import Foundation

/// Timestamped diagnostic log for beacon provisioning.
/// Captures every step so we can diagnose failures.
@MainActor
final class ProvisionLog: ObservableObject {
    struct Entry: Identifiable {
        let id = UUID()
        let timestamp: Date
        let phase: String      // "connect", "discover", "auth", "write", "verify"
        let message: String
        let isError: Bool

        var formatted: String {
            let t = Self.formatter.string(from: timestamp)
            let prefix = isError ? "❌" : "✅"
            return "\(t) [\(phase)] \(prefix) \(message)"
        }

        private static let formatter: DateFormatter = {
            let f = DateFormatter()
            f.dateFormat = "HH:mm:ss.SSS"
            return f
        }()
    }

    @Published private(set) var entries: [Entry] = []
    private var startTime: Date?

    /// Clear log for a new provisioning attempt
    func reset() {
        entries = []
        startTime = Date()
    }

    /// Add a log entry
    func log(_ phase: String, _ message: String, isError: Bool = false) {
        let entry = Entry(timestamp: Date(), phase: phase, message: message, isError: isError)
        entries.append(entry)
    }

    /// Elapsed time since reset
    var elapsed: String {
        guard let start = startTime else { return "0.0s" }
        let seconds = Date().timeIntervalSince(start)
        return String(format: "%.1fs", seconds)
    }

    /// Full log as shareable text
    var fullText: String {
        let header = "Payfrit Beacon Diagnostic Log"
        let time = "Session: \(elapsed)"
        let lines = entries.map { $0.formatted }
        return ([header, time, "---"] + lines).joined(separator: "\n")
    }
}