import { fetchAllLocations } from '@/app/lib/actions/locationActions';
import { fetchAvailableYears } from '@/app/lib/actions/monthActions';
import { getUserSettings } from '@/app/lib/actions/userSettingsActions';
import { BillingLocation, YearMonth } from '@/app/lib/db-types';
import { FC, useEffect } from 'react';
import { MonthLocationList } from '@/app/ui/MonthLocationList';
import { redirect } from 'next/navigation';

export interface HomePageProps {
  searchParams?: {
    year?: string;
    month?: string;
  };
}

const ParamsYearInvalidMessage:FC<{ firstAvailableYear?: number }> = ({ firstAvailableYear }) => {

  // Redirect to the first available year after showing the message
  useEffect(() => {
    if(firstAvailableYear) {
      redirect(`/?year=${firstAvailableYear}`);
    } else {
      redirect(`/`);
    }
  });

  return(
    <main className="flex min-h-screen flex-col p-6 bg-base-300">
      <p className="text-center text-2xl text-red-500">The year specified in the URL is invalid ... redirecting</p>
    </main>
    );
};

export const HomePage:FC<HomePageProps> = async ({ searchParams }) => {

  /** years found in the DB sorted descending */
  let availableYears: number[];

  try {
    availableYears = await fetchAvailableYears();
  } catch (error:any) {
    return (
      <main className="flex min-h-screen flex-col p-6 bg-base-300">
        <p className="text-center text-2xl text-red-500">{error.message}</p>
      </main>);
  }

  const paramsYear = searchParams?.year ? Number(searchParams.year) : null;
  let selectedYear:number;

  // IF year is set via params, check if it's valid
  if(paramsYear) {

    // IF the database is in it's initial state
    //  THEN show message param being invalid AND redirect to root page
    if(availableYears.length === 0) {
      return (<ParamsYearInvalidMessage />);
    }

    // IF the year specified in the params is not found in the DB
    //  THEN show message param being invalid AND redirect to page showing first available year
    if(!availableYears.includes(paramsYear))  {
      return (<ParamsYearInvalidMessage firstAvailableYear={availableYears[0]} />);
    }

    selectedYear = paramsYear;
  } else {
    const currYear = new Date().getFullYear();

    // IF current year is available in DB THEN use it
    // ELSE use the latest year found in the DB
    selectedYear = availableYears.includes(currYear) ? currYear : availableYears[0];
  }

  const locations = await fetchAllLocations(selectedYear);
  const userSettings = await getUserSettings();

  // group locations by month
  const months = locations.reduce((acc, location) => {
    const {year, month} =  location.yearMonth;
    const key = `${year}-${month}`;

    const locationsInMonth = acc[key];

    if(locationsInMonth) {
      return({
        ...acc,
        [key]: {
          yearMonth: location.yearMonth,
          locations: [...locationsInMonth.locations, location],
          unpaidTotal: locationsInMonth.unpaidTotal + location.bills.reduce((acc, bill) => !bill.paid ? acc + (bill.payedAmount ?? 0) : acc, 0),
          payedTotal: locationsInMonth.payedTotal + location.bills.reduce((acc, bill) => bill.paid ? acc + (bill.payedAmount ?? 0) : acc, 0)
        }
      })
    }

    return({
      ...acc,
      [key]: {
        yearMonth: location.yearMonth,
        locations: [location],
        unpaidTotal: location.bills.reduce((acc, bill) => !bill.paid ? acc + (bill.payedAmount ?? 0) : acc, 0),
        payedTotal: location.bills.reduce((acc, bill) => bill.paid ? acc + (bill.payedAmount ?? 0) : acc, 0)
      }
    });
  }, {} as {[key:string]:{
    yearMonth: YearMonth,
    locations: BillingLocation[],
    unpaidTotal: number,
    payedTotal: number
  } });

 return (
    <MonthLocationList availableYears={availableYears} months={months} userSettings={userSettings} />
  );
}

export default HomePage;