namespace WebDrop.Core;

/// <summary>谁能做什么。规则只写在这里,服务和测试都调用它。</summary>
public static class ChannelPolicy
{
    public static bool IsOwner(Principal p) => p.Role == Role.Owner;

    public static bool CanRead(Principal p) => p.Role >= Role.Read;

    /// <summary>成员写入需要频道允许上传,且服务端持有写令牌哈希。</summary>
    public static bool CanWrite(Channel channel, Principal p) =>
        p.Role == Role.Owner
        || (p.Role == Role.Write && channel.Settings.MembersCanUpload && channel.WriteHash is not null);

    public static bool CanDeleteItem(Channel channel, Item item, Principal p)
    {
        if (p.Role == Role.Owner) return true;
        if (p.Role < Role.Read) return false;
        return channel.Settings.DeletePolicy switch
        {
            DeletePolicy.Anyone => true,
            DeletePolicy.Own => item.AuthorHash.AsSpan().SequenceEqual(p.EndpointHash),
            _ => false,
        };
    }
}