import { useState } from "react";
import { axiosInstance } from "../lib/api";

interface UseExportReturn {
  exportSnapshot: (format: "csv" | "xlsx") => Promise<void>;
  exportAuditTrail: (format: "csv" | "xlsx") => Promise<void>;
  isLoading: boolean;
  error: string | null;
}

/**
 * Custom hook for managing inventory export operations.
 * Handles API calls, file downloads, and error management.
 *
 * @returns Object with export functions and state
 */
export function useExport(): UseExportReturn {
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  /**
   * Extract filename from Content-Disposition header.
   * Handles both inline and attachment disposition.
   */
  const extractFilenameFromHeader = (contentDisposition: string): string => {
    const match = contentDisposition.match(/filename="?([^"]+)"?/);
    return match ? match[1] : `export_${Date.now()}`;
  };

  /**
   * Trigger file download from blob response.
   */
  const downloadFile = (blob: Blob, filename: string) => {
    const url = URL.createObjectURL(blob);
    const link = document.createElement("a");
    link.href = url;
    link.download = filename;
    document.body.appendChild(link);
    link.click();
    document.body.removeChild(link);
    URL.revokeObjectURL(url);
  };

  /**
   * Export inventory snapshot in specified format.
   */
  const exportSnapshot = async (format: "csv" | "xlsx"): Promise<void> => {
    setIsLoading(true);
    setError(null);

    try {
      const response = await axiosInstance.get(
        `/admin/reports/export?format=${format}&type=inventory`,
        {
          responseType: "blob"
        }
      );

      // Extract filename from response headers
      const contentDisposition = response.headers["content-disposition"] || "";
      const filename = contentDisposition
        ? extractFilenameFromHeader(contentDisposition)
        : `inventory_snapshot_${new Date().toISOString().split("T")[0]}.${format}`;

      // Trigger download
      downloadFile(response.data, filename);
    } catch (err) {
      const errorMessage =
        err instanceof Error ? err.message : "Failed to export inventory snapshot";
      setError(errorMessage);
      throw err;
    } finally {
      setIsLoading(false);
    }
  };

  /**
   * Export audit trail in specified format.
   */
  const exportAuditTrail = async (format: "csv" | "xlsx"): Promise<void> => {
    setIsLoading(true);
    setError(null);

    try {
      const response = await axiosInstance.get(
        `/admin/reports/export?format=${format}&type=audit`,
        {
          responseType: "blob"
        }
      );

      // Extract filename from response headers
      const contentDisposition = response.headers["content-disposition"] || "";
      const filename = contentDisposition
        ? extractFilenameFromHeader(contentDisposition)
        : `audit_trail_${new Date().toISOString().split("T")[0]}.${format}`;

      // Trigger download
      downloadFile(response.data, filename);
    } catch (err) {
      const errorMessage =
        err instanceof Error ? err.message : "Failed to export audit trail";
      setError(errorMessage);
      throw err;
    } finally {
      setIsLoading(false);
    }
  };

  return {
    exportSnapshot,
    exportAuditTrail,
    isLoading,
    error,
  };
}