import {
  createContext,
  ReactNode,
  useContext,
  useMemo,
  useState,
} from "react";

export interface BirthdayEntry {
  id: string;
  name: string;
  date: string;
}

interface AddBirthdayInput {
  name: string;
  date: string;
}

interface BirthdaysContextValue {
  birthdays: BirthdayEntry[];
  addBirthday: (input: AddBirthdayInput) => void;
}

const BirthdaysContext = createContext<BirthdaysContextValue | undefined>(
  undefined
);

export function BirthdaysProvider({ children }: { children: ReactNode }) {
  const [birthdays, setBirthdays] = useState<BirthdayEntry[]>([]);

  const value = useMemo(
    () => ({
      birthdays,
      addBirthday: ({ name, date }: AddBirthdayInput) => {
        const trimmedName = name.trim();

        if (!trimmedName) {
          return;
        }

        setBirthdays((currentBirthdays) => [
          ...currentBirthdays,
          {
            id: `${Date.now()}-${Math.random().toString(36).slice(2, 8)}`,
            name: trimmedName,
            date,
          },
        ]);
      },
    }),
    [birthdays]
  );

  return (
    <BirthdaysContext.Provider value={value}>
      {children}
    </BirthdaysContext.Provider>
  );
}

export function useBirthdays() {
  const context = useContext(BirthdaysContext);

  if (!context) {
    throw new Error("useBirthdays must be used within a BirthdaysProvider");
  }

  return context;
}