/**
 * BullMQ worker: generate lesson content for a blueprint.
 *
 * Idempotent: checks `job` ledger before generating.
 * On success: writes lesson to Redis cache and updates job status.
 * On failure: increments attempt count; sets status to 'failed' after processing.
 */
import { Worker } from 'bullmq';
import { eq, and } from 'drizzle-orm';
import { db } from '../src/lib/db';
import { jobs, blueprints, concepts, lessons } from '../src/lib/db/schema';
import { generateLesson } from '../src/lib/generation/generate-lesson';
import { verifyLesson } from '../src/lib/verification/verify-content';
import { getLessonResponse } from '../src/lib/db/queries';
import { setCachedLesson } from '../src/lib/cache/lesson';
import { appendStreamSegment, markStreamDone } from '../src/lib/cache/stream';
import { enqueuePromoteBlueprint } from '../src/lib/jobs/queue';
import type { GenerateLessonJobData } from '../src/lib/jobs/queue';

const connection = {
  url: process.env.REDIS_URL ?? 'redis://localhost:6379',
};

const worker = new Worker<GenerateLessonJobData>(
  'generate-lesson',
  async (job) => {
    const { intentKey, blueprintId, idempotencyKey, locale = 'en', depth = 'standard', ageGroup = 'adult', difficultyLevel = 1, ord = 0 } = job.data;

    // 1. Idempotency check — find the job row by idempotency key
    const [jobRow] = await db
      .select({ id: jobs.id, status: jobs.status, attempts: jobs.attempts })
      .from(jobs)
      .where(eq(jobs.id, idempotencyKey))
      .limit(1);

    if (jobRow?.status === 'done') {
      // Already completed — warm cache if needed and return
      const cached = await getLessonResponse(intentKey, undefined, locale, depth as import('../src/lib/generation/depth').LessonDepth, ageGroup as import('../src/schemas/preferences').AgeGroup);
      if (cached?.state === 'ready') {
        await setCachedLesson(intentKey, locale, cached, depth as import('../src/lib/generation/depth').LessonDepth, ageGroup as import('../src/schemas/preferences').AgeGroup);
      }
      return;
    }

    // Mark running
    await db
      .update(jobs)
      .set({ status: 'running', attempts: (jobRow?.attempts ?? 0) + 1 })
      .where(eq(jobs.id, idempotencyKey));

    // 2. Check lesson at this ord doesn't already exist
    const [existingLesson] = await db
      .select({ id: lessons.id })
      .from(lessons)
      .where(
        and(
          eq(lessons.blueprintId, blueprintId),
          eq(lessons.locale, locale),
          eq(lessons.depth, depth),
          eq(lessons.ageGroup, ageGroup),
          eq(lessons.ord, ord),
        ),
      )
      .limit(1);

    if (existingLesson) {
      const cached = await getLessonResponse(intentKey, undefined, locale, depth as import('../src/lib/generation/depth').LessonDepth, ageGroup as import('../src/schemas/preferences').AgeGroup);
      if (cached?.state === 'ready') {
        await setCachedLesson(intentKey, locale, cached, depth as import('../src/lib/generation/depth').LessonDepth, ageGroup as import('../src/schemas/preferences').AgeGroup);
      }
      await db.update(jobs).set({ status: 'done' }).where(eq(jobs.id, idempotencyKey));
      return;
    }

    // 3. Fetch blueprint + concepts at this ord
    const [blueprint] = await db
      .select()
      .from(blueprints)
      .where(eq(blueprints.id, blueprintId))
      .limit(1);

    if (!blueprint) throw new Error(`Blueprint not found: ${blueprintId}`);

    // For ord=0 use all concepts (backward compat); for ord>0 use concepts at that ord.
    const conceptRows = await db
      .select({ id: concepts.id, name: concepts.name, ord: concepts.ord, retrievalCtxRef: concepts.retrievalCtxRef })
      .from(concepts)
      .where(
        ord === 0
          ? eq(concepts.blueprintId, blueprintId)
          : and(eq(concepts.blueprintId, blueprintId), eq(concepts.ord, ord)),
      );

    if (conceptRows.length === 0) throw new Error(`No concepts at ord=${ord} for blueprint: ${blueprintId}`);

    // 4. Generate lesson — onSegment pushes each segment to Redis as it's persisted,
    //    so SSE clients receive progressive delivery without waiting for the full batch.
    const { lessonId } = await generateLesson({
      blueprintId,
      lessonOrd: ord,
      topicTitle: blueprint.title,
      conceptsToGenerate: conceptRows.map((c) => ({
        id: c.id,
        name: c.name,
        retrievalCtxRef: c.retrievalCtxRef,
      })),
      locale,
      depth: depth as import('../src/lib/generation/depth').LessonDepth,
      ageGroup: ageGroup as import('../src/schemas/preferences').AgeGroup,
      difficultyLevel: difficultyLevel as 1 | 2 | 3,
      onSegment: (seg) =>
        appendStreamSegment(
          intentKey, locale, seg,
          depth as import('../src/lib/generation/depth').LessonDepth,
          ageGroup as import('../src/schemas/preferences').AgeGroup,
          ord,
        ),
    });

    // Signal SSE clients that the stream is complete.
    await markStreamDone(
      intentKey, locale,
      depth as import('../src/lib/generation/depth').LessonDepth,
      ageGroup as import('../src/schemas/preferences').AgeGroup,
      ord,
    );

    // 5. T1 verification (non-blocking for serve — T2 + promotion handled by promote-blueprint job)
    await verifyLesson({ lessonId, runT2: false });

    // 6. Write to Redis cache (position-keyed)
    const lesson = await getLessonResponse(intentKey, undefined, locale, depth as import('../src/lib/generation/depth').LessonDepth, ageGroup as import('../src/schemas/preferences').AgeGroup);
    if (lesson?.state === 'ready') {
      await setCachedLesson(intentKey, locale, lesson, depth as import('../src/lib/generation/depth').LessonDepth, ageGroup as import('../src/schemas/preferences').AgeGroup, ord);
    }

    // 7. Update job ledger
    await db.update(jobs).set({ status: 'done' }).where(eq(jobs.id, idempotencyKey));

    // 8. Enqueue blueprint promotion (T2 verify + misconceptions)
    const promoteKey = `promote-blueprint:${blueprintId}:v1`;
    const [existingPromote] = await db
      .select({ id: jobs.id })
      .from(jobs)
      .where(eq(jobs.idempotencyKey, promoteKey))
      .limit(1);

    if (!existingPromote) {
      const [promoteJobRow] = await db
        .insert(jobs)
        .values({
          type: 'promote-blueprint',
          idempotencyKey: promoteKey,
          status: 'pending',
          payloadJson: { blueprintId, intentKey, lessonId },
        })
        .returning({ id: jobs.id });

      await enqueuePromoteBlueprint({
        blueprintId,
        intentKey,
        idempotencyKey: promoteJobRow.id,
      });
    }
  },
  { connection, concurrency: 2 },
);

worker.on('failed', async (job, err) => {
  if (job?.data.idempotencyKey) {
    await db
      .update(jobs)
      .set({ status: 'failed' })
      .where(eq(jobs.id, job.data.idempotencyKey));
  }
  console.error('[generate-lesson] job failed:', err);
});

export default worker;