import SwiftUI
import PDFKit

struct LeadPDFPreview: View {
    let document: LeadDocument
    let leadID: String
    let salesCode: String
    let repository: any LeadDetailRepository
    let onLogout: () -> Void
    var signedURL: URL? = nil
    @State private var model = LeadFileViewModel()
    @State private var retryID = 0
    @State private var showsPreview = false
    @Environment(\.dismiss) private var dismiss

    var body: some View {
        NavigationStack {
            ZStack {
                if let url = signedURL ?? model.url {
                    LeadPDFView(url: url)
                    .fullScreenCover(isPresented: $showsPreview) {
                        LeadDocumentPreview(url: url)
                    }
                } else if let message = model.message {
                    ContentUnavailableView {
                        Label("PDF konnte nicht geöffnet werden", systemImage: "doc.badge.ellipsis")
                    } description: { Text(message) } actions: {
                        if model.needsLogin {
                            Button("Erneut anmelden", action: onLogout)
                        } else if model.allowsRetry {
                            Button("Erneut versuchen") { retryID += 1 }
                        }
                    }
                } else {
                    ProgressView("PDF wird heruntergeladen …")
                }
            }
            .navigationTitle(document.title)
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button(role: .cancel) { dismiss() }
                        .labelStyle(.iconOnly)
                }
                ToolbarItem(placement: .topBarTrailing) {
                    Button("In Vorschau öffnen", systemImage: "arrow.up.left.and.arrow.down.right") {
                        showsPreview = true
                    }
                    .labelStyle(.iconOnly)
                    .disabled(signedURL == nil && model.url == nil)
                }
            }
            .task(id: retryID) {
                guard signedURL == nil else { return }
                await model.load {
                    try await DownloadLeadDocumentUseCase(repository: repository)
                        .execute(document, leadID: leadID, salesCode: salesCode)
                }
            }
        }
    }
}