using Fleet.Core;
using Fleet.Identity;

namespace MoShiro.Backend.Application;

/// <summary>
/// 节点的属主：创建加入码时选定的 passkey 凭证 id，写进安装命令，节点注册时固定在本地。
/// 属主必须是操作员集合里的凭证；<see cref="BackendOptions.RequireOwner"/> 打开时（默认）必须已经有信任根，并且至少选一把——
/// 不选属主的节点没有人能授权它的敏感操作，也就不该存在。没有明确指定时默认是操作员集合里的全部 passkey。
/// </summary>
public static class OwnerPolicy
{
    public static Result<string[]> Resolve(bool required, OperatorSet? set, IReadOnlyList<string>? requested)
    {
        if (set is null)
        {
            return required
                ? ValidationError.Fail<string[]>("controllers", "set up the trust root first (System, Trust): every node needs an owner passkey")
                : Result<string[]>.Ok([]);
        }

        string[] chosen = requested is null ? [.. set.Keys.Select(k => k.CredentialId)] : [.. requested.Distinct(StringComparer.Ordinal)];
        if (chosen.Any(c => set.Keys.All(k => k.CredentialId != c)))
        {
            return ValidationError.Fail<string[]>("controllers", "must be passkeys of the operator set");
        }

        return required && chosen.Length == 0
            ? ValidationError.Fail<string[]>("controllers", "pick at least one owner passkey: a node's owner is who its sensitive sessions and data are bound to")
            : Result<string[]>.Ok(chosen);
    }
}