unlock is an earned capability, not a buy signal.

import type { DatabaseSync } from 'node:sqlite';
import type { Alert } from '../AlertEngine.ts';
import { createAlert, buildDedupKey } from '../AlertEngine.ts';
import type { AlertProducer } from './types.ts';
import { readComparisonState, writeComparisonState, getSubscribedUsers, persistAlert, isDuplicate } from './types.ts';

/** Human-readable tier names for the payload/unlock display. */
const UNLOCK_LABELS: Record<string, string> = {
  tier_a: 'A tier',
  tier_a_star: 'A* tier',
  covered_income: 'covered income strategies',
  uncovered_income: 'uncovered income strategies',
};

export const convictionUnlockProducer: AlertProducer = {
  alertType: 'conviction_unlock',
  frequency: 'batched',

  async check(db: DatabaseSync): Promise<Alert[]> {
    const alerts: Alert[] = [];

    // Newest unlock per user.
    const rows = db.prepare(
      `SELECT s.user_id, s.unlock, s.earned_at, s.evidence
         FROM sizing_unlocks s
         JOIN (SELECT user_id, MAX(earned_at) AS max_earned
                 FROM sizing_unlocks
                GROUP BY user_id) m
           ON s.user_id = m.user_id AND s.earned_at = m.max_earned
        ORDER BY s.earned_at DESC`,
    ).all() as Array<{ user_id: string; unlock: string; earned_at: string; evidence: string | null }>;

    for (const row of rows) {
      const userId = row.user_id;
      const prev = readComparisonState(db, userId, 'conviction_unlock');
      const prevState = prev ? JSON.parse(prev.state) : { lastEarnedAt: null, lastUnlock: null };

      if (prevState.lastEarnedAt === row.earned_at && prevState.lastUnlock === row.unlock) {
        continue;
      }

      // First observation records the watermark without firing (existing
      // unlocks at boot shouldn't page anyone).
      if (prevState.lastUnlock === null) {
        writeComparisonState(db, userId, 'conviction_unlock', {
          lastEarnedAt: row.earned_at,
          lastUnlock: row.unlock,
        });
        continue;
      }

      // A genuinely new unlock → notify the earning user first (they are the
      // primary subscriber; a global subscription is honored too).
      const users = new Set(getSubscribedUsers(db, 'conviction_unlock', userId));
      users.add(userId);
      for (const uid of users) {
        const eventId = `${userId}:${row.unlock}:${row.earned_at}`;
        const dedupKey = buildDedupKey('conviction_unlock', undefined, eventId);
        if (isDuplicate(db, dedupKey)) continue;

        const label = UNLOCK_LABELS[row.unlock] ?? row.unlock;
        const description =
          `Your trading history now qualifies for the ${label} conviction tier` +
          (row.evidence ? `. Evidence: ${row.evidence}` : '') +
          `. Sizing at this tier uses the higher conviction multiplier.`;

        const alert = createAlert(
          crypto.randomUUID(),
          uid,
          'conviction_unlock',
          undefined,
          description,
          eventId,
          { unlock: row.unlock, earnedAt: row.earned_at, evidence: row.evidence },
        );
        persistAlert(db, alert);
        alerts.push(alert);
      }

      writeComparisonState(db, userId, 'conviction_unlock', {
        lastEarnedAt: row.earned_at,
        lastUnlock: row.unlock,
      });
    }

    return alerts;
  },
};