import LChatCore
import SwiftUI

// 🤖 Invite a brand-new person straight into a DM (the web's inviteSomeone,
// natively): type their name, get a join link to share. The link's #fragment
// carries the one-time secret — it never touches the server, so share it
// over any channel you trust.
struct InviteSomeoneView: View {
    @ObservedObject var store: ThreadStore
    let onCreated: (String?) -> Void

    @State private var name = ""
    @State private var busy = false
    @State private var error: String?
    @State private var link: String?
    @State private var copied = false

    var body: some View {
        Group {
            if let link {
                ready(link: link)
            } else {
                form
            }
        }
        .navigationTitle("Invite someone")
        .navigationBarTitleDisplayMode(.inline)
    }

    // Step 1: their name + a PROMINENT create button (a bare button row in a
    // List reads as another text field — the lesson from the first device run).
    private var form: some View {
        VStack(spacing: 16) {
            Form {
                Section {
                    TextField("Their name", text: $name)
                        .textInputAutocapitalization(.words)
                        .onSubmit(create)
                } footer: {
                    Text("Creates a pending chat with them and a join link only they can use.")
                }
                if let error {
                    Section { Text(error).font(.footnote).foregroundStyle(.red) }
                }
            }
            Button {
                create()
            } label: {
                HStack(spacing: 8) {
                    if busy { ProgressView().tint(.white) }
                    Text(busy ? "Creating…" : "Create invite")
                        .font(.body.weight(.semibold))
                }
                .frame(maxWidth: .infinity)
                .padding(.vertical, 4)
            }
            .buttonStyle(.borderedProminent)
            .disabled(busy || name.trimmingCharacters(in: .whitespaces).isEmpty)
            .padding(.horizontal, 20)
            .padding(.bottom, 16)
        }
        .background(Color(.systemGroupedBackground))
    }

    // Step 2: the link itself, Copy, and the system share sheet. The content
    // scrolls (large Dynamic Type / small screens); the buttons pin below it.
    private func ready(link: String) -> some View {
        ScrollView {
            VStack(spacing: 18) {
                Image(systemName: "person.badge.plus")
                    .font(.system(size: 40))
                    .foregroundStyle(Color.accentColor)
                    .padding(.top, 24)
                Text("Invite ready")
                    .font(.title3.weight(.semibold))
                Text("Send this link to \(name.trimmingCharacters(in: .whitespaces)) — it's their one-time key into your chat. A new one can be minted later if it's lost.")
                    .font(.callout)
                    .foregroundStyle(.secondary)
                    .multilineTextAlignment(.center)
                    .padding(.horizontal, 24)
                Text(link)
                    .font(.footnote.monospaced())
                    .lineLimit(3)
                    .truncationMode(.middle)
                    .textSelection(.enabled)
                    .padding(12)
                    .frame(maxWidth: .infinity)
                    .background(Color(.secondarySystemGroupedBackground),
                                in: RoundedRectangle(cornerRadius: 10))
                    .padding(.horizontal, 20)
            }
        }
        .safeAreaInset(edge: .bottom) {
            VStack(spacing: 10) {
                if let url = URL(string: link) {
                    ShareLink(item: url) {
                        Label("Share invite link", systemImage: "square.and.arrow.up")
                            .font(.body.weight(.semibold))
                            .frame(maxWidth: .infinity)
                            .padding(.vertical, 4)
                    }
                    .buttonStyle(.borderedProminent)
                }
                Button {
                    UIPasteboard.general.string = link
                    copied = true
                } label: {
                    Label(copied ? "Copied" : "Copy link",
                          systemImage: copied ? "checkmark" : "doc.on.doc")
                        .frame(maxWidth: .infinity)
                        .padding(.vertical, 4)
                }
                .buttonStyle(.bordered)
            }
            .padding(.horizontal, 20)
            .padding(.top, 10)
            .padding(.bottom, 16)
            .background(Color(.systemGroupedBackground))
        }
        .background(Color(.systemGroupedBackground))
    }

    private func create() {
        let trimmed = name.trimmingCharacters(in: .whitespaces)
        guard !trimmed.isEmpty, !busy else { return }
        busy = true
        error = nil
        Task {
            let r = await store.inviteSomeone(name: trimmed)
            busy = false
            if let l = r.link {
                link = l
            } else {
                error = r.error ?? "Couldn't create the invite."
            }
        }
    }
}