import Combine
import SwiftUI

struct SessionDetailView: View {
    let sessionId: UUID
    @EnvironmentObject var dataManager: ClimbingDataManager
    @Environment(\.dismiss) private var dismiss
    @State private var showingDeleteAlert = false
    @State private var showingAddAttempt = false
    @State private var editingAttempt: Attempt?
    @State private var attemptToDelete: Attempt?
    @State private var currentTime = Date()

    private var session: ClimbSession? {
        dataManager.session(withId: sessionId)
    }

    private func startTimer() {
        // Update every 5 seconds instead of 1 second for better performance
        timer = Timer.scheduledTimer(withTimeInterval: 5.0, repeats: true) { _ in
            currentTime = Date()
        }
    }

    private func stopTimer() {
        timer?.invalidate()
        timer = nil
    }

    private var gym: Gym? {
        guard let session = session else { return nil }
        return dataManager.gym(withId: session.gymId)
    }

    private var attempts: [Attempt] {
        dataManager.attempts(forSession: sessionId)
    }

    private var attemptsWithProblems: [(Attempt, Problem)] {
        attempts.compactMap { attempt in
            guard let problem = dataManager.problem(withId: attempt.problemId) else { return nil }
            return (attempt, problem)
        }.sorted { $0.0.timestamp < $1.0.timestamp }
    }

    private var sessionStats: SessionStats {
        calculateSessionStats()
    }

    @State private var timer: Timer?

    var body: some View {
        ScrollView {
            LazyVStack(spacing: 20) {
                if let session = session, let gym = gym {
                    SessionHeaderCard(
                        session: session, gym: gym, stats: sessionStats, currentTime: currentTime)

                    SessionStatsCard(stats: sessionStats)

                    AttemptsSection(
                        attemptsWithProblems: attemptsWithProblems,
                        attemptToDelete: $attemptToDelete,
                        editingAttempt: $editingAttempt)
                } else {
                    Text("Session not found")
                        .foregroundColor(.secondary)
                }
            }
            .padding()
        }
        .onAppear {
            startTimer()
        }
        .onDisappear {
            stopTimer()
        }
        .navigationTitle("Session Details")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItemGroup(placement: .navigationBarTrailing) {
                if let session = session {
                    if session.status == .active {
                        Button("End Session") {
                            dataManager.endSession(session.id)
                            dismiss()
                        }
                        .foregroundColor(.orange)
                    } else {
                        Menu {
                            Button(role: .destructive) {
                                showingDeleteAlert = true
                            } label: {
                                Label("Delete Session", systemImage: "trash")
                            }
                        } label: {
                            Image(systemName: "ellipsis.circle")
                        }
                    }
                }
            }
        }
        .alert(
            "Delete Attempt",
            isPresented: Binding<Bool>(
                get: { attemptToDelete != nil },
                set: { if !$0 { attemptToDelete = nil } }
            )
        ) {
            Button("Cancel", role: .cancel) {
                attemptToDelete = nil
            }
            Button("Delete", role: .destructive) {
                if let attempt = attemptToDelete {
                    dataManager.deleteAttempt(attempt)
                    attemptToDelete = nil
                }
            }
        } message: {
            if let attempt = attemptToDelete,
                let problem = dataManager.problem(withId: attempt.problemId)
            {
                Text(
                    "Are you sure you want to delete this attempt on \"\(problem.name ?? "Unknown Problem")\"? This action cannot be undone."
                )
            } else {
                Text("Are you sure you want to delete this attempt? This action cannot be undone.")
            }
        }
        .overlay(alignment: .bottomTrailing) {
            if session?.status == .active {
                Button(action: { showingAddAttempt = true }) {
                    Image(systemName: "plus")
                        .font(.title2)
                        .foregroundColor(.white)
                        .frame(width: 56, height: 56)
                        .background(Circle().fill(.blue))
                        .shadow(radius: 4)
                }
                .padding()
            }
        }
        .alert("Delete Session", isPresented: $showingDeleteAlert) {
            Button("Cancel", role: .cancel) {}
            Button("Delete", role: .destructive) {
                if let session = session {
                    dataManager.deleteSession(session)
                    dismiss()
                }
            }
        } message: {
            Text(
                "Are you sure you want to delete this session? This will also delete all attempts associated with this session."
            )
        }
        .sheet(isPresented: $showingAddAttempt) {
            if let session = session, let gym = gym {
                AddAttemptView(session: session, gym: gym)
            }
        }
        .sheet(item: $editingAttempt) { attempt in
            EditAttemptView(attempt: attempt)
        }
    }

    private func calculateSessionStats() -> SessionStats {
        let successfulAttempts = attempts.filter { $0.result.isSuccessful }
        let uniqueProblems = Set(attempts.map { $0.problemId })
        let completedProblems = Set(successfulAttempts.map { $0.problemId })

        return SessionStats(
            totalAttempts: attempts.count,
            successfulAttempts: successfulAttempts.count,
            uniqueProblemsAttempted: uniqueProblems.count,
            uniqueProblemsCompleted: completedProblems.count
        )
    }

}

struct SessionHeaderCard: View {
    let session: ClimbSession
    let gym: Gym
    let stats: SessionStats
    let currentTime: Date

    var body: some View {
        VStack(alignment: .leading, spacing: 16) {
            VStack(alignment: .leading, spacing: 8) {
                Text(gym.name)
                    .font(.title)
                    .fontWeight(.bold)

                Text(formatDate(session.date))
                    .font(.title2)
                    .foregroundColor(.blue)

                if session.status == .active {
                    if let startTime = session.startTime {
                        Text("Duration: \(formatDuration(from: startTime, to: currentTime))")
                            .font(.subheadline)
                            .foregroundColor(.secondary)
                    }
                } else if let duration = session.duration {
                    Text("Duration: \(duration) minutes")
                        .font(.subheadline)
                        .foregroundColor(.secondary)
                }

                if let notes = session.notes, !notes.isEmpty {
                    Text(notes)
                        .font(.body)
                        .padding(.top, 4)
                }
            }

            // Status indicator
            HStack {
                Image(systemName: session.status == .active ? "play.fill" : "checkmark.circle.fill")
                    .foregroundColor(session.status == .active ? .green : .blue)

                Text(session.status == .active ? "In Progress" : "Completed")
                    .font(.subheadline)
                    .fontWeight(.medium)
                    .foregroundColor(session.status == .active ? .green : .blue)

                Spacer()
            }
            .padding(.horizontal, 12)
            .padding(.vertical, 6)
            .background(
                RoundedRectangle(cornerRadius: 8)
                    .fill((session.status == .active ? Color.green : Color.blue).opacity(0.1))
            )
        }
        .padding()
        .background(
            RoundedRectangle(cornerRadius: 16)
                .fill(.regularMaterial)
        )
    }

    private func formatDate(_ date: Date) -> String {
        let formatter = DateFormatter()
        formatter.dateStyle = .full
        return formatter.string(from: date)
    }

    private func formatDuration(from start: Date, to end: Date) -> String {
        let interval = end.timeIntervalSince(start)
        let hours = Int(interval) / 3600
        let minutes = Int(interval) % 3600 / 60
        let seconds = Int(interval) % 60

        if hours > 0 {
            return String(format: "%dh %dm %ds", hours, minutes, seconds)
        } else if minutes > 0 {
            return String(format: "%dm %ds", minutes, seconds)
        } else {
            return String(format: "%ds", seconds)
        }
    }
}

struct SessionStatsCard: View {
    let stats: SessionStats

    var body: some View {
        VStack(alignment: .leading, spacing: 16) {
            Text("Session Stats")
                .font(.title2)
                .fontWeight(.bold)

            if stats.totalAttempts == 0 {
                Text("No attempts recorded yet")
                    .foregroundColor(.secondary)
                    .frame(maxWidth: .infinity, alignment: .center)
                    .padding()
            } else {
                LazyVGrid(columns: Array(repeating: GridItem(.flexible()), count: 2), spacing: 16) {
                    StatItem(label: "Total Attempts", value: "\(stats.totalAttempts)")
                    StatItem(label: "Problems", value: "\(stats.uniqueProblemsAttempted)")
                    StatItem(label: "Completed", value: "\(stats.uniqueProblemsCompleted)")
                }
            }
        }
        .padding()
        .background(
            RoundedRectangle(cornerRadius: 16)
                .fill(.regularMaterial)
        )
    }
}

struct StatItem: View {
    let label: String
    let value: String

    var body: some View {
        VStack(spacing: 4) {
            Text(value)
                .font(.title2)
                .fontWeight(.bold)
                .foregroundColor(.blue)

            Text(label)
                .font(.caption)
                .foregroundColor(.secondary)
        }
        .frame(maxWidth: .infinity)
    }
}

struct AttemptsSection: View {
    let attemptsWithProblems: [(Attempt, Problem)]
    @Binding var attemptToDelete: Attempt?
    @Binding var editingAttempt: Attempt?
    @EnvironmentObject var dataManager: ClimbingDataManager

    var body: some View {
        VStack(alignment: .leading, spacing: 16) {
            Text("Attempts (\(attemptsWithProblems.count))")
                .font(.title2)
                .fontWeight(.bold)

            if attemptsWithProblems.isEmpty {
                VStack(spacing: 12) {
                    Image(systemName: "hand.raised.slash")
                        .font(.title)
                        .foregroundColor(.secondary)

                    Text("No attempts yet")
                        .font(.headline)
                        .foregroundColor(.secondary)

                    Text("Start attempting problems to see your progress!")
                        .font(.subheadline)
                        .foregroundColor(.secondary)
                        .multilineTextAlignment(.center)
                }
                .frame(maxWidth: .infinity)
                .padding()
                .background(
                    RoundedRectangle(cornerRadius: 16)
                        .fill(.regularMaterial)
                )
            } else {
                List {
                    ForEach(attemptsWithProblems.indices, id: \.self) { index in
                        let (attempt, problem) = attemptsWithProblems[index]
                        AttemptCard(attempt: attempt, problem: problem)
                            .listRowBackground(Color.clear)
                            .listRowSeparator(.hidden)
                            .listRowInsets(EdgeInsets(top: 6, leading: 0, bottom: 6, trailing: 0))
                            .swipeActions(edge: .trailing, allowsFullSwipe: true) {
                                Button(role: .destructive) {
                                    // Add haptic feedback for delete action
                                    let impactFeedback = UIImpactFeedbackGenerator(style: .medium)
                                    impactFeedback.impactOccurred()
                                    attemptToDelete = attempt
                                } label: {
                                    Label("Delete", systemImage: "trash")
                                }
                                .accessibilityLabel("Delete attempt")
                                .accessibilityHint("Removes this attempt from the session")

                                Button {
                                    editingAttempt = attempt
                                } label: {
                                    Label("Edit", systemImage: "pencil")
                                }
                                .tint(.blue)
                                .accessibilityLabel("Edit attempt")
                                .accessibilityHint("Modify the details of this attempt")
                            }
                            .onTapGesture {
                                editingAttempt = attempt
                            }
                    }
                }
                .listStyle(.plain)
                .scrollDisabled(true)
                .frame(height: CGFloat(attemptsWithProblems.count) * 120)
            }
        }

    }
}

struct AttemptCard: View {
    let attempt: Attempt
    let problem: Problem

    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            HStack {
                VStack(alignment: .leading, spacing: 4) {
                    Text(problem.name ?? "Unknown Problem")
                        .font(.headline)
                        .fontWeight(.semibold)

                    Text("\(problem.difficulty.system.displayName): \(problem.difficulty.grade)")
                        .font(.subheadline)
                        .foregroundColor(.blue)

                    if let location = problem.location {
                        Text(location)
                            .font(.caption)
                            .foregroundColor(.secondary)
                    }
                }

                Spacer()

                VStack(alignment: .trailing, spacing: 8) {
                    AttemptResultBadge(result: attempt.result)
                }
            }

            if let notes = attempt.notes, !notes.isEmpty {
                Text(notes)
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            }

            if let highestHold = attempt.highestHold, !highestHold.isEmpty {
                Text("Highest hold: \(highestHold)")
                    .font(.caption)
                    .foregroundColor(.secondary)
            }
        }
        .padding()
        .background(.regularMaterial)
        .cornerRadius(12)
        .shadow(radius: 2)
    }
}

struct AttemptResultBadge: View {
    let result: AttemptResult

    private var badgeColor: Color {
        switch result {
        case .success, .flash:
            return .green
        case .fall:
            return .orange
        case .noProgress:
            return .red
        }
    }

    var body: some View {
        Text(result.displayName)
            .font(.caption)
            .fontWeight(.medium)
            .padding(.horizontal, 8)
            .padding(.vertical, 4)
            .background(
                RoundedRectangle(cornerRadius: 6)
                    .fill(badgeColor.opacity(0.1))
            )
            .foregroundColor(badgeColor)
            .overlay(
                RoundedRectangle(cornerRadius: 6)
                    .stroke(badgeColor.opacity(0.3), lineWidth: 1)
            )
    }
}

struct SessionStats {
    let totalAttempts: Int
    let successfulAttempts: Int
    let uniqueProblemsAttempted: Int
    let uniqueProblemsCompleted: Int
}

#Preview {
    NavigationView {
        SessionDetailView(sessionId: UUID())
            .environmentObject(ClimbingDataManager.preview)
    }
}