import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { generateText } from "ai";
import { requireSession } from "@/lib/api-auth";
import { applyRateLimit } from "@/lib/rate-limit";
import { getModelConfigForUseCase } from "@/lib/ai/resolve-user-key";
import { resolveModel } from "@/lib/ai/factory";
import { db, recipes, eq, and } from "@epicure/db";
import { getUserPrivateBio, buildUserBioContext } from "@/lib/ai/user-bio";

const Schema = z.object({
  recipeId: z.string().uuid(),
  question: z.string().min(1).max(500),
});

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

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

  const limited = await applyRateLimit(`rl:ai:${session!.user.id}`, 30, 60);
  if (limited) return limited;

  const recipe = await db.query.recipes.findFirst({
    where: and(eq(recipes.id, parsed.data.recipeId), eq(recipes.authorId, session!.user.id)),
    with: {
      ingredients: { orderBy: (t, { asc }) => asc(t.order) },
      steps: { orderBy: (t, { asc }) => asc(t.order) },
    },
  });

  if (!recipe) {
    return NextResponse.json({ error: "Recipe not found" }, { status: 404 });
  }

  const ingredientList = recipe.ingredients
    .map((ing) => [ing.quantity, ing.unit, ing.rawName, ing.note ? `(${ing.note})` : ""].filter(Boolean).join(" "))
    .join("\n");

  const stepList = recipe.steps
    .map((s, i) => `${i + 1}. ${s.instruction}`)
    .join("\n");

  const recipeContext = `
Recipe: ${recipe.title}
${recipe.description ? `Description: ${recipe.description}` : ""}
Difficulty: ${recipe.difficulty ?? "unknown"}
Prep: ${recipe.prepMins ?? 0}min | Cook: ${recipe.cookMins ?? 0}min | Servings: ${recipe.baseServings}

INGREDIENTS:
${ingredientList || "None listed"}

STEPS:
${stepList || "None listed"}
`.trim();

  const [config, privateBio] = await Promise.all([
    getModelConfigForUseCase(session!.user.id, "text"),
    getUserPrivateBio(session!.user.id),
  ]);
  const model = resolveModel(config);
  const bioContext = buildUserBioContext(privateBio);

  const { text } = await generateText({
    model,
    system: `You are a helpful culinary assistant. Answer questions about the following recipe concisely and accurately. If a question is not related to the recipe or cooking, politely redirect. Keep answers under 200 words.

${recipeContext}${bioContext}`,
    prompt: parsed.data.question,
  });

  return NextResponse.json({ answer: text });
}