import SwiftUI

struct MonthlyCheckInView: View {
    @EnvironmentObject var accountStore: AccountStore
    @StateObject private var viewModel = MonthlyCheckInViewModel()
    let referenceDate: Date
    let duplicatePrevious: Bool

    @State private var monthlyNote: String
    @State private var starRating: Int
    @State private var selectedMood: MonthlyCheckInMood?
    @FocusState private var noteFocused: Bool
    @State private var editingSnapshot: Snapshot?
    @State private var addingSource: InvestmentSource?
    @State private var didApplyDuplicate = false

    init(referenceDate: Date = Date(), duplicatePrevious: Bool = false) {
        self.referenceDate = referenceDate
        self.duplicatePrevious = duplicatePrevious
        _monthlyNote = State(initialValue: MonthlyCheckInStore.note(for: referenceDate))
        _starRating = State(initialValue: MonthlyCheckInStore.rating(for: referenceDate) ?? 0)
        _selectedMood = State(initialValue: MonthlyCheckInStore.mood(for: referenceDate))
    }

    private var lastCompletionDate: Date? {
        MonthlyCheckInStore.latestCompletionDate()
    }

    private var checkInProgress: Double {
        guard let last = lastCompletionDate,
              let nextDate = nextCheckInDate else { return 1 }
        let totalDays = Double(max(1, last.startOfDay.daysBetween(nextDate.startOfDay)))
        guard totalDays > 0 else { return 1 }
        let elapsedDays = Double(last.startOfDay.daysBetween(Date()))
        return min(max(elapsedDays / totalDays, 0), 1)
    }

    private var checkInIntervalMonths: Int {
        if accountStore.showAllAccounts || accountStore.selectedAccount == nil {
            return NotificationFrequency.monthly.months
        }
        let account = accountStore.selectedAccount
        let frequency = account?.frequency ?? .monthly
        if frequency == .custom {
            return max(1, Int(account?.customFrequencyMonths ?? 1))
        }
        if frequency == .never {
            return NotificationFrequency.monthly.months
        }
        return frequency.months
    }

    private var nextCheckInDate: Date? {
        guard let last = lastCompletionDate else { return nil }
        return last.adding(months: checkInIntervalMonths)
    }

    private var canAddNewCheckIn: Bool {
        lastCompletionDate == nil || checkInProgress >= 0.7
    }

    var body: some View {
        ScrollView {
            VStack(spacing: 20) {
                headerCard
                summaryCard
                reflectionCard
                sourcesCard
                notesCard
                journalCard
            }
            .padding()
        }
        .navigationTitle("Monthly Check-in")
        .navigationBarTitleDisplayMode(.inline)
        .onAppear {
            viewModel.selectedAccount = accountStore.selectedAccount
            viewModel.showAllAccounts = accountStore.showAllAccounts
            viewModel.selectedRange = DateRange.month(containing: referenceDate)
            if duplicatePrevious, !didApplyDuplicate {
                viewModel.duplicatePreviousMonthSnapshots(referenceDate: referenceDate)
                didApplyDuplicate = true
            }
            viewModel.refresh()
            monthlyNote = MonthlyCheckInStore.note(for: referenceDate)
            starRating = MonthlyCheckInStore.rating(for: referenceDate) ?? 0
            selectedMood = MonthlyCheckInStore.mood(for: referenceDate)
        }
        .onReceive(accountStore.$selectedAccount) { account in
            viewModel.selectedAccount = account
            viewModel.selectedRange = DateRange.month(containing: referenceDate)
            viewModel.refresh()
        }
        .onReceive(accountStore.$showAllAccounts) { showAll in
            viewModel.showAllAccounts = showAll
            viewModel.selectedRange = DateRange.month(containing: referenceDate)
            viewModel.refresh()
        }
        .sheet(item: $editingSnapshot) { snapshot in
            if let source = snapshot.source {
                AddSnapshotView(source: source, snapshot: snapshot)
            }
        }
        .sheet(item: $addingSource) { source in
            AddSnapshotView(source: source)
        }
        .onChange(of: starRating) { _, newValue in
            MonthlyCheckInStore.setRating(newValue == 0 ? nil : newValue, for: referenceDate)
        }
        .onChange(of: selectedMood) { _, newValue in
            MonthlyCheckInStore.setMood(newValue, for: referenceDate)
        }
    }

    private var headerCard: some View {
        VStack(alignment: .leading, spacing: 8) {
            Text("This Month")
                .font(.headline)

            if let date = lastCompletionDate {
                Text(
                    String(
                        format: NSLocalizedString("last_check_in", comment: ""),
                        date.friendlyDescription
                    )
                )
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            } else {
                Text("No check-in yet this month")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            }

            VStack(alignment: .leading, spacing: 6) {
                ProgressView(value: checkInProgress)
                    .tint(.appSecondary)

                if let nextDate = nextCheckInDate {
                    Text(
                        String(
                            format: NSLocalizedString("next_check_in", comment: ""),
                            nextDate.mediumDateString
                        )
                    )
                        .font(.caption)
                        .foregroundColor(.secondary)
                } else {
                    Text("Start your first check-in anytime.")
                        .font(.caption)
                        .foregroundColor(.secondary)
                }
            }

            Button {
                let now = Date()
                let completionDate = referenceDate.isSameMonth(as: now)
                    ? now
                    : min(referenceDate.endOfMonth, now)
                MonthlyCheckInStore.setCompletionDate(completionDate, for: referenceDate)
                viewModel.refresh()
            } label: {
                Text("Mark Check-in Complete")
                    .font(.subheadline.weight(.semibold))
                    .frame(maxWidth: .infinity)
                    .padding(.vertical, 10)
                    .background(Color.appPrimary.opacity(0.1))
                    .cornerRadius(AppConstants.UI.cornerRadius)
            }
            .disabled(!canAddNewCheckIn)

            if !canAddNewCheckIn {
                Text("Editing stays open. New check-ins unlock after 70% of the month.")
                    .font(.caption)
                    .foregroundColor(.secondary)
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    private var reflectionCard: some View {
        VStack(alignment: .leading, spacing: 12) {
            HStack {
                Text("Monthly Pulse")
                    .font(.headline)
                Spacer()
                Text("Optional")
                    .font(.caption)
                    .foregroundColor(.secondary)
            }

            VStack(alignment: .leading, spacing: 8) {
                Text("Rate this month")
                    .font(.subheadline.weight(.semibold))

                HStack(spacing: 8) {
                    ForEach(1...5, id: \.self) { value in
                        Button {
                            withAnimation(.easeInOut(duration: AppConstants.Animation.shortDuration)) {
                                starRating = value == starRating ? 0 : value
                            }
                        } label: {
                            Image(systemName: value <= starRating ? "star.fill" : "star")
                                .font(.title3)
                                .foregroundColor(value <= starRating ? .appSecondary : .secondary)
                                .padding(8)
                                .background(
                                    Circle()
                                        .fill(value <= starRating ? Color.appSecondary.opacity(0.12) : Color.gray.opacity(0.08))
                                )
                        }
                        .buttonStyle(.plain)
                    }

                    Button {
                        withAnimation(.easeInOut(duration: AppConstants.Animation.shortDuration)) {
                            starRating = 0
                        }
                    } label: {
                        Text("Skip")
                            .font(.caption.weight(.semibold))
                            .padding(.horizontal, 10)
                            .padding(.vertical, 6)
                            .background(Color.gray.opacity(0.12))
                            .cornerRadius(AppConstants.UI.smallCornerRadius)
                    }
                }
            }

            VStack(alignment: .leading, spacing: 8) {
                Text("How did it feel?")
                    .font(.subheadline.weight(.semibold))

                ScrollView(.horizontal, showsIndicators: false) {
                    HStack(spacing: 10) {
                        ForEach(MonthlyCheckInMood.allCases) { mood in
                            Button {
                                withAnimation(.easeInOut(duration: AppConstants.Animation.shortDuration)) {
                                    selectedMood = selectedMood == mood ? nil : mood
                                }
                            } label: {
                                moodPill(for: mood)
                            }
                            .buttonStyle(.plain)
                        }
                    }
                }
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    private var summaryCard: some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Monthly Summary")
                .font(.headline)

            HStack {
                VStack(alignment: .leading, spacing: 4) {
                    Text("Starting")
                        .font(.caption)
                        .foregroundColor(.secondary)
                    Text(viewModel.monthlySummary.formattedStartingValue)
                        .font(.subheadline.weight(.semibold))
                }
                Spacer()
                VStack(alignment: .trailing, spacing: 4) {
                    Text("Ending")
                        .font(.caption)
                        .foregroundColor(.secondary)
                    Text(viewModel.monthlySummary.formattedEndingValue)
                        .font(.subheadline.weight(.semibold))
                }
            }

            HStack {
                VStack(alignment: .leading, spacing: 4) {
                    Text("Contributions")
                        .font(.caption)
                        .foregroundColor(.secondary)
                    Text(viewModel.monthlySummary.formattedContributions)
                        .font(.subheadline.weight(.semibold))
                }
                Spacer()
                VStack(alignment: .trailing, spacing: 4) {
                    Text("Net Performance")
                        .font(.caption)
                        .foregroundColor(.secondary)
                    Text("\(viewModel.monthlySummary.formattedNetPerformance) (\(viewModel.monthlySummary.formattedNetPerformancePercentage))")
                        .font(.subheadline.weight(.semibold))
                        .foregroundColor(viewModel.monthlySummary.netPerformance >= 0 ? .positiveGreen : .negativeRed)
                }
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    private var sourcesCard: some View {
        VStack(alignment: .leading, spacing: 12) {
            HStack {
                Text("Update Sources")
                    .font(.headline)
                Spacer()
                Text("\(viewModel.sources.count)")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            }

            if viewModel.sources.isEmpty {
                Text("Add sources to start your monthly check-in.")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            } else {
                ForEach(viewModel.sources) { source in
                    let latestSnapshot = source.latestSnapshot
                    let updatedThisCycle = isSnapshotInCurrentCycle(latestSnapshot)
                    Button {
                        if updatedThisCycle, let snapshot = latestSnapshot {
                            editingSnapshot = snapshot
                        } else {
                            addingSource = source
                        }
                    } label: {
                        HStack {
                            Circle()
                                .fill(source.category?.color ?? .gray)
                                .frame(width: 8, height: 8)

                            VStack(alignment: .leading, spacing: 2) {
                                Text(source.name)
                                    .font(.subheadline.weight(.medium))
                                Text(updatedThisCycle ? "Updated this cycle" : "Needs update")
                                    .font(.caption2)
                                    .foregroundColor(updatedThisCycle ? .positiveGreen : .secondary)
                            }

                            Spacer()

                            Text(latestSnapshot?.date.relativeDescription ?? String(localized: "date_never"))
                                .font(.caption)
                                .foregroundColor(.secondary)

                            Image(systemName: "chevron.right")
                                .font(.caption)
                                .foregroundColor(.secondary)
                        }
                    }
                    .buttonStyle(.plain)
                }
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    private var notesCard: some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Monthly Note")
                .font(.headline)

            TextEditor(text: $monthlyNote)
                .frame(minHeight: 120)
                .padding(8)
                .background(Color.gray.opacity(0.08))
                .cornerRadius(12)
                .focused($noteFocused)
                .onChange(of: monthlyNote) { _, newValue in
                    MonthlyCheckInStore.setNote(newValue, for: referenceDate)
                }

            HStack(spacing: 12) {
                NavigationLink {
                    MonthlyNoteEditorView(date: referenceDate, note: $monthlyNote)
                } label: {
                    Text("Open Full Note")
                        .font(.subheadline.weight(.semibold))
                        .frame(maxWidth: .infinity)
                        .padding(.vertical, 8)
                        .background(Color.appSecondary.opacity(0.12))
                        .cornerRadius(AppConstants.UI.cornerRadius)
                }
                .buttonStyle(.plain)

                Button {
                    viewModel.duplicatePreviousMonthSnapshots(referenceDate: referenceDate)
                    viewModel.refresh()
                } label: {
                    Text("Duplicate Previous")
                        .font(.subheadline.weight(.semibold))
                        .frame(maxWidth: .infinity)
                        .padding(.vertical, 8)
                        .background(Color.appPrimary.opacity(0.12))
                        .cornerRadius(AppConstants.UI.cornerRadius)
                }
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    private var journalCard: some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Snapshot Notes")
                .font(.headline)

            if viewModel.recentNotes.isEmpty {
                Text("No snapshot notes for this month.")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            } else {
                ForEach(viewModel.recentNotes) { snapshot in
                    VStack(alignment: .leading, spacing: 4) {
                        Text(snapshot.source?.name ?? "Source")
                            .font(.subheadline.weight(.semibold))
                        Text(snapshot.notes ?? "")
                            .font(.subheadline)
                            .foregroundColor(.secondary)
                        Text(snapshot.date.friendlyDescription)
                            .font(.caption)
                            .foregroundColor(.secondary)
                    }

                    if snapshot.id != viewModel.recentNotes.last?.id {
                        Divider()
                    }
                }
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }
}

struct AchievementsView: View {
    let referenceDate: Date

    private var achievementStatuses: [MonthlyCheckInAchievementStatus] {
        MonthlyCheckInStore.achievementStatuses(referenceDate: referenceDate)
    }

    private var unlockedAchievements: [MonthlyCheckInAchievementStatus] {
        achievementStatuses.filter { $0.isUnlocked }
    }

    private var lockedAchievements: [MonthlyCheckInAchievementStatus] {
        achievementStatuses.filter { !$0.isUnlocked }
    }

    var body: some View {
        ScrollView {
            VStack(spacing: 16) {
                headerCard

                achievementSection(
                    title: String(localized: "achievements_unlocked_title"),
                    subtitle: unlockedAchievements.isEmpty
                        ? String(localized: "achievements_unlocked_empty")
                        : nil,
                    achievements: unlockedAchievements,
                    isLocked: false
                )

                achievementSection(
                    title: String(localized: "achievements_locked_title"),
                    subtitle: lockedAchievements.isEmpty
                        ? String(localized: "achievements_locked_empty")
                        : nil,
                    achievements: lockedAchievements,
                    isLocked: true
                )
            }
            .padding()
        }
        .navigationTitle(String(localized: "achievements_nav_title"))
        .navigationBarTitleDisplayMode(.inline)
    }

    private var headerCard: some View {
        let total = max(achievementStatuses.count, 1)
        let unlockedCount = unlockedAchievements.count
        let progress = Double(unlockedCount) / Double(total)

        return VStack(alignment: .leading, spacing: 8) {
            Text(String(localized: "achievements_progress_title"))
                .font(.headline)
            ProgressView(value: progress)
                .tint(.appSecondary)
            Text(
                String(
                    format: NSLocalizedString("achievements_unlocked_count", comment: ""),
                    unlockedCount,
                    achievementStatuses.count
                )
            )
                .font(.subheadline)
                .foregroundColor(.secondary)
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    private func achievementSection(
        title: String,
        subtitle: String?,
        achievements: [MonthlyCheckInAchievementStatus],
        isLocked: Bool
    ) -> some View {
        VStack(alignment: .leading, spacing: 12) {
            Text(title)
                .font(.headline)

            if let subtitle {
                Text(subtitle)
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            }

            if achievements.isEmpty {
                EmptyView()
            } else {
                ForEach(achievements) { status in
                    achievementRow(status, isLocked: isLocked)
                }
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    private func achievementRow(_ status: MonthlyCheckInAchievementStatus, isLocked: Bool) -> some View {
        HStack(alignment: .center, spacing: 12) {
            ZStack {
                Circle()
                    .fill(isLocked ? Color.gray.opacity(0.2) : Color.appSecondary.opacity(0.18))
                    .frame(width: 42, height: 42)
                Image(systemName: status.achievement.icon)
                    .font(.headline)
                    .foregroundColor(isLocked ? .secondary : .appSecondary)
            }

            VStack(alignment: .leading, spacing: 2) {
                Text(status.achievement.title)
                    .font(.subheadline.weight(.semibold))
                Text(status.achievement.detail)
                    .font(.caption)
                    .foregroundColor(.secondary)
            }

            Spacer()

            if isLocked {
                Image(systemName: "lock.fill")
                    .font(.caption)
                    .foregroundColor(.secondary)
            }
        }
        .padding(10)
        .background(isLocked ? Color.gray.opacity(0.08) : Color.appSecondary.opacity(0.12))
        .cornerRadius(AppConstants.UI.smallCornerRadius)
    }
}

private extension MonthlyCheckInView {
    func isSnapshotInCurrentCycle(_ snapshot: Snapshot?) -> Bool {
        guard let snapshot, let last = lastCompletionDate else { return false }
        return snapshot.date >= Calendar.current.startOfDay(for: last)
    }

    @ViewBuilder
    func moodPill(for mood: MonthlyCheckInMood) -> some View {
        let isSelected = selectedMood == mood
        HStack(alignment: .center, spacing: 8) {
            Image(systemName: mood.iconName)
                .font(.body)
                .foregroundColor(isSelected ? moodColor(for: mood) : .secondary)
            VStack(alignment: .leading, spacing: 2) {
                Text(mood.title)
                    .font(.subheadline.weight(.semibold))
                Text(mood.detail)
                    .font(.caption2)
                    .foregroundColor(.secondary)
            }
        }
        .padding(10)
        .background(isSelected ? moodColor(for: mood).opacity(0.16) : Color.gray.opacity(0.08))
        .overlay(
            RoundedRectangle(cornerRadius: AppConstants.UI.smallCornerRadius)
                .stroke(isSelected ? moodColor(for: mood) : Color.clear, lineWidth: 1)
        )
        .cornerRadius(AppConstants.UI.smallCornerRadius)
    }

    func moodColor(for mood: MonthlyCheckInMood) -> Color {
        switch mood {
        case .energized: return .appSecondary
        case .confident: return .appPrimary
        case .balanced: return .teal
        case .cautious: return .orange
        case .stressed: return .red
        }
    }

}

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