import SwiftUI

// Tamper-evidence failure banner (docs/tamper-evidence.md, #573): the native
// twin of the web's #integrity-banner. Shown ONLY when this space fails an
// integrity check (a fork/rollback/withheld/bad-signature the E2E rule is meant
// to make un-hideable) — never for "all clear" (a pulled /integrity self-check
// covers that). An inline band occupying layout, never a floating overlay;
// amber with a ⚠️ so it's never colour-alone. `onDetails` runs /integrity so
// the full read-out shows in place.
public struct IntegrityBanner: View {
    @ObservedObject var monitor: IntegrityMonitor
    let onDetails: () -> Void

    public init(monitor: IntegrityMonitor, onDetails: @escaping () -> Void) {
        self.monitor = monitor
        self.onDetails = onDetails
    }

    private var title: String {
        let n = monitor.unresolved.count
        return n > 1 ? "Integrity check failed (\(n.formatted()) alerts)" : "Integrity check failed"
    }

    private var message: String {
        guard let latest = monitor.unresolved.last else { return "" }
        return IntegrityMonitor.alertMessage(latest.kind)
            + " Keep this device — its records are the evidence — and contact your space's admin."
    }

    public var body: some View {
        if !monitor.unresolved.isEmpty {
            HStack(alignment: .top, spacing: 10) {
                Image(systemName: "exclamationmark.triangle.fill")
                    .foregroundStyle(.white)
                    .accessibilityHidden(true)
                VStack(alignment: .leading, spacing: 4) {
                    Text(title).font(.subheadline).bold()
                    Text(message).font(.footnote)
                    HStack(spacing: 8) {
                        Button("What's this?") { onDetails() }
                            .buttonStyle(.borderedProminent)
                        Button("Dismiss") { monitor.acknowledge() }
                            .buttonStyle(.bordered)
                    }
                    .controlSize(.small)
                    .padding(.top, 2)
                }
                Spacer(minLength: 0)
            }
            .foregroundStyle(.white)
            .tint(.white)
            .padding(.horizontal, 14)
            .padding(.vertical, 10)
            .frame(maxWidth: .infinity, alignment: .leading)
            .background(Color(red: 0.72, green: 0.42, blue: 0.05)) // amber, holds in light + dark
            .accessibilityElement(children: .contain)
            .accessibilityLabel("Integrity check failed. \(message)")
        }
    }
}