using System.Text.Json;
using System.Text.Json.Serialization;
using Workflow.Domain.Enums;

namespace Workflow.Domain.Engine;

/// <summary>
/// X6 graph 的强类型模型，与 X6 toJSON/fromJSON 原生格式兼容。
/// 替代裸 JsonDocument，供 ProcessEngine / 校验器 / 迁移脚本统一读写。
/// 顶层结构为 { nodes: [], edges: [] }（X6 fromJSON 支持的两种等价格式之一）。
/// </summary>
public sealed class WorkflowGraph
{
    [JsonPropertyName("nodes")]
    public List<GraphNode> Nodes { get; set; } = new();

    [JsonPropertyName("edges")]
    public List<GraphEdge> Edges { get; set; } = new();

    /// <summary>空图工厂（容错用）。</summary>
    public static WorkflowGraph Empty() => new();
}

/// <summary>
/// X6 节点。shape 决定渲染器并反推 NodeType（见 <see cref="WorkflowShapeMap"/>）；
/// 业务配置统一进 data；x/y/width/height/ports 为几何与渲染信息。
/// </summary>
public sealed class GraphNode
{
    [JsonPropertyName("id")]
    public string Id { get; set; } = string.Empty;

    [JsonPropertyName("shape")]
    public string Shape { get; set; } = string.Empty;

    [JsonPropertyName("x")]
    public double X { get; set; }

    [JsonPropertyName("y")]
    public double Y { get; set; }

    [JsonPropertyName("width")]
    public double? Width { get; set; }

    [JsonPropertyName("height")]
    public double? Height { get; set; }

    [JsonPropertyName("angle")]
    public double? Angle { get; set; }

    [JsonPropertyName("visible")]
    public bool? Visible { get; set; }

    /// <summary>业务数据（节点配置）。替代旧 WorkflowNode.Config 字符串字段。</summary>
    [JsonPropertyName("data")]
    public JsonElement? Data { get; set; }

    /// <summary>显示名（对应旧 WorkflowNode.Name）。</summary>
    public string? GetTitle() => Data.TryGetString("title");

    [JsonPropertyName("ports")]
    public JsonElement? Ports { get; set; }
}

/// <summary>
/// X6 边。source/target 用 { cell, port } 结构；几何信息（vertices/router/connector）放顶层；
/// 业务字段（edgeType/condition/order）放 data。
/// </summary>
public sealed class GraphEdge
{
    [JsonPropertyName("id")]
    public string Id { get; set; } = string.Empty;

    [JsonPropertyName("shape")]
    public string? Shape { get; set; }

    [JsonPropertyName("source")]
    public GraphEndpoint Source { get; set; } = new();

    [JsonPropertyName("target")]
    public GraphEndpoint Target { get; set; } = new();

    /// <summary>业务数据：edgeType / condition / order。</summary>
    [JsonPropertyName("data")]
    public JsonElement? Data { get; set; }

    [JsonPropertyName("label")]
    public JsonElement? Label { get; set; }

    [JsonPropertyName("vertices")]
    public List<GraphPoint>? Vertices { get; set; }

    [JsonPropertyName("router")]
    public JsonElement? Router { get; set; }

    [JsonPropertyName("connector")]
    public JsonElement? Connector { get; set; }

    /// <summary>边类型（Normal=0/Approved=1/Rejected=2）。缺省为 Normal。</summary>
    public EdgeType GetEdgeType() => Data.TryGetInt32("edgeType") is { } v ? (EdgeType)v : EdgeType.Normal;

    /// <summary>条件表达式（Condition/ExclusiveGateway 出边）。</summary>
    public string? GetCondition() => Data.TryGetString("condition");

    /// <summary>分支评估顺序（值小优先）。</summary>
    public int GetOrder() => Data.TryGetInt32("order") ?? 0;
}

public sealed class GraphEndpoint
{
    /// <summary>节点 id（对应 GraphNode.Id）。</summary>
    [JsonPropertyName("cell")]
    public string? Cell { get; set; }

    /// <summary>端口 id（top/right/bottom/left）。</summary>
    [JsonPropertyName("port")]
    public string? Port { get; set; }
}

public sealed class GraphPoint
{
    [JsonPropertyName("x")]
    public double X { get; set; }

    [JsonPropertyName("y")]
    public double Y { get; set; }
}

/// <summary>
/// JsonElement? 安全取值扩展：统一处理 Nullable 解构与 ValueKind 校验，
/// 避免 WorkflowGraph 各 getter 重复 null 检查。
/// </summary>
internal static class GraphJsonExtensions
{
    public static string? TryGetString(this JsonElement? element, string name) =>
        element is { ValueKind: JsonValueKind.Object } el
        && el.TryGetProperty(name, out var p)
        && p.ValueKind == JsonValueKind.String
            ? p.GetString()
            : null;

    public static int? TryGetInt32(this JsonElement? element, string name) =>
        element is { ValueKind: JsonValueKind.Object } el
        && el.TryGetProperty(name, out var p)
        && (p.ValueKind == JsonValueKind.Number || p.ValueKind == JsonValueKind.String)
        && p.TryGetInt32(out var n)
            ? n
            : null;
}