namespace Uwaa.Pleroma;

public class Attachment
{
    /// <summary>
    /// The ID of the attachment in the database.
    /// </summary>
    [JsonPropertyName("id")]
    public string ID { get; set; } = null!;

    /// <summary>
    /// Alternate text that describes what is in the media attachment, to be used for the visually impaired or when media attachments do not load
    /// </summary>
    [JsonPropertyName("description")]
    public string? Description { get; set; }

    /// <summary>
    /// Additional pleroma-specific data.
    /// </summary>
    [JsonPropertyName("pleroma")]
    public PleromaAttachmentData Pleroma { get; set; } = null!;

    /// <summary>
    /// The location of a scaled-down preview of the attachment
    /// </summary>
    [JsonPropertyName("preview_url")]
    public string PreviewURL { get; set; } = null!;

    /// <summary>
    /// The location of the full-size original attachment on the remote website. String (URL), or null if the attachment is local
    /// </summary>
    [JsonPropertyName("remote_url")]
    public string? RemoteURL { get; set; }

    /// <summary>
    /// A shorter URL for the attachment
    /// </summary>
    [JsonPropertyName("text_url")]
    public string? TextURL { get; set; }

    /// <summary>
    /// The type of the attachment
    /// </summary>
    [JsonPropertyName("type")]
    public AttachmentType Type { get; set; }

    /// <summary>
    /// The location of the original full-size attachment
    /// </summary>
    [JsonPropertyName("url")]
    public string URL { get; set; } = null!;

    /// <summary>
    /// Downloads the attachment.
    /// </summary>
    public async Task<byte[]> Download()
    {
        using HttpClient client = new HttpClient();
        HttpResponseMessage res = await client.GetAsync(URL);
        return await res.Content.ReadAsByteArrayAsync();
    }
}

[JsonConverter(typeof(EnumLowerCaseConverter<AttachmentType>))]
public enum AttachmentType
{
    Unknown,
    Image,
    Video,
    Audio,
}

/// <summary>
/// Additional pleroma-specific data for an <see cref="Attachment"/>.
/// </summary>
public class PleromaAttachmentData
{
    /// <summary>
    /// MIME type of the attachment
    /// </summary>
    [JsonPropertyName("mime_type")]
    public string MIMEType { get; set; } = null!;

    /// <summary>
    /// Name of the attachment, typically the filename
    /// </summary>
    [JsonPropertyName("name")]
    public string Name { get; set; } = null!;
}

[JsonConverter(typeof(MediaIDConverter))]
public readonly struct MediaID(string id)
{
    public static implicit operator MediaID(string id) => new MediaID(id);

    public static implicit operator MediaID(Attachment attachment) => new MediaID(attachment.ID);

    public readonly string ID = id;

    public override string ToString() => ID;
}

class MediaIDConverter : JsonConverter<MediaID>
{
    public override bool CanConvert(Type type) => type.IsAssignableTo(typeof(MediaID));

    public override MediaID Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        return new MediaID(reader.GetString() ?? throw new NullReferenceException("Expected a string, got null"));
    }

    public override void Write(Utf8JsonWriter writer, MediaID value, JsonSerializerOptions options)
    {
        writer.WriteStringValue(value.ID);
    }
}