Add TimeToLeave feature checklist and plan (50)

Add TimeToLeave feature checklist and plan

apps/web/src/hooks/useDepartureTime.ts

@@ -0,0 +1,78 @@
+"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]);
+}