import SwiftUI

/// A collapsed "Preview" row under a markup editor. Expanded, it renders
/// the draft with `FormattedBodyView`, the view the app's threads use, so
/// what it shows is what the app will show once the text is sent. It sits
/// under the editor rather than replacing it, so the draft stays in view.
struct MarkupPreview: View {

    let text: String
    let format: String?
    let identifier: String

    @State private var expanded = false

    var body: some View {
        DisclosureGroup(isExpanded: $expanded) {
            if text.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
                Text("Nothing to preview.")
                    .font(.gbSans(.subheadline))
                    .foregroundStyle(.secondary)
            } else {
                FormattedBodyView(text: text, format: format)
                    .padding(.vertical, 4)
            }
        } label: {
            Text("Preview")
                .font(.gbSans(.subheadline))
        }
        .accessibilityIdentifier(identifier)
        // The keyboard would cover the rendered text.
        .onChange(of: expanded) { _, isExpanded in
            if isExpanded {
                UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder),
                                                to: nil, from: nil, for: nil)
            }
        }
    }

    /// The format a file's contents render in, or nil for a file shown as
    /// source. The same extensions the forge renders a README or wiki
    /// page from.
    static func format(forFile name: String) -> String? {
        switch (name as NSString).pathExtension.lowercased() {
        case "org": "org"
        case "md", "markdown": "md"
        default: nil
        }
    }
}