import * as Linking from "expo-linking";
import { router } from "expo-router";
import { useEffect, useRef } from "react";
import { Alert, Platform } from "react-native";

import { useAccounts } from "@/contexts/AccountsContext";
import { useAppLock } from "@/contexts/AppLockContext";
import { DEFAULT_CLOCK_DESCRIPTION, resolveClockDescription, resolveEffectiveHourlyRate } from "@/lib/time-clock";
import { getLastTimeClockClientId } from "@/lib/time-clock-prefs";
import { parseShortcutUrl, type ParsedShortcut } from "@/lib/shortcuts";
import { api } from "@/lib/trpc";

/**
 * Handles deep links from the Shortcuts app, Siri, and Live Activities.
 * Mounted inside the authenticated app shell.
 */
export function ShortcutHandler() {
  const { activeAccountId } = useAccounts();
  const { isLocked } = useAppLock();
  const url = Linking.useURL();
  const utils = api.useUtils();
  const clientsQuery = api.clients.getAll.useQuery();
  const runningQuery = api.timeEntries.getRunning.useQuery();
  const processedRef = useRef<string | null>(null);
  const pendingRef = useRef<ParsedShortcut | null>(null);

  const clockIn = api.timeEntries.clockIn.useMutation();
  const clockOut = api.timeEntries.clockOut.useMutation();

  useEffect(() => {
    void Linking.getInitialURL().then((initialUrl) => {
      const parsed = parseShortcutUrl(initialUrl);
      if (parsed) pendingRef.current = parsed;
    });
  }, []);

  useEffect(() => {
    const parsed = parseShortcutUrl(url);
    if (parsed) pendingRef.current = parsed;
  }, [url]);

  useEffect(() => {
    if (isLocked || !activeAccountId || clientsQuery.isLoading || runningQuery.isLoading) return;

    const pending = pendingRef.current;
    if (!pending) return;

    const key = JSON.stringify(pending);
    if (processedRef.current === key) return;
    processedRef.current = key;
    pendingRef.current = null;

    void (async () => {
      if (pending.action === "open-timer") {
        router.push("/(app)/timer");
        return;
      }

      if (pending.action === "clock-out") {
        if (!runningQuery.data) {
          router.push("/(app)/timer");
          if (Platform.OS === "ios") {
            Alert.alert("No timer running", "There is nothing to clock out.");
          }
          return;
        }

        try {
          await clockOut.mutateAsync({});
          await Promise.all([
            utils.timeEntries.getRunning.invalidate(),
            utils.timeEntries.getAll.invalidate(),
            utils.invoices.getAll.invalidate(),
            utils.dashboard.getStats.invalidate(),
          ]);
          router.push("/(app)/timer");
        } catch (err) {
          Alert.alert(
            "Clock out failed",
            err instanceof Error ? err.message : "Could not stop the timer.",
          );
          router.push("/(app)/timer");
        }
        return;
      }

      if (pending.action === "clock-in") {
        if (runningQuery.data) {
          router.push("/(app)/timer");
          if (Platform.OS === "ios") {
            Alert.alert("Timer already running", "Stop the current timer before clocking in again.");
          }
          return;
        }

        const clientId =
          pending.clientId || (await getLastTimeClockClientId(activeAccountId)) || "";

        if (!clientId) {
          router.push("/(app)/timer");
          Alert.alert(
            "Choose a client",
            "Open the time clock and pick a client once — shortcuts will use it next time.",
          );
          return;
        }

        const client = (clientsQuery.data ?? []).find((entry) => entry.id === clientId);
        const rate = resolveEffectiveHourlyRate("", client?.defaultHourlyRate);

        try {
          await clockIn.mutateAsync({
            clientId,
            description: resolveClockDescription(pending.title || DEFAULT_CLOCK_DESCRIPTION),
            rate: rate ?? undefined,
          });
          await utils.timeEntries.getRunning.invalidate();
          router.push("/(app)/timer");
        } catch (err) {
          Alert.alert(
            "Clock in failed",
            err instanceof Error ? err.message : "Could not start the timer.",
          );
          router.push("/(app)/timer");
        }
      }
    })();
  }, [
    activeAccountId,
    clockIn,
    clockOut,
    clientsQuery.data,
    clientsQuery.isLoading,
    isLocked,
    runningQuery.data,
    runningQuery.isLoading,
    utils,
  ]);

  return null;
}