perfect-postcode/frontend/src/hooks/useHexagonSelection.test.ts

import { act, renderHook, waitFor } from '@testing-library/react';
import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';

import { useHexagonSelection } from './useHexagonSelection';
import type { FeatureMeta, HexagonStatsResponse, PostcodeGeometry } from '../types';

vi.mock('../lib/pocketbase', () => ({
  default: { authStore: { isValid: false, token: '' } },
}));

vi.mock('../lib/analytics', () => ({
  trackEvent: vi.fn(),
}));

const postcodeGeometry: PostcodeGeometry = {
  type: 'Polygon',
  coordinates: [
    [
      [-0.12, 51.5],
      [-0.11, 51.5],
      [-0.11, 51.51],
      [-0.12, 51.51],
      [-0.12, 51.5],
    ],
  ],
};

function stats(count: number): HexagonStatsResponse {
  return {
    count,
    numeric_features: [],
    enum_features: [],
    central_postcode: 'SW1A 1AA',
  };
}

function jsonResponse(body: unknown): Response {
  return new Response(JSON.stringify(body), {
    status: 200,
    headers: { 'Content-Type': 'application/json' },
  });
}

describe('useHexagonSelection', () => {
  const requests: string[] = [];
  const features: FeatureMeta[] = [{ name: 'Price', type: 'numeric', min: 0, max: 100 }];

  beforeEach(() => {
    requests.length = 0;
    vi.stubGlobal(
      'fetch',
      vi.fn((input: string | URL | Request) => {
        const url = new URL(String(input), 'http://localhost');
        requests.push(`${url.pathname}${url.search}`);

        if (url.pathname === '/api/postcode-stats') {
          const emptyPostcode = url.searchParams.get('postcode') === 'EMPTY 1AA';
          return Promise.resolve(
            jsonResponse(stats(url.searchParams.has('filters') || emptyPostcode ? 0 : 4))
          );
        }

        if (url.pathname === '/api/hexagon-stats') {
          return Promise.resolve(jsonResponse(stats(12)));
        }

        return Promise.resolve(new Response(null, { status: 404 }));
      })
    );
  });

  afterEach(() => {
    vi.unstubAllGlobals();
  });

  it('keeps a postcode search selected when filters exclude its properties', async () => {
    const { result } = renderHook(() =>
      useHexagonSelection({
        filters: { Price: [0, 50] },
        features,
        hexagonData: [],
        resolution: 9,
        usePostcodeView: true,
        travelTimeEntries: [],
      })
    );

    act(() => {
      result.current.handleLocationSearch('SW1A 1AA', postcodeGeometry, 51.505, -0.115);
    });

    await waitFor(() => {
      expect(result.current.selectedHexagon).toEqual({
        id: 'SW1A 1AA',
        type: 'postcode',
        resolution: 9,
        lockedResolution: true,
      });
    });

    expect(result.current.selectedPostcodeGeometry).toBe(postcodeGeometry);
    await waitFor(() => {
      expect(result.current.areaStats?.count).toBe(0);
      expect(result.current.unfilteredAreaCount).toBe(4);
    });
    expect(requests.some((url) => url.startsWith('/api/hexagon-stats'))).toBe(false);
  });

  it('keeps a postcode search selected when stats are based on all properties', async () => {
    const { result } = renderHook(() =>
      useHexagonSelection({
        filters: { Price: [0, 50] },
        features,
        hexagonData: [],
        resolution: 9,
        usePostcodeView: true,
        travelTimeEntries: [],
      })
    );

    act(() => {
      result.current.setAreaStatsUseFilters(false);
    });
    act(() => {
      result.current.handleLocationSearch('SW1A 1AA', postcodeGeometry, 51.505, -0.115);
    });

    await waitFor(() => {
      expect(result.current.selectedHexagon).toEqual({
        id: 'SW1A 1AA',
        type: 'postcode',
        resolution: 9,
        lockedResolution: true,
      });
    });

    expect(result.current.areaStats?.count).toBe(4);
    expect(result.current.unfilteredAreaCount).toBeNull();
    expect(requests.some((url) => url.startsWith('/api/hexagon-stats'))).toBe(false);
  });

  it('keeps an empty postcode search selected instead of widening to hexagons', async () => {
    const { result } = renderHook(() =>
      useHexagonSelection({
        filters: {},
        features,
        hexagonData: [],
        resolution: 9,
        usePostcodeView: true,
        travelTimeEntries: [],
      })
    );

    act(() => {
      result.current.handleLocationSearch('EMPTY 1AA', postcodeGeometry, 51.505, -0.115);
    });

    await waitFor(() => {
      expect(result.current.areaStats?.count).toBe(0);
    });

    expect(result.current.selectedHexagon).toEqual({
      id: 'EMPTY 1AA',
      type: 'postcode',
      resolution: 9,
      lockedResolution: true,
    });
    expect(result.current.selectedPostcodeGeometry).toBe(postcodeGeometry);
    expect(requests.some((url) => url.startsWith('/api/hexagon-stats'))).toBe(false);
  });

  it('does not convert a searched postcode back to a hexagon while the map reaches postcode zoom', async () => {
    const { result } = renderHook(() =>
      useHexagonSelection({
        filters: {},
        features,
        hexagonData: [],
        resolution: 9,
        usePostcodeView: false,
        travelTimeEntries: [],
      })
    );

    act(() => {
      result.current.handleLocationSearch('SW1A 1AA', postcodeGeometry, 51.505, -0.115);
    });

    await waitFor(() => {
      expect(result.current.areaStats?.count).toBe(4);
    });

    expect(result.current.selectedHexagon).toEqual({
      id: 'SW1A 1AA',
      type: 'postcode',
      resolution: 9,
      lockedResolution: true,
    });
    expect(result.current.selectedPostcodeGeometry).toBe(postcodeGeometry);
    expect(requests.some((url) => url.startsWith('/api/postcode/'))).toBe(false);
    expect(requests.some((url) => url.startsWith('/api/hexagon-stats'))).toBe(false);
  });
});