using System;
using System.Collections.Generic;

namespace FurnitureExporter;

internal sealed class PendingExportSession
{
    public PendingExportSession(string documentKey, IReadOnlyList<string> panelHandles)
    {
        DocumentKey = documentKey;
        PanelHandles = panelHandles;
        CreatedAtUtc = DateTime.UtcNow;
    }

    public string DocumentKey { get; }
    public DateTime CreatedAtUtc { get; }
    public IReadOnlyList<string> PanelHandles { get; }
}

/// <summary>
/// 导出向导的“暂停/恢复”会话管理。
/// 仅保存在内存中（不落盘），用于允许用户在两步之间调整图层显示等操作。
/// </summary>
internal static class ExportSessionManager
{
    private static readonly object Sync = new();
    private static readonly Dictionary<string, PendingExportSession> Sessions =
        new(StringComparer.OrdinalIgnoreCase);

    public static PendingExportSession? Get(string documentKey)
    {
        if (string.IsNullOrWhiteSpace(documentKey)) return null;

        lock (Sync)
        {
            Sessions.TryGetValue(documentKey, out var session);
            return session;
        }
    }

    public static PendingExportSession SetPanels(string documentKey, IReadOnlyList<string> panelHandles)
    {
        if (string.IsNullOrWhiteSpace(documentKey))
            throw new ArgumentException("documentKey is required", nameof(documentKey));

        if (panelHandles == null)
            throw new ArgumentNullException(nameof(panelHandles));

        lock (Sync)
        {
            var session = new PendingExportSession(documentKey, panelHandles);
            Sessions[documentKey] = session;
            return session;
        }
    }

    public static void Clear(string documentKey)
    {
        if (string.IsNullOrWhiteSpace(documentKey)) return;

        lock (Sync)
        {
            Sessions.Remove(documentKey);
        }
    }
}