//
//  CanonicalDataProvider.swift
//  SportsTime
//
//  DataProvider implementation that reads from SwiftData canonical models.
//  This is the primary data source after bootstrap completes.
//

import Foundation
import SwiftData

actor CanonicalDataProvider: DataProvider {

    // MARK: - Properties

    private let modelContainer: ModelContainer

    // Caches for converted domain objects (rebuilt on first access)
    private var cachedTeams: [Team]?
    private var cachedStadiums: [Stadium]?
    private var teamsByCanonicalId: [String: Team] = [:]
    private var stadiumsByCanonicalId: [String: Stadium] = [:]
    private var teamUUIDByCanonicalId: [String: UUID] = [:]
    private var stadiumUUIDByCanonicalId: [String: UUID] = [:]

    // MARK: - Initialization

    init(modelContainer: ModelContainer) {
        self.modelContainer = modelContainer
    }

    // MARK: - DataProvider Protocol

    func fetchTeams(for sport: Sport) async throws -> [Team] {
        try await loadCachesIfNeeded()
        return cachedTeams?.filter { $0.sport == sport } ?? []
    }

    func fetchAllTeams() async throws -> [Team] {
        try await loadCachesIfNeeded()
        return cachedTeams ?? []
    }

    func fetchStadiums() async throws -> [Stadium] {
        try await loadCachesIfNeeded()
        return cachedStadiums ?? []
    }

    func fetchGames(sports: Set<Sport>, startDate: Date, endDate: Date) async throws -> [Game] {
        try await loadCachesIfNeeded()

        let context = ModelContext(modelContainer)

        // Fetch canonical games within date range
        let sportStrings = sports.map { $0.rawValue }
        let descriptor = FetchDescriptor<CanonicalGame>(
            predicate: #Predicate<CanonicalGame> { game in
                sportStrings.contains(game.sport) &&
                game.dateTime >= startDate &&
                game.dateTime <= endDate &&
                game.deprecatedAt == nil
            },
            sortBy: [SortDescriptor(\.dateTime)]
        )

        let canonicalGames = try context.fetch(descriptor)

        // Convert to domain models
        return canonicalGames.compactMap { canonical -> Game? in
            guard let homeTeamUUID = teamUUIDByCanonicalId[canonical.homeTeamCanonicalId],
                  let awayTeamUUID = teamUUIDByCanonicalId[canonical.awayTeamCanonicalId],
                  let stadiumUUID = stadiumUUIDByCanonicalId[canonical.stadiumCanonicalId] else {
                return nil
            }

            return Game(
                id: canonical.uuid,
                homeTeamId: homeTeamUUID,
                awayTeamId: awayTeamUUID,
                stadiumId: stadiumUUID,
                dateTime: canonical.dateTime,
                sport: canonical.sportEnum ?? .mlb,
                season: canonical.season,
                isPlayoff: canonical.isPlayoff,
                broadcastInfo: canonical.broadcastInfo
            )
        }
    }

    func fetchGame(by id: UUID) async throws -> Game? {
        try await loadCachesIfNeeded()

        let context = ModelContext(modelContainer)

        // Search by UUID
        let descriptor = FetchDescriptor<CanonicalGame>(
            predicate: #Predicate<CanonicalGame> { game in
                game.uuid == id && game.deprecatedAt == nil
            }
        )

        guard let canonical = try context.fetch(descriptor).first else {
            return nil
        }

        guard let homeTeamUUID = teamUUIDByCanonicalId[canonical.homeTeamCanonicalId],
              let awayTeamUUID = teamUUIDByCanonicalId[canonical.awayTeamCanonicalId],
              let stadiumUUID = stadiumUUIDByCanonicalId[canonical.stadiumCanonicalId] else {
            return nil
        }

        return Game(
            id: canonical.uuid,
            homeTeamId: homeTeamUUID,
            awayTeamId: awayTeamUUID,
            stadiumId: stadiumUUID,
            dateTime: canonical.dateTime,
            sport: canonical.sportEnum ?? .mlb,
            season: canonical.season,
            isPlayoff: canonical.isPlayoff,
            broadcastInfo: canonical.broadcastInfo
        )
    }

    func fetchRichGames(sports: Set<Sport>, startDate: Date, endDate: Date) async throws -> [RichGame] {
        try await loadCachesIfNeeded()

        let games = try await fetchGames(sports: sports, startDate: startDate, endDate: endDate)
        let teamsById = Dictionary(uniqueKeysWithValues: (cachedTeams ?? []).map { ($0.id, $0) })
        let stadiumsById = Dictionary(uniqueKeysWithValues: (cachedStadiums ?? []).map { ($0.id, $0) })

        return games.compactMap { game in
            guard let homeTeam = teamsById[game.homeTeamId],
                  let awayTeam = teamsById[game.awayTeamId],
                  let stadium = stadiumsById[game.stadiumId] else {
                return nil
            }
            return RichGame(game: game, homeTeam: homeTeam, awayTeam: awayTeam, stadium: stadium)
        }
    }

    // MARK: - Additional Queries

    /// Fetch stadium by canonical ID (useful for visit tracking)
    func fetchStadium(byCanonicalId canonicalId: String) async throws -> Stadium? {
        try await loadCachesIfNeeded()
        return stadiumsByCanonicalId[canonicalId]
    }

    /// Fetch team by canonical ID
    func fetchTeam(byCanonicalId canonicalId: String) async throws -> Team? {
        try await loadCachesIfNeeded()
        return teamsByCanonicalId[canonicalId]
    }

    /// Find stadium by name (matches aliases)
    func findStadium(byName name: String) async throws -> Stadium? {
        let context = ModelContext(modelContainer)

        // Precompute lowercased name outside the predicate
        let lowercasedName = name.lowercased()

        // First try exact alias match
        let aliasDescriptor = FetchDescriptor<StadiumAlias>(
            predicate: #Predicate<StadiumAlias> { alias in
                alias.aliasName == lowercasedName
            }
        )

        if let alias = try context.fetch(aliasDescriptor).first,
           let stadiumCanonicalId = Optional(alias.stadiumCanonicalId) {
            return try await fetchStadium(byCanonicalId: stadiumCanonicalId)
        }

        return nil
    }

    /// Invalidate caches (call after sync completes)
    func invalidateCaches() {
        cachedTeams = nil
        cachedStadiums = nil
        teamsByCanonicalId.removeAll()
        stadiumsByCanonicalId.removeAll()
        teamUUIDByCanonicalId.removeAll()
        stadiumUUIDByCanonicalId.removeAll()
    }

    // MARK: - Private Helpers

    private func loadCachesIfNeeded() async throws {
        guard cachedTeams == nil else { return }

        let context = ModelContext(modelContainer)

        // Load stadiums
        let stadiumDescriptor = FetchDescriptor<CanonicalStadium>(
            predicate: #Predicate<CanonicalStadium> { stadium in
                stadium.deprecatedAt == nil
            }
        )
        let canonicalStadiums = try context.fetch(stadiumDescriptor)

        cachedStadiums = canonicalStadiums.map { canonical in
            let stadium = canonical.toDomain()
            stadiumsByCanonicalId[canonical.canonicalId] = stadium
            stadiumUUIDByCanonicalId[canonical.canonicalId] = stadium.id
            return stadium
        }

        // Load teams
        let teamDescriptor = FetchDescriptor<CanonicalTeam>(
            predicate: #Predicate<CanonicalTeam> { team in
                team.deprecatedAt == nil
            }
        )
        let canonicalTeams = try context.fetch(teamDescriptor)

        cachedTeams = canonicalTeams.compactMap { canonical -> Team? in
            guard let stadiumUUID = stadiumUUIDByCanonicalId[canonical.stadiumCanonicalId] else {
                // Generate a placeholder UUID for teams without known stadiums
                let placeholderUUID = CanonicalStadium.deterministicUUID(from: canonical.stadiumCanonicalId)
                let team = canonical.toDomain(stadiumUUID: placeholderUUID)
                teamsByCanonicalId[canonical.canonicalId] = team
                teamUUIDByCanonicalId[canonical.canonicalId] = team.id
                return team
            }

            let team = canonical.toDomain(stadiumUUID: stadiumUUID)
            teamsByCanonicalId[canonical.canonicalId] = team
            teamUUIDByCanonicalId[canonical.canonicalId] = team.id
            return team
        }
    }
}