import SwiftUI
import Charts

struct ChartsContainerView: View {
    @EnvironmentObject var accountStore: AccountStore
    @StateObject private var viewModel: ChartsViewModel
    @StateObject private var goalsViewModel = GoalsViewModel()
    @AppStorage("calmModeEnabled") private var calmModeEnabled = true

    init(iapService: IAPService) {
        _viewModel = StateObject(wrappedValue: ChartsViewModel(iapService: iapService))
    }

    var body: some View {
        NavigationStack {
            ZStack {
                AppBackground()

                ScrollView {
                    VStack(spacing: 20) {
                        // Chart Type Selector
                        chartTypeSelector

                        // Time Range Selector
                        if viewModel.selectedChartType != .allocation &&
                           viewModel.selectedChartType != .performance &&
                           viewModel.selectedChartType != .riskReturn {
                            timeRangeSelector
                        }

                        // Category Filter
                        if viewModel.selectedChartType == .evolution ||
                           viewModel.selectedChartType == .prediction {
                            categoryFilter
                        }

                        // Chart Content
                        chartContent
                    }
                    .padding()
                }
            }
            .navigationTitle("Charts")
            .sheet(isPresented: $viewModel.showingPaywall) {
                PaywallView()
            }
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    accountFilterMenu
                }
            }
            .onAppear {
                viewModel.selectedAccount = accountStore.selectedAccount
                viewModel.showAllAccounts = accountStore.showAllAccounts
                viewModel.loadData()
                goalsViewModel.selectedAccount = accountStore.selectedAccount
                goalsViewModel.showAllAccounts = accountStore.showAllAccounts
                goalsViewModel.refresh()
                viewModel.updatePredictionTargetDate(goalsViewModel.goals)
            }
            // Performance: Use onChange instead of onReceive for cleaner state updates
            .onChange(of: accountStore.selectedAccount) { _, newAccount in
                viewModel.selectedAccount = newAccount
                goalsViewModel.selectedAccount = newAccount
                goalsViewModel.refresh()
                viewModel.updatePredictionTargetDate(goalsViewModel.goals)
            }
            .onChange(of: accountStore.showAllAccounts) { _, showAll in
                viewModel.showAllAccounts = showAll
                goalsViewModel.showAllAccounts = showAll
                goalsViewModel.refresh()
                viewModel.updatePredictionTargetDate(goalsViewModel.goals)
            }
            .onChange(of: goalsViewModel.goals) { _, goals in
                viewModel.updatePredictionTargetDate(goals)
            }
        }
    }

    // MARK: - Chart Type Selector

    private var chartTypeSelector: some View {
        ScrollView(.horizontal, showsIndicators: false) {
            HStack(spacing: 12) {
                ForEach(viewModel.availableChartTypes(calmModeEnabled: calmModeEnabled)) { chartType in
                    ChartTypeButton(
                        chartType: chartType,
                        isSelected: viewModel.selectedChartType == chartType,
                        isPremium: chartType.isPremium,
                        userIsPremium: viewModel.isPremium
                    ) {
                        viewModel.selectChart(chartType)
                    }
                }
            }
            .padding(.horizontal, 4)
        }
    }

    // MARK: - Time Range Selector

    private var timeRangeSelector: some View {
        HStack(spacing: 8) {
            ForEach(ChartsViewModel.TimeRange.allCases) { range in
                Button {
                    viewModel.selectedTimeRange = range
                } label: {
                    Text(range.rawValue)
                        .font(.subheadline.weight(.medium))
                        .padding(.horizontal, 16)
                        .padding(.vertical, 8)
                        .background(
                            viewModel.selectedTimeRange == range
                                ? Color.appPrimary
                                : Color.gray.opacity(0.1)
                        )
                        .foregroundColor(
                            viewModel.selectedTimeRange == range
                                ? .white
                                : .primary
                        )
                        .cornerRadius(20)
                }
            }
        }
    }

    // MARK: - Category Filter

    @ViewBuilder
    private var categoryFilter: some View {
        let availableCategories = viewModel.availableCategories(for: viewModel.selectedChartType)
        if !availableCategories.isEmpty {
            ScrollView(.horizontal, showsIndicators: false) {
                HStack(spacing: 8) {
                    if availableCategories.count > 1 {
                        Button {
                            viewModel.selectedCategory = nil
                        } label: {
                            Text("All")
                                .font(.caption.weight(.medium))
                                .padding(.horizontal, 12)
                                .padding(.vertical, 6)
                                .background(
                                    viewModel.selectedCategory == nil
                                        ? Color.appPrimary
                                        : Color.gray.opacity(0.1)
                                )
                                .foregroundColor(
                                    viewModel.selectedCategory == nil
                                        ? .white
                                        : .primary
                                )
                                .cornerRadius(16)
                        }
                    }

                    ForEach(availableCategories) { category in
                        Button {
                            viewModel.selectedCategory = category
                        } label: {
                            HStack(spacing: 4) {
                                Circle()
                                    .fill(category.color)
                                    .frame(width: 8, height: 8)
                                Text(category.name)
                            }
                            .font(.caption.weight(.medium))
                            .padding(.horizontal, 12)
                            .padding(.vertical, 6)
                            .background(
                                viewModel.selectedCategory?.id == category.id
                                    ? category.color
                                    : Color.gray.opacity(0.1)
                            )
                            .foregroundColor(
                                viewModel.selectedCategory?.id == category.id
                                    ? .white
                                    : .primary
                            )
                            .cornerRadius(16)
                        }
                    }
                }
            }
        }
    }

    // MARK: - Chart Content

    @ViewBuilder
    private var chartContent: some View {
        if viewModel.isLoading {
            ProgressView()
                .frame(height: 300)
        } else if !viewModel.hasData {
            emptyStateView
        } else {
            switch viewModel.selectedChartType {
            case .evolution:
                EvolutionChartView(
                    data: viewModel.evolutionData,
                    categoryData: viewModel.categoryEvolutionData,
                    goals: goalsViewModel.goals
                )
            case .allocation:
                AllocationPieChart(data: viewModel.allocationData)
            case .performance:
                PerformanceBarChart(data: viewModel.performanceData)
            case .contributions:
                ContributionsChartView(data: viewModel.contributionsData)
            case .rollingReturn:
                RollingReturnChartView(data: viewModel.rollingReturnData)
            case .riskReturn:
                RiskReturnChartView(data: viewModel.riskReturnData)
            case .cashflow:
                CashflowStackedChartView(data: viewModel.cashflowData)
            case .drawdown:
                DrawdownChart(data: viewModel.drawdownData)
            case .volatility:
                VolatilityChartView(data: viewModel.volatilityData)
            case .prediction:
                PredictionChartView(
                    predictions: viewModel.predictionData,
                    historicalData: viewModel.evolutionData
                )
            }
        }
    }

    private var emptyStateView: some View {
        VStack(spacing: 16) {
            Image(systemName: "chart.bar.xaxis")
                .font(.system(size: 48))
                .foregroundColor(.secondary)

            Text("No Data Available")
                .font(.headline)

            Text("Add some investment sources and snapshots to see charts.")
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
        }
        .frame(height: 300)
    }

    private var accountFilterMenu: some View {
        Menu {
            Button {
                accountStore.selectAllAccounts()
            } label: {
                HStack {
                    Text("All Accounts")
                    if accountStore.showAllAccounts {
                        Image(systemName: "checkmark")
                    }
                }
            }

            Divider()

            ForEach(accountStore.accounts) { account in
                Button {
                    accountStore.selectAccount(account)
                } label: {
                    HStack {
                        Text(account.name)
                        if accountStore.selectedAccount?.id == account.id && !accountStore.showAllAccounts {
                            Image(systemName: "checkmark")
                        }
                    }
                }
            }
        } label: {
            Image(systemName: "person.2.circle")
        }
    }
}

// MARK: - Chart Type Button

struct ChartTypeButton: View {
    let chartType: ChartsViewModel.ChartType
    let isSelected: Bool
    let isPremium: Bool
    let userIsPremium: Bool
    let action: () -> Void

    var body: some View {
        Button(action: action) {
            VStack(spacing: 8) {
                ZStack(alignment: .topTrailing) {
                    Image(systemName: chartType.icon)
                        .font(.title2)

                    if isPremium && !userIsPremium {
                        Image(systemName: "lock.fill")
                            .font(.caption2)
                            .foregroundColor(.appWarning)
                            .offset(x: 8, y: -4)
                    }
                }

                Text(chartType.rawValue)
                    .font(.caption)
            }
            .frame(width: 80, height: 70)
            .background(
                isSelected
                    ? LinearGradient.appPrimaryGradient
                    : LinearGradient(
                        colors: [
                            Color(.systemBackground).opacity(0.85),
                            Color(.systemBackground).opacity(0.85)
                        ],
                        startPoint: .top,
                        endPoint: .bottom
                    )
            )
            .foregroundColor(isSelected ? .white : .primary)
            .cornerRadius(AppConstants.UI.cornerRadius)
            .shadow(color: .black.opacity(0.05), radius: 4, y: 2)
        }
    }
}

// MARK: - Evolution Chart View

struct EvolutionChartView: View {
    let data: [(date: Date, value: Decimal)]
    let categoryData: [CategoryEvolutionPoint]
    let goals: [Goal]

    @State private var selectedDataPoint: (date: Date, value: Decimal)?
    @State private var chartMode: ChartMode = .total
    @State private var showGoalLines = false

    enum ChartMode: String, CaseIterable, Identifiable {
        case total = "Total"
        case byCategory = "By Category"

        var id: String { rawValue }
    }

    private var stackedCategoryData: [CategoryEvolutionPoint] {
        guard !categoryData.isEmpty else { return [] }

        let totalsByCategory = categoryData.reduce(into: [String: Decimal]()) { result, point in
            result[point.categoryName, default: 0] += point.value
        }

        let categoryOrder = totalsByCategory
            .sorted { $0.value > $1.value }
            .map { $0.key }
        let orderIndex = Dictionary(uniqueKeysWithValues: categoryOrder.enumerated().map { ($0.element, $0.offset) })

        let groupedByDate = Dictionary(grouping: categoryData) { $0.date }
        let sortedDates = groupedByDate.keys.sorted()

        var stacked: [CategoryEvolutionPoint] = []

        for date in sortedDates {
            guard let points = groupedByDate[date] else { continue }
            let sortedPoints = points.sorted {
                (orderIndex[$0.categoryName] ?? Int.max) < (orderIndex[$1.categoryName] ?? Int.max)
            }

            var running: Decimal = 0
            for point in sortedPoints {
                running += point.value
                stacked.append(CategoryEvolutionPoint(
                    date: point.date,
                    categoryName: point.categoryName,
                    colorHex: point.colorHex,
                    value: running
                ))
            }
        }

        return stacked
    }

    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            headerView
            modePicker
            chartSection
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    private var headerView: some View {
        HStack {
            Text("Portfolio Evolution")
                .font(.headline)

            Spacer()

            if let selected = selectedDataPoint, chartMode == .total {
                VStack(alignment: .trailing, spacing: 2) {
                    Text(selected.value.compactCurrencyString)
                        .font(.subheadline.weight(.semibold))
                    Text(selected.date.monthYearString)
                        .font(.caption)
                        .foregroundColor(.secondary)
                }
            }

            Button {
                showGoalLines.toggle()
            } label: {
                Image(systemName: showGoalLines ? "target" : "slash.circle")
                    .foregroundColor(.secondary)
            }
            .disabled(goals.isEmpty)
            .accessibilityLabel(showGoalLines ? "Hide goals" : "Show goals")
        }
    }

    private var modePicker: some View {
        Picker("Evolution Mode", selection: $chartMode) {
            ForEach(ChartMode.allCases) { mode in
                Text(mode.rawValue).tag(mode)
            }
        }
        .pickerStyle(.segmented)
    }

    @ViewBuilder
    private var chartSection: some View {
        if data.count >= 2 {
            chartView
        } else {
            Text("Not enough data")
                .foregroundColor(.secondary)
                .frame(height: 300)
        }
    }

    private var chartView: some View {
        Chart {
            chartMarks
        }
        .chartForegroundStyleScale(domain: chartCategoryNames, range: chartCategoryColors)
        .chartXAxis {
            AxisMarks(values: .stride(by: .month, count: 2)) { value in
                AxisValueLabel(format: .dateTime.month(.abbreviated))
            }
        }
        .chartYAxis {
            AxisMarks(position: .leading) { value in
                AxisValueLabel {
                    if let doubleValue = value.as(Double.self) {
                        Text(Decimal(doubleValue).shortCurrencyString)
                            .font(.caption)
                    }
                }
            }
        }
        .chartOverlay { proxy in
            if chartMode == .total {
                GeometryReader { geometry in
                    Rectangle()
                        .fill(.clear)
                        .contentShape(Rectangle())
                        .gesture(
                            DragGesture(minimumDistance: 0)
                                .onChanged { value in
                                    guard let plotFrameAnchor = proxy.plotFrame else { return }
                                    let plotFrame = geometry[plotFrameAnchor]
                                    let x = value.location.x - plotFrame.origin.x
                                    guard let date: Date = proxy.value(atX: x) else { return }

                                    if let closest = data.min(by: {
                                        abs($0.date.timeIntervalSince(date)) < abs($1.date.timeIntervalSince(date))
                                    }) {
                                        selectedDataPoint = closest
                                    }
                                }
                                .onEnded { _ in
                                    selectedDataPoint = nil
                                }
                        )
                }
            }
        }
        .frame(height: 300)
        // Performance: Use GPU rendering for smoother scrolling on older devices
        .drawingGroup()
    }

    @ChartContentBuilder
    private var chartMarks: some ChartContent {
        switch chartMode {
        case .total:
            ForEach(data, id: \.date) { item in
                LineMark(
                    x: .value("Date", item.date),
                    y: .value("Value", NSDecimalNumber(decimal: item.value).doubleValue)
                )
                .foregroundStyle(Color.appPrimary)
                .interpolationMethod(.catmullRom)

                PointMark(
                    x: .value("Date", item.date),
                    y: .value("Value", NSDecimalNumber(decimal: item.value).doubleValue)
                )
                .foregroundStyle(Color.appPrimary)
                .symbolSize(30)

                AreaMark(
                    x: .value("Date", item.date),
                    y: .value("Value", NSDecimalNumber(decimal: item.value).doubleValue)
                )
                .foregroundStyle(
                    LinearGradient(
                        colors: [Color.appPrimary.opacity(0.3), Color.appPrimary.opacity(0.0)],
                        startPoint: .top,
                        endPoint: .bottom
                    )
                )
                .interpolationMethod(.catmullRom)
            }
        case .byCategory:
            ForEach(categoryData) { item in
                AreaMark(
                    x: .value("Date", item.date),
                    y: .value("Value", NSDecimalNumber(decimal: item.value).doubleValue)
                )
                .foregroundStyle(by: .value("Category", item.categoryName))
                .interpolationMethod(.catmullRom)
                .opacity(0.5)
            }

            ForEach(stackedCategoryData) { item in
                LineMark(
                    x: .value("Date", item.date),
                    y: .value("Value", NSDecimalNumber(decimal: item.value).doubleValue)
                )
                .foregroundStyle(by: .value("Category", item.categoryName))
                .interpolationMethod(.catmullRom)

                PointMark(
                    x: .value("Date", item.date),
                    y: .value("Value", NSDecimalNumber(decimal: item.value).doubleValue)
                )
                .foregroundStyle(by: .value("Category", item.categoryName))
                .symbolSize(18)
            }
        }

        if showGoalLines {
            ForEach(goals) { goal in
                RuleMark(y: .value("Goal", NSDecimalNumber(decimal: goal.targetDecimal).doubleValue))
                    .foregroundStyle(Color.appSecondary.opacity(0.4))
                    .lineStyle(StrokeStyle(lineWidth: 1, dash: [6, 4]))
            }
        }
    }

    private var chartCategoryNames: [String] {
        let names = Array(Set(categoryData.map { $0.categoryName })).sorted()
        return names
    }

    private var chartCategoryColors: [Color] {
        chartCategoryNames.map { name in
            if let hex = categoryData.first(where: { $0.categoryName == name })?.colorHex {
                return Color(hex: hex) ?? .gray
            }
            return .gray
        }
    }
}

// MARK: - Contributions Chart

struct ContributionsChartView: View {
    let data: [(date: Date, amount: Decimal)]

    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Contributions")
                .font(.headline)

            if data.isEmpty {
                Text("No contributions yet.")
                    .foregroundColor(.secondary)
                    .frame(height: 260)
            } else {
                Chart {
                    ForEach(data, id: \.date) { item in
                        BarMark(
                            x: .value("Month", item.date),
                            y: .value("Amount", NSDecimalNumber(decimal: item.amount).doubleValue)
                        )
                        .foregroundStyle(Color.appSecondary)
                        .cornerRadius(6)
                    }
                }
                .chartXAxis {
                    AxisMarks(values: .stride(by: .month, count: 2)) { value in
                        AxisValueLabel(format: .dateTime.month(.abbreviated))
                    }
                }
                .chartYAxis {
                    AxisMarks(position: .leading) { value in
                        AxisValueLabel {
                            if let doubleValue = value.as(Double.self) {
                                Text(Decimal(doubleValue).shortCurrencyString)
                                    .font(.caption)
                            }
                        }
                    }
                }
                .frame(height: 260)
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }
}

// MARK: - Rolling 12-Month Return

struct RollingReturnChartView: View {
    let data: [(date: Date, value: Double)]

    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Rolling 12-Month Return")
                .font(.headline)

            if data.isEmpty {
                Text("Not enough data for rolling returns.")
                    .foregroundColor(.secondary)
                    .frame(height: 260)
            } else {
                Chart {
                    ForEach(data, id: \.date) { item in
                        LineMark(
                            x: .value("Month", item.date),
                            y: .value("Return", item.value)
                        )
                        .foregroundStyle(Color.appPrimary)
                        .interpolationMethod(.catmullRom)

                        PointMark(
                            x: .value("Month", item.date),
                            y: .value("Return", item.value)
                        )
                        .foregroundStyle(Color.appPrimary)
                        .symbolSize(24)
                    }
                }
                .chartXAxis {
                    AxisMarks(values: .stride(by: .month, count: 2)) { value in
                        AxisValueLabel(format: .dateTime.month(.abbreviated))
                    }
                }
                .chartYAxis {
                    AxisMarks(position: .leading) { value in
                        AxisValueLabel {
                            if let doubleValue = value.as(Double.self) {
                                Text(String(format: "%.1f%%", doubleValue))
                                    .font(.caption)
                            }
                        }
                    }
                }
                .frame(height: 260)
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }
}

// MARK: - Risk vs Return

struct RiskReturnChartView: View {
    let data: [(category: String, cagr: Double, volatility: Double, color: String)]

    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Risk vs Return")
                .font(.headline)

            if data.isEmpty {
                Text("Not enough data to compare categories.")
                    .foregroundColor(.secondary)
                    .frame(height: 260)
            } else {
                Chart {
                    ForEach(data, id: \.category) { item in
                        PointMark(
                            x: .value("Volatility", item.volatility),
                            y: .value("CAGR", item.cagr)
                        )
                        .foregroundStyle(Color(hex: item.color) ?? .gray)
                        .symbolSize(60)
                        .annotation(position: .top) {
                            Text(item.category)
                                .font(.caption2)
                                .foregroundColor(.secondary)
                        }
                    }
                }
                .chartXAxis {
                    AxisMarks(position: .bottom) { value in
                        AxisValueLabel {
                            if let doubleValue = value.as(Double.self) {
                                Text(String(format: "%.1f%%", doubleValue))
                                    .font(.caption)
                            }
                        }
                    }
                }
                .chartYAxis {
                    AxisMarks(position: .leading) { value in
                        AxisValueLabel {
                            if let doubleValue = value.as(Double.self) {
                                Text(String(format: "%.1f%%", doubleValue))
                                    .font(.caption)
                            }
                        }
                    }
                }
                .frame(height: 260)
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }
}

// MARK: - Net Performance vs Contributions

struct CashflowStackedChartView: View {
    let data: [(date: Date, contributions: Decimal, netPerformance: Decimal)]

    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Net Performance vs Contributions")
                .font(.headline)

            if data.isEmpty {
                Text("Not enough data to compare cashflow.")
                    .foregroundColor(.secondary)
                    .frame(height: 260)
            } else {
                Chart {
                    ForEach(data, id: \.date) { item in
                        let contributionValue = NSDecimalNumber(decimal: item.contributions).doubleValue
                        let netValue = NSDecimalNumber(decimal: item.netPerformance).doubleValue
                        let stackedEnd = contributionValue + netValue

                        BarMark(
                            x: .value("Month", item.date),
                            yStart: .value("Start", 0),
                            yEnd: .value("Contributions", contributionValue)
                        )
                        .foregroundStyle(Color.appSecondary.opacity(0.8))

                        BarMark(
                            x: .value("Month", item.date),
                            yStart: .value("Start", contributionValue),
                            yEnd: .value("Net", stackedEnd)
                        )
                        .foregroundStyle(netValue >= 0 ? Color.positiveGreen : Color.negativeRed)
                    }
                }
                .chartXAxis {
                    AxisMarks(values: .stride(by: .month, count: 2)) { value in
                        AxisValueLabel(format: .dateTime.month(.abbreviated))
                    }
                }
                .chartYAxis {
                    AxisMarks(position: .leading) { value in
                        AxisValueLabel {
                            if let doubleValue = value.as(Double.self) {
                                Text(Decimal(doubleValue).shortCurrencyString)
                                    .font(.caption)
                            }
                        }
                    }
                }
                .frame(height: 260)
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }
}

#Preview {
    ChartsContainerView(iapService: IAPService())
        .environmentObject(AccountStore(iapService: IAPService()))
}