Epicure/apps/web/app/api/v1/ai/substitute/route.ts

import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { requireSession } from "@/lib/api-auth";
import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
import { applyRateLimit } from "@/lib/rate-limit";
import { getDefaultProviderWithKey } from "@/lib/ai/resolve-user-key";
import { substituteIngredient } from "@/lib/ai/features/substitute-ingredient";

const Schema = z.object({
  ingredient: z.string().min(1).max(200),
  recipeTitle: z.string().max(200).optional(),
  provider: z.enum(["openai", "anthropic", "openrouter", "ollama"]).optional(),
  model: z.string().optional(),
});

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

  const context = parsed.data.recipeTitle
    ? `recipe "${parsed.data.recipeTitle}"`
    : "a general recipe";

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

  const locale = (session!.user as { locale?: string }).locale ?? "en";

  const result = await withAiQuota(session!.user.id, session!.user.tier as "free" | "pro", () =>
    substituteIngredient(parsed.data.ingredient, context, aiConfig, locale)
  );
  if (!result.ok) return result.response;

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