using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;

namespace WxAgent.Core;

public sealed record WechatMomentSnapshot(
    string Author,
    string Text,
    string Fingerprint,
    string? Time = null,
    int ImageCount = 0,
    bool IsLiked = false);

public sealed record WechatMessageContent(
    ChatMessageType Type,
    string Text,
    Uri? Url = null,
    QuotedMessageSnapshot? Quote = null);

public sealed record WechatNoteContentPart(string Kind, string Value);

public sealed record WechatNoteContent(IReadOnlyList<WechatNoteContentPart> Parts)
{
    public string ToMarkdown() => string.Join(
        Environment.NewLine + Environment.NewLine,
        Parts.Select(part => part.Kind == "file" ? $"[{Path.GetFileName(part.Value)}]({part.Value})" : part.Value));
}

public enum WechatMomentPrivacy
{
    Public,
    TagWhitelist,
    TagBlacklist
}

public sealed record WechatMomentPublishOptions(
    WechatMomentPrivacy Privacy = WechatMomentPrivacy.Public,
    IReadOnlyList<string>? Tags = null)
{
    public void Validate()
    {
        if (!Enum.IsDefined(Privacy))
            throw new WxAgentException(WxAgentErrorCode.InvalidArgument, "Unknown moment privacy mode.");
        if (Privacy != WechatMomentPrivacy.Public)
            WechatOperationPolicy.ValidateNames(Tags ?? [], nameof(Tags));
    }
}

public static partial class WechatMessageContentParser
{
    [GeneratedRegex(@"https?://[^\s<>\]\[\)）]+", RegexOptions.IgnoreCase | RegexOptions.CultureInvariant)]
    private static partial Regex UrlRegex();

    public static Uri? GetUrl(ChatMessageSnapshot message)
    {
        ArgumentNullException.ThrowIfNull(message);
        var match = UrlRegex().Match(message.Text);
        return match.Success && Uri.TryCreate(match.Value.TrimEnd('.', ',', '。', '，'), UriKind.Absolute, out var uri) ? uri : null;
    }

    public static WechatMessageContent GetContent(ChatMessageSnapshot message)
    {
        ArgumentNullException.ThrowIfNull(message);
        return new WechatMessageContent(message.Type, message.Text, GetUrl(message), message.Quote);
    }

    public static string ToMarkdown(ChatMessageSnapshot message)
    {
        ArgumentNullException.ThrowIfNull(message);
        var content = GetContent(message);
        var body = content.Type switch
        {
            ChatMessageType.Image => $"![图片]({content.Url?.AbsoluteUri ?? string.Empty})",
            ChatMessageType.Video => $"[视频]({content.Url?.AbsoluteUri ?? string.Empty})",
            ChatMessageType.File => $"[文件]({content.Url?.AbsoluteUri ?? string.Empty})",
            ChatMessageType.Voice => $"> 语音：{content.Text}",
            ChatMessageType.Link when content.Url is not null => $"[{LinkTitle(content.Text, content.Url)}]({content.Url.AbsoluteUri})",
            _ => content.Text
        };
        if (content.Quote is null) return body;
        var quote = string.Join(Environment.NewLine, content.Quote.Text.Split('\n').Select(line => $"> {line}"));
        return $"{quote}{Environment.NewLine}{Environment.NewLine}{body}";
    }

    public static string MomentFingerprint(string author, string text, string? time)
    {
        var bytes = SHA256.HashData(Encoding.UTF8.GetBytes($"{author}\n{text}\n{time}"));
        return Convert.ToHexString(bytes).ToLowerInvariant();
    }

    private static string LinkTitle(string text, Uri url)
    {
        var title = UrlRegex().Replace(text, string.Empty, 1).Trim();
        return string.IsNullOrWhiteSpace(title) ? url.Host : title;
    }
}