import assert from 'node:assert';
import { describe, it } from 'node:test';

import { Timetable } from '../../router.js';
import { Stop } from '../../stops/stops.js';
import { StopsIndex } from '../../stops/stopsIndex.js';
import { Route } from '../../timetable/route.js';
import { timeFromHMS, timeFromString } from '../../timetable/time.js';
import {
  RouteTypes,
  ServiceRoute,
  StopAdjacency,
  TransferTypes,
} from '../../timetable/timetable.js';
import { Query } from '../query.js';
import { Result } from '../result.js';
import { RoutingState, TransferEdge, VehicleEdge } from '../router.js';

const NB_STOPS = 7;

describe('Result', () => {
  const stop1: Stop = {
    id: 0,
    sourceStopId: 'stop1',
    name: 'Lausanne',
    lat: 0,
    lon: 0,
    children: [],
    parent: undefined,
    locationType: 'SIMPLE_STOP_OR_PLATFORM',
  };

  const stop2: Stop = {
    id: 1,
    sourceStopId: 'stop2',
    name: 'Fribourg',
    lat: 0,
    lon: 0,
    children: [],
    parent: undefined,
    locationType: 'SIMPLE_STOP_OR_PLATFORM',
  };

  const stop3: Stop = {
    id: 2,
    sourceStopId: 'stop3',
    name: 'Bern',
    lat: 0,
    lon: 0,
    children: [],
    parent: undefined,
    locationType: 'SIMPLE_STOP_OR_PLATFORM',
  };

  const stop4: Stop = {
    id: 3,
    sourceStopId: 'stop4',
    name: 'Olten',
    lat: 0,
    lon: 0,
    children: [],
    parent: undefined,
    locationType: 'SIMPLE_STOP_OR_PLATFORM',
  };

  const parentStop: Stop = {
    id: 4,
    sourceStopId: 'parent',
    name: 'Basel',
    lat: 0,
    lon: 0,
    children: [5, 6],
    parent: undefined,
    locationType: 'SIMPLE_STOP_OR_PLATFORM',
  };

  const childStop1: Stop = {
    id: 5,
    sourceStopId: 'child1',
    name: 'Basel Pl. 1',
    lat: 0,
    lon: 0,
    children: [],
    parent: 4,
    locationType: 'SIMPLE_STOP_OR_PLATFORM',
  };

  const childStop2: Stop = {
    id: 6,
    sourceStopId: 'child2',
    name: 'Basel Pl. 2',
    lat: 0,
    lon: 0,
    children: [],
    parent: 4,
    locationType: 'SIMPLE_STOP_OR_PLATFORM',
  };

  const stopsAdjacency: StopAdjacency[] = [
    { routes: [0] },
    { routes: [0] },
    { routes: [0, 1] },
    { routes: [1] },
    { routes: [1] },
    { routes: [1] },
    { routes: [1] },
  ];

  const routesAdjacency = [
    Route.of({
      id: 0,
      serviceRouteId: 0,
      trips: [
        {
          stops: [
            {
              id: 0,
              arrivalTime: timeFromString('08:00:00'),
              departureTime: timeFromString('08:05:00'),
            },
            {
              id: 1,
              arrivalTime: timeFromString('08:30:00'),
              departureTime: timeFromString('08:35:00'),
            },
            {
              id: 2,
              arrivalTime: timeFromString('09:00:00'),
              departureTime: timeFromString('09:05:00'),
            },
          ],
        },
      ],
    }),
    Route.of({
      id: 1,
      serviceRouteId: 1,
      trips: [
        {
          stops: [
            {
              id: 2,
              arrivalTime: timeFromString('09:10:00'),
              departureTime: timeFromString('09:15:00'),
            },
            {
              id: 3,
              arrivalTime: timeFromString('09:45:00'),
              departureTime: timeFromString('09:50:00'),
            },
            {
              id: 5,
              arrivalTime: timeFromString('10:10:00'),
              departureTime: timeFromString('10:15:00'),
            },
          ],
        },
      ],
    }),
  ];

  const routes: ServiceRoute[] = [
    { type: RouteTypes.RAIL, name: 'Line 1', routes: [0] },
    { type: RouteTypes.RAIL, name: 'Line 2', routes: [1] },
  ];

  const mockStopsIndex = new StopsIndex([
    stop1,
    stop2,
    stop3,
    stop4,
    parentStop,
    childStop1,
    childStop2,
  ]);
  const mockTimetable = new Timetable(stopsAdjacency, routesAdjacency, routes);

  const mockQuery = new Query.Builder()
    .from(0)
    .to(new Set([2, 3]))
    .departureTime(timeFromHMS(8, 0, 0))
    .build();

  describe('bestRoute', () => {
    it('should return undefined when no route exists', () => {
      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({ nbStops: NB_STOPS, destinations: [2, 3] }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRoute();
      assert.strictEqual(route, undefined);
    });

    it('should return undefined for unreachable destination', () => {
      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [2, 3],
          arrivals: [[1, timeFromHMS(8, 30, 0), 0]],
          graph: [[[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]]],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRoute(3); // stop 3 not in arrivals
      assert.strictEqual(route, undefined);
    });

    it('should return route to closest destination when multiple destinations exist', () => {
      const vehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 0, 0),
        stopIndex: 0,
        hopOffStopIndex: 2,
        routeId: 0,
        tripIndex: 0,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [2, 3],
          arrivals: [
            [0, timeFromHMS(8, 0, 0), 0],
            [2, timeFromHMS(9, 0, 0), 1],
            [3, timeFromHMS(9, 30, 0), 1],
          ],
          graph: [
            [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [[2, vehicleEdge]], // round 1
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRoute();
      assert(route);
      assert.strictEqual(route.legs.length, 1);
      const firstLeg = route.legs[0];
      assert(firstLeg);
      assert.strictEqual(firstLeg.from.id, 0);
      assert.strictEqual(firstLeg.to.id, 2);
    });

    it('should return route to fastest child stop when parent stop is queried', () => {
      const vehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(10, 10, 0),
        stopIndex: 0,
        hopOffStopIndex: 2,
        routeId: 1,
        tripIndex: 0,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [2],
          destinations: [4],
          arrivals: [
            [2, timeFromHMS(9, 10, 0), 1],
            [5, timeFromHMS(10, 10, 0), 2],
            [6, timeFromHMS(10, 30, 0), 2],
          ],
          graph: [
            [[2, { stopId: 2, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [
              [
                2,
                {
                  arrival: timeFromHMS(9, 10, 0),
                  stopIndex: 0,
                  hopOffStopIndex: 2,
                  routeId: 0,
                  tripIndex: 0,
                },
              ],
            ], // round 1
            [[5, vehicleEdge]], // round 2
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRoute(4);
      assert(route);
      assert.strictEqual(route.legs.length, 2);
      const lastLeg = route.legs[route.legs.length - 1];
      assert(lastLeg);
      assert.strictEqual(lastLeg.to.id, 5); // faster child
    });

    it('should handle simple single-leg route reconstruction', () => {
      const vehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 0, 0),
        stopIndex: 0,
        hopOffStopIndex: 2,
        routeId: 0,
        tripIndex: 0,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [2],
          arrivals: [
            [0, timeFromHMS(8, 0, 0), 0],
            [2, timeFromHMS(9, 0, 0), 1],
          ],
          graph: [
            [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [[2, vehicleEdge]], // round 1
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRoute(2);
      assert(route);
      assert.strictEqual(route.legs.length, 1);
      const firstLeg = route.legs[0];
      assert(firstLeg);
      assert.strictEqual(firstLeg.from.id, 0);
      assert.strictEqual(firstLeg.to.id, 2);
    });

    it('should handle multi-leg route with transfer', () => {
      const firstVehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 0, 0),
        stopIndex: 0,
        hopOffStopIndex: 2,
        routeId: 0,
        tripIndex: 0,
      };

      const secondVehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 45, 0),
        stopIndex: 0,
        hopOffStopIndex: 1,
        routeId: 1,
        tripIndex: 0,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [3],
          arrivals: [
            [0, timeFromHMS(8, 0, 0), 0],
            [2, timeFromHMS(9, 0, 0), 1],
            [3, timeFromHMS(9, 45, 0), 2],
          ],
          graph: [
            [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [[2, firstVehicleEdge]], // round 1
            [[3, secondVehicleEdge]], // round 2
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRoute(3);
      assert(route);
      assert.strictEqual(route.legs.length, 2);
      const firstLeg = route.legs[0];
      const secondLeg = route.legs[1];
      assert(firstLeg);
      assert(secondLeg);
      assert.strictEqual(firstLeg.from.id, 0);
      assert.strictEqual(firstLeg.to.id, 2);
      assert.strictEqual(secondLeg.from.id, 2);
      assert.strictEqual(secondLeg.to.id, 3);
    });
  });

  describe('bestRouteToStopId', () => {
    it('should return route when given a single SourceStopId', () => {
      const vehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 0, 0),
        stopIndex: 0,
        hopOffStopIndex: 2,
        routeId: 0,
        tripIndex: 0,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [2],
          arrivals: [
            [0, timeFromHMS(8, 0, 0), 0],
            [2, timeFromHMS(9, 0, 0), 1],
          ],
          graph: [
            [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [[2, vehicleEdge]], // round 1
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRouteToSourceStopId('stop3');
      assert(route);
      assert.strictEqual(route.legs.length, 1);
      const firstLeg = route.legs[0];
      assert(firstLeg);
      assert.strictEqual(firstLeg.from.id, 0);
      assert.strictEqual(firstLeg.to.id, 2);
    });

    it('should return route to closest destination when given a Set of SourceStopIds', () => {
      const vehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 0, 0),
        stopIndex: 0,
        hopOffStopIndex: 2,
        routeId: 0,
        tripIndex: 0,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [2, 3],
          arrivals: [
            [0, timeFromHMS(8, 0, 0), 0],
            [2, timeFromHMS(9, 0, 0), 1],
            [3, timeFromHMS(9, 45, 0), 1],
          ],
          graph: [
            [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [[2, vehicleEdge]], // round 1
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRouteToSourceStopId(new Set(['stop3', 'stop4']));
      assert(route);
      assert.strictEqual(route.legs.length, 1);
      const firstLeg = route.legs[0];
      assert(firstLeg);
      assert.strictEqual(firstLeg.from.id, 0);
      assert.strictEqual(firstLeg.to.id, 2); // stop 2 arrives faster
    });
  });

  describe('continuous trips', () => {
    it('should handle single continuous trip correctly', () => {
      const firstVehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(8, 30, 0),
        stopIndex: 0,
        hopOffStopIndex: 1,
        routeId: 0,
        tripIndex: 0,
      };

      const continuousVehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 0, 0),
        stopIndex: 1,
        hopOffStopIndex: 2,
        routeId: 0,
        tripIndex: 0,
        continuationOf: firstVehicleEdge,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [2],
          arrivals: [
            [0, timeFromHMS(8, 0, 0), 0],
            [1, timeFromHMS(8, 30, 0), 1],
            [2, timeFromHMS(9, 0, 0), 1],
          ],
          graph: [
            [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [
              [1, firstVehicleEdge],
              [2, continuousVehicleEdge],
            ], // round 1
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRoute(2);
      assert(route);
      assert.strictEqual(route.legs.length, 1);
      const leg = route.legs[0];
      assert(leg);
      assert.strictEqual(leg.from.id, 0);
      assert.strictEqual(leg.to.id, 2);
    });

    it('should handle continuous trips with route change mid-journey', () => {
      const firstVehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 0, 0),
        stopIndex: 0,
        hopOffStopIndex: 2,
        routeId: 0,
        tripIndex: 0,
      };

      const continuousVehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 45, 0),
        stopIndex: 0,
        hopOffStopIndex: 1,
        routeId: 1,
        tripIndex: 0,
        continuationOf: firstVehicleEdge,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [3],
          arrivals: [
            [0, timeFromHMS(8, 0, 0), 0],
            [3, timeFromHMS(9, 45, 0), 1],
          ],
          graph: [
            [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [[3, continuousVehicleEdge]], // round 1
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const route = result.bestRoute(3);
      assert(route);
      assert.strictEqual(route.legs.length, 1);
      const leg = route.legs[0];
      assert(leg);
      assert.strictEqual(leg.from.id, 0);
      assert.strictEqual(leg.to.id, 3);
    });

    it('should handle route reconstruction with actual transfer edges', () => {
      const firstVehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(8, 30, 0),
        stopIndex: 0,
        hopOffStopIndex: 1,
        routeId: 0,
        tripIndex: 0,
      };
      const transferEdge: TransferEdge = {
        arrival: timeFromHMS(8, 35, 0),
        from: 1,
        to: 2,
        type: TransferTypes.RECOMMENDED,
        minTransferTime: 5,
      };
      const secondVehicleEdge: VehicleEdge = {
        arrival: timeFromHMS(9, 15, 0),
        stopIndex: 0,
        hopOffStopIndex: 1,
        routeId: 1,
        tripIndex: 0,
      };

      const state = RoutingState.fromTestData({
        nbStops: NB_STOPS,
        origins: [0],
        destinations: [3],
        arrivals: [
          [0, timeFromHMS(8, 0, 0), 0],
          [1, timeFromHMS(8, 30, 0), 1],
          [2, timeFromHMS(8, 35, 0), 1],
          [3, timeFromHMS(9, 15, 0), 2],
        ],
        graph: [
          [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
          [
            [1, firstVehicleEdge],
            [2, transferEdge],
          ], // round 1
          [[3, secondVehicleEdge]], // round 2
        ],
      });

      const result = new Result(
        mockQuery.to,
        state,
        mockStopsIndex,
        mockTimetable,
      );
      const route = result.bestRoute(3);
      assert(route);
      assert.strictEqual(
        route.legs.length,
        3,
        'Route should have vehicle + transfer + vehicle legs',
      );

      const firstLeg = route.legs[0];
      const transferLeg = route.legs[1];
      const thirdLeg = route.legs[2];
      assert(firstLeg);
      assert(transferLeg);
      assert(thirdLeg);

      assert.strictEqual(firstLeg.from.id, 0);
      assert.strictEqual(firstLeg.to.id, 1);
      assert('departureTime' in firstLeg);
      assert('route' in firstLeg);

      assert.strictEqual(transferLeg.from.id, 1);
      assert.strictEqual(transferLeg.to.id, 2);
      assert('type' in transferLeg);
      assert('minTransferTime' in transferLeg);
      assert.strictEqual(transferLeg.type, 'RECOMMENDED');

      assert.strictEqual(thirdLeg.from.id, 2);
      assert.strictEqual(thirdLeg.to.id, 3);
      assert('departureTime' in thirdLeg);
      assert('route' in thirdLeg);

      // Verify the routing state recorded the correct leg numbers.
      assert.strictEqual(state.getArrival(1)?.legNumber, 1);
      assert.strictEqual(state.getArrival(2)?.legNumber, 1);
      assert.strictEqual(state.getArrival(3)?.legNumber, 2);
    });
  });

  describe('arrivalAt', () => {
    it('should return arrival time for a reachable stop', () => {
      const arrivalTime = { arrival: timeFromHMS(9, 0, 0), legNumber: 1 };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          destinations: [2],
          arrivals: [[2, timeFromHMS(9, 0, 0), 1]],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const arrival = result.arrivalAt(2);
      assert.deepStrictEqual(arrival, arrivalTime);
    });

    it('should return undefined for unreachable stop', () => {
      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          destinations: [2],
          arrivals: [[2, timeFromHMS(9, 0, 0), 1]],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const arrival = result.arrivalAt(3);
      assert.strictEqual(arrival, undefined);
    });

    it('should return earliest arrival among equivalent stops', () => {
      const earlierArrival = { arrival: timeFromHMS(9, 0, 0), legNumber: 1 };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          destinations: [4],
          arrivals: [
            [5, timeFromHMS(9, 0, 0), 1], // child1 – faster
            [6, timeFromHMS(9, 30, 0), 1], // child2 – slower
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const arrival = result.arrivalAt(4);
      assert.deepStrictEqual(arrival, earlierArrival);
    });

    it('should respect maxTransfers constraint', () => {
      const directArrival = { arrival: timeFromHMS(9, 30, 0), legNumber: 1 };
      const transferArrival = { arrival: timeFromHMS(9, 0, 0), legNumber: 2 };

      const vehicleEdge1: VehicleEdge = {
        arrival: timeFromHMS(9, 30, 0),
        stopIndex: 0,
        hopOffStopIndex: 2,
        routeId: 0,
        tripIndex: 0,
      };

      const vehicleEdge2: VehicleEdge = {
        arrival: timeFromHMS(9, 45, 0),
        stopIndex: 0,
        hopOffStopIndex: 1,
        routeId: 1,
        tripIndex: 0,
      };

      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          origins: [0],
          destinations: [2],
          // The best overall arrival at stop 2 is 9:00 (leg 2), coming from a
          // route with a transfer — even though the graph edges themselves arrive
          // later. This tests that arrivalAt respects the maxTransfers limit by
          // falling back to the graph rather than the global best.
          arrivals: [[2, timeFromHMS(9, 0, 0), 2]],
          graph: [
            [[0, { stopId: 0, arrival: timeFromHMS(8, 0, 0) }]], // round 0 – origins
            [[2, vehicleEdge1]], // round 1 – direct (9:30)
            [[2, vehicleEdge2]], // round 2 – with transfer
          ],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      // With maxTransfers = 0, only round 1 is considered → direct arrival.
      const arrivalWithLimit = result.arrivalAt(2, 0);
      assert.deepStrictEqual(arrivalWithLimit, directArrival);

      // Without a limit, the global best is returned.
      const arrivalWithoutLimit = result.arrivalAt(2);
      assert.deepStrictEqual(arrivalWithoutLimit, transferArrival);
    });

    it('should handle non-existent stops', () => {
      const result = new Result(
        mockQuery.to,
        RoutingState.fromTestData({
          nbStops: NB_STOPS,
          destinations: [2],
          arrivals: [[2, timeFromHMS(9, 0, 0), 1]],
        }),
        mockStopsIndex,
        mockTimetable,
      );

      const arrival = result.arrivalAt(324);
      assert.strictEqual(arrival, undefined);
    });
  });
});