import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { db, recipes, recipeIngredients, recipeSteps, recipeBatchDishes } from "@epicure/db";
import { requireSessionOrApiKey } from "@/lib/api-auth";
import { applyRateLimit } from "@/lib/rate-limit";
import { getDefaultProviderWithKey } from "@/lib/ai/resolve-user-key";
import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
import { generateBatchCook } from "@/lib/ai/features/generate-batch-cook";
import { getUserPrivateBio } from "@/lib/ai/user-bio";
import { parseQuantity } from "@/lib/parse-quantity";
import { checkTierLimitInTransaction, TierLimitError } from "@/lib/tiers";

const Schema = z.object({
  dinners: z.number().int().min(0).max(6).default(4),
  lunches: z.number().int().min(0).max(6).default(0),
  servings: z.number().int().min(1).max(12).default(4),
  dietaryPrefs: z.string().max(200).optional(),
  difficulty: z.enum(["easy", "medium", "hard"]).optional(),
  description: z.string().max(500).optional(),
});

export async function POST(req: NextRequest) {
  const { session, response } = await requireSessionOrApiKey(req);
  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", issues: parsed.error.issues }, { status: 400 });
  }
  if (parsed.data.dinners + parsed.data.lunches < 1) {
    return NextResponse.json({ error: "Choose at least one dinner or lunch" }, { status: 400 });
  }

  const limited = await applyRateLimit(`rl:ai:${session!.user.id}`, 3, 60);
  if (limited) return limited;

  const userId = session!.user.id;
  const locale = (session!.user as { locale?: string }).locale ?? "en";
  const [configResult, privateBio] = await Promise.all([
    resolveAiConfigOrError(() => getDefaultProviderWithKey(userId, "text")),
    getUserPrivateBio(userId),
  ]);
  if (!configResult.ok) return configResult.response;
  const config = configResult.data;

  const result = await withAiQuota(userId, session!.user.tier as "free" | "pro" | "family", () =>
    generateBatchCook(
      {
        dinners: parsed.data.dinners,
        lunches: parsed.data.lunches,
        servings: parsed.data.servings,
        dietaryPrefs: parsed.data.dietaryPrefs,
        difficulty: parsed.data.difficulty,
        description: parsed.data.description,
      },
      { ...config, userContext: privateBio ?? undefined },
      locale
    ), { skipQuota: config.isByok }
  );
  if (!result.ok) return result.response;
  const plan = result.data;

  const recipeId = crypto.randomUUID();

  try {
    await db.transaction(async (tx) => {
    await checkTierLimitInTransaction(tx, userId, session!.user.tier as "free" | "pro" | "family", "recipe");
    await tx.insert(recipes).values({
      id: recipeId,
      authorId: userId,
      title: plan.title,
      description: plan.description,
      baseServings: parsed.data.servings,
      visibility: "private",
      aiGenerated: true,
      isBatchCook: true,
      language: locale,
      prepMins: plan.prepMins,
      cookMins: plan.cookMins,
    });

    if (plan.ingredients.length > 0) {
      await tx.insert(recipeIngredients).values(
        plan.ingredients.map((ing, i) => ({
          id: crypto.randomUUID(),
          recipeId,
          rawName: ing.rawName,
          quantity: parseQuantity(ing.quantity) ?? null,
          unit: ing.unit ?? null,
          order: i,
        }))
      );
    }

    if (plan.steps.length > 0) {
      await tx.insert(recipeSteps).values(
        plan.steps.map((step, i) => ({
          id: crypto.randomUUID(),
          recipeId,
          instruction: step.instruction,
          order: i,
          appliesTo: step.appliesTo,
        }))
      );
    }

    if (plan.dishes.length > 0) {
      await tx.insert(recipeBatchDishes).values(
        plan.dishes.map((dish, i) => ({
          id: crypto.randomUUID(),
          recipeId,
          name: dish.name,
          description: dish.description,
          order: i,
          fridgeDays: dish.fridgeDays,
          freezerFriendly: dish.freezerFriendly,
          freezerNote: dish.freezerNote ?? null,
          dayOfInstructions: dish.dayOfInstructions,
        }))
      );
    }
    });
  } catch (err) {
    if (err instanceof TierLimitError) {
      return NextResponse.json({ error: "Recipe limit reached for your tier" }, { status: 403 });
    }
    throw err;
  }

  return NextResponse.json({ id: recipeId });
}