/**
 * Device location state store.
 *
 * Tracks the user's current GPS location and its human-readable address.
 * Updated periodically by a foreground location service.
 */
import { create } from 'zustand';
import { immer } from 'zustand/middleware/immer';

// ─── State Shape ─────────────────────────────────────────────────────────────

interface LocationState {
  /** Current GPS coordinates (null when location is unavailable) */
  currentLocation: { lat: number; lng: number } | null;
  /** Reverse-geocoded address string for the current location */
  locationAddress: string | null;
  /** Most recent location error, if any */
  locationError: string | null;
  /** Whether location services are currently tracking */
  isTracking: boolean;
}

// ─── Actions ─────────────────────────────────────────────────────────────────

interface LocationActions {
  /** Update the current GPS coordinates */
  setLocation: (lat: number, lng: number) => void;
  /** Update the reverse-geocoded address */
  setAddress: (address: string | null) => void;
  /** Set a location error */
  setError: (error: string | null) => void;
  /** Clear all location state (e.g., on logout) */
  clearLocation: () => void;
  /** Toggle the tracking flag */
  setTracking: (value: boolean) => void;
}

// ─── Store ───────────────────────────────────────────────────────────────────

export const useLocationStore = create<LocationState & LocationActions>()(
  immer((set) => ({
    // Initial state
    currentLocation: null,
    locationAddress: null,
    locationError: null,
    isTracking: false,

    // Actions
    setLocation: (lat, lng) =>
      set((state) => {
        state.currentLocation = { lat, lng };
        state.locationError = null;
      }),

    setAddress: (address) =>
      set((state) => {
        state.locationAddress = address;
      }),

    setError: (error) =>
      set((state) => {
        state.locationError = error;
      }),

    clearLocation: () =>
      set((state) => {
        state.currentLocation = null;
        state.locationAddress = null;
        state.locationError = null;
        state.isTracking = false;
      }),

    setTracking: (value) =>
      set((state) => {
        state.isTracking = value;
      }),
  })),
);

// ─── Selectors ───────────────────────────────────────────────────────────────

export const selectHasLocation = (state: LocationState) =>
  state.currentLocation !== null;

export const selectFormattedLocation = (state: LocationState) => {
  if (!state.currentLocation) return null;
  const { lat, lng } = state.currentLocation;
  return {
    lat,
    lng,
    address: state.locationAddress ?? `${lat.toFixed(6)}, ${lng.toFixed(6)}`,
  };
};