"use server";

import { randomBytes } from "node:crypto";
import { revalidatePath } from "next/cache";
import { z } from "zod";
import { getServerSession } from "@/lib/auth/guards";
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 { rateLimit, LIMITS } from "@/lib/ratelimit";
import { isFlagEnabled } from "@/lib/flags";
import { moderateText } from "@/lib/ai/moderation";
import type { UsageMetric } from "@/lib/billing/plans";
import type { GenerationType } from "@/lib/queue/jobs";
import type { Prisma } from "@prisma/client";

const speakerSchema = z.object({
  speakerKey: z.string().min(1).max(40),
  displayName: z.string().min(1).max(60),
  elevenVoiceId: z.string().min(1).max(60),
});

const createSchema = z.object({
  title: z.string().max(120).optional(),
  topic: z.string().min(10, "Describe your topic in a bit more detail").max(2000),
  tone: z.string().min(1),
  format: z.enum(["SOLO", "INTERVIEW", "MULTI_HOST"]),
  language: z.string().min(2).max(5),
  targetLengthMin: z.number().int().min(1).max(180),
  audience: z.string().max(200).optional(),
  speakers: z.array(speakerSchema).min(1).max(6),
});

export type CreateEpisodeInput = z.infer<typeof createSchema>;
export type CreateEpisodeResult =
  | { ok: true; episodeId: string }
  | { ok: false; error: string; limited?: boolean };

export async function createEpisodeAction(input: CreateEpisodeInput): Promise<CreateEpisodeResult> {
  const session = await getServerSession();
  if (!session) return { ok: false, error: "You must be signed in." };

  const rl = await rateLimit("generation", session.user.id, LIMITS.generation);
  if (!rl.ok) {
    return { ok: false, error: `Too many requests. Try again in ${rl.retryAfterSec}s.` };
  }

  if (!(await isFlagEnabled("episode_generation_enabled"))) {
    return { ok: false, error: "Episode generation is temporarily paused. Please try again shortly." };
  }

  const parsed = createSchema.safeParse(input);
  if (!parsed.success) {
    return { ok: false, error: parsed.error.issues[0]?.message ?? "Invalid input." };
  }
  const data = parsed.data;
  const activeOrgId = session.session.activeOrganizationId;

  const { plan, subjectId, subjectType } = await getEffectivePlan(session.user.id, activeOrgId);
  if (data.targetLengthMin > plan.limits.maxEpisodeMinutes) {
    return {
      ok: false,
      error: `The ${plan.name} plan supports episodes up to ${plan.limits.maxEpisodeMinutes} minutes.`,
      limited: true,
    };
  }

  // Screen the requested topic before spending any quota or 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 {
        ok: false,
        error: "This topic may violate our content policy and can't be generated. Please revise it and try again.",
      };
    }
  }

  // Reserve quota atomically up front (a full generation consumes script,
  // audio and 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(session.user.id, "script", activeOrgId);
    reserved.push("script");
    await reserveLimit(session.user.id, "audio", activeOrgId);
    reserved.push("audio");
    await reserveLimit(session.user.id, "art", activeOrgId);
    reserved.push("art");
  } catch (err) {
    await refundReserved();
    if (err instanceof LimitExceededError) {
      return {
        ok: false,
        error: `You've reached your monthly ${err.check.metric} limit on the ${err.check.plan} plan. Upgrade to keep creating.`,
        limited: true,
      };
    }
    throw err;
  }

  try {
    const episode = await prisma.episode.create({
      data: {
        userId: session.user.id,
        organizationId: activeOrgId ?? undefined,
        title: data.title?.trim() || deriveTitle(data.topic),
        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: data.speakers.map((s) => ({
            speakerKey: s.speakerKey,
            displayName: s.displayName,
            elevenVoiceId: s.elevenVoiceId,
          })),
        },
        jobs: { create: { type: "full", status: "queued" } },
      },
    });

    await enqueueEpisodeGeneration(
      { episodeId: episode.id, type: "full" },
      { priority: plan.features.includes("priority_generation") ? 10 : 0 }
    );

    revalidatePath("/episodes");
    revalidatePath("/dashboard");
    return { ok: true, episodeId: episode.id };
  } catch (err) {
    await refundReserved();
    throw err;
  }
}

export async function regenerateAction(
  episodeId: string,
  type: GenerationType
): Promise<{ ok: boolean; error?: string }> {
  const session = await getServerSession();
  if (!session) return { ok: false, error: "You must be signed in." };

  const rl = await rateLimit("generation", session.user.id, LIMITS.generation);
  if (!rl.ok) {
    return { ok: false, error: `Too many requests. Try again in ${rl.retryAfterSec}s.` };
  }

  if (!(await isFlagEnabled("episode_generation_enabled"))) {
    return { ok: false, error: "Episode generation is temporarily paused. Please try again shortly." };
  }

  const episode = await prisma.episode.findUnique({
    where: { id: episodeId },
    select: { userId: true, organizationId: true },
  });
  if (!episode) return { ok: false, error: "Episode not found." };
  if (episode.userId !== session.user.id && session.user.role !== "admin") {
    return { ok: false, error: "Not allowed." };
  }

  const activeOrgId = session.session.activeOrganizationId;
  const { subjectId, subjectType } = await getEffectivePlan(session.user.id, activeOrgId);

  // Reserve the metrics this regeneration will consume up front. The worker
  // won't re-meter; refund below if enqueue fails. See meter.ts invariant.
  const metrics: UsageMetric[] =
    type === "art" ? ["art"] : type === "audio" ? ["audio"] : ["script", "audio"];
  const reserved: UsageMetric[] = [];
  const refundReserved = async () => {
    for (const m of reserved) await refundUsage(subjectId, subjectType, m);
  };
  try {
    for (const m of metrics) {
      await reserveLimit(session.user.id, m, activeOrgId);
      reserved.push(m);
    }
  } catch (err) {
    await refundReserved();
    if (err instanceof LimitExceededError) {
      return { ok: false, error: `Monthly ${err.check.metric} limit reached on the ${err.check.plan} plan.` };
    }
    throw err;
  }

  try {
    await prisma.episode.update({
      where: { id: episodeId },
      data: { status: "QUEUED", stage: "Queued for regeneration", errorMessage: null },
    });
    await prisma.generationJob.create({ data: { episodeId, type, status: "queued" } });
    await enqueueEpisodeGeneration({ episodeId, type });
  } catch (err) {
    await refundReserved();
    throw err;
  }

  revalidatePath(`/episodes/${episodeId}`);
  return { ok: true };
}

const scriptContentSchema = z.object({
  title: z.string().min(1),
  sections: z
    .array(
      z.object({
        id: z.string().min(1),
        title: z.string().min(1),
        turns: z.array(z.object({ speakerKey: z.string(), text: z.string() })).min(1),
      })
    )
    .min(1),
});

export async function updateScriptAction(
  episodeId: string,
  content: unknown
): Promise<{ ok: boolean; error?: string }> {
  const session = await getServerSession();
  if (!session) return { ok: false, error: "You must be signed in." };

  const episode = await prisma.episode.findUnique({
    where: { id: episodeId },
    select: { userId: true },
  });
  if (!episode || episode.userId !== session.user.id) return { ok: false, error: "Not allowed." };

  const parsed = scriptContentSchema.safeParse(content);
  if (!parsed.success) return { ok: false, error: "Invalid script format." };

  await prisma.script.update({
    where: { episodeId },
    data: { content: parsed.data as unknown as Prisma.InputJsonValue, version: { increment: 1 } },
  });
  revalidatePath(`/episodes/${episodeId}`);
  return { ok: true };
}

export async function regenerateSectionAction(
  episodeId: string,
  sectionId: string
): Promise<{ ok: boolean; error?: string; section?: { id: string; title: string; turns: { speakerKey: string; text: string }[] } }> {
  const session = await getServerSession();
  if (!session) return { ok: false, error: "You must be signed in." };

  const episode = await prisma.episode.findUnique({
    where: { id: episodeId },
    include: { speakers: true, script: true },
  });
  if (!episode || (episode.userId !== session.user.id && session.user.role !== "admin")) {
    return { ok: false, error: "Not allowed." };
  }
  if (!episode.script) return { ok: false, error: "No script to edit yet." };

  const rl = await rateLimit("generation", session.user.id, LIMITS.generation);
  if (!rl.ok) {
    return { ok: false, error: `Too many requests. Try again in ${rl.retryAfterSec}s.` };
  }

  const activeOrgId = session.session.activeOrganizationId;
  // Reserve the script unit atomically up front. This synchronous action does
  // NOT increment afterwards (that would double-count) — it refunds on failure.
  try {
    await reserveLimit(session.user.id, "script", activeOrgId);
  } catch (err) {
    if (err instanceof LimitExceededError) {
      return { ok: false, error: `Monthly script limit reached on the ${err.check.plan} plan.` };
    }
    throw err;
  }

  const ownerId = episode.organizationId ?? episode.userId;
  const ownerType = episode.organizationId ? "organization" : "user";

  // Imported lazily so the AI SDK never reaches client bundles importing this file.
  const { scriptProvider } = await import("@/lib/ai/providers");
  const { recordCost, scriptCostUsd } = await import("@/lib/ai/cost");

  const config = {
    title: episode.title,
    topic: episode.topic,
    tone: episode.tone,
    format: episode.format,
    language: episode.language,
    targetLengthMin: episode.targetLengthMin,
    audience: episode.audience ?? undefined,
    speakers: episode.speakers.map((s) => ({ speakerKey: s.speakerKey, displayName: s.displayName })),
  };
  const current = episode.script.content as unknown as {
    title: string;
    sections: { id: string; title: string; turns: { speakerKey: string; text: string }[] }[];
  };

  let section: { id: string; title: string; turns: { speakerKey: string; text: string }[] };
  let usage: { inputTokens: number; outputTokens: number };
  try {
    ({ section, usage } = await scriptProvider().regenerateSection(config, current, sectionId));
    const updated = {
      ...current,
      sections: current.sections.map((s) => (s.id === sectionId ? section : s)),
    };

    await prisma.script.update({
      where: { episodeId },
      data: { content: updated as unknown as Prisma.InputJsonValue, version: { increment: 1 } },
    });
  } catch (err) {
    // Generation/save failed — refund the script unit we reserved.
    await refundUsage(ownerId, ownerType, "script");
    throw err;
  }

  // No incrementUsage here: the unit was already reserved above.
  await recordCost({
    provider: "openai",
    operation: "script",
    units: usage.inputTokens + usage.outputTokens,
    costUsd: scriptCostUsd(usage),
    episodeId,
    userId: episode.userId,
  });

  revalidatePath(`/episodes/${episodeId}`);
  return { ok: true, section };
}

export async function repurposeAction(
  episodeId: string,
  format: "blog" | "social_thread" | "newsletter"
): Promise<{ ok: boolean; error?: string; content?: { title: string; body: string } }> {
  const session = await getServerSession();
  if (!session) return { ok: false, error: "You must be signed in." };

  const episode = await prisma.episode.findUnique({
    where: { id: episodeId },
    include: { script: true },
  });
  if (!episode || (episode.userId !== session.user.id && session.user.role !== "admin")) {
    return { ok: false, error: "Not allowed." };
  }
  if (!episode.script) return { ok: false, error: "Generate the episode first." };

  const rl = await rateLimit("repurpose", session.user.id, LIMITS.repurpose);
  if (!rl.ok) {
    return { ok: false, error: `Too many requests. Try again in ${rl.retryAfterSec}s.` };
  }

  const activeOrgId = session.session.activeOrganizationId;
  // Reserve the repurpose unit atomically up front; refund on failure. This
  // synchronous action does NOT increment afterwards (that would double-count).
  try {
    await reserveLimit(session.user.id, "repurpose", activeOrgId);
  } catch (err) {
    if (err instanceof LimitExceededError) {
      return { ok: false, error: `Monthly repurpose limit reached on the ${err.check.plan} plan.` };
    }
    throw err;
  }

  const ownerId = episode.organizationId ?? episode.userId;
  const ownerType = episode.organizationId ? "organization" : "user";

  const { repurposeScript } = await import("@/lib/ai/pipeline/repurpose");
  const { recordCost, scriptCostUsd } = await import("@/lib/ai/cost");

  let content: { title: string; body: string };
  let usage: { inputTokens: number; outputTokens: number };
  try {
    ({ content, usage } = await repurposeScript(
      episode.script.content as unknown as Parameters<typeof repurposeScript>[0],
      format
    ));

    await prisma.repurposedContent.create({
      data: { episodeId, type: format, content: content as unknown as Prisma.InputJsonValue },
    });
  } catch (err) {
    // Generation/save failed — refund the repurpose unit we reserved.
    await refundUsage(ownerId, ownerType, "repurpose");
    throw err;
  }

  // No incrementUsage here: the unit was already reserved above.
  await recordCost({
    provider: "openai",
    operation: "repurpose",
    units: usage.inputTokens + usage.outputTokens,
    costUsd: scriptCostUsd(usage),
    episodeId,
    userId: episode.userId,
  });

  revalidatePath(`/episodes/${episodeId}/repurpose`);
  return { ok: true, content };
}

export async function deleteEpisodeAction(episodeId: string): Promise<{ ok: boolean; error?: string }> {
  const session = await getServerSession();
  if (!session) return { ok: false, error: "You must be signed in." };
  const episode = await prisma.episode.findUnique({
    where: { id: episodeId },
    select: { userId: true },
  });
  if (!episode || (episode.userId !== session.user.id && session.user.role !== "admin")) {
    return { ok: false, error: "Not allowed." };
  }
  await prisma.episode.delete({ where: { id: episodeId } });
  revalidatePath("/episodes");
  return { ok: true };
}

/**
 * Toggle public sharing for an episode. When enabled, mints a random url-safe
 * `shareId` (reachable at /p/<shareId> with no auth) and stamps `sharedAt`;
 * when disabled, clears both so the public page 404s. Ownership-checked.
 */
export async function setEpisodeShareAction(
  episodeId: string,
  enabled: boolean
): Promise<{ ok: boolean; error?: string; shareId?: string | null }> {
  const session = await getServerSession();
  if (!session) return { ok: false, error: "You must be signed in." };

  const episode = await prisma.episode.findUnique({
    where: { id: episodeId },
    select: { userId: true, shareId: true, status: true },
  });
  if (!episode || (episode.userId !== session.user.id && session.user.role !== "admin")) {
    return { ok: false, error: "Not allowed." };
  }

  if (enabled) {
    if (episode.status !== "READY") {
      return { ok: false, error: "Finish generating the episode before sharing it." };
    }
    // Reuse an existing shareId if one was already minted (stable public URL).
    const shareId = episode.shareId ?? randomShareId();
    await prisma.episode.update({
      where: { id: episodeId },
      data: { shareId, sharedAt: new Date() },
    });
    revalidatePath(`/episodes/${episodeId}`);
    return { ok: true, shareId };
  }

  await prisma.episode.update({
    where: { id: episodeId },
    data: { shareId: null, sharedAt: null },
  });
  revalidatePath(`/episodes/${episodeId}`);
  return { ok: true, shareId: null };
}

/** url-safe base64 token (~22 chars, 128 bits) for public share links. */
function randomShareId(): string {
  return randomBytes(16).toString("base64url");
}

function deriveTitle(topic: string): string {
  const trimmed = topic.trim().replace(/\s+/g, " ");
  return trimmed.length <= 60 ? trimmed : trimmed.slice(0, 57) + "…";
}