frontend/src/hooks/useDocument.js

import { useState, useCallback } from "react";
import { uploadDocument, getChunks, MOCK_CHUNKS } from "../services/api";

export function useDocument() {
  const [document,       setDocument]       = useState(null);
  const [chunks,         setChunks]         = useState([]);
  const [uploading,      setUploading]      = useState(false);
  const [uploadProgress, setUploadProgress] = useState(0);
  const [loadingChunks,  setLoadingChunks]  = useState(false);
  const [error,          setError]          = useState(null);

  const upload = useCallback(async (fileOrFiles) => {
    const files = Array.isArray(fileOrFiles) ? fileOrFiles : [fileOrFiles];
    const validFiles = files.filter(Boolean);
    if (!validFiles.length) return;

    setUploading(true);
    setError(null);
    setUploadProgress(0);
    try {
      let lastUploaded = null;
      for (let index = 0; index < validFiles.length; index += 1) {
        const file = validFiles[index];
        const fd = new FormData();
        fd.append("file", file);
        const { data } = await uploadDocument(fd, (progress) => {
          const current = Math.max(0, Math.min(100, Number(progress) || 0));
          const overall = ((index + current / 100) / validFiles.length) * 100;
          setUploadProgress(Math.round(overall));
        });
        lastUploaded = data;
      }
      if (lastUploaded) {
        setDocument(lastUploaded);
      }
    } catch (err) {
      setError(err.response?.data?.detail || err.message || "Upload failed");
      console.error("Upload error:", err);
    } finally {
      setUploading(false);
    }
  }, []);

  const fetchChunks = useCallback(async (docId, configId) => {
  setLoadingChunks(true);
  setError(null);
  try {
    const { data } = await getChunks(docId, configId);
    const chunkData = data?.chunks || data;
    if (Array.isArray(chunkData) && chunkData.length > 0) {
      setChunks(chunkData);
    } else {
      setChunks(MOCK_CHUNKS);
    }
  } catch (e) {
    console.error("[Chunks] Error:", e);
    setChunks(MOCK_CHUNKS);
    setError(e.message);
  } finally {
    setLoadingChunks(false);
  }
}, []);

  const clearDocument = () => { setDocument(null); setChunks([]); };

  const selectDocument = useCallback((doc) => {
    setDocument(doc || null);
  }, []);

  return { document, chunks, uploading, uploadProgress, loadingChunks, error, upload, fetchChunks, clearDocument, selectDocument };
}