import { askAI } from "./openrouter";
import { useRuntimeConfig } from "#imports";

type UploadType = "slides" | "past_paper" | "lab_worksheet";

const PAST_PAPER_RE = /exam|past[\s_-]?paper|specimen|mock|resit|20(1[9]|2[0-6])/i;
const LAB_RE = /lab|worksheet|practical|experiment|\bprac\b/i;
const SLIDES_RE = /lecture|slides|\blec\b|week\d|topic\d|chapter/i;

export async function detectUploadType(filename: string, extractedText: string): Promise<UploadType> {
  const name = filename.toLowerCase();

  // layer 1 — filename heuristics
  if (PAST_PAPER_RE.test(name)) return "past_paper";
  if (LAB_RE.test(name)) return "lab_worksheet";
  if (SLIDES_RE.test(name)) return "slides";

  // layer 2 — AI classification
  const opening = extractedText.slice(0, 1500);

  const prompt = `You are classifying a university document. Based on the filename and the opening text, classify it as exactly one of: past_paper, lab_worksheet, or slides.

past_paper: an exam or test with questions students must answer under exam conditions
lab_worksheet: a practical worksheet with experiments, procedures, or guided tasks
slides: lecture slides or course notes presenting theory and concepts

Filename: ${filename}
Opening text: ${opening}

Respond with only one of: past_paper, lab_worksheet, slides`;

  try {
    const config = useRuntimeConfig();
    const classificationModel = (config as any).openrouterClassificationModel ?? "anthropic/claude-haiku-4-5";

    const { text } = await askAI(
      [{ role: "user", content: prompt }],
      { model: classificationModel, temperature: 0 }
    );

    const result = text.trim().toLowerCase() as UploadType;
    if (result === "past_paper" || result === "lab_worksheet" || result === "slides") {
      return result;
    }
  } catch {
    // fall through to default
  }

  return "slides";
}