import { useState, useEffect } from "preact/hooks";
import type { Trip, Day, DayStop } from "./types";

export interface TripTimeState {
  now: Date;
  todayIdx: number;
  currentStopIdx: number;
  nextStopIdx: number;
  today: Day | null;
  currentStop: DayStop | null;
  nextStop: DayStop | null;
  tripStarted: boolean;
  tripEnded: boolean;
}

function parseTime(timeStr: string, dateStr: string): Date | null {
  const m = timeStr.replace(/^~\s*/, "").match(/^(\d{1,2}):(\d{2})\s*(AM|PM)$/i);
  if (!m) return null;
  let hours = parseInt(m[1]);
  const mins = parseInt(m[2]);
  const ampm = m[3].toUpperCase();
  if (ampm === "PM" && hours !== 12) hours += 12;
  if (ampm === "AM" && hours === 12) hours = 0;
  const d = new Date(dateStr + "T00:00:00");
  d.setHours(hours, mins, 0, 0);
  return d;
}

function parseTimeRange(str: string, dateStr: string): { start: Date; end: Date } | null {
  const parts = str.match(/^(\d{1,2}:\d{2}\s*(?:AM|PM))\s*[-–]\s*(\d{1,2}:\d{2}\s*(?:AM|PM))$/i);
  if (parts) {
    const start = parseTime(parts[1].trim(), dateStr);
    const end = parseTime(parts[2].trim(), dateStr);
    if (start && end) return { start, end };
  }
  return null;
}

export function useTripTime(trip: Trip): TripTimeState {
  const [now, setNow] = useState(new Date());

  useEffect(() => {
    const id = setInterval(() => setNow(new Date()), 30000);
    return () => clearInterval(id);
  }, []);

  const todayStr = now.toLocaleDateString("en-CA");

  const todayIdx = trip.days.findIndex(d => d.date === todayStr);
  const today = todayIdx >= 0 ? trip.days[todayIdx] : null;

  const firstDate = trip.meta.dates[0];
  const lastDate = trip.meta.dates[trip.meta.dates.length - 1];
  const tripStarted = todayStr >= firstDate;
  const tripEnded = todayStr > lastDate;

  let currentStopIdx = -1;
  let nextStopIdx = -1;

  if (today) {
    for (let i = today.stops.length - 1; i >= 0; i--) {
      const stop = today.stops[i];
      const timeRef = stop.arrival || stop.departure;
      if (!timeRef) continue;

      const range = parseTimeRange(timeRef, today.date);
      if (range) {
        if (now >= range.start && now <= range.end) {
          currentStopIdx = i;
          nextStopIdx = i + 1 < today.stops.length ? i + 1 : -1;
          break;
        }
        if (now > range.end) {
          nextStopIdx = i + 1 < today.stops.length ? i + 1 : -1;
          break;
        }
        continue;
      }

      const t = parseTime(timeRef, today.date);
      if (t && now >= t) {
        currentStopIdx = i;
        nextStopIdx = i + 1 < today.stops.length ? i + 1 : -1;
        break;
      }
    }

    if (currentStopIdx === -1 && nextStopIdx === -1 && today.stops.length > 0) {
      for (let i = 0; i < today.stops.length; i++) {
        const ref = today.stops[i].arrival || today.stops[i].departure;
        if (!ref) continue;
        const range = parseTimeRange(ref, today.date);
        const t = range ? range.start : parseTime(ref, today.date);
        if (t && now < t) {
          nextStopIdx = i;
        }
        break;
      }
    }
  }

  return {
    now,
    todayIdx,
    currentStopIdx,
    nextStopIdx,
    today,
    currentStop: today && currentStopIdx >= 0 ? today.stops[currentStopIdx] : null,
    nextStop: today && nextStopIdx >= 0 ? today.stops[nextStopIdx] : null,
    tripStarted,
    tripEnded,
  };
}