"use client";

import { useMemo } from "react";
import type { Journey } from "@timetoleave/core";
import { useReminderSettings } from "@/hooks/useReminderSettings";

interface DepartureTimeResult {
  departureTime: Date | null;
  arrivalTime: Date | null;
  mode: "train" | "bike" | null;
}

export function useDepartureTime(
  eventTime: Date,
  journeys: Journey[] | null,
  bikeRoute: number | null, // duration in seconds
  activeMode: "train" | "bike" | null
): DepartureTimeResult {
  const { arrivalBufferMinutes } = useReminderSettings();

  return useMemo(() => {
    // Calculate target arrival time (event time minus buffer)
    const targetArrivalTime = new Date(eventTime);
    targetArrivalTime.setMinutes(targetArrivalTime.getMinutes() - arrivalBufferMinutes);

    // Filter out cancelled journeys
    const validJourneys = journeys?.filter(journey => !journey.cancelled) || [];

    let departureTime: Date | null = null;
    let arrivalTime: Date | null = null;
    let mode: "train" | "bike" | null = null;

    // Handle train mode
    if (activeMode === "train" && validJourneys.length > 0) {
      // Find journeys that arrive before or at the target arrival time
      const onTimeJourneys = validJourneys.filter(journey =>
        journey.sA.getTime() <= targetArrivalTime.getTime()
      );

      if (onTimeJourneys.length > 0) {
        // Pick the journey with the latest departure time
        const bestJourney = onTimeJourneys.reduce((latest, current) =>
          current.sD.getTime() > latest.sD.getTime() ? current : latest
        );

        departureTime = new Date(bestJourney.sD);
        arrivalTime = new Date(bestJourney.sA);
        mode = "train";
      }
    }

    // Handle bike mode
    if (activeMode === "bike" && bikeRoute !== null && bikeRoute > 0) {
      // Convert bike route duration from seconds to milliseconds
      const bikeDurationMs = bikeRoute * 1000;

      // Calculate arrival time by subtracting bike duration from event time
      const calculatedArrivalTime = new Date(eventTime);
      calculatedArrivalTime.setTime(calculatedArrivalTime.getTime() - bikeDurationMs);

      // Calculate departure time by subtracting bike duration from calculated arrival time
      const calculatedDepartureTime = new Date(calculatedArrivalTime);
      calculatedDepartureTime.setTime(calculatedArrivalTime.getTime() - bikeDurationMs);

      // Calculate how much earlier we need to account for arrival buffer
      const totalBufferMs = arrivalBufferMinutes * 60 * 1000;
      const totalTravelTimeMs = bikeDurationMs * 2 + totalBufferMs;

      departureTime = new Date(eventTime);
      departureTime.setTime(eventTime.getTime() - totalTravelTimeMs);

      arrivalTime = new Date(calculatedArrivalTime);
      mode = "bike";
    }

    return { departureTime, arrivalTime, mode };
  }, [eventTime, journeys, bikeRoute, activeMode, arrivalBufferMinutes]);
}