//
//  TripPlanningEngineTests.swift
//  SportsTimeTests
//
//  TDD specification tests for TripPlanningEngine.
//

import Testing
import Foundation
import CoreLocation
@testable import SportsTime

@Suite("TripPlanningEngine")
struct TripPlanningEngineTests {

    // MARK: - Test Data

    private let nycCoord = CLLocationCoordinate2D(latitude: 40.7580, longitude: -73.9855)
    private let bostonCoord = CLLocationCoordinate2D(latitude: 42.3467, longitude: -71.0972)
    private let chicagoCoord = CLLocationCoordinate2D(latitude: 41.8827, longitude: -87.6233)
    private let laCoord = CLLocationCoordinate2D(latitude: 34.0430, longitude: -118.2673)

    // MARK: - Specification Tests: Driving Constraints

    @Test("DrivingConstraints: calculates maxDailyDrivingHours correctly")
    func drivingConstraints_maxDailyHours() {
        let constraints = DrivingConstraints(numberOfDrivers: 2, maxHoursPerDriverPerDay: 6.0)
        #expect(constraints.maxDailyDrivingHours == 12.0)
    }

    @Test("DrivingConstraints: clamps negative drivers to 1")
    func drivingConstraints_clampsNegativeDrivers() {
        let constraints = DrivingConstraints(numberOfDrivers: -5, maxHoursPerDriverPerDay: 8.0)
        #expect(constraints.numberOfDrivers == 1)
        #expect(constraints.maxDailyDrivingHours == 8.0)
    }

    @Test("DrivingConstraints: clamps zero hours to minimum")
    func drivingConstraints_clampsZeroHours() {
        let constraints = DrivingConstraints(numberOfDrivers: 1, maxHoursPerDriverPerDay: 0)
        #expect(constraints.maxHoursPerDriverPerDay == 1.0)
    }

    // MARK: - Specification Tests: Trip Preferences Computed Properties

    @Test("totalDriverHoursPerDay: defaults to 8 hours when nil")
    func totalDriverHoursPerDay_default() {
        let prefs = TripPreferences(
            numberOfDrivers: 1,
            maxDrivingHoursPerDriver: nil
        )
        #expect(prefs.totalDriverHoursPerDay == 8.0)
    }

    @Test("totalDriverHoursPerDay: multiplies by number of drivers")
    func totalDriverHoursPerDay_multipleDrivers() {
        let prefs = TripPreferences(
            numberOfDrivers: 2,
            maxDrivingHoursPerDriver: 6.0
        )
        #expect(prefs.totalDriverHoursPerDay == 12.0)
    }

    @Test("effectiveTripDuration: uses explicit tripDuration when set")
    func effectiveTripDuration_explicit() {
        let prefs = TripPreferences(
            tripDuration: 5
        )
        #expect(prefs.effectiveTripDuration == 5)
    }

    @Test("effectiveTripDuration: calculates from date range when tripDuration is nil")
    func effectiveTripDuration_calculated() {
        let calendar = TestClock.calendar
        let startDate = calendar.date(from: DateComponents(year: 2026, month: 6, day: 15))!
        let endDate = calendar.date(from: DateComponents(year: 2026, month: 6, day: 22))!

        let prefs = TripPreferences(
            startDate: startDate,
            endDate: endDate,
            tripDuration: nil
        )
        #expect(prefs.effectiveTripDuration == 8) // 8 days inclusive (15th through 22nd)
    }

    // MARK: - Invariant Tests

    @Test("Invariant: totalDriverHoursPerDay > 0")
    func invariant_totalDriverHoursPositive() {
        let prefs1 = TripPreferences(numberOfDrivers: 1)
        #expect(prefs1.totalDriverHoursPerDay > 0)
        #expect(prefs1.totalDriverHoursPerDay == 8.0)  // 1 driver × 8 hrs

        let prefs2 = TripPreferences(numberOfDrivers: 3, maxDrivingHoursPerDriver: 4)
        #expect(prefs2.totalDriverHoursPerDay > 0)
        #expect(prefs2.totalDriverHoursPerDay == 12.0)  // 3 drivers × 4 hrs
    }

    @Test("Invariant: effectiveTripDuration >= 1")
    func invariant_effectiveTripDurationMinimum() {
        let testCases: [Int?] = [nil, 1, 5, 10]

        for duration in testCases {
            let prefs = TripPreferences(tripDuration: duration)
            #expect(prefs.effectiveTripDuration >= 1)
        }

        // Verify specific value for nil duration with default dates
        let prefsNil = TripPreferences(tripDuration: nil)
        #expect(prefsNil.effectiveTripDuration == 8)  // Default 7-day range = 8 days inclusive
    }

    // MARK: - Travel Segment Validation

    @Test("planTrip: multi-stop result always has travel segments")
    func planTrip_multiStopResult_alwaysHasTravelSegments() {
        let baseDate = TestFixtures.date(year: 2026, month: 6, day: 1, hour: 19, minute: 0)
        let day2 = TestClock.calendar.date(byAdding: .day, value: 1, to: baseDate)!
        let day3 = TestClock.calendar.date(byAdding: .day, value: 2, to: baseDate)!

        let game1 = TestFixtures.game(city: "New York", dateTime: baseDate)
        let game2 = TestFixtures.game(city: "Boston", dateTime: day2)
        let game3 = TestFixtures.game(city: "Philadelphia", dateTime: day3)

        let stadiums = TestFixtures.stadiumMap(for: [game1, game2, game3])

        let prefs = TripPreferences(
            planningMode: .dateRange,
            sports: [.mlb],
            startDate: baseDate,
            endDate: day3
        )

        let request = PlanningRequest(
            preferences: prefs,
            availableGames: [game1, game2, game3],
            teams: [:],
            stadiums: stadiums
        )

        let engine = TripPlanningEngine()
        let result = engine.planItineraries(request: request)

        guard case .success(let options) = result else { Issue.record("Expected .success, got \(result)"); return }
        for option in options {
            #expect(option.isValid, "Every returned option must be valid (segments = stops - 1)")
            if option.stops.count > 1 {
                #expect(option.travelSegments.count == option.stops.count - 1)
            }
        }
    }

    @Test("planTrip: N stops always have exactly N-1 travel segments")
    func planTrip_nStops_haveExactlyNMinus1Segments() {
        let baseDate = TestFixtures.date(year: 2026, month: 6, day: 1, hour: 19, minute: 0)

        // Create 5 games across cities to produce routes of varying lengths
        let cities = ["New York", "Boston", "Philadelphia", "Chicago", "Detroit"]
        var games: [Game] = []
        for (i, city) in cities.enumerated() {
            let date = TestClock.calendar.date(byAdding: .day, value: i, to: baseDate)!
            games.append(TestFixtures.game(city: city, dateTime: date))
        }

        let stadiums = TestFixtures.stadiumMap(for: games)
        let endDate = TestClock.calendar.date(byAdding: .day, value: cities.count, to: baseDate)!

        let prefs = TripPreferences(
            planningMode: .dateRange,
            sports: [.mlb],
            startDate: baseDate,
            endDate: endDate
        )

        let request = PlanningRequest(
            preferences: prefs,
            availableGames: games,
            teams: [:],
            stadiums: stadiums
        )

        let engine = TripPlanningEngine()
        let result = engine.planItineraries(request: request)

        guard case .success(let options) = result else { Issue.record("Expected .success, got \(result)"); return }
        #expect(!options.isEmpty, "Should produce at least one option")
        for option in options {
            if option.stops.count > 1 {
                #expect(option.travelSegments.count == option.stops.count - 1,
                       "Option with \(option.stops.count) stops must have exactly \(option.stops.count - 1) segments, got \(option.travelSegments.count)")
            } else {
                #expect(option.travelSegments.isEmpty,
                       "Single-stop option must have 0 segments")
            }
        }
    }

    @Test("ItineraryOption.isValid: correctly validates segment count")
    func planTrip_invalidOptions_areFilteredOut() {
        // Create a valid ItineraryOption manually with wrong segment count
        let stop1 = ItineraryStop(
            city: "New York", state: "NY",
            coordinate: nycCoord,
            games: ["g1"], arrivalDate: Date(), departureDate: Date(),
            location: LocationInput(name: "New York", coordinate: nycCoord),
            firstGameStart: Date()
        )
        let stop2 = ItineraryStop(
            city: "Boston", state: "MA",
            coordinate: bostonCoord,
            games: ["g2"], arrivalDate: Date(), departureDate: Date(),
            location: LocationInput(name: "Boston", coordinate: bostonCoord),
            firstGameStart: Date()
        )

        // Invalid: 2 stops but 0 segments
        let invalidOption = ItineraryOption(
            rank: 1, stops: [stop1, stop2],
            travelSegments: [],
            totalDrivingHours: 0, totalDistanceMiles: 0,
            geographicRationale: "test"
        )
        #expect(!invalidOption.isValid, "2 stops with 0 segments should be invalid")

        // Valid: 2 stops with 1 segment
        let segment = TestFixtures.travelSegment(from: "New York", to: "Boston")
        let validOption = ItineraryOption(
            rank: 1, stops: [stop1, stop2],
            travelSegments: [segment],
            totalDrivingHours: 3.5, totalDistanceMiles: 215,
            geographicRationale: "test"
        )
        #expect(validOption.isValid, "2 stops with 1 segment should be valid")
    }

    @Test("planTrip: inverted date range returns failure")
    func planTrip_invertedDateRange_returnsFailure() {
        let endDate = TestFixtures.date(year: 2026, month: 6, day: 1)
        let startDate = TestFixtures.date(year: 2026, month: 6, day: 10)

        let prefs = TripPreferences(
            planningMode: .dateRange,
            sports: [.mlb],
            startDate: startDate,
            endDate: endDate
        )

        let request = PlanningRequest(
            preferences: prefs,
            availableGames: [],
            teams: [:],
            stadiums: [:]
        )

        let engine = TripPlanningEngine()
        let result = engine.planItineraries(request: request)

        #expect(!result.isSuccess)
        if let failure = result.failure {
            #expect(failure.reason == .missingDateRange)
        }
    }

    // MARK: - Helper Methods

    private func makeStadium(
        id: String,
        city: String,
        coordinate: CLLocationCoordinate2D
    ) -> Stadium {
        Stadium(
            id: id,
            name: "\(city) Stadium",
            city: city,
            state: "XX",
            latitude: coordinate.latitude,
            longitude: coordinate.longitude,
            capacity: 40000,
            sport: .mlb
        )
    }

    private func makeGame(
        id: String,
        stadiumId: String,
        dateTime: Date
    ) -> Game {
        Game(
            id: id,
            homeTeamId: "team1",
            awayTeamId: "team2",
            stadiumId: stadiumId,
            dateTime: dateTime,
            sport: .mlb,
            season: "2026"
        )
    }
}