import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { requireSessionOrApiKey } from "@/lib/api-auth";
import { applyRateLimit } from "@/lib/rate-limit";
import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
import { regenerateRecipe } from "@/lib/ai/features/regenerate-recipe";
import { withUserKey } from "@/lib/ai/resolve-user-key";

const Schema = z.object({
  title: z.string().min(1).max(200),
  description: z.string().max(2000).optional(),
  baseServings: z.number().int().min(1).max(100),
  difficulty: z.enum(["easy", "medium", "hard"]).optional(),
  ingredients: z.array(z.object({
    rawName: z.string().min(1).max(200),
    quantity: z.union([z.string(), z.number()]).optional(),
    unit: z.string().max(50).optional(),
  })).max(100),
  steps: z.array(z.object({ instruction: z.string().min(1).max(2000) })).max(100),
  instruction: z.string().min(1).max(500),
  language: z.string().max(10).default("en"),
  provider: z.enum(["openai", "anthropic", "openrouter", "ollama"]).optional(),
  model: z.string().optional(),
});

// No recipeId, no DB access — this is a stateless AI transform over whatever
// draft the editor currently holds (including unsaved edits), not the saved
// row. The caller merges the result into their own in-progress form state.
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 });
  }

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

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

  const { instruction, language, ...current } = parsed.data;

  const result = await withAiQuota(session!.user.id, session!.user.tier as "free" | "pro", () =>
    regenerateRecipe(current, instruction, { ...aiConfig, language }), { skipQuota: aiConfig.isByok }
  );
  if (!result.ok) return result.response;

  return NextResponse.json(result.data);
}