import { useCallback, useMemo, useState } from "react";

/* ================= TYPES ================= */

export interface FileItem {
  id: string;
  file: File;
  path: string;
  progress: number;
  status: "idle" | "uploading" | "done" | "error";
  url?: string;
  error?: string;
}

/* ================= HOOK ================= */

export function useFileUpload() {
  const [files, setFiles] = useState<FileItem[]>([]);
  const [isUploading, setIsUploading] = useState(false);

  /* ---------- ADD FILES ---------- */
  const addFiles = useCallback((input: FileList | File[]) => {
    const list = Array.from(input).map<FileItem>((file) => ({
      id: crypto.randomUUID(),
      file,
      path: file.name, // mặc định
      progress: 0,
      status: "idle",
    }));

    setFiles((prev) => [...prev, ...list]);
  }, []);

  /* ---------- REMOVE FILE ---------- */
  const removeFile = useCallback((id: string) => {
    setFiles((prev) => prev.filter((f) => f.id !== id));
  }, []);

  /* ---------- UPDATE PATH ---------- */
  const updateFilePath = useCallback((id: string, path: string) => {
    setFiles((prev) =>
      prev.map((f) =>
        f.id === id ? { ...f, path } : f
      )
    );
  }, []);

  /* ---------- UPLOAD SINGLE ---------- */
  const uploadOne = useCallback(async (item: FileItem) => {
    const form = new FormData();
    form.append("file", item.file);
    form.append("path", item.path);

    return new Promise<void>((resolve, reject) => {
      const xhr = new XMLHttpRequest();
      xhr.open("POST", "/api/upload");

      xhr.upload.onprogress = (e) => {
        if (!e.lengthComputable) return;
        const percent = Math.round((e.loaded / e.total) * 100);

        setFiles((prev) =>
          prev.map((f) =>
            f.id === item.id
              ? { ...f, progress: percent, status: "uploading" }
              : f
          )
        );
      };

      xhr.onload = () => {
        if (xhr.status >= 200 && xhr.status < 300) {
          const res = JSON.parse(xhr.responseText);
          setFiles((prev) =>
            prev.map((f) =>
              f.id === item.id
                ? {
                    ...f,
                    progress: 100,
                    status: "done",
                    url: res.url,
                  }
                : f
            )
          );
          resolve();
        } else {
          reject(new Error("Upload failed"));
        }
      };

      xhr.onerror = () => reject(new Error("Network error"));
      xhr.send(form);
    });
  }, []);

  /* ---------- START UPLOAD (App.tsx dùng) ---------- */
  const startUpload = useCallback(async () => {
    if (isUploading) return;
    setIsUploading(true);

    try {
      for (const f of files) {
        if (f.status === "idle") {
          await uploadOne(f);
        }
      }
    } finally {
      setIsUploading(false);
    }
  }, [files, uploadOne, isUploading]);

  /* ---------- RETURN (KHỚP App.tsx) ---------- */
  return {
    files,            // ✅ App.tsx dùng
    isUploading,      // ✅ App.tsx dùng
    addFiles,
    removeFile,       // ✅ App.tsx dùng
    updateFilePath,   // ✅ App.tsx dùng
    startUpload,      // ✅ App.tsx dùng
  };
}