import SwiftUI
import Charts

// MARK: - FinanceView

struct FinanceView: View {
    @EnvironmentObject var authManager: AuthManager
    @State private var selectedTab = 0
    @State private var selectedMonth = Calendar.current.component(.month, from: Date())
    @State private var selectedYear = Calendar.current.component(.year, from: Date())

    var body: some View {
        ZStack {
            Color(hex: "0a0a1a").ignoresSafeArea()
            VStack(spacing: 0) {
                // Header with month picker
                HStack {
                    Text("Финансы").font(.title.bold()).foregroundColor(.white)
                    Spacer()
                    HStack(spacing: 8) {
                        Button(action: { prevMonth() }) {
                            Image(systemName: "chevron.left").foregroundColor(Color(hex: "8888aa"))
                        }
                        Text(monthLabel())
                            .font(.subheadline).foregroundColor(.white)
                            .frame(minWidth: 80)
                        Button(action: { nextMonth() }) {
                            Image(systemName: "chevron.right").foregroundColor(Color(hex: "8888aa"))
                        }
                    }
                }
                .padding(.horizontal)
                .padding(.top, 16)
                .padding(.bottom, 12)

                Picker("", selection: $selectedTab) {
                    Text("Обзор").tag(0)
                    Text("Транзакции").tag(1)
                    Text("Аналитика").tag(2)
                }
                .pickerStyle(.segmented)
                .padding(.horizontal)
                .padding(.bottom, 12)

                switch selectedTab {
                case 0: FinanceOverviewTab(month: selectedMonth, year: selectedYear)
                case 1: FinanceTransactionsTab(month: selectedMonth, year: selectedYear)
                default: FinanceAnalyticsTab(month: selectedMonth, year: selectedYear)
                }
            }
        }
    }

    func monthLabel() -> String {
        let df = DateFormatter()
        df.dateFormat = "LLLL yyyy"
        df.locale = Locale(identifier: "ru_RU")
        var comps = DateComponents(); comps.month = selectedMonth; comps.year = selectedYear
        if let d = Calendar.current.date(from: comps) { return df.string(from: d) }
        return "\(selectedMonth)/\(selectedYear)"
    }

    func prevMonth() {
        if selectedMonth == 1 { selectedMonth = 12; selectedYear -= 1 }
        else { selectedMonth -= 1 }
    }

    func nextMonth() {
        if selectedMonth == 12 { selectedMonth = 1; selectedYear += 1 }
        else { selectedMonth += 1 }
    }
}

// MARK: - FinanceOverviewTab

struct FinanceOverviewTab: View {
    @EnvironmentObject var authManager: AuthManager
    let month: Int
    let year: Int
    @State private var summary: FinanceSummary?
    @State private var categories: [FinanceCategory] = []
    @State private var isLoading = true

    var expenseByCategory: [CategorySpend] {
        (summary?.byCategory ?? []).filter { ($0.total ?? 0) > 0 }.sorted { ($0.total ?? 0) > ($1.total ?? 0) }
    }

    var dailyPoints: [DailySpend] { summary?.daily ?? [] }

    var body: some View {
        ScrollView {
            VStack(spacing: 16) {
                if isLoading {
                    ProgressView().tint(Color(hex: "0D9488")).padding(.top, 40)
                } else {
                    // Summary Card
                    if let s = summary { FinanceSummaryCard2(summary: s) }

                    // Top Expenses
                    if !expenseByCategory.isEmpty {
                        VStack(alignment: .leading, spacing: 10) {
                            Text("Топ расходов").font(.subheadline.bold()).foregroundColor(.white)
                            ForEach(expenseByCategory.prefix(5)) { cat in
                                let total = summary?.totalExpense ?? 1
                                let pct = (cat.total ?? 0) / max(total, 1)
                                VStack(spacing: 4) {
                                    HStack {
                                        Text(cat.icon ?? "💸").font(.subheadline)
                                        Text(cat.categoryName ?? "—").font(.callout).foregroundColor(.white)
                                        Spacer()
                                        Text(formatAmt(cat.total ?? 0)).font(.callout.bold()).foregroundColor(Color(hex: "ff4757"))
                                        Text("\(Int(pct * 100))%").font(.caption2).foregroundColor(Color(hex: "8888aa"))
                                    }
                                    GeometryReader { geo in
                                        ZStack(alignment: .leading) {
                                            RoundedRectangle(cornerRadius: 3).fill(Color.white.opacity(0.07))
                                            RoundedRectangle(cornerRadius: 3)
                                                .fill(Color(hex: "ff4757").opacity(0.7))
                                                .frame(width: geo.size.width * CGFloat(pct))
                                        }
                                    }
                                    .frame(height: 5)
                                }
                            }
                        }
                        .padding(16)
                        .background(RoundedRectangle(cornerRadius: 16).fill(Color.white.opacity(0.04)))
                        .padding(.horizontal)
                    }

                    // Pie Chart
                    if expenseByCategory.count > 1 {
                        VStack(alignment: .leading, spacing: 8) {
                            Text("Расходы по категориям").font(.subheadline.bold()).foregroundColor(.white)
                            Chart(expenseByCategory) { cat in
                                SectorMark(
                                    angle: .value("Сумма", cat.total ?? 0),
                                    innerRadius: .ratio(0.55),
                                    angularInset: 2
                                )
                                .foregroundStyle(by: .value("Кат.", cat.categoryName ?? "—"))
                                .cornerRadius(4)
                            }
                            .frame(height: 200)
                            .chartForegroundStyleScale(range: Gradient(colors: [
                                Color(hex: "0D9488"), Color(hex: "6366f1"), Color(hex: "f59e0b"),
                                Color(hex: "ec4899"), Color(hex: "14b8a6"), Color(hex: "8b5cf6")
                            ]))
                        }
                        .padding(16)
                        .background(RoundedRectangle(cornerRadius: 16).fill(Color.white.opacity(0.04)))
                        .padding(.horizontal)
                    }

                    // Daily Line Chart
                    if !dailyPoints.isEmpty {
                        VStack(alignment: .leading, spacing: 8) {
                            Text("Ежедневные траты").font(.subheadline.bold()).foregroundColor(.white)
                            let df: DateFormatter = {
                                let d = DateFormatter(); d.dateFormat = "yyyy-MM-dd"; return d
                            }()
                            Chart(dailyPoints.compactMap { p -> (Date, Double)? in
                                guard let d = df.date(from: p.date) else { return nil }
                                return (d, p.expense ?? p.total ?? 0)
                            }, id: \.0) { item in
                                AreaMark(x: .value("День", item.0), y: .value("Сумма", item.1))
                                    .foregroundStyle(LinearGradient(colors: [Color(hex: "ff4757").opacity(0.4), Color.clear], startPoint: .top, endPoint: .bottom))
                                LineMark(x: .value("День", item.0), y: .value("Сумма", item.1))
                                    .foregroundStyle(Color(hex: "ff4757"))
                                    .lineStyle(StrokeStyle(lineWidth: 2))
                            }
                            .chartXAxis {
                                AxisMarks(values: .stride(by: .day, count: 5)) { _ in
                                    AxisValueLabel(format: .dateTime.day()).foregroundStyle(Color(hex: "8888aa"))
                                    AxisGridLine().foregroundStyle(Color.white.opacity(0.05))
                                }
                            }
                            .chartYAxis {
                                AxisMarks { v in
                                    AxisGridLine().foregroundStyle(Color.white.opacity(0.05))
                                    AxisValueLabel().foregroundStyle(Color(hex: "8888aa"))
                                }
                            }
                            .frame(height: 140)
                        }
                        .padding(16)
                        .background(RoundedRectangle(cornerRadius: 16).fill(Color.white.opacity(0.04)))
                        .padding(.horizontal)
                    }
                }
                Spacer(minLength: 80)
            }
            .padding(.top, 8)
        }
        .task { await load() }
        .onChange(of: month) { _ in Task { await load() } }
        .onChange(of: year) { _ in Task { await load() } }
        .refreshable { await load(refresh: true) }
    }

    func load(refresh: Bool = false) async {
        if !refresh { isLoading = true }
        async let s = APIService.shared.getFinanceSummary(token: authManager.token, month: month, year: year)
        async let c = APIService.shared.getFinanceCategories(token: authManager.token)
        summary = try? await s
        categories = (try? await c) ?? []
        isLoading = false
    }

    func formatAmt(_ v: Double) -> String {
        v >= 1000 ? String(format: "%.0f ₽", v) : String(format: "%.0f ₽", v)
    }
}

// MARK: - FinanceSummaryCard2

struct FinanceSummaryCard2: View {
    let summary: FinanceSummary
    var body: some View {
        VStack(spacing: 16) {
            VStack(spacing: 4) {
                Text("Баланс месяца").font(.subheadline).foregroundColor(Color(hex: "8888aa"))
                Text(formatAmt(summary.balance ?? 0))
                    .font(.system(size: 34, weight: .bold))
                    .foregroundColor((summary.balance ?? 0) >= 0 ? Color(hex: "0D9488") : Color(hex: "ff4757"))
            }
            HStack {
                VStack(spacing: 4) {
                    Text("Доходы").font(.caption).foregroundColor(Color(hex: "8888aa"))
                    Text("+\(formatAmt(summary.totalIncome ?? 0))")
                        .font(.callout.bold()).foregroundColor(Color(hex: "0D9488"))
                }
                Spacer()
                VStack(spacing: 4) {
                    Text("Расходы").font(.caption).foregroundColor(Color(hex: "8888aa"))
                    Text("-\(formatAmt(summary.totalExpense ?? 0))")
                        .font(.callout.bold()).foregroundColor(Color(hex: "ff4757"))
                }
                Spacer()
                VStack(spacing: 4) {
                    Text("Перенос").font(.caption).foregroundColor(Color(hex: "8888aa"))
                    Text("\(formatAmt(summary.carriedOver ?? 0))")
                        .font(.callout.bold()).foregroundColor(.white)
                }
            }
        }
        .padding(20)
        .background(
            LinearGradient(colors: [Color(hex: "1a1a3e"), Color(hex: "12122a")], startPoint: .topLeading, endPoint: .bottomTrailing)
        )
        .cornerRadius(20)
        .overlay(RoundedRectangle(cornerRadius: 20).stroke(Color(hex: "0D9488").opacity(0.3), lineWidth: 1))
        .padding(.horizontal)
    }

    func formatAmt(_ v: Double) -> String { String(format: "%.0f ₽", v) }
}

// MARK: - FinanceTransactionsTab

struct FinanceTransactionsTab: View {
    @EnvironmentObject var authManager: AuthManager
    let month: Int
    let year: Int
    @State private var transactions: [FinanceTransaction] = []
    @State private var categories: [FinanceCategory] = []
    @State private var isLoading = true
    @State private var showAdd = false

    var groupedByDay: [(key: String, value: [FinanceTransaction])] {
        let grouped = Dictionary(grouping: transactions) { $0.dateOnly }
        return grouped.sorted { $0.key > $1.key }
    }

    var body: some View {
        ZStack(alignment: .bottomTrailing) {
            Group {
                if isLoading {
                    ProgressView().tint(Color(hex: "0D9488")).padding(.top, 40)
                    Spacer()
                } else if transactions.isEmpty {
                    VStack { EmptyState(icon: "creditcard", text: "Нет транзакций"); Spacer() }
                } else {
                    List {
                        ForEach(groupedByDay, id: \.key) { section in
                            Section(header:
                                Text(formatSectionDate(section.key))
                                    .font(.caption).foregroundColor(Color(hex: "8888aa"))
                            ) {
                                ForEach(section.value) { tx in
                                    FinanceTxRow(transaction: tx, categories: categories)
                                        .listRowBackground(Color.clear)
                                        .listRowSeparator(.hidden)
                                }
                                .onDelete { idx in
                                    let toDelete = idx.map { section.value[$0] }
                                    Task {
                                        for tx in toDelete { try? await APIService.shared.deleteTransaction(token: authManager.token, id: tx.id) }
                                        await load(refresh: true)
                                    }
                                }
                            }
                        }
                    }
                    .listStyle(.plain)
                    .scrollContentBackground(.hidden)
                }
            }
            .refreshable { await load(refresh: true) }

            Button(action: { showAdd = true }) {
                ZStack {
                    Circle()
                        .fill(LinearGradient(colors: [Color(hex: "0D9488"), Color(hex: "14b8a6")], startPoint: .topLeading, endPoint: .bottomTrailing))
                        .frame(width: 56, height: 56)
                        .shadow(color: Color(hex: "0D9488").opacity(0.4), radius: 8, y: 4)
                    Image(systemName: "plus").font(.title2.bold()).foregroundColor(.white)
                }
            }
            .padding(.bottom, 90)
            .padding(.trailing, 20)
        }
        .task { await load() }
        .onChange(of: month) { _ in Task { await load() } }
        .onChange(of: year) { _ in Task { await load() } }
        .sheet(isPresented: $showAdd) {
            AddTransactionView(isPresented: $showAdd, categories: categories) { await load(refresh: true) }
                .presentationDetents([.medium, .large])
                .presentationDragIndicator(.visible)
                .presentationBackground(Color(hex: "0a0a1a"))
        }
    }

    func load(refresh: Bool = false) async {
        if !refresh { isLoading = true }
        async let t = APIService.shared.getTransactions(token: authManager.token, month: month, year: year)
        async let c = APIService.shared.getFinanceCategories(token: authManager.token)
        transactions = (try? await t) ?? []
        categories = (try? await c) ?? []
        isLoading = false
    }

    func formatSectionDate(_ s: String) -> String {
        let parts = s.split(separator: "-")
        guard parts.count == 3 else { return s }
        return "\(parts[2]).\(parts[1]).\(parts[0])"
    }
}

// MARK: - FinanceTxRow

struct FinanceTxRow: View {
    let transaction: FinanceTransaction
    let categories: [FinanceCategory]
    var cat: FinanceCategory? { categories.first { $0.id == transaction.categoryId } }
    var isIncome: Bool { transaction.type == "income" }
    var body: some View {
        HStack(spacing: 12) {
            ZStack {
                Circle()
                    .fill((isIncome ? Color(hex: "0D9488") : Color(hex: "ff4757")).opacity(0.12))
                    .frame(width: 40, height: 40)
                Text(cat?.icon ?? (isIncome ? "💰" : "💸")).font(.title3)
            }
            VStack(alignment: .leading, spacing: 2) {
                Text(transaction.description ?? cat?.name ?? "Операция")
                    .font(.callout).foregroundColor(.white)
                Text(transaction.dateFormatted).font(.caption2).foregroundColor(Color(hex: "8888aa"))
            }
            Spacer()
            Text("\(isIncome ? "+" : "-")\(formatAmt(transaction.amount))")
                .font(.callout.bold())
                .foregroundColor(isIncome ? Color(hex: "0D9488") : Color(hex: "ff4757"))
        }
        .padding(12)
        .background(RoundedRectangle(cornerRadius: 12).fill(Color.white.opacity(0.04)))
        .padding(.horizontal)
        .padding(.vertical, 2)
    }
    func formatAmt(_ v: Double) -> String { String(format: "%.0f ₽", v) }
}

// MARK: - FinanceAnalyticsTab

struct FinanceAnalyticsTab: View {
    @EnvironmentObject var authManager: AuthManager
    let month: Int
    let year: Int
    @State private var analytics: FinanceAnalytics?
    @State private var isLoading = true

    var body: some View {
        ScrollView {
            VStack(spacing: 16) {
                if isLoading {
                    ProgressView().tint(Color(hex: "0D9488")).padding(.top, 40)
                } else {
                    // Bar chart by category
                    if let cats = analytics?.byCategory, !cats.isEmpty {
                        VStack(alignment: .leading, spacing: 8) {
                            Text("Расходы по категориям").font(.subheadline.bold()).foregroundColor(.white)
                            Chart(cats.sorted { ($0.total ?? 0) > ($1.total ?? 0) }.prefix(8).map { $0 }) { cat in
                                BarMark(
                                    x: .value("Сумма", cat.total ?? 0),
                                    y: .value("Кат.", cat.categoryName ?? "—")
                                )
                                .foregroundStyle(Color(hex: "ff4757"))
                                .cornerRadius(4)
                                .annotation(position: .trailing) {
                                    Text(formatAmt(cat.total ?? 0)).font(.caption2).foregroundColor(Color(hex: "8888aa"))
                                }
                            }
                            .chartXAxis {
                                AxisMarks { _ in AxisGridLine().foregroundStyle(Color.white.opacity(0.05)) }
                            }
                            .frame(height: 250)
                        }
                        .padding(16)
                        .background(RoundedRectangle(cornerRadius: 16).fill(Color.white.opacity(0.04)))
                        .padding(.horizontal)
                    }

                    // Month comparison
                    if let cur = analytics?.currentMonth, let prev = analytics?.previousMonth {
                        MonthComparisonCard(current: cur, previous: prev)
                    }

                    if analytics?.byCategory == nil && analytics?.currentMonth == nil {
                        EmptyState(icon: "chart.bar", text: "Нет данных для аналитики")
                    }
                }
                Spacer(minLength: 80)
            }
            .padding(.top, 8)
        }
        .task { await load() }
        .onChange(of: month) { _ in Task { await load() } }
        .onChange(of: year) { _ in Task { await load() } }
        .refreshable { await load(refresh: true) }
    }

    func load(refresh: Bool = false) async {
        if !refresh { isLoading = true }
        analytics = try? await APIService.shared.getFinanceAnalytics(token: authManager.token, month: month, year: year)
        isLoading = false
    }

    func formatAmt(_ v: Double) -> String { v >= 1000 ? String(format: "%.0f", v) : String(format: "%.0f", v) }
}

// MARK: - MonthComparisonCard

struct MonthComparisonCard: View {
    let current: FinanceSummary
    let previous: FinanceSummary
    var diff: Double { (current.totalExpense ?? 0) - (previous.totalExpense ?? 0) }
    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Сравнение с прошлым месяцем").font(.subheadline.bold()).foregroundColor(.white)
            HStack {
                VStack(spacing: 4) {
                    Text("Этот месяц").font(.caption).foregroundColor(Color(hex: "8888aa"))
                    Text(formatAmt(current.totalExpense ?? 0)).font(.headline.bold()).foregroundColor(Color(hex: "ff4757"))
                }
                Spacer()
                VStack(spacing: 4) {
                    Text("Прошлый").font(.caption).foregroundColor(Color(hex: "8888aa"))
                    Text(formatAmt(previous.totalExpense ?? 0)).font(.headline.bold()).foregroundColor(Color(hex: "8888aa"))
                }
                Spacer()
                VStack(spacing: 4) {
                    Text("Изменение").font(.caption).foregroundColor(Color(hex: "8888aa"))
                    Text("\(diff > 0 ? "+" : "")\(formatAmt(diff))").font(.headline.bold())
                        .foregroundColor(diff > 0 ? Color(hex: "ff4757") : Color(hex: "0D9488"))
                }
            }
        }
        .padding(16)
        .background(RoundedRectangle(cornerRadius: 16).fill(Color.white.opacity(0.04)))
        .padding(.horizontal)
    }
    func formatAmt(_ v: Double) -> String { String(format: "%.0f ₽", v) }
}