using System.Text.Json;
using Workflow.Domain.Engine;
using Workflow.Domain.Entities;

namespace Workflow.Application.Engine;

/// <summary>
/// WorkflowGraph（X6 JSON 强类型）与 WorkflowNode/WorkflowEdge（领域实体）的双向适配层。
/// 使 ProcessEngine 从「读关系表」切换到「读 X6 JSON 快照」时，下游所有 Process*Async 方法零改动——
/// 引擎启动时把图映射成内存实体集合，FindNodeAsync/GetOutgoingEdges 等改查内存集合即可。
///
/// ID 兼容约定（见技术方案文档 5.7）：X6 节点/边 id 用纯 Guid 字符串（前端 crypto.randomUUID() 生成），
/// 不带 "node_" 前缀，保证 Guid ↔ string 无损往返（WorkflowToken.NodeId 是 Guid）。
/// </summary>
public static class WorkflowGraphAdapter
{
    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web);

    /// <summary>把 WorkflowGraph 映射成内存 WorkflowNode 集合（供 ProcessEngine 查询）。</summary>
    public static List<WorkflowNode> ToNodes(WorkflowGraph graph, Guid definitionId)
    {
        var nodes = new List<WorkflowNode>(graph.Nodes.Count);
        foreach (var gn in graph.Nodes)
        {
            var nodeType = WorkflowShapeMap.ToNodeType(gn.Shape);
            if (nodeType is null) continue; // 未知 shape 跳过（发布校验已拦截）

            nodes.Add(new WorkflowNode
            {
                Id = ParseGuid(gn.Id),
                DefinitionId = definitionId,
                NodeType = nodeType.Value,
                Name = gn.GetTitle() ?? nodeType.Value.ToString(),
                // Config：把 data 对象序列化回字符串，复用现有 NodeConfigParser 解析链
                Config = gn.Data is { ValueKind: JsonValueKind.Object or JsonValueKind.Array } data
                    ? data.GetRawText()
                    : null,
                // 审批节点绑定的表单定义 id（钉钉式树编译进 data.formDefinitionId）。
                // ApproveTaskCommandHandler.SaveNodeFormDataAsync 据此加载表单做字段权限校验。
                FormDefinitionId = TryGetFormDefinitionId(gn.Data),
                PositionX = (int)Math.Round(gn.X),
                PositionY = (int)Math.Round(gn.Y),
                // 审计字段填充非空默认值（实体是 IFullAudit，避免下游 null 引用）
                CreatedBy = "system",
                UpdatedBy = "system",
            });
        }
        return nodes;
    }

    /// <summary>把 WorkflowGraph 映射成内存 WorkflowEdge 集合（供 ProcessEngine 查询）。</summary>
    public static List<WorkflowEdge> ToEdges(WorkflowGraph graph, Guid definitionId)
    {
        var edges = new List<WorkflowEdge>(graph.Edges.Count);
        foreach (var ge in graph.Edges)
        {
            var sourceId = ParseGuid(ge.Source.Cell);
            var targetId = ParseGuid(ge.Target.Cell);
            if (sourceId == Guid.Empty || targetId == Guid.Empty) continue;

            edges.Add(new WorkflowEdge
            {
                Id = ParseGuid(ge.Id),
                DefinitionId = definitionId,
                SourceNodeId = sourceId,
                TargetNodeId = targetId,
                EdgeType = ge.GetEdgeType(),
                Label = null, // 引擎不读 Label
                Condition = ge.GetCondition(),
                Order = ge.GetOrder(),
                CreatedBy = "system",
                UpdatedBy = "system",
            });
        }
        return edges;
    }

    /// <summary>纯 Guid 字符串解析为 Guid；非法返回 Guid.Empty（适配层会跳过）。</summary>
    private static Guid ParseGuid(string? id)
    {
        if (string.IsNullOrWhiteSpace(id)) return Guid.Empty;
        return Guid.TryParse(id, out var g) ? g : Guid.Empty;
    }

    /// <summary>从节点 data.formDefinitionId（钉钉式树编译产物）提取表单定义 id。</summary>
    private static Guid? TryGetFormDefinitionId(System.Text.Json.JsonElement? data)
    {
        if (data is not { ValueKind: System.Text.Json.JsonValueKind.Object } obj) return null;
        if (!obj.TryGetProperty("formDefinitionId", out var prop)) return null;
        var raw = prop.ValueKind == System.Text.Json.JsonValueKind.String ? prop.GetString() : null;
        return Guid.TryParse(raw, out var g) ? g : null;
    }
}