import SwiftUI

// 引擎日志独立界面（#3）：展示 EngineController.logs 环形缓冲里最近 N 条 console.warn/error，分级配色、
// 可选中复制、可一键清空。从设置页「查看日志」进入。便于在真机上（无 Web Inspector）定位 SSE / 鉴权 /
// 传输失败原因——此前只能在设置页看到孤零零一行 lastEngineLog。
struct LogView: View
{
    @Environment(EngineController.self) private var engine

    var body: some View
    {
        Group
        {
            if engine.logs.isEmpty
            {
                ContentUnavailableView(t("ios.logs.empty"), systemImage: "doc.text")
            }
            else
            {
                List
                {
                    ForEach(engine.logs)
                    { entry in
                        logRow(entry)
                    }
                }
                .listStyle(.plain)
            }
        }
        .navigationTitle(t("ios.logs.title"))
        .navigationBarTitleDisplayMode(.inline)
        .toolbar
        {
            if !engine.logs.isEmpty
            {
                ToolbarItem(placement: .topBarTrailing)
                {
                    Button(role: .destructive) { engine.clearLogs() }
                    label: { Label(t("ios.logs.clear"), systemImage: "trash") }
                }
            }
        }
    }

    private func logRow(_ entry: LogEntry) -> some View
    {
        VStack(alignment: .leading, spacing: 4)
        {
            HStack(spacing: 6)
            {
                Image(systemName: levelSymbol(entry.level))
                    .font(.caption)
                    .foregroundStyle(levelTint(entry.level))
                Text(timeString(entry.at))
                    .font(.caption2)
                    .foregroundStyle(.secondary)
                    .monospacedDigit()
            }
            Text(entry.message)
                .font(.caption.monospaced())
                .foregroundStyle(.primary)
                .textSelection(.enabled)
                .fixedSize(horizontal: false, vertical: true)
        }
        .padding(.vertical, 2)
    }

    private func levelSymbol(_ level: String) -> String
    {
        switch level
        {
        case "error": return "xmark.octagon.fill"
        case "warn": return "exclamationmark.triangle.fill"
        default: return "info.circle"
        }
    }

    private func levelTint(_ level: String) -> Color
    {
        switch level
        {
        case "error": return .red
        case "warn": return .orange
        default: return .secondary
        }
    }

    private func timeString(_ date: Date) -> String
    {
        let f = DateFormatter()
        f.dateFormat = "HH:mm:ss"
        return f.string(from: date)
    }
}