import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { and, eq } from "@epicure/db";
import { db, recipes } from "@epicure/db";
import { requireSessionOrApiKey } from "@/lib/api-auth";
import { applyRateLimit } from "@/lib/rate-limit";
import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
import { suggestPairings } from "@/lib/ai/features/suggest-pairings";
import { withUserKey } from "@/lib/ai/resolve-user-key";
import { getUserPrivateBio } from "@/lib/ai/user-bio";
import { requireFeatureEnabled, FeatureDisabledError } from "@/lib/feature-flags";

const Schema = z.object({
  count: z.number().int().min(1).max(6).default(4),
  provider: z.enum(["openai", "anthropic", "openrouter", "ollama"]).optional(),
  model: z.string().optional(),
});

type Params = { params: Promise<{ id: string }> };

export async function POST(req: NextRequest, { params }: Params) {
  const { session, response } = await requireSessionOrApiKey(req);
  if (response) return response;

  const limited = await applyRateLimit(`rl:ai:${session!.user.id}`, 10, 60);
  if (limited) return limited;

  try {
    await requireFeatureEnabled(session!.user.id, "meal_pairing");
  } catch (err) {
    if (err instanceof FeatureDisabledError) {
      return NextResponse.json(
        { error: "This feature isn't available on your plan", code: "FEATURE_DISABLED", featureKey: err.featureKey },
        { status: 403 }
      );
    }
    throw err;
  }

  const { id } = await params;

  // Allow pairings for own recipes or public recipes
  const recipe = await db.query.recipes.findFirst({
    where: and(eq(recipes.id, id)),
    with: { ingredients: true },
  });
  if (!recipe || (recipe.visibility === "private" && recipe.authorId !== session!.user.id)) {
    return NextResponse.json({ error: "Not found" }, { status: 404 });
  }

  const body = await req.json() as unknown;
  const parsed = Schema.safeParse(body ?? {});
  if (!parsed.success) return NextResponse.json({ error: "Validation error" }, { status: 400 });

  const [configResult, privateBio] = await Promise.all([
    resolveAiConfigOrError(() =>
      withUserKey(session!.user.id, { provider: parsed.data.provider, model: parsed.data.model })
    ),
    getUserPrivateBio(session!.user.id),
  ]);
  if (!configResult.ok) return configResult.response;
  const aiConfig = configResult.data;

  const result = await withAiQuota(session!.user.id, session!.user.tier as "free" | "pro" | "family", () =>
    suggestPairings(
      {
        title: recipe.title,
        description: recipe.description,
        difficulty: recipe.difficulty,
        dietaryTags: recipe.dietaryTags as Record<string, boolean> | null,
        ingredients: recipe.ingredients,
      },
      parsed.data.count,
      { ...aiConfig, userContext: privateBio ?? undefined },
      (session!.user as { locale?: string }).locale ?? "en"
    ), { skipQuota: aiConfig.isByok }
  );
  if (!result.ok) return result.response;

  return NextResponse.json({ pairings: result.data });
}
