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 { getModelConfigForUseCase } from "@/lib/ai/resolve-user-key";
import { scanPantryPhoto } from "@/lib/ai/features/scan-pantry-photo";

const Schema = z.object({
  imageBase64: z.string().max(14_000_000),
  mimeType: z.enum(["image/jpeg", "image/png", "image/webp"]),
});

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 userId = session!.user.id;

  const limited = await applyRateLimit(`rl:ai:${userId}`, 10, 60);
  if (limited) return limited;

  const configResult = await resolveAiConfigOrError(() => getModelConfigForUseCase(userId, "vision"));
  if (!configResult.ok) return configResult.response;
  const aiConfig = configResult.data;

  // Fall back to vision-capable defaults if no explicit model configured
  if (!aiConfig.model) {
    if (aiConfig.provider === "openai") aiConfig.model = "gpt-4o";
    else if (aiConfig.provider === "anthropic") aiConfig.model = "claude-sonnet-4-6";
  }

  const result = await withAiQuota(userId, session!.user.tier as "free" | "pro", () =>
    scanPantryPhoto(parsed.data.imageBase64, parsed.data.mimeType, aiConfig)
  );
  if (!result.ok) return result.response;

  return NextResponse.json(result.data);
}