import Foundation
import Observation

@Observable
@MainActor
final class LeagueCenterViewModel {
    var scheduleGames: [StatsGame] = []
    var standings: [StandingsDivisionRecord] = []
    var teams: [LeagueTeamSummary] = []

    var selectedTeam: TeamProfile?
    var roster: [RosterPlayerSummary] = []
    var selectedPlayer: PlayerProfile?

    var isLoadingOverview = false
    var isLoadingTeam = false
    var isLoadingPlayer = false

    var overviewErrorMessage: String?
    var teamErrorMessage: String?
    var playerErrorMessage: String?

    private let statsAPI = MLBStatsAPI()
    private(set) var scheduleDate = Date()

    private var seasonString: String {
        String(Calendar.current.component(.year, from: scheduleDate))
    }

    private var scheduleDateString: String {
        Self.scheduleFormatter.string(from: scheduleDate)
    }

    var displayDateString: String {
        Self.displayFormatter.string(from: scheduleDate)
    }

    func loadInitial() async {
        isLoadingOverview = true
        overviewErrorMessage = nil

        async let scheduleTask = statsAPI.fetchSchedule(date: scheduleDateString)
        async let standingsTask = statsAPI.fetchStandingsRecords(season: seasonString)
        async let teamsTask = statsAPI.fetchLeagueTeams(season: seasonString)

        do {
            scheduleGames = try await scheduleTask
            standings = try await standingsTask
            teams = try await teamsTask

            if selectedTeam == nil, let firstTeam = teams.first {
                await selectTeam(firstTeam.id)
            }
        } catch {
            overviewErrorMessage = "Failed to load league information."
        }

        isLoadingOverview = false
    }

    func goToPreviousDay() async {
        scheduleDate = Calendar.current.date(byAdding: .day, value: -1, to: scheduleDate) ?? scheduleDate
        await loadSchedule()
    }

    func goToNextDay() async {
        scheduleDate = Calendar.current.date(byAdding: .day, value: 1, to: scheduleDate) ?? scheduleDate
        await loadSchedule()
    }

    func goToToday() async {
        scheduleDate = Date()
        await loadSchedule()
    }

    func loadSchedule() async {
        do {
            scheduleGames = try await statsAPI.fetchSchedule(date: scheduleDateString)
        } catch {
            overviewErrorMessage = "Failed to load schedule."
        }
    }

    func selectTeam(_ teamID: Int) async {
        isLoadingTeam = true
        teamErrorMessage = nil
        selectedPlayer = nil
        playerErrorMessage = nil

        do {
            async let profileTask = statsAPI.fetchTeamProfile(teamID: teamID, season: seasonString)
            async let rosterTask = statsAPI.fetchTeamRoster(teamID: teamID, season: seasonString)

            selectedTeam = try await profileTask
            roster = try await rosterTask

            if let firstPlayer = roster.first {
                await selectPlayer(firstPlayer.id)
            }
        } catch {
            teamErrorMessage = "Failed to load team details."
            roster = []
        }

        isLoadingTeam = false
    }

    func selectPlayer(_ playerID: Int) async {
        isLoadingPlayer = true
        playerErrorMessage = nil

        do {
            selectedPlayer = try await statsAPI.fetchPlayerProfile(personID: playerID, season: seasonString)
        } catch {
            playerErrorMessage = "Failed to load player details."
        }

        isLoadingPlayer = false
    }

    private static let scheduleFormatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "yyyy-MM-dd"
        return formatter
    }()

    private static let displayFormatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "EEEE, MMM d"
        return formatter
    }()
}