namespace AibisDream.SaveSystem
{
    /// <summary>
    /// 可存点被拒绝的原因，供日志与 UI 提示使用。
    /// </summary>
    public enum SavePointRejectReason
    {
        None,
        Restoring,
        GamePaused,
        NoActiveNode,
        StartNode,
        FunctionNode,
        NoAutoSave
    }

    /// <summary>
    /// 可存点判定器。
    /// <para>
    /// P3 只搭框架：规则不是最终版，后续随 Yarn 节点 tags 整理和章节策略扩展而更新。
    /// 当前所有 FixState 均放行，不可存状态由 Yarn 节点流程控制。
    /// </para>
    /// </summary>
    public static class SavePointEvaluator
    {
        /// <summary>
        /// 当前是否可以自动存档。
        /// </summary>
        public static bool CanAutoSave(out SavePointRejectReason reason)
        {
            if (SaveRestoreOrchestrator.IsRestoring)
            {
                reason = SavePointRejectReason.Restoring;
                return false;
            }

            if (GameManager.Instance != null && GameManager.Instance.state.isInPause)
            {
                reason = SavePointRejectReason.GamePaused;
                return false;
            }

            var (nodeName, tags) = DialogController.Instance != null
                ? DialogController.Instance.GetCurrentNodeContext()
                : (null, null);

            if (string.IsNullOrEmpty(nodeName))
            {
                reason = SavePointRejectReason.NoActiveNode;
                return false;
            }

            if (nodeName == "Start")
            {
                reason = SavePointRejectReason.StartNode;
                return false;
            }

            if (tags != null && IsTagPresent(tags, "function"))
            {
                reason = SavePointRejectReason.FunctionNode;
                return false;
            }

            reason = SavePointRejectReason.None;
            return true;
        }

        /// <summary>
        /// 当前是否可以手动存档。
        /// 手动档 = 复制最近自动档，因此需要当前可自动存档且自动档存在。
        /// </summary>
        public static bool CanManualSave(out SavePointRejectReason reason)
        {
            if (!CanAutoSave(out reason))
            {
                return false;
            }

            if (!SlotDirectory.Exists(SlotIndex.Auto))
            {
                reason = SavePointRejectReason.NoAutoSave;
                return false;
            }

            reason = SavePointRejectReason.None;
            return true;
        }

        private static bool IsTagPresent(System.Collections.Generic.IReadOnlyList<string> tags, string tag)
        {
            if (tags == null) return false;

            foreach (var t in tags)
            {
                if (t == tag)
                {
                    return true;
                }
            }

            return false;
        }
    }
}