import SwiftUI

struct ONUListView: View {
    let connection: MCMSConnection
    @State private var vm: ONUListViewModel
    private let title: String

    init(connection: MCMSConnection, stateFilter: ONULifecycleState? = nil, title: String = "ONUs") {
        self.connection = connection
        self.title = title
        _vm = State(initialValue: ONUListViewModel(connection: connection, stateFilter: stateFilter))
    }

    var body: some View {
        @Bindable var vm = vm
        Group {
            switch vm.phase {
            case .idle:
                LoadingView(label: "Loading ONUs…")
            case .loading where vm.onus.isEmpty:
                LoadingView(label: "Loading ONUs…")
            case .failed(let msg):
                ErrorStateView(message: msg) { Task { await vm.load() } }
            default:
                list
            }
        }
        .navigationTitle(title)
        .searchable(text: $vm.search, prompt: "Name, serial, or OLT")
        .task { if vm.phase == .idle { await vm.load() } }
        .refreshable { await vm.load() }
    }

    private var list: some View {
        List(vm.filtered) { onu in
            NavigationLink {
                ONUDetailView(connection: connection, onuId: onu.id)
            } label: {
                row(onu)
            }
        }
        .listStyle(.plain)
        .overlay {
            if vm.filtered.isEmpty {
                if vm.search.isEmpty {
                    ContentUnavailableView("No ONUs", systemImage: "point.3.connected.trianglepath.dotted")
                } else {
                    ContentUnavailableView.search(text: vm.search)
                }
            }
        }
    }

    private func row(_ onu: ONUStateDoc) -> some View {
        HStack {
            VStack(alignment: .leading, spacing: 4) {
                Text(onu.displayName).font(.body.weight(.medium))
                if let sub = subtitle(onu) {
                    Text(sub).font(.caption).foregroundStyle(.secondary)
                }
            }
            Spacer()
            StateBadge(text: onu.lifecycle.label, color: onu.lifecycle.color)
        }
    }

    /// Secondary line: the serial (shown only when a name is the title) and parent OLT.
    private func subtitle(_ onu: ONUStateDoc) -> String? {
        var parts: [String] = []
        if onu.resolvedName != nil { parts.append(onu.id) }
        if let olt = onu.parentOLT { parts.append("OLT \(olt)") }
        return parts.isEmpty ? nil : parts.joined(separator: " · ")
    }
}