using System.Collections.ObjectModel;
using System.Reflection;

using WPFluent.Extensions;

namespace WPFluent.Appearance;

/// <summary>
/// 管理资源字典
/// </summary>
internal class ResourceDictionaryManager
{

    /// <summary>
    /// 获取命名空间，例如正在搜索的资源库。
    /// </summary>
    private string SearchNamespace { get; } = Assembly.GetExecutingAssembly().GetName().Name;

    /// <summary>
    /// 查找资源 <see cref="ResourceDictionary"/> 
    /// </summary>
    /// <param name="resourceLookup">任何部分的资源名称。</param>
    /// <returns><see cref="ResourceDictionary"/>, <see langword="null"/>如果不存在，返回null</returns>
    public ResourceDictionary? LookupDictionary(string resourceLookup)
    {
        Collection<ResourceDictionary> applicationDictionaries = ThemeManager.Current.Resources.MergedDictionaries;

        if (applicationDictionaries.Count == 0)
        {
            return null;
        }

        foreach (ResourceDictionary t in applicationDictionaries)
        {
            string resourceDictionaryUri;

            if (t?.Source != null)
            {
                resourceDictionaryUri = t.Source.ToString();

                if (resourceDictionaryUri.Contains(SearchNamespace, StringComparison.OrdinalIgnoreCase) &&
                    resourceDictionaryUri.Contains(resourceLookup, StringComparison.OrdinalIgnoreCase))
                {
                    return t;
                }
            }

            foreach (ResourceDictionary? t1 in t!.MergedDictionaries)
            {
                if (t1?.Source == null)
                {
                    continue;
                }

                resourceDictionaryUri = t1.Source.ToString();

                if (!resourceDictionaryUri.Contains(SearchNamespace, StringComparison.OrdinalIgnoreCase) ||
                    !resourceDictionaryUri.Contains(resourceLookup, StringComparison.OrdinalIgnoreCase))
                {
                    continue;
                }

                return t1;
            }
        }

        return null;
    }

    /// <summary>
    /// 更新应用程序中的资源字典
    /// </summary>
    /// <param name="resourceLookup">要查找的资源名称的一部分</param>
    /// <param name="newResourceUri">用于替换的新资源的有效Uri</param>
    /// <returns>如果字典Uri已更新则返回true，否则返回false</returns>
    public bool UpdateDictionary(string resourceLookup, Uri? newResourceUri)
    {
        // 获取应用程序的合并资源字典集合
        var applicationDictionaries = ThemeManager
            .Current
            .Resources
            .MergedDictionaries;

        // 如果没有资源字典或新的Uri为空，则返回false
        if (applicationDictionaries.Count == 0 || newResourceUri is null)
        {
            return false;
        }

        // 遍历顶层资源字典
        for (var i = 0; i < applicationDictionaries.Count; i++)
        {
            string sourceUri;

            // 检查当前资源字典是否有Source
            if (applicationDictionaries[i]?.Source != null)
            {
                sourceUri = applicationDictionaries[i].Source.ToString();

                // 检查资源Uri是否匹配搜索条件
                if (sourceUri.Contains(SearchNamespace, StringComparison.OrdinalIgnoreCase) &&
                    sourceUri.Contains(resourceLookup, StringComparison.OrdinalIgnoreCase))
                {
                    // 使用新的Uri更新资源字典
                    applicationDictionaries[i] = new() { Source = newResourceUri };

                    return true;
                }
            }

            // 遍历合并的子资源字典
            for (var j = 0; j < applicationDictionaries[i].MergedDictionaries.Count; j++)
            {
                if (applicationDictionaries[i].MergedDictionaries[j]?.Source == null)
                {
                    continue;
                }

                sourceUri = applicationDictionaries[i].MergedDictionaries[j].Source.ToString();

                // 检查子资源字典Uri是否匹配搜索条件
                if (!sourceUri.Contains(SearchNamespace, StringComparison.OrdinalIgnoreCase) ||
                    !sourceUri.Contains(resourceLookup, StringComparison.OrdinalIgnoreCase))
                {
                    continue;
                }

                // 使用新的Uri更新子资源字典
                applicationDictionaries[i].MergedDictionaries[j] = new ResourceDictionary { Source = newResourceUri };

                return true;
            }
        }

        // 未找到匹配的资源字典，返回false
        return false;
    }
}