import { and, eq, lt, or, isNull, sql } from 'drizzle-orm';
import { db } from '../db';
import { nudges } from './schema';
import type { NudgeSelect } from '../types';

/** Create or replace the schedule for one session. Re-arming resets the count — it is a new night. */
export async function setNudge(params: {
  userId: number;
  sessionId: string;
  message: string;
  everySeconds: number;
  maxCount: number;
}): Promise<NudgeSelect> {
  const [row] = await db
    .insert(nudges)
    .values({ ...params, enabled: true, sentCount: 0, lastFiredAt: null })
    .onConflictDoUpdate({
      target: [nudges.userId, nudges.sessionId],
      set: {
        message: params.message,
        everySeconds: params.everySeconds,
        maxCount: params.maxCount,
        enabled: true,
        sentCount: 0,
        lastFiredAt: null,
        updatedAt: new Date(),
      },
    })
    .returning();
  return row!;
}

export async function getNudge(userId: number, sessionId: string): Promise<NudgeSelect | null> {
  const [row] = await db
    .select()
    .from(nudges)
    .where(and(eq(nudges.userId, userId), eq(nudges.sessionId, sessionId)))
    .limit(1);
  return row ?? null;
}

export async function cancelNudge(userId: number, sessionId: string): Promise<void> {
  await db.delete(nudges).where(and(eq(nudges.userId, userId), eq(nudges.sessionId, sessionId)));
}

/**
 * Everything the scheduler should consider this tick.
 *
 * Due means: enabled, under its ceiling, and either never fired or last fired at least `every_seconds`
 * ago. Whether the session is actually IDLE is not asked here — that lives in the sidecar, not the
 * database, and the scheduler checks it immediately before speaking.
 */
export async function dueNudges(now: Date = new Date()): Promise<NudgeSelect[]> {
  return db
    .select()
    .from(nudges)
    .where(
      and(
        eq(nudges.enabled, true),
        lt(nudges.sentCount, nudges.maxCount),
        or(
          isNull(nudges.lastFiredAt),
          lt(nudges.lastFiredAt, sql`${now} - (${nudges.everySeconds} * interval '1 second')`),
        ),
      ),
    );
}

/** One nudge delivered. Disables itself on reaching the ceiling rather than leaving a spent row armed. */
export async function recordNudgeSent(id: number): Promise<void> {
  await db
    .update(nudges)
    .set({
      sentCount: sql`${nudges.sentCount} + 1`,
      lastFiredAt: new Date(),
      updatedAt: new Date(),
      enabled: sql`${nudges.sentCount} + 1 < ${nudges.maxCount}`,
    })
    .where(eq(nudges.id, id));
}