import { useState, useCallback } from "react";

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

export interface UploadItem {
  id: string;
  file: File;
  progress: number; // 0 → 100
  status: "idle" | "uploading" | "done" | "error";
  url?: string;
  error?: string;
}

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

export function useFileUpload() {
  const [uploads, setUploads] = useState<UploadItem[]>([]);

  /* ---------- ADD FILE ---------- */
  const addFiles = useCallback((files: FileList | File[]) => {
    const list = Array.from(files).map((file) => ({
      id: crypto.randomUUID(),
      file,
      progress: 0,
      status: "idle" as const,
    }));

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

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

    setUploads((prev) =>
      prev.map((u) =>
        u.id === item.id
          ? { ...u, status: "uploading", progress: 0 }
          : u
      )
    );

    try {
      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);
        setUploads((prev) =>
          prev.map((u) =>
            u.id === item.id ? { ...u, progress: percent } : u
          )
        );
      };

      const result: any = await new Promise((resolve, reject) => {
        xhr.onload = () => {
          if (xhr.status >= 200 && xhr.status < 300) {
            resolve(JSON.parse(xhr.responseText));
          } else {
            reject(new Error("Upload failed"));
          }
        };
        xhr.onerror = () => reject(new Error("Network error"));
        xhr.send(form);
      });

      setUploads((prev) =>
        prev.map((u) =>
          u.id === item.id
            ? {
                ...u,
                status: "done",
                progress: 100,
                url: result.url,
              }
            : u
        )
      );
    } catch (err: any) {
      setUploads((prev) =>
        prev.map((u) =>
          u.id === item.id
            ? {
                ...u,
                status: "error",
                error: err.message || "Upload error",
              }
            : u
        )
      );
    }
  }, []);

  /* ---------- UPLOAD ALL ---------- */
  const uploadAll = useCallback(async () => {
    for (const item of uploads) {
      if (item.status === "idle") {
        await uploadFile(item);
      }
    }
  }, [uploads, uploadFile]);

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

  /* ---------- RESET ---------- */
  const reset = useCallback(() => {
    setUploads([]);
  }, []);

  return {
    uploads,
    addFiles,
    uploadFile,
    uploadAll,
    remove,
    reset,
  };
}