import SwiftUI
import VoiceCatCore

/// iPhone channels tab: a drill-down browser. The root list shows only top-level channels;
/// tapping (or VoiceOver-activating) a channel pushes `ChannelDetailView`, which shows the
/// people in it and any sub-channels. Joining is an explicit action inside the detail view.
struct ChannelBrowserView: View {
    @Bindable var session: SessionState
    @State private var showCreateChannel = false

    var body: some View {
        NavigationStack {
            List {
                ForEach(rootChannels) { ch in
                    NavigationLink {
                        ChannelDetailView(channel: ch, session: session)
                    } label: {
                        ChannelRow(channel: ch, session: session)
                    }
                    .swipeActions(edge: .trailing) {
                        if session.permissions.isAdmin {
                            Button(role: .destructive) {
                                session.deleteChannel(ch.id)
                            } label: {
                                Label("Delete", systemImage: "trash")
                            }
                        }
                    }
                }
            }
            .navigationTitle("Channels")
            .toolbar {
                if session.permissions.canCreateTempChannel || session.permissions.isAdmin {
                    ToolbarItem(placement: .primaryAction) {
                        Button {
                            showCreateChannel = true
                        } label: {
                            Image(systemName: "plus")
                        }
                        .accessibilityLabel("Create channel")
                    }
                }
            }
            .sheet(isPresented: $showCreateChannel) {
                ChannelEditView(channelId: nil, session: session)
            }
        }
    }

    private var rootChannels: [Channel] {
        session.channels
            .filter { $0.parentId == 0 }
            .sorted { $0.name < $1.name }
    }
}

/// Shared channel row used by the iPhone browser and detail views. Mirrors the look of the
/// iPad `ChannelTreeView` row but keyed on a `Channel` rather than a tree `ChannelNode`.
struct ChannelRow: View {
    let channel: Channel
    let session: SessionState

    var body: some View {
        let isCurrent = session.currentChannelId == channel.id
        let usersHere = session.users.filter { $0.channelId == channel.id }

        HStack(spacing: 8) {
            Image(systemName: channel.passwordProtected ? "lock.fill" : "number")
                .foregroundStyle(isCurrent ? .blue : .secondary)
                .imageScale(.small)
            VStack(alignment: .leading, spacing: 1) {
                Text(channel.name)
                    .fontWeight(isCurrent ? .semibold : .regular)
                if !channel.topic.isEmpty {
                    Text(channel.topic)
                        .font(.caption2)
                        .foregroundStyle(.secondary)
                        .lineLimit(1)
                }
            }
            Spacer()
            if !usersHere.isEmpty {
                Text("\(usersHere.count)")
                    .font(.caption)
                    .foregroundStyle(.secondary)
            }
        }
        .accessibilityElement(children: .combine)
        .accessibilityLabel("\(channel.name)\(isCurrent ? ", current" : "")\(channel.passwordProtected ? ", password protected" : "")\(!usersHere.isEmpty ? ", \(usersHere.count) users" : "")")
    }
}