import CoreData
import Foundation
import Observation
import SwiftUI
import Swinject

extension Stat {
    @Observable final class StateModel: BaseStateModel<Provider> {
        @ObservationIgnored @Injected() var settings: SettingsManager!
        var highLimit: Decimal = 180
        var lowLimit: Decimal = 70
        var hbA1cDisplayUnit: HbA1cDisplayUnit = .percent
        var timeInRangeChartStyle: TimeInRangeChartStyle = .vertical
        var units: GlucoseUnits = .mgdL
        var glucoseFromPersistence: [GlucoseStored] = []
        var loopStatRecords: [LoopStatRecord] = []
        var groupedLoopStats: [LoopStatsByPeriod] = []
        var mealStats: [MealStats] = []
        var tddStats: [TDD] = []
        var bolusStats: [BolusStats] = []
        var selectedDurationForGlucoseStats: Duration = .Today {
            didSet {
                setupGlucoseArray(for: selectedDurationForGlucoseStats)
            }
        }

        var selectedDurationForInsulinStats: StatsTimeInterval = .Day
        var selectedDurationForMealStats: StatsTimeInterval = .Day

        var selectedDurationForLoopStats: Duration = .Today {
            didSet {
                setupLoopStatRecords()
            }
        }

        let context = CoreDataStack.shared.newTaskContext()
        let viewContext = CoreDataStack.shared.persistentContainer.viewContext
        let determinationFetchContext = CoreDataStack.shared.newTaskContext()
        let loopTaskContext = CoreDataStack.shared.newTaskContext()
        let mealTaskContext = CoreDataStack.shared.newTaskContext()
        let bolusTaskContext = CoreDataStack.shared.newTaskContext()

        enum Duration: String, CaseIterable, Identifiable {
            case Today
            case Day = "D"
            case Week = "W"
            case Month = "M"
            case Total = "3 M"

            var id: Self { self }
        }

        enum StatsTimeInterval: String, CaseIterable, Identifiable {
            case Day = "D"
            case Week = "W"
            case Month = "M"
            case Total = "3 M"

            var id: Self { self }
        }

        var hourlyStats: [HourlyStats] = []
        var glucoseRangeStats: [GlucoseRangeStats] = []

        override func subscribe() {
            setupGlucoseArray(for: .Today)
            setupTDDs()
            setupBolusStats()
            setupLoopStatRecords()
            setupMealStats()
            highLimit = settingsManager.settings.high
            lowLimit = settingsManager.settings.low
            units = settingsManager.settings.units
            hbA1cDisplayUnit = settingsManager.settings.hbA1cDisplayUnit
            timeInRangeChartStyle = settingsManager.settings.timeInRangeChartStyle
        }

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

                // Calculate hourly stats and glucose range stats asynchronously with fetched glucose IDs
                async let hourlyStats: () = calculateHourlyStatsForGlucoseAreaChart(from: ids)
                async let glucoseRangeStats: () = calculateGlucoseRangeStatsForStackedChart(from: ids)
                _ = await (hourlyStats, glucoseRangeStats)
            }
        }

        private func fetchGlucose(for duration: Duration) async -> [NSManagedObjectID] {
            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
            }

            let results = await CoreDataStack.shared.fetchEntitiesAsync(
                ofType: GlucoseStored.self,
                onContext: context,
                predicate: predicate,
                key: "date",
                ascending: false,
                batchSize: 100,
                propertiesToFetch: ["glucose", "objectID"]
            )

            return await context.perform {
                guard let fetchedResults = results as? [[String: Any]] else { return [] }

                return fetchedResults.compactMap { $0["objectID"] as? NSManagedObjectID }
            }
        }

        @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)"
                )
            }
        }
    }

    @Observable final class UpdateTimer {
        private var workItem: DispatchWorkItem?

        func scheduleUpdate(action: @escaping () -> Void) {
            workItem?.cancel()

            let newWorkItem = DispatchWorkItem {
                Task { @MainActor in
                    action()
                }
            }
            workItem = newWorkItem

            DispatchQueue.main.asyncAfter(deadline: .now() + 0.05, execute: newWorkItem)
        }
    }
}