import SwiftUI

struct CommunityEventsView: View {
    @StateObject private var viewModel = CommunityEventViewModel()
    @State private var showingCreateSheet = false
    @State private var selectedTab: EventTab = .upcoming

    enum EventTab: String, CaseIterable {
        case upcoming, ongoing, past
    }

    var body: some View {
        NavigationView {
            Group {
                if viewModel.isLoading && viewModel.events.isEmpty {
                    loadingView
                } else if currentEvents.isEmpty {
                    emptyStateView
                } else {
                    eventListView
                }
            }
            .navigationTitle("Community Events")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    Button {
                        showingCreateSheet = true
                    } label: {
                        Image(systemName: "plus")
                    }
                }
            }
            .sheet(isPresented: $showingCreateSheet) {
                CreateEventSheet()
            }
        }
        .onAppear {
            Task {
                await viewModel.fetchEvents()
            }
        }
    }

    private var currentEvents: [CommunityEvent] {
        switch selectedTab {
        case .upcoming: return viewModel.upcomingEvents
        case .ongoing: return viewModel.ongoingEvents
        case .past: return viewModel.pastEvents
        }
    }

    private var eventListView: some View {
        List {
            Picker("Events", selection: $selectedTab) {
                ForEach(EventTab.allCases, id: \.self) { tab in
                    Text(tab.rawValue.capitalized).tag(tab)
                }
            }
            .pickerStyle(.segmented)
            .padding(.top, 8)

            Section(currentSectionTitle) {
                ForEach(currentEvents) { event in
                    NavigationLink(destination: CommunityEventDetailView(event: event)) {
                        EventRowView(event: event)
                    }
                }
            }
        }
        .listStyle(.insetGrouped)
        .refreshable {
            await viewModel.fetchEvents()
        }
    }

    private var currentSectionTitle: String {
        switch selectedTab {
        case .upcoming: return "Upcoming"
        case .ongoing: return "Happening Now"
        case .past: return "Past Events"
        }
    }

    private var loadingView: some View {
        VStack(spacing: 16) {
            ProgressView()
            Text("Loading Events...")
                .font(.subheadline)
                .foregroundColor(.secondary)
        }
        .padding(.vertical, 60)
    }

    private var emptyStateView: some View {
        VStack(spacing: 16) {
            Image(systemName: "person.3.fill")
                .font(.system(size: 64))
                .foregroundColor(.secondary)
            Text("No \(selectedTab.rawValue) Events")
                .font(.title2)
                .fontWeight(.semibold)
            Text("Create or discover community running events in your area.")
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
                .padding(.horizontal, 32)
        }
        .padding(.vertical, 60)
    }
}

struct CreateEventSheet: View {
    @Environment(\.dismiss) var dismiss
    @State private var title = ""
    @State private var description = ""
    @State private var eventType: EventType = .groupRun
    @State private var location = ""
    @State private var distanceKm = ""
    @State private var maxParticipants = ""

    var body: some View {
        NavigationView {
            Form {
                Section("Event Details") {
                    TextField("Event Title", text: $title)
                    TextField("Description", text: $description)
                    TextField("Location", text: $location)
                }

                Section("Type") {
                    Picker("Event Type", selection: $eventType) {
                        ForEach(EventType.allCases, id: \.self) { type in
                            Text(type.displayName).tag(type)
                        }
                    }
                }

                Section("Optional") {
                    TextField("Distance (km)", text: $distanceKm)
                        .keyboardType(.decimalPad)
                    TextField("Max Participants", text: $maxParticipants)
                        .keyboardType(.numberPad)
                }
            }
            .navigationTitle("Create Event")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button("Cancel") { dismiss() }
                }
                ToolbarItem(placement: .navigationBarTrailing) {
                    Button("Create") {
                        let request = CreateEventRequest(
                            title: title,
                            description: description,
                            eventType: eventType,
                            location: location,
                            latitude: 0,
                            longitude: 0,
                            startDate: Date(),
                            endDate: Date().addingTimeInterval(3600),
                            distanceKm: Double(distanceKm),
                            maxParticipants: Int(maxParticipants),
                            difficulty: nil
                        )
                        dismiss()
                    }
                    .disabled(title.isEmpty || location.isEmpty)
                }
            }
        }
    }
}

struct EventRowView: View {
    let event: CommunityEvent

    var body: some View {
        HStack(spacing: 12) {
            Image(systemName: event.eventType.icon)
                .font(.system(size: 24))
                .foregroundColor(event.eventType.color)
                .frame(width: 44, height: 44)
                .background(event.eventType.color.opacity(0.15))
                .cornerRadius(10)

            VStack(alignment: .leading, spacing: 4) {
                Text(event.title)
                    .font(.headline)
                Text("\(event.location) \u2022 \(event.organizerName)")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
                HStack(spacing: 8) {
                    Text(formatDate(event.startDate))
                        .font(.caption)
                        .foregroundColor(.secondary)
                    if let spots = event.availableSpots, spots > 0 {
                        Text("\(spots) spots left")
                            .font(.caption2)
                            .foregroundColor(.green)
                    }
                }
            }

            Spacer()

            switch event.rsvpStatus {
            case .going:
                Image(systemName: "checkmark.circle.fill")
                    .foregroundColor(.green)
            case .maybe:
                Image(systemName: "questionmark.circle.fill")
                    .foregroundColor(.orange)
            case .notGoing:
                Image(systemName: "xmark.circle.fill")
                    .foregroundColor(.red)
            case .pending:
                Image(systemName: "circle")
                    .foregroundColor(.secondary)
            }
        }
        .padding(.vertical, 4)
    }

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

#Preview {
    CommunityEventsView()
}