import SwiftUI

struct LinkScreen: View {
    @EnvironmentObject private var app: AppModel
    @State private var code: String?
    @State private var linkUrl = ""
    @State private var status = "Verbinden…"
    @State private var error: String?

    var body: some View {
        ZStack {
            LinearGradient(
                colors: [
                    Color(red: 0.12, green: 0.04, blue: 0.06),
                    McColors.bg,
                    Color(red: 0.04, green: 0.05, blue: 0.1),
                ],
                startPoint: .topLeading,
                endPoint: .bottomTrailing
            )
            .ignoresSafeArea()

            VStack(spacing: 18) {
                Text("VMC")
                    .font(McFonts.brand)
                    .foregroundStyle(McColors.accent)
                    .shadow(color: McColors.accent.opacity(0.4), radius: 18)

                Text("Koppel dit apparaat")
                    .font(McFonts.title)
                    .foregroundStyle(McColors.text)

                Text("Open je Vonas-account, voer deze code in en bevestig.")
                    .font(McFonts.body)
                    .foregroundStyle(McColors.textDim)
                    .multilineTextAlignment(.center)
                    .padding(.horizontal, 28)

                if let code {
                    Text(code)
                        .font(.system(size: 42, weight: .bold, design: .monospaced))
                        .foregroundStyle(McColors.text)
                        .padding(.vertical, 10)
                        .padding(.horizontal, 22)
                        .background(McColors.surface.opacity(0.9), in: RoundedRectangle(cornerRadius: 16, style: .continuous))
                        .overlay(
                            RoundedRectangle(cornerRadius: 16, style: .continuous)
                                .stroke(McColors.accent.opacity(0.35), lineWidth: 1)
                        )
                } else if error == nil {
                    ProgressView().tint(.white)
                }

                if !linkUrl.isEmpty {
                    Text(linkUrl)
                        .font(McFonts.caption)
                        .foregroundStyle(McColors.textDim)
                }

                Text(status)
                    .font(McFonts.caption)
                    .foregroundStyle(McColors.textDim)

                if let error {
                    Text(error)
                        .font(McFonts.body)
                        .foregroundStyle(McColors.danger)
                        .multilineTextAlignment(.center)
                        .padding(.horizontal)
                    Button("Opnieuw") { Task { await startLink() } }
                        .buttonStyle(McPrimaryButtonStyle())
                }
            }
            .padding()
            .frame(maxWidth: 420)
        }
        .task { await startLink() }
    }

    private func startLink() async {
        error = nil
        code = nil
        status = "Verbinden…"
        await app.api.configure(baseUrl: app.store.apiBase, token: nil)
        do {
            let created = try await app.api.createDeviceCode(deviceName: AppModel.deviceName)
            code = created.code
            linkUrl = created.linkUrl ?? ""
            status = "Wachten tot je de code bevestigt…"
            let interval = max(created.pollIntervalSeconds ?? 2, 2)
            while true {
                try await Task.sleep(nanoseconds: UInt64(interval) * 1_000_000_000)
                switch try await app.api.pollDeviceCode(code: created.code) {
                case .linked(let token, let name):
                    status = "Welkom, \(name)"
                    try await Task.sleep(nanoseconds: 700_000_000)
                    await app.didLink(token: token)
                    return
                case .expired:
                    status = "Code verlopen"
                    error = "Code verlopen — probeer opnieuw"
                    return
                case .alreadyLinked:
                    status = "Al gekoppeld"
                    error = "Al gekoppeld — herstart de app"
                    return
                case .pending:
                    break
                }
            }
        } catch {
            self.error = error.localizedDescription
            status = "Mislukt"
        }
    }
}