//
//  TripPlanningEngineTests.swift
//  SportsTimeTests
//
//  Fresh test suite for the rewritten trip planning engine.
//  Organized by scenario and validation type.
//

import XCTest
import CoreLocation
@testable import SportsTime

final class TripPlanningEngineTests: XCTestCase {

    var engine: TripPlanningEngine!

    override func setUp() {
        super.setUp()
        engine = TripPlanningEngine()
    }

    override func tearDown() {
        engine = nil
        super.tearDown()
    }

    // MARK: - Test Data Helpers

    func makeGame(
        id: UUID = UUID(),
        dateTime: Date,
        stadiumId: UUID = UUID(),
        homeTeamId: UUID = UUID(),
        awayTeamId: UUID = UUID(),
        sport: Sport = .mlb
    ) -> Game {
        Game(
            id: id,
            homeTeamId: homeTeamId,
            awayTeamId: awayTeamId,
            stadiumId: stadiumId,
            dateTime: dateTime,
            sport: sport,
            season: "2026"
        )
    }

    func makeStadium(
        id: UUID = UUID(),
        name: String = "Test Stadium",
        city: String = "Test City",
        state: String = "TS",
        latitude: Double = 40.0,
        longitude: Double = -74.0
    ) -> Stadium {
        Stadium(
            id: id,
            name: name,
            city: city,
            state: state,
            latitude: latitude,
            longitude: longitude,
            capacity: 40000
        )
    }

    func makeTeam(
        id: UUID = UUID(),
        name: String = "Test Team",
        city: String = "Test City",
        stadiumId: UUID = UUID()
    ) -> Team {
        Team(
            id: id,
            name: name,
            abbreviation: "TST",
            sport: .mlb,
            city: city,
            stadiumId: stadiumId
        )
    }

    func makePreferences(
        startDate: Date = Date(),
        endDate: Date = Date().addingTimeInterval(86400 * 7),
        sports: Set<Sport> = [.mlb],
        mustSeeGameIds: Set<UUID> = [],
        startLocation: LocationInput? = nil,
        endLocation: LocationInput? = nil,
        numberOfDrivers: Int = 1,
        maxDrivingHoursPerDriver: Double = 8.0
    ) -> TripPreferences {
        TripPreferences(
            planningMode: .dateRange,
            startLocation: startLocation,
            endLocation: endLocation,
            sports: sports,
            mustSeeGameIds: mustSeeGameIds,
            travelMode: .drive,
            startDate: startDate,
            endDate: endDate,
            numberOfStops: nil,
            tripDuration: nil,
            leisureLevel: .moderate,
            mustStopLocations: [],
            preferredCities: [],
            routePreference: .balanced,
            needsEVCharging: false,
            lodgingType: .hotel,
            numberOfDrivers: numberOfDrivers,
            maxDrivingHoursPerDriver: maxDrivingHoursPerDriver,
            catchOtherSports: false
        )
    }

    func makeRequest(
        preferences: TripPreferences,
        games: [Game],
        teams: [UUID: Team] = [:],
        stadiums: [UUID: Stadium] = [:]
    ) -> PlanningRequest {
        PlanningRequest(
            preferences: preferences,
            availableGames: games,
            teams: teams,
            stadiums: stadiums
        )
    }

    // MARK: - Scenario A Tests (Date Range)

    func test_ScenarioA_ValidDateRange_ReturnsItineraries() {
        // Given: A date range with games
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 7)

        let stadiumId = UUID()
        let homeTeamId = UUID()
        let awayTeamId = UUID()

        let stadium = makeStadium(id: stadiumId, city: "New York", latitude: 40.7128, longitude: -74.0060)
        let homeTeam = makeTeam(id: homeTeamId, name: "Yankees", city: "New York")
        let awayTeam = makeTeam(id: awayTeamId, name: "Red Sox", city: "Boston")

        let game = makeGame(
            dateTime: startDate.addingTimeInterval(86400 * 2),
            stadiumId: stadiumId,
            homeTeamId: homeTeamId,
            awayTeamId: awayTeamId
        )

        let preferences = makePreferences(startDate: startDate, endDate: endDate)
        let request = makeRequest(
            preferences: preferences,
            games: [game],
            teams: [homeTeamId: homeTeam, awayTeamId: awayTeam],
            stadiums: [stadiumId: stadium]
        )

        // When
        let result = engine.planItineraries(request: request)

        // Then
        XCTAssertTrue(result.isSuccess, "Should return success for valid date range with games")
        XCTAssertFalse(result.options.isEmpty, "Should return at least one itinerary option")
    }

    func test_ScenarioA_EmptyDateRange_ReturnsFailure() {
        // Given: An invalid date range (end before start)
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(-86400) // End before start

        let preferences = makePreferences(startDate: startDate, endDate: endDate)
        let request = makeRequest(preferences: preferences, games: [])

        // When
        let result = engine.planItineraries(request: request)

        // Then
        XCTAssertFalse(result.isSuccess, "Should fail for invalid date range")
        if case .failure(let failure) = result {
            XCTAssertEqual(failure.reason, .missingDateRange, "Should fail with missingDateRange")
        }
    }

    func test_ScenarioA_NoGamesInRange_ReturnsFailure() {
        // Given: A valid date range but no games
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 7)

        let preferences = makePreferences(startDate: startDate, endDate: endDate)
        let request = makeRequest(preferences: preferences, games: [])

        // When
        let result = engine.planItineraries(request: request)

        // Then
        XCTAssertFalse(result.isSuccess, "Should fail when no games in range")
    }

    // MARK: - Scenario B Tests (Selected Games)

    func test_ScenarioB_SelectedGamesWithinRange_ReturnsSuccess() {
        // Given: Selected games within date range
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 7)

        let gameId = UUID()
        let stadiumId = UUID()
        let homeTeamId = UUID()
        let awayTeamId = UUID()

        let stadium = makeStadium(id: stadiumId, city: "Chicago", latitude: 41.8781, longitude: -87.6298)
        let homeTeam = makeTeam(id: homeTeamId, name: "Cubs", city: "Chicago")
        let awayTeam = makeTeam(id: awayTeamId, name: "Cardinals", city: "St. Louis")

        let game = makeGame(
            id: gameId,
            dateTime: startDate.addingTimeInterval(86400 * 3),
            stadiumId: stadiumId,
            homeTeamId: homeTeamId,
            awayTeamId: awayTeamId
        )

        let preferences = makePreferences(
            startDate: startDate,
            endDate: endDate,
            mustSeeGameIds: [gameId]
        )

        let request = makeRequest(
            preferences: preferences,
            games: [game],
            teams: [homeTeamId: homeTeam, awayTeamId: awayTeam],
            stadiums: [stadiumId: stadium]
        )

        // When
        let result = engine.planItineraries(request: request)

        // Then
        XCTAssertTrue(result.isSuccess, "Should succeed when selected games are within date range")
    }

    func test_ScenarioB_SelectedGameOutsideDateRange_ReturnsFailure() {
        // Given: A selected game outside the date range
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 7)

        let gameId = UUID()
        let stadiumId = UUID()
        let homeTeamId = UUID()
        let awayTeamId = UUID()

        // Game is 10 days after start, but range is only 7 days
        let game = makeGame(
            id: gameId,
            dateTime: startDate.addingTimeInterval(86400 * 10),
            stadiumId: stadiumId,
            homeTeamId: homeTeamId,
            awayTeamId: awayTeamId
        )

        let preferences = makePreferences(
            startDate: startDate,
            endDate: endDate,
            mustSeeGameIds: [gameId]
        )

        let request = makeRequest(
            preferences: preferences,
            games: [game],
            teams: [:],
            stadiums: [:]
        )

        // When
        let result = engine.planItineraries(request: request)

        // Then
        XCTAssertFalse(result.isSuccess, "Should fail when selected game is outside date range")
        if case .failure(let failure) = result {
            if case .dateRangeViolation(let games) = failure.reason {
                XCTAssertEqual(games.count, 1, "Should report one game out of range")
                XCTAssertEqual(games.first?.id, gameId, "Should report the correct game")
            } else {
                XCTFail("Expected dateRangeViolation failure reason")
            }
        }
    }

    // MARK: - Scenario C Tests (Start + End Locations)

    func test_ScenarioC_LinearRoute_ReturnsSuccess() {
        // Given: Start and end locations with games along the way
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 7)

        let startLocation = LocationInput(
            name: "Chicago",
            coordinate: CLLocationCoordinate2D(latitude: 41.8781, longitude: -87.6298)
        )
        let endLocation = LocationInput(
            name: "New York",
            coordinate: CLLocationCoordinate2D(latitude: 40.7128, longitude: -74.0060)
        )

        // Stadium in Cleveland (along the route)
        let stadiumId = UUID()
        let homeTeamId = UUID()
        let awayTeamId = UUID()

        let stadium = makeStadium(
            id: stadiumId,
            city: "Cleveland",
            latitude: 41.4993,
            longitude: -81.6944
        )

        let game = makeGame(
            dateTime: startDate.addingTimeInterval(86400 * 2),
            stadiumId: stadiumId,
            homeTeamId: homeTeamId,
            awayTeamId: awayTeamId
        )

        let preferences = makePreferences(
            startDate: startDate,
            endDate: endDate,
            startLocation: startLocation,
            endLocation: endLocation
        )

        let request = makeRequest(
            preferences: preferences,
            games: [game],
            teams: [homeTeamId: makeTeam(id: homeTeamId), awayTeamId: makeTeam(id: awayTeamId)],
            stadiums: [stadiumId: stadium]
        )

        // When
        let result = engine.planItineraries(request: request)

        // Then
        XCTAssertTrue(result.isSuccess, "Should succeed for linear route with games")
    }

    // MARK: - Travel Segment Invariant Tests

    func test_TravelSegmentCount_EqualsStopsMinusOne() {
        // Given: A multi-stop itinerary
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 7)

        var stadiums: [UUID: Stadium] = [:]
        var teams: [UUID: Team] = [:]
        var games: [Game] = []

        // Create 3 games in 3 cities
        let cities = [
            ("New York", 40.7128, -74.0060),
            ("Philadelphia", 39.9526, -75.1652),
            ("Washington DC", 38.9072, -77.0369)
        ]

        for (index, (city, lat, lon)) in cities.enumerated() {
            let stadiumId = UUID()
            let homeTeamId = UUID()
            let awayTeamId = UUID()

            stadiums[stadiumId] = makeStadium(id: stadiumId, city: city, latitude: lat, longitude: lon)
            teams[homeTeamId] = makeTeam(id: homeTeamId, city: city)
            teams[awayTeamId] = makeTeam(id: awayTeamId)

            let game = makeGame(
                dateTime: startDate.addingTimeInterval(86400 * Double(index + 1)),
                stadiumId: stadiumId,
                homeTeamId: homeTeamId,
                awayTeamId: awayTeamId
            )
            games.append(game)
        }

        let preferences = makePreferences(startDate: startDate, endDate: endDate)
        let request = makeRequest(
            preferences: preferences,
            games: games,
            teams: teams,
            stadiums: stadiums
        )

        // When
        let result = engine.planItineraries(request: request)

        // Then
        if case .success(let options) = result, let option = options.first {
            let expectedSegments = option.stops.count - 1
            XCTAssertEqual(
                option.travelSegments.count,
                max(0, expectedSegments),
                "Travel segments should equal stops - 1"
            )
            XCTAssertTrue(option.isValid, "Itinerary should pass validity check")
        }
    }

    func test_SingleStopItinerary_HasZeroTravelSegments() {
        // Given: A single game (single stop)
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 7)

        let stadiumId = UUID()
        let homeTeamId = UUID()
        let awayTeamId = UUID()

        let stadium = makeStadium(id: stadiumId, latitude: 40.7128, longitude: -74.0060)
        let homeTeam = makeTeam(id: homeTeamId)
        let awayTeam = makeTeam(id: awayTeamId)

        let game = makeGame(
            dateTime: startDate.addingTimeInterval(86400 * 2),
            stadiumId: stadiumId,
            homeTeamId: homeTeamId,
            awayTeamId: awayTeamId
        )

        let preferences = makePreferences(startDate: startDate, endDate: endDate)
        let request = makeRequest(
            preferences: preferences,
            games: [game],
            teams: [homeTeamId: homeTeam, awayTeamId: awayTeam],
            stadiums: [stadiumId: stadium]
        )

        // When
        let result = engine.planItineraries(request: request)

        // Then
        if case .success(let options) = result, let option = options.first {
            if option.stops.count == 1 {
                XCTAssertEqual(option.travelSegments.count, 0, "Single stop should have zero travel segments")
            }
        }
    }

    // MARK: - Driving Constraints Tests

    func test_DrivingConstraints_MultipleDrivers_IncreasesCapacity() {
        // Given: Two drivers instead of one
        let constraints1 = DrivingConstraints(numberOfDrivers: 1, maxHoursPerDriverPerDay: 8.0)
        let constraints2 = DrivingConstraints(numberOfDrivers: 2, maxHoursPerDriverPerDay: 8.0)

        // Then
        XCTAssertEqual(constraints1.maxDailyDrivingHours, 8.0, "Single driver = 8 hours max")
        XCTAssertEqual(constraints2.maxDailyDrivingHours, 16.0, "Two drivers = 16 hours max")
    }

    // MARK: - Ranking Tests

    func test_ItineraryOptions_AreRanked() {
        // Given: Multiple games that could form different routes
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 14)

        var stadiums: [UUID: Stadium] = [:]
        var teams: [UUID: Team] = [:]
        var games: [Game] = []

        // Create games with coordinates
        let locations = [
            ("City1", 40.0, -74.0),
            ("City2", 40.5, -73.5),
            ("City3", 41.0, -73.0)
        ]

        for (index, (city, lat, lon)) in locations.enumerated() {
            let stadiumId = UUID()
            let homeTeamId = UUID()
            let awayTeamId = UUID()

            stadiums[stadiumId] = makeStadium(id: stadiumId, city: city, latitude: lat, longitude: lon)
            teams[homeTeamId] = makeTeam(id: homeTeamId)
            teams[awayTeamId] = makeTeam(id: awayTeamId)

            let game = makeGame(
                dateTime: startDate.addingTimeInterval(86400 * Double(index + 1)),
                stadiumId: stadiumId,
                homeTeamId: homeTeamId,
                awayTeamId: awayTeamId
            )
            games.append(game)
        }

        let preferences = makePreferences(startDate: startDate, endDate: endDate)
        let request = makeRequest(
            preferences: preferences,
            games: games,
            teams: teams,
            stadiums: stadiums
        )

        // When
        let result = engine.planItineraries(request: request)

        // Then
        if case .success(let options) = result {
            for (index, option) in options.enumerated() {
                XCTAssertEqual(option.rank, index + 1, "Options should be ranked 1, 2, 3, ...")
            }
        }
    }

    // MARK: - Edge Case Tests

    func test_NoGamesAvailable_ReturnsExplicitFailure() {
        // Given: Empty games array
        let startDate = Date()
        let endDate = startDate.addingTimeInterval(86400 * 7)

        let preferences = makePreferences(startDate: startDate, endDate: endDate)
        let request = makeRequest(preferences: preferences, games: [])

        // When
        let result = engine.planItineraries(request: request)

        // Then
        XCTAssertFalse(result.isSuccess, "Should return failure for no games")
        XCTAssertNotNil(result.failure, "Should have explicit failure reason")
    }
}