using SharedKernel.Extensions;
using System.Text.RegularExpressions;

namespace Application.Common;

/// <summary>
/// 게시판 알림 메일 템플릿의 {변수} 토큰 빌더.
/// EmailTemplateExtensions.Render() 의 입력으로 사용한다.
/// </summary>
internal static class ForumNotifyRenderer
{
    private static readonly Regex HtmlTagRegex = new("<[^>]+>", RegexOptions.Compiled);
    private static readonly Regex WhitespaceRegex = new(@"\s+", RegexOptions.Compiled);

    /// <summary>HTML 태그 제거 후 maxLength 자로 자른 미리보기 텍스트</summary>
    public static string ToPreview(string? html, int maxLength = 200)
    {
        if (string.IsNullOrWhiteSpace(html))
        {
            return string.Empty;
        }

        var text = HtmlTagRegex.Replace(html, " ");
        text = System.Net.WebUtility.HtmlDecode(text);
        text = WhitespaceRegex.Replace(text, " ").Trim();

        return text.Length <= maxLength ? text : text[..maxLength] + "…";
    }

    /// <summary>게시글 작성 알림용 토큰 — {SiteName} {BoardName} {PostID} {PostSubject} {AuthorName} {AuthorEmail} {CreatedAt} {IsSecret} {PostContentPreview}</summary>
    public static (string Key, string Value)[] PostTokens(string? siteName, string boardName, Domain.Entities.Forum.Posts.Post post) => [
        ("SiteName", siteName ?? string.Empty),
        ("BoardName", boardName),
        ("PostID", post.ID.ToString()),
        ("PostSubject", post.Subject),
        ("AuthorName", post.Name ?? post.SID ?? "-"),
        ("AuthorEmail", post.Email ?? "-"),
        ("CreatedAt", post.CreatedAt.GetDateAt()),
        ("IsSecret", post.IsSecret ? "비밀글" : "공개"),
        ("PostContentPreview", ToPreview(post.Content))
    ];

    /// <summary>댓글/답글 작성 알림용 토큰 — 게시글 토큰 + {CommentContent} {CommentAuthorName} {CommentCreatedAt}</summary>
    public static (string Key, string Value)[] CommentTokens(string? siteName, string boardName, Domain.Entities.Forum.Posts.Post post, Domain.Entities.Forum.Comments.Comment comment) => [
        ..PostTokens(siteName, boardName, post),
        ("CommentContent", ToPreview(comment.Content, 500)),
        ("CommentAuthorName", comment.Name ?? comment.SID ?? "-"),
        ("CommentCreatedAt", comment.CreatedAt.GetDateAt())
    ];
}