import CoreData
import Foundation
import SwiftUI
import Swinject

extension Stat {
    final class StateModel: BaseStateModel<Provider> {
        @Injected() var settings: SettingsManager!
        @Published var highLimit: Decimal = 10 / 0.0555
        @Published var lowLimit: Decimal = 4 / 0.0555
        @Published var overrideUnit: Bool = false
        @Published var layingChart: Bool = false
        @Published var units: GlucoseUnits = .mmolL
        @Published var glucoseFromPersistence: [GlucoseStored] = []

        @Published var selectedDuration: Duration = .Today

        private let context = CoreDataStack.shared.newTaskContext()
        private let viewContext = CoreDataStack.shared.persistentContainer.viewContext

        enum Duration: String, CaseIterable, Identifiable {
            case Today
            case Day
            case Week
            case Month
            case Total
            var id: Self { self }
        }

        override func subscribe() {
            /// Default is today
            setupGlucoseArray(for: .Today)
            highLimit = settingsManager.settings.high
            lowLimit = settingsManager.settings.low
            units = settingsManager.settings.units
            overrideUnit = settingsManager.settings.overrideHbA1cUnit
            layingChart = settingsManager.settings.oneDimensionalGraph
        }

        func setupGlucoseArray(for duration: Duration) {
            Task {
                let ids = await self.fetchGlucose(for: duration)
                await updateGlucoseArray(with: ids)
            }
        }

        private func fetchGlucose(for duration: Duration) async -> [NSManagedObjectID] {
            await context.perform {
                let predicate: NSPredicate

                switch duration {
                case .Day:
                    predicate = NSPredicate.glucoseForStatsDay
                case .Week:
                    predicate = NSPredicate.glucoseForStatsWeek
                case .Today:
                    predicate = NSPredicate.glucoseForStatsToday
                case .Month:
                    predicate = NSPredicate.glucoseForStatsMonth
                case .Total:
                    predicate = NSPredicate.glucoseForStatsTotal
                }

                return CoreDataStack.shared.fetchEntities(
                    ofType: GlucoseStored.self,
                    onContext: self.context,
                    predicate: predicate,
                    key: "date",
                    ascending: false,
                    batchSize: 100,
                    propertiesToFetch: ["glucose", "date"]
                ).map(\.objectID)
            }
        }

        @MainActor private func updateGlucoseArray(with IDs: [NSManagedObjectID]) {
            do {
                let glucoseObjects = try IDs.compactMap { id in
                    try viewContext.existingObject(with: id) as? GlucoseStored
                }
                glucoseFromPersistence = glucoseObjects
            } catch {
                debugPrint(
                    "Home State: \(#function) \(DebuggingIdentifiers.failed) error while updating the glucose array: \(error.localizedDescription)"
                )
            }
        }
    }
}