import Foundation
import SwiftUI

@MainActor
class TrainingPlanViewModel: ObservableObject {
    @Published var plans: [TrainingPlan] = []
    @Published var selectedPlan: TrainingPlan?
    @Published var isLoading: Bool = false
    @Published var error: TrainingPlanError?

    private let service: TrainingPlanServiceProtocol

    init(service: TrainingPlanServiceProtocol = TrainingPlanService()) {
        self.service = service
    }

    func fetchPlans(type: PlanType? = nil, difficulty: Difficulty? = nil) async {
        isLoading = true
        error = nil
        defer { isLoading = false }

        do {
            plans = try await service.listPlans(type: type, difficulty: difficulty)
        } catch let error as TrainingPlanError {
            self.error = error
        } catch {
            print("Failed to fetch training plans: \(error)")
        }
    }

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

        do {
            selectedPlan = try await service.getPlan(id: id)
        } catch let error as TrainingPlanError {
            self.error = error
        } catch {
            print("Failed to get plan: \(error)")
        }
    }

    func generatePlan(request: GeneratePlanRequest) async -> TrainingPlan? {
        isLoading = true
        error = nil
        defer { isLoading = false }

        do {
            let plan = try await service.generatePlan(request: request)
            plans.insert(plan, at: 0)
            return plan
        } catch let error as TrainingPlanError {
            self.error = error
            return nil
        } catch {
            print("Failed to generate plan: \(error)")
            return nil
        }
    }

    func followPlan(id: String) async {
        do {
            try await service.followPlan(id: id)
            if let index = plans.firstIndex(where: { $0.id == id }) {
                plans[index].isFollowing = true
                objectWillChange.send()
            }
        } catch {
            print("Failed to follow plan: \(error)")
        }
    }

    func unfollowPlan(id: String) async {
        do {
            try await service.unfollowPlan(id: id)
            if let index = plans.firstIndex(where: { $0.id == id }) {
                plans[index].isFollowing = false
                objectWillChange.send()
            }
        } catch {
            print("Failed to unfollow plan: \(error)")
        }
    }

    func updateSessionStatus(sessionId: String, status: SessionStatus) async {
        do {
            try await service.updateSessionStatus(sessionId: sessionId, status: status)
            if var plan = selectedPlan {
                for weekIndex in plan.weeklyWorkouts.indices {
                    for sessionIndex in plan.weeklyWorkouts[weekIndex].dailySessions.indices {
                        if plan.weeklyWorkouts[weekIndex].dailySessions[sessionIndex].id == sessionId {
                            plan.weeklyWorkouts[weekIndex].dailySessions[sessionIndex].status = status
                            selectedPlan = plan
                            return
                        }
                    }
                }
            }
        } catch {
            print("Failed to update session status: \(error)")
        }
    }

    var planTypes: [PlanType] { PlanType.allCases }
    var difficulties: [Difficulty] { Difficulty.allCases }
}