//
//  ScenarioAPlannerTests.swift
//  SportsTimeTests
//
//  Tests for ScenarioAPlanner tree exploration logic.
//  Verifies that we correctly find all geographically sensible route variations.
//

import XCTest
import CoreLocation
@testable import SportsTime

final class ScenarioAPlannerTests: XCTestCase {

    // MARK: - Test Helpers

    /// Creates a stadium at a specific coordinate
    private func makeStadium(
        id: UUID = UUID(),
        city: String,
        lat: Double,
        lon: Double
    ) -> Stadium {
        Stadium(
            id: id,
            name: "\(city) Arena",
            city: city,
            state: "ST",
            latitude: lat,
            longitude: lon,
            capacity: 20000
        )
    }

    /// Creates a game at a stadium on a specific day
    private func makeGame(
        stadiumId: UUID,
        daysFromNow: Int
    ) -> Game {
        let date = Calendar.current.date(byAdding: .day, value: daysFromNow, to: Date())!
        return Game(
            id: UUID(),
            homeTeamId: UUID(),
            awayTeamId: UUID(),
            stadiumId: stadiumId,
            dateTime: date,
            sport: .nba,
            season: "2025-26"
        )
    }

    /// Creates a date range from now
    private func makeDateRange(days: Int) -> DateInterval {
        let start = Date()
        let end = Calendar.current.date(byAdding: .day, value: days, to: start)!
        return DateInterval(start: start, end: end)
    }

    /// Runs ScenarioA planning and returns the result
    private func plan(
        games: [Game],
        stadiums: [Stadium],
        dateRange: DateInterval
    ) -> ItineraryResult {
        let stadiumDict = Dictionary(uniqueKeysWithValues: stadiums.map { ($0.id, $0) })

        // Create preferences with the date range
        let preferences = TripPreferences(
            planningMode: .dateRange,
            startDate: dateRange.start,
            endDate: dateRange.end,
            numberOfDrivers: 1,
            maxDrivingHoursPerDriver: 8.0
        )

        let request = PlanningRequest(
            preferences: preferences,
            availableGames: games,
            teams: [:],  // Not needed for ScenarioA tests
            stadiums: stadiumDict
        )

        let planner = ScenarioAPlanner()
        return planner.plan(request: request)
    }

    // MARK: - Test 1: Empty games returns failure

    func test_emptyGames_returnsNoGamesInRangeFailure() {
        let result = plan(
            games: [],
            stadiums: [],
            dateRange: makeDateRange(days: 10)
        )

        if case .failure(let failure) = result {
            XCTAssertEqual(failure.reason, .noGamesInRange)
        } else {
            XCTFail("Expected failure, got success")
        }
    }

    // MARK: - Test 2: Single game always succeeds

    func test_singleGame_alwaysSucceeds() {
        let stadium = makeStadium(city: "New York", lat: 40.7, lon: -74.0)
        let game = makeGame(stadiumId: stadium.id, daysFromNow: 1)

        let result = plan(
            games: [game],
            stadiums: [stadium],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            XCTAssertEqual(options.count, 1)
            XCTAssertEqual(options[0].stops.count, 1)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 3: Two games always succeeds (no zig-zag possible)

    func test_twoGames_alwaysSucceeds() {
        let ny = makeStadium(city: "New York", lat: 40.7, lon: -74.0)
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)

        let games = [
            makeGame(stadiumId: ny.id, daysFromNow: 1),
            makeGame(stadiumId: la.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [ny, la],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            XCTAssertGreaterThanOrEqual(options.count, 1)
            // Should have option with both games
            let twoGameOption = options.first { $0.stops.count == 2 }
            XCTAssertNotNil(twoGameOption)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 4: Linear route (West to East) - all games included

    func test_linearRouteWestToEast_allGamesIncluded() {
        // LA → Denver → Chicago → New York (linear progression)
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let den = makeStadium(city: "Denver", lat: 39.7, lon: -104.9)
        let chi = makeStadium(city: "Chicago", lat: 41.8, lon: -87.6)
        let ny = makeStadium(city: "New York", lat: 40.7, lon: -74.0)

        let games = [
            makeGame(stadiumId: la.id, daysFromNow: 1),
            makeGame(stadiumId: den.id, daysFromNow: 3),
            makeGame(stadiumId: chi.id, daysFromNow: 5),
            makeGame(stadiumId: ny.id, daysFromNow: 7)
        ]

        let result = plan(
            games: games,
            stadiums: [la, den, chi, ny],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            // Best option should include all 4 games
            XCTAssertEqual(options[0].stops.count, 4)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 5: Linear route (North to South) - all games included

    func test_linearRouteNorthToSouth_allGamesIncluded() {
        // Seattle → SF → LA → San Diego (linear south)
        let sea = makeStadium(city: "Seattle", lat: 47.6, lon: -122.3)
        let sf = makeStadium(city: "San Francisco", lat: 37.7, lon: -122.4)
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let sd = makeStadium(city: "San Diego", lat: 32.7, lon: -117.1)

        let games = [
            makeGame(stadiumId: sea.id, daysFromNow: 1),
            makeGame(stadiumId: sf.id, daysFromNow: 2),
            makeGame(stadiumId: la.id, daysFromNow: 3),
            makeGame(stadiumId: sd.id, daysFromNow: 4)
        ]

        let result = plan(
            games: games,
            stadiums: [sea, sf, la, sd],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            XCTAssertEqual(options[0].stops.count, 4)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 6: Zig-zag pattern creates multiple options (NY → TX → SC)

    func test_zigZagPattern_createsMultipleOptions() {
        // NY (day 1) → TX (day 2) → SC (day 3) = zig-zag
        // Should create options: [NY,TX], [NY,SC], [TX,SC], etc.
        let ny = makeStadium(city: "New York", lat: 40.7, lon: -74.0)
        let tx = makeStadium(city: "Dallas", lat: 32.7, lon: -96.8)
        let sc = makeStadium(city: "Charleston", lat: 32.7, lon: -79.9)

        let games = [
            makeGame(stadiumId: ny.id, daysFromNow: 1),
            makeGame(stadiumId: tx.id, daysFromNow: 2),
            makeGame(stadiumId: sc.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [ny, tx, sc],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            // Should have multiple options due to zig-zag
            XCTAssertGreaterThan(options.count, 1)
        } else {
            XCTFail("Expected success with multiple options")
        }
    }

    // MARK: - Test 7: Cross-country zig-zag creates many branches

    func test_crossCountryZigZag_createsManyBranches() {
        // NY → TX → SC → CA → MN = extreme zig-zag
        let ny = makeStadium(city: "New York", lat: 40.7, lon: -74.0)
        let tx = makeStadium(city: "Dallas", lat: 32.7, lon: -96.8)
        let sc = makeStadium(city: "Charleston", lat: 32.7, lon: -79.9)
        let ca = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let mn = makeStadium(city: "Minneapolis", lat: 44.9, lon: -93.2)

        let games = [
            makeGame(stadiumId: ny.id, daysFromNow: 1),
            makeGame(stadiumId: tx.id, daysFromNow: 2),
            makeGame(stadiumId: sc.id, daysFromNow: 3),
            makeGame(stadiumId: ca.id, daysFromNow: 4),
            makeGame(stadiumId: mn.id, daysFromNow: 5)
        ]

        let result = plan(
            games: games,
            stadiums: [ny, tx, sc, ca, mn],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            // Should have many options from all the branching
            XCTAssertGreaterThan(options.count, 3)
            // No option should have all 5 games (too much zig-zag)
            let maxGames = options.map { $0.stops.count }.max() ?? 0
            XCTAssertLessThan(maxGames, 5)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 8: Fork at third game - both branches explored

    func test_forkAtThirdGame_bothBranchesExplored() {
        // NY → Chicago → ? (fork: either Dallas OR Miami, not both)
        let ny = makeStadium(city: "New York", lat: 40.7, lon: -74.0)
        let chi = makeStadium(city: "Chicago", lat: 41.8, lon: -87.6)
        let dal = makeStadium(city: "Dallas", lat: 32.7, lon: -96.8)
        let mia = makeStadium(city: "Miami", lat: 25.7, lon: -80.2)

        let games = [
            makeGame(stadiumId: ny.id, daysFromNow: 1),
            makeGame(stadiumId: chi.id, daysFromNow: 2),
            makeGame(stadiumId: dal.id, daysFromNow: 3),
            makeGame(stadiumId: mia.id, daysFromNow: 4)
        ]

        let result = plan(
            games: games,
            stadiums: [ny, chi, dal, mia],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            // Should have options including Dallas and options including Miami
            let citiesInOptions = options.flatMap { $0.stops.map { $0.city } }
            XCTAssertTrue(citiesInOptions.contains("Dallas") || citiesInOptions.contains("Miami"))
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 9: All games in same city - single option with all games

    func test_allGamesSameCity_singleOptionWithAllGames() {
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)

        let games = [
            makeGame(stadiumId: la.id, daysFromNow: 1),
            makeGame(stadiumId: la.id, daysFromNow: 2),
            makeGame(stadiumId: la.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [la],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            // All games at same stadium = 1 stop with 3 games
            XCTAssertEqual(options[0].stops.count, 1)
            XCTAssertEqual(options[0].stops[0].games.count, 3)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 10: Nearby cities - all included (no zig-zag)

    func test_nearbyCities_allIncluded() {
        // LA → Anaheim → San Diego (all nearby, < 100 miles)
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let ana = makeStadium(city: "Anaheim", lat: 33.8, lon: -117.9)
        let sd = makeStadium(city: "San Diego", lat: 32.7, lon: -117.1)

        let games = [
            makeGame(stadiumId: la.id, daysFromNow: 1),
            makeGame(stadiumId: ana.id, daysFromNow: 2),
            makeGame(stadiumId: sd.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [la, ana, sd],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            // All nearby = should have option with all 3
            XCTAssertEqual(options[0].stops.count, 3)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 11: Options sorted by game count (most games first)

    func test_optionsSortedByGameCount_mostGamesFirst() {
        // Create a scenario with varying option sizes
        let ny = makeStadium(city: "New York", lat: 40.7, lon: -74.0)
        let chi = makeStadium(city: "Chicago", lat: 41.8, lon: -87.6)
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)

        let games = [
            makeGame(stadiumId: ny.id, daysFromNow: 1),
            makeGame(stadiumId: chi.id, daysFromNow: 2),
            makeGame(stadiumId: la.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [ny, chi, la],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            // Options should be sorted: most games first
            for i in 0..<(options.count - 1) {
                XCTAssertGreaterThanOrEqual(
                    options[i].stops.count,
                    options[i + 1].stops.count
                )
            }
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 12: Rank numbers are sequential

    func test_rankNumbers_areSequential() {
        let ny = makeStadium(city: "New York", lat: 40.7, lon: -74.0)
        let tx = makeStadium(city: "Dallas", lat: 32.7, lon: -96.8)
        let sc = makeStadium(city: "Charleston", lat: 32.7, lon: -79.9)

        let games = [
            makeGame(stadiumId: ny.id, daysFromNow: 1),
            makeGame(stadiumId: tx.id, daysFromNow: 2),
            makeGame(stadiumId: sc.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [ny, tx, sc],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            for (index, option) in options.enumerated() {
                XCTAssertEqual(option.rank, index + 1)
            }
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 13: Games outside date range are excluded

    func test_gamesOutsideDateRange_areExcluded() {
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)

        let games = [
            makeGame(stadiumId: la.id, daysFromNow: 1),   // In range
            makeGame(stadiumId: la.id, daysFromNow: 15),  // Out of range
            makeGame(stadiumId: la.id, daysFromNow: 3)    // In range
        ]

        let result = plan(
            games: games,
            stadiums: [la],
            dateRange: makeDateRange(days: 5)  // Only 5 days
        )

        if case .success(let options) = result {
            // Should only have 2 games (day 1 and day 3)
            XCTAssertEqual(options[0].stops[0].games.count, 2)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 14: Maximum 10 options returned

    func test_maximum10Options_returned() {
        // Create many cities that could generate lots of combinations
        let cities: [(String, Double, Double)] = [
            ("City1", 40.0, -74.0),
            ("City2", 38.0, -90.0),
            ("City3", 35.0, -106.0),
            ("City4", 33.0, -117.0),
            ("City5", 37.0, -122.0),
            ("City6", 45.0, -93.0),
            ("City7", 42.0, -83.0)
        ]

        let stadiums = cities.map { makeStadium(city: $0.0, lat: $0.1, lon: $0.2) }
        let games = stadiums.enumerated().map { makeGame(stadiumId: $1.id, daysFromNow: $0 + 1) }

        let result = plan(
            games: games,
            stadiums: stadiums,
            dateRange: makeDateRange(days: 15)
        )

        if case .success(let options) = result {
            XCTAssertLessThanOrEqual(options.count, 10)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 15: Each option has travel segments

    func test_eachOption_hasTravelSegments() {
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let sf = makeStadium(city: "San Francisco", lat: 37.7, lon: -122.4)
        let sea = makeStadium(city: "Seattle", lat: 47.6, lon: -122.3)

        let games = [
            makeGame(stadiumId: la.id, daysFromNow: 1),
            makeGame(stadiumId: sf.id, daysFromNow: 3),
            makeGame(stadiumId: sea.id, daysFromNow: 5)
        ]

        let result = plan(
            games: games,
            stadiums: [la, sf, sea],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            for option in options {
                // Invariant: travelSegments.count == stops.count - 1
                if option.stops.count > 1 {
                    XCTAssertEqual(
                        option.travelSegments.count,
                        option.stops.count - 1
                    )
                }
            }
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 16: Single game options are included

    func test_singleGameOptions_areIncluded() {
        let ny = makeStadium(city: "New York", lat: 40.7, lon: -74.0)
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let mia = makeStadium(city: "Miami", lat: 25.7, lon: -80.2)

        let games = [
            makeGame(stadiumId: ny.id, daysFromNow: 1),
            makeGame(stadiumId: la.id, daysFromNow: 2),
            makeGame(stadiumId: mia.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [ny, la, mia],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            // Should include single-game options
            let singleGameOptions = options.filter { $0.stops.count == 1 }
            XCTAssertGreaterThan(singleGameOptions.count, 0)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 17: Chronological order preserved in each option

    func test_chronologicalOrder_preservedInEachOption() {
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let den = makeStadium(city: "Denver", lat: 39.7, lon: -104.9)
        let chi = makeStadium(city: "Chicago", lat: 41.8, lon: -87.6)

        let games = [
            makeGame(stadiumId: la.id, daysFromNow: 1),
            makeGame(stadiumId: den.id, daysFromNow: 3),
            makeGame(stadiumId: chi.id, daysFromNow: 5)
        ]

        let result = plan(
            games: games,
            stadiums: [la, den, chi],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            for option in options {
                // Verify stops are in chronological order
                for i in 0..<(option.stops.count - 1) {
                    XCTAssertLessThanOrEqual(
                        option.stops[i].arrivalDate,
                        option.stops[i + 1].arrivalDate
                    )
                }
            }
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 18: Geographic rationale includes city names

    func test_geographicRationale_includesCityNames() {
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let sf = makeStadium(city: "San Francisco", lat: 37.7, lon: -122.4)

        let games = [
            makeGame(stadiumId: la.id, daysFromNow: 1),
            makeGame(stadiumId: sf.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [la, sf],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            let twoStopOption = options.first { $0.stops.count == 2 }
            XCTAssertNotNil(twoStopOption)
            XCTAssertTrue(twoStopOption!.geographicRationale.contains("Los Angeles"))
            XCTAssertTrue(twoStopOption!.geographicRationale.contains("San Francisco"))
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 19: Total driving hours calculated for each option

    func test_totalDrivingHours_calculatedForEachOption() {
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)
        let sf = makeStadium(city: "San Francisco", lat: 37.7, lon: -122.4)

        let games = [
            makeGame(stadiumId: la.id, daysFromNow: 1),
            makeGame(stadiumId: sf.id, daysFromNow: 3)
        ]

        let result = plan(
            games: games,
            stadiums: [la, sf],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            let twoStopOption = options.first { $0.stops.count == 2 }
            XCTAssertNotNil(twoStopOption)
            // LA to SF is ~380 miles, ~6 hours
            XCTAssertGreaterThan(twoStopOption!.totalDrivingHours, 4)
            XCTAssertLessThan(twoStopOption!.totalDrivingHours, 10)
        } else {
            XCTFail("Expected success")
        }
    }

    // MARK: - Test 20: Coastal route vs inland route - both explored

    func test_coastalVsInlandRoute_bothExplored() {
        // SF → either Sacramento (inland) or Monterey (coastal) → LA
        let sf = makeStadium(city: "San Francisco", lat: 37.7, lon: -122.4)
        let sac = makeStadium(city: "Sacramento", lat: 38.5, lon: -121.4)  // Inland
        let mon = makeStadium(city: "Monterey", lat: 36.6, lon: -121.9)    // Coastal
        let la = makeStadium(city: "Los Angeles", lat: 34.0, lon: -118.2)

        let games = [
            makeGame(stadiumId: sf.id, daysFromNow: 1),
            makeGame(stadiumId: sac.id, daysFromNow: 2),
            makeGame(stadiumId: mon.id, daysFromNow: 3),
            makeGame(stadiumId: la.id, daysFromNow: 4)
        ]

        let result = plan(
            games: games,
            stadiums: [sf, sac, mon, la],
            dateRange: makeDateRange(days: 10)
        )

        if case .success(let options) = result {
            let citiesInOptions = Set(options.flatMap { $0.stops.map { $0.city } })
            // Both Sacramento and Monterey should appear in some option
            XCTAssertTrue(citiesInOptions.contains("Sacramento") || citiesInOptions.contains("Monterey"))
        } else {
            XCTFail("Expected success")
        }
    }
}