import { NextRequest } from "next/server";
import { z } from "zod";
import { verifyApiKey, bearerKey } from "@/lib/apikeys";
import { prisma } from "@/lib/db";
import { getEffectivePlan } from "@/lib/billing/subscription";
import { reserveLimit, LimitExceededError } from "@/lib/usage/limits";
import { refundUsage } from "@/lib/usage/meter";
import { enqueueEpisodeGeneration } from "@/lib/queue/pgboss";
import { FORMAT_SPEAKERS } from "@/lib/episodes/options";
import { DEFAULT_VOICE_IDS, VOICE_CATALOG } from "@/lib/ai/voices";
import { rateLimit, LIMITS } from "@/lib/ratelimit";
import { isFlagEnabled } from "@/lib/flags";
import { moderateText } from "@/lib/ai/moderation";
import type { UsageMetric } from "@/lib/billing/plans";

export const dynamic = "force-dynamic";

async function authorize(req: NextRequest) {
  return verifyApiKey(bearerKey(req.headers.get("authorization")));
}

/** GET /api/v1/episodes — list the caller's episodes. */
export async function GET(req: NextRequest) {
  const auth = await authorize(req);
  if (!auth) return Response.json({ error: "Invalid API key" }, { status: 401 });

  const rl = await rateLimit("read", auth.userId, LIMITS.read);
  if (!rl.ok) {
    return Response.json(
      { error: "Rate limit exceeded" },
      { status: 429, headers: { "Retry-After": String(rl.retryAfterSec ?? 60) } }
    );
  }

  const episodes = await prisma.episode.findMany({
    where: { userId: auth.userId },
    orderBy: { createdAt: "desc" },
    take: 50,
    select: { id: true, title: true, status: true, format: true, language: true, createdAt: true },
  });
  return Response.json({ episodes });
}

const createSchema = z.object({
  topic: z.string().min(10).max(2000),
  title: z.string().max(120).optional(),
  tone: z.string().default("Conversational"),
  format: z.enum(["SOLO", "INTERVIEW", "MULTI_HOST"]).default("SOLO"),
  language: z.string().min(2).max(5).default("en"),
  targetLengthMin: z.number().int().min(1).max(180).default(5),
  audience: z.string().max(200).optional(),
});

/** POST /api/v1/episodes — create + generate an episode. */
export async function POST(req: NextRequest) {
  const auth = await authorize(req);
  if (!auth) return Response.json({ error: "Invalid API key" }, { status: 401 });

  const rl = await rateLimit("api", auth.userId, LIMITS.api);
  if (!rl.ok) {
    return Response.json(
      { error: "Rate limit exceeded" },
      { status: 429, headers: { "Retry-After": String(rl.retryAfterSec ?? 60) } }
    );
  }

  if (!(await isFlagEnabled("episode_generation_enabled"))) {
    return Response.json({ error: "Episode generation is temporarily paused" }, { status: 503 });
  }

  const parsed = createSchema.safeParse(await req.json().catch(() => ({})));
  if (!parsed.success) {
    return Response.json({ error: parsed.error.issues[0]?.message ?? "Invalid body" }, { status: 400 });
  }
  const data = parsed.data;

  const { plan, subjectId, subjectType } = await getEffectivePlan(auth.userId);
  if (data.targetLengthMin > plan.limits.maxEpisodeMinutes) {
    return Response.json(
      { error: `Plan supports episodes up to ${plan.limits.maxEpisodeMinutes} minutes` },
      { status: 402 }
    );
  }

  // Screen the requested topic before reserving quota or spending AI budget.
  if (await isFlagEnabled("ai_moderation_enabled")) {
    const mod = await moderateText([data.title, data.topic, data.audience].filter(Boolean).join("\n"));
    if (mod.flagged) {
      return Response.json(
        { error: "Topic violates the content policy and cannot be generated" },
        { status: 422 }
      );
    }
  }

  // Atomically reserve quota up front (full generation = script+audio+art). The
  // worker won't re-meter; we refund below if create/enqueue fails. See the
  // metering invariant in lib/usage/meter.ts.
  const reserved: UsageMetric[] = [];
  const refundReserved = async () => {
    for (const m of reserved) await refundUsage(subjectId, subjectType, m);
  };
  try {
    await reserveLimit(auth.userId, "script");
    reserved.push("script");
    await reserveLimit(auth.userId, "audio");
    reserved.push("audio");
    await reserveLimit(auth.userId, "art");
    reserved.push("art");
  } catch (err) {
    await refundReserved();
    if (err instanceof LimitExceededError) {
      return Response.json({ error: `Monthly ${err.check.metric} limit reached` }, { status: 402 });
    }
    throw err;
  }

  const speakers = FORMAT_SPEAKERS[data.format].map((s, i) => ({
    speakerKey: s.speakerKey,
    displayName: s.defaultName,
    elevenVoiceId: DEFAULT_VOICE_IDS[s.speakerKey] ?? VOICE_CATALOG[i % VOICE_CATALOG.length].id,
  }));

  try {
    const episode = await prisma.episode.create({
      data: {
        userId: auth.userId,
        title: data.title?.trim() || data.topic.slice(0, 60),
        topic: data.topic,
        tone: data.tone,
        format: data.format,
        language: data.language,
        targetLengthMin: data.targetLengthMin,
        audience: data.audience,
        status: "QUEUED",
        stage: "Queued for generation",
        speakers: { create: speakers },
        jobs: { create: { type: "full", status: "queued" } },
      },
    });
    await enqueueEpisodeGeneration({ episodeId: episode.id, type: "full" });

    return Response.json({ id: episode.id, status: episode.status }, { status: 201 });
  } catch (err) {
    await refundReserved();
    throw err;
  }
}