import Foundation
import SwiftUI

@MainActor
class ChallengeViewModel: ObservableObject {
    @Published var challenges: [Challenge] = []
    @Published var selectedChallenge: Challenge?
    @Published var leaderboard: [LeaderboardEntry] = []
    @Published var isLoading: Bool = false
    @Published var error: ChallengeError?
    @Published var filter: ChallengeFilter = ChallengeFilter()

    private let service: ChallengeServiceProtocol

    init(service: ChallengeServiceProtocol = ChallengeService()) {
        self.service = service
    }

    func fetchChallenges() async {
        isLoading = true
        error = nil
        defer { isLoading = false }

        do {
            challenges = try await service.listChallenges(filter: filter)
        } catch let error as ChallengeError {
            self.error = error
        } catch {
            print("Failed to fetch challenges: \(error)")
        }
    }

    func selectChallenge(id: String) async {
        isLoading = true
        error = nil
        defer { isLoading = false }

        do {
            let result = try await service.getChallenge(id: id)
            selectedChallenge = result.challenge
            if let index = challenges.firstIndex(where: { $0.id == id }) {
                challenges[index] = result.challenge
                objectWillChange.send()
            }
        } catch let error as ChallengeError {
            self.error = error
        } catch {
            print("Failed to get challenge: \(error)")
        }
    }

    func createChallenge(request: CreateChallengeRequest) async -> Challenge? {
        isLoading = true
        error = nil
        defer { isLoading = false }

        do {
            let challenge = try await service.createChallenge(request: request)
            challenges.insert(challenge, at: 0)
            objectWillChange.send()
            return challenge
        } catch let error as ChallengeError {
            self.error = error
            return nil
        } catch {
            print("Failed to create challenge: \(error)")
            return nil
        }
    }

    func updateChallenge(id: String, request: UpdateChallengeRequest) async {
        isLoading = true
        error = nil
        defer { isLoading = false }

        do {
            let updatedChallenge = try await service.updateChallenge(id: id, request: request)
            if let index = challenges.firstIndex(where: { $0.id == id }) {
                challenges[index] = updatedChallenge
                objectWillChange.send()
            }
            if selectedChallenge?.id == id {
                selectedChallenge = updatedChallenge
            }
        } catch let error as ChallengeError {
            self.error = error
        } catch {
            print("Failed to update challenge: \(error)")
        }
    }

    func joinChallenge(id: String) async {
        do {
            try await service.joinChallenge(id: id)
            if let index = challenges.firstIndex(where: { $0.id == id }) {
                challenges[index].participationStatus = .participating
                challenges[index].participantCount += 1
                objectWillChange.send()
            }
        } catch {
            print("Failed to join challenge: \(error)")
        }
    }

    func leaveChallenge(id: String) async {
        do {
            try await service.leaveChallenge(id: id)
            if let index = challenges.firstIndex(where: { $0.id == id }) {
                challenges[index].participationStatus = .notParticipating
                challenges[index].participantCount = max(0, challenges[index].participantCount - 1)
                objectWillChange.send()
            }
        } catch {
            print("Failed to leave challenge: \(error)")
        }
    }

    func fetchLeaderboard(challengeId: String) async {
        isLoading = true
        error = nil
        defer { isLoading = false }

        do {
            leaderboard = try await service.getLeaderboard(challengeId: challengeId)
        } catch let error as ChallengeError {
            self.error = error
        } catch {
            print("Failed to fetch leaderboard: \(error)")
        }
    }

    func submitProgress(challengeId: String, progress: ProgressSubmission) async {
        do {
            let result = try await service.submitProgress(challengeId: challengeId, progress: progress)
            if let index = challenges.firstIndex(where: { $0.id == challengeId }) {
                challenges[index].userProgress = result.progress
                objectWillChange.send()
            }
            if selectedChallenge?.id == challengeId {
                selectedChallenge?.userProgress = result.progress
            }
        } catch {
            print("Failed to submit progress: \(error)")
        }
    }

    var activeChallenges: [Challenge] {
        challenges.filter { $0.isActive }.sorted { $0.endDate < $1.endDate }
    }

    var upcomingChallenges: [Challenge] {
        challenges.filter { $0.isUpcoming }.sorted { $0.startDate < $1.startDate }
    }

    var completedChallenges: [Challenge] {
        challenges.filter { $0.isCompleted }.sorted { $0.endDate > $1.endDate }
    }

    var userChallenges: [Challenge] {
        challenges.filter { $0.participationStatus == .participating }
    }

    var challengeTypes: [ChallengeType] { ChallengeType.allCases }
    var challengeStatuses: [ChallengeStatus] { ChallengeStatus.allCases }
}