import { useCallback } from "react";
import type { SyntheticEvent } from "react";
import { isValidEmail } from "../../utils/isValidEmail";
import type { User } from "./PeopleSearch";

export function usePasteHandler({
  freeSolo,
  selectedUsers,
  onChange,
  setQuery,
  setInputError,
  t,
}: {
  freeSolo?: boolean;
  selectedUsers: User[];
  onChange: (event: SyntheticEvent, users: User[]) => void;
  setQuery: (value: string) => void;
  setInputError: (error: string | null) => void;
  t: (key: string) => string;
}) {
  return useCallback(
    (event: React.ClipboardEvent<HTMLInputElement>) => {
      if (!freeSolo) return;

      const pasted = event.clipboardData.getData("text/plain");
      if (!pasted) return;

      // Split by comma, semicolon, newline, or whitespace
      const chunks = pasted
        .split(/[,;\n\r\s]+/)
        .map((s) => s.trim())
        .filter(Boolean);

      // If there is only one chunk, let the default Autocomplete behaviour handle it
      if (chunks.length <= 1) return;

      event.preventDefault();

      const existingEmails = new Set(selectedUsers.map((u) => u.email));
      const validUsers: User[] = [];
      const invalid: string[] = [];

      for (const chunk of chunks) {
        if (!isValidEmail(chunk)) {
          invalid.push(chunk);
        } else if (!existingEmails.has(chunk)) {
          existingEmails.add(chunk);
          validUsers.push({ email: chunk, displayName: chunk });
        }
        // silently skip duplicates
      }

      if (validUsers.length > 0) {
        onChange(event, [...selectedUsers, ...validUsers]);
      }

      if (invalid.length > 0) {
        // Leave the invalid text in the input for manual correction
        setQuery(invalid.join(", "));
        setInputError(
          t("peopleSearch.invalidEmail").replace("%{email}", invalid.join(", "))
        );
      } else {
        setQuery("");
        setInputError(null);
      }
    },
    [freeSolo, selectedUsers, onChange, setQuery, setInputError, t]
  );
}