import SwiftUI

struct AddEditSessionView: View {
    let sessionId: UUID?
    @EnvironmentObject var dataManager: ClimbingDataManager
    @Environment(\.dismiss) private var dismiss

    @State private var selectedGym: Gym?
    @State private var sessionDate = Date()
    @State private var notes = ""
    @State private var isEditing = false

    private var existingSession: ClimbSession? {
        guard let sessionId = sessionId else { return nil }
        return dataManager.session(withId: sessionId)
    }

    init(sessionId: UUID? = nil) {
        self.sessionId = sessionId
    }

    var body: some View {
        NavigationStack {
            Form {
                GymSelectionSection()
                SessionDetailsSection()
            }
            .navigationTitle(isEditing ? "Edit Session" : "New Session")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button("Cancel") {
                        dismiss()
                    }
                }

                ToolbarItem(placement: .navigationBarTrailing) {
                    Button("Save") {
                        saveSession()
                    }
                    .disabled(selectedGym == nil)
                }
            }
        }
        .onAppear {
            loadExistingSession()
        }
    }

    @ViewBuilder
    private func GymSelectionSection() -> some View {
        Section("Select Gym") {
            if dataManager.gyms.isEmpty {
                Text("No gyms available. Add a gym first.")
                    .foregroundColor(.secondary)
            } else {
                ForEach(dataManager.gyms, id: \.id) { gym in
                    HStack {
                        VStack(alignment: .leading, spacing: 4) {
                            Text(gym.name)
                                .font(.headline)

                            if let location = gym.location, !location.isEmpty {
                                Text(location)
                                    .font(.caption)
                                    .foregroundColor(.secondary)
                            }
                        }

                        Spacer()

                        if selectedGym?.id == gym.id {
                            Image(systemName: "checkmark.circle.fill")
                                .foregroundColor(.blue)
                        }
                    }
                    .contentShape(Rectangle())
                    .onTapGesture {
                        selectedGym = gym
                    }
                }
            }
        }
    }

    @ViewBuilder
    private func SessionDetailsSection() -> some View {
        Section("Session Details") {
            DatePicker(
                "Date",
                selection: $sessionDate,
                displayedComponents: [.date]
            )

            VStack(alignment: .leading, spacing: 8) {
                Text("Notes (Optional)")
                    .font(.headline)

                TextEditor(text: $notes)
                    .frame(minHeight: 100)
                    .padding(8)
                    .background(
                        RoundedRectangle(cornerRadius: 8)
                            .fill(.quaternary)
                    )
            }
        }
    }

    private func loadExistingSession() {
        if let session = existingSession {
            isEditing = true
            selectedGym = dataManager.gym(withId: session.gymId)
            sessionDate = session.date
            notes = session.notes ?? ""
        }
    }

    private func saveSession() {
        guard let gym = selectedGym else { return }

        if isEditing, let session = existingSession {
            let updatedSession = session.updated(notes: notes.isEmpty ? nil : notes)
            dataManager.updateSession(updatedSession)
        } else {
            dataManager.startSession(gymId: gym.id, notes: notes.isEmpty ? nil : notes)
        }

        dismiss()
    }
}

#Preview {
    AddEditSessionView()
        .environmentObject(ClimbingDataManager.preview)
}