import CoreData
import Foundation
import Observation
import SwiftUI
import Swinject

extension Stat {
    /// Defines the available types of glucose charts
    enum GlucoseChartType: String, CaseIterable {
        /// Ambulatory Glucose Profile showing percentile ranges
        case percentile = "Percentile"
        /// Time-based distribution of glucose ranges
        case distribution = "Distribution"
    }

    /// Defines the available types of insulin charts
    enum InsulinChartType: String, CaseIterable {
        /// Shows total daily insulin doses
        case totalDailyDose = "Total Daily Dose"
        /// Shows distribution of bolus types
        case bolusDistribution = "Bolus Distribution"
    }

    /// Defines the available types of looping charts
    enum LoopingChartType: String, CaseIterable {
        /// Shows loop completion and success rates
        case loopingPerformance = "Looping Performance"
        /// Shows CGM connection status over time
        case cgmConnectionTrace = "CGM Connection Trace"
        /// Shows Trio pump uptime statistics
        case trioUpTime = "Trio Up-Time"
    }

    /// Defines the available types of meal charts
    enum MealChartType: String, CaseIterable {
        /// Shows total meal statistics
        case totalMeals = "Total Meals"
        /// Shows correlation between meals and glucose excursions
        case mealToHypoHyperDistribution = "Meal to Hypo/Hyper"
    }

    @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 tddStats: [TDD] = []
        var bolusStats: [BolusStats] = []
        var hourlyStats: [HourlyStats] = []
        var glucoseRangeStats: [GlucoseRangeStats] = []

        // Cache for Meal Stats
        var hourlyMealStats: [MealStats] = []
        var dailyMealStats: [MealStats] = []
        var dailyAveragesCache: [Date: (carbs: Double, fat: Double, protein: Double)] = [:]

        // Cache for TDD Stats
        var hourlyTDDStats: [TDDStats] = []
        var dailyTDDStats: [TDDStats] = []
        var tddAveragesCache: [Date: Double] = [:]

        // Cache for Bolus Stats
        var hourlyBolusStats: [BolusStats] = []
        var dailyBolusStats: [BolusStats] = []
        var bolusAveragesCache: [Date: (manual: Double, smb: Double, external: Double)] = [:]

        // Selected Duration for Glucose Stats
        var selectedDurationForGlucoseStats: Duration = .Today {
            didSet {
                setupGlucoseArray(for: selectedDurationForGlucoseStats)
            }
        }

        // Selected Duration for Insulin Stats
        var selectedDurationForInsulinStats: StatsTimeInterval = .Day

        // Selected Duration for Meal Stats
        var selectedDurationForMealStats: StatsTimeInterval = .Day

        // Selected Duration for Loop Stats
        var selectedDurationForLoopStats: Duration = .Today {
            didSet {
                setupLoopStatRecords()
            }
        }

        // Selected Glucose Chart Type
        var selectedGlucoseChartType: GlucoseChartType = .percentile

        // Selected Insulin Chart Type
        var selectedInsulinChartType: InsulinChartType = .totalDailyDose

        // Selected Looping Chart Type
        var selectedLoopingChartType: LoopingChartType = .loopingPerformance

        // Selected Meal Chart Type
        var selectedMealChartType: MealChartType = .totalMeals

        // Fetching Contexts
        let context = CoreDataStack.shared.newTaskContext()
        let viewContext = CoreDataStack.shared.persistentContainer.viewContext
        let tddTaskContext = CoreDataStack.shared.newTaskContext()
        let loopTaskContext = CoreDataStack.shared.newTaskContext()
        let mealTaskContext = CoreDataStack.shared.newTaskContext()
        let bolusTaskContext = CoreDataStack.shared.newTaskContext()

        /// Defines the available time periods for duration-based statistics
        enum Duration: String, CaseIterable, Identifiable {
            /// Current day
            case Today
            /// Single day view
            case Day = "D"
            /// Week view
            case Week = "W"
            /// Month view
            case Month = "M"
            /// Three month view
            case Total = "3 M"

            var id: Self { self }
        }

        /// Defines the available time intervals for statistical analysis
        enum StatsTimeInterval: String, CaseIterable, Identifiable {
            /// Single day interval
            case Day = "D"
            /// Week interval
            case Week = "W"
            /// Month interval
            case Month = "M"
            /// Three month interval
            case Total = "3 M"

            var id: Self { self }
        }

        /// Defines the main categories of statistics available in the app
        enum StatisticViewType: String, CaseIterable, Identifiable {
            /// Glucose-related statistics including AGP and distributions
            case glucose
            /// Insulin delivery statistics including TDD and bolus distributions
            case insulin
            /// Loop performance and system status statistics
            case looping
            /// Meal-related statistics and correlations
            case meals

            var id: String { rawValue }

            var title: String {
                switch self {
                case .glucose: return "Glucose"
                case .insulin: return "Insulin"
                case .looping: return "Looping"
                case .meals: return "Meals"
                }
            }
        }

        override func subscribe() {
            setupGlucoseArray(for: .Today)
            setupTDDStats()
            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?

        /// Schedules a delayed update action
        /// - Parameter action: The closure to execute after the delay
        /// Cancels any previously scheduled update before scheduling a new one
        func scheduleUpdate(action: @escaping () -> Void) {
            workItem?.cancel()

            let newWorkItem = DispatchWorkItem {
                action()
            }
            workItem = newWorkItem

            DispatchQueue.main.asyncAfter(deadline: .now() + 0.1, execute: newWorkItem)
        }
    }
}