using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Workflow.Application.Features.WorkflowDefinitions.Commands;
using Workflow.Domain.Entities;
using Workflow.Domain.Enums;
using Workflow.Domain.Exceptions;
using Workflow.Infrastructure.Persistence;
using Xunit;

namespace Workflow.Tests.Handlers;

public class NodeCommandHandlerTests
{
    private static WorkflowDbContext CreateDbContext()
    {
        var options = new DbContextOptionsBuilder<WorkflowDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;
        return new WorkflowDbContext(options);
    }

    private static async Task<WorkflowDefinition> SeedDefinition(WorkflowDbContext db)
    {
        var definition = new WorkflowDefinition
        {
            Id = Guid.NewGuid(),
            Name = "Test Workflow",
            Code = $"test-wf-{Guid.NewGuid():N}",
            Status = DefinitionStatus.Draft,
            Version = 1
        };
        db.WorkflowDefinitions.Add(definition);
        await db.SaveChangesAsync();
        return definition;
    }

    private static async Task<FormDefinition> SeedFormDefinition(WorkflowDbContext db)
    {
        var form = new FormDefinition
        {
            Id = Guid.NewGuid(),
            Name = "Approval Form",
            Code = $"approval-form-{Guid.NewGuid():N}",
            Status = FormStatus.Published,
            Version = 1,
            SchemaJson = """{"type":"object","properties":{}}"""
        };
        db.FormDefinitions.Add(form);
        await db.SaveChangesAsync();
        return form;
    }

    #region CreateNode

    [Fact]
    public async Task CreateNode_ReturnsNodeDto()
    {
        // Arrange
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);

        var handler = new CreateNodeCommandHandler(db);
        var command = new CreateNodeCommand(
            DefinitionId: definition.Id,
            NodeType: NodeType.Start,
            Name: "Start Node",
            Config: null,
            PositionX: 100,
            PositionY: 200,
            FormDefinitionId: null
        );

        // Act
        var result = await handler.Handle(command, CancellationToken.None);

        // Assert
        result.Should().NotBeNull();
        result.Name.Should().Be("Start Node");
        result.NodeType.Should().Be(NodeType.Start);
        result.PositionX.Should().Be(100);
        result.PositionY.Should().Be(200);
        result.Config.Should().BeNull();
        result.Id.Should().NotBeEmpty();

        var entity = await db.WorkflowNodes.FindAsync(result.Id);
        entity.Should().NotBeNull();
        entity!.DefinitionId.Should().Be(definition.Id);
    }

    [Fact]
    public async Task CreateNode_WithFormDefinition_SavesFormRelation()
    {
        // Arrange
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);
        var form = await SeedFormDefinition(db);

        var handler = new CreateNodeCommandHandler(db);
        var command = new CreateNodeCommand(
            DefinitionId: definition.Id,
            NodeType: NodeType.Approval,
            Name: "Manager Approval",
            Config: null,
            PositionX: 100,
            PositionY: 200,
            FormDefinitionId: form.Id
        );

        // Act
        var result = await handler.Handle(command, CancellationToken.None);

        // Assert
        result.FormDefinitionId.Should().Be(form.Id);
        result.FormName.Should().Be("Approval Form");

        var entity = await db.WorkflowNodes.FindAsync(result.Id);
        entity.Should().NotBeNull();
        entity!.FormDefinitionId.Should().Be(form.Id);
    }

    [Fact]
    public async Task CreateNode_WithMissingDefinition_ThrowsNotFoundException()
    {
        // Arrange
        await using var db = CreateDbContext();
        var handler = new CreateNodeCommandHandler(db);
        var command = new CreateNodeCommand(
            DefinitionId: Guid.NewGuid(),
            NodeType: NodeType.Approval,
            Name: "Orphan Node",
            Config: null,
            PositionX: 0,
            PositionY: 0,
            FormDefinitionId: null
        );

        // Act
        var act = () => handler.Handle(command, CancellationToken.None);

        // Assert
        await act.Should().ThrowAsync<NotFoundException>();
    }

    /// <summary>
    /// 不变量：仅 Approval/Cc 节点可绑定表单。非审批/抄送节点（如 Condition）
    /// 携带 FormDefinitionId 时必须被拒绝，与 UI 契约（NodePropertyDrawer.vue:199）一致。
    /// </summary>
    [Theory]
    [InlineData(NodeType.Start)]
    [InlineData(NodeType.End)]
    [InlineData(NodeType.Condition)]
    [InlineData(NodeType.Parallel)]
    [InlineData(NodeType.SubProcess)]
    public async Task CreateNode_NonApprovalOrCcWithForm_ThrowsBusinessException(NodeType nodeType)
    {
        // Arrange
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);
        var form = await SeedFormDefinition(db);

        var handler = new CreateNodeCommandHandler(db);
        var command = new CreateNodeCommand(
            DefinitionId: definition.Id,
            NodeType: nodeType,
            Name: $"{nodeType} Node",
            Config: null,
            PositionX: 0,
            PositionY: 0,
            FormDefinitionId: form.Id
        );

        // Act
        var act = () => handler.Handle(command, CancellationToken.None);

        // Assert
        await act.Should().ThrowAsync<BusinessException>()
            .WithMessage("*表单*审批*抄送*");

        // 不得创建任何节点
        var nodes = await db.WorkflowNodes.ToListAsync();
        nodes.Should().BeEmpty();
    }

    /// <summary>
    /// 回归保护：Approval 节点仍可正常绑定表单。
    /// </summary>
    [Theory]
    [InlineData(NodeType.Approval)]
    [InlineData(NodeType.Cc)]
    public async Task CreateNode_ApprovalOrCcWithForm_Succeeds(NodeType nodeType)
    {
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);
        var form = await SeedFormDefinition(db);

        var handler = new CreateNodeCommandHandler(db);
        var command = new CreateNodeCommand(
            DefinitionId: definition.Id,
            NodeType: nodeType,
            Name: $"{nodeType} Node",
            Config: null,
            PositionX: 0,
            PositionY: 0,
            FormDefinitionId: form.Id
        );

        var result = await handler.Handle(command, CancellationToken.None);
        result.FormDefinitionId.Should().Be(form.Id);
    }

    #endregion

    #region UpdateNode

    [Fact]
    public async Task UpdateNode_UpdatesNameAndPosition()
    {
        // Arrange
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);

        var nodeId = Guid.NewGuid();
        db.WorkflowNodes.Add(new WorkflowNode
        {
            Id = nodeId,
            DefinitionId = definition.Id,
            NodeType = NodeType.Approval,
            Name = "Old Name",
            PositionX = 50,
            PositionY = 50
        });
        await db.SaveChangesAsync();

        var handler = new UpdateNodeCommandHandler(db);
        var command = new UpdateNodeCommand(
            NodeId: nodeId,
            Name: "Updated Name",
            Config: "{\"timeout\": 300}",
            PositionX: 200,
            PositionY: 300,
            FormDefinitionId: null
        );

        // Act
        var result = await handler.Handle(command, CancellationToken.None);

        // Assert
        result.Should().NotBeNull();
        result.Name.Should().Be("Updated Name");
        result.Config.Should().Be("{\"timeout\": 300}");
        result.PositionX.Should().Be(200);
        result.PositionY.Should().Be(300);
        result.Id.Should().Be(nodeId);

        var entity = await db.WorkflowNodes.FindAsync(nodeId);
        entity.Should().NotBeNull();
        entity!.Name.Should().Be("Updated Name");
        entity.PositionX.Should().Be(200);
    }

    [Fact]
    public async Task UpdateNode_WithFormDefinition_UpdatesFormRelation()
    {
        // Arrange
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);
        var form = await SeedFormDefinition(db);

        var nodeId = Guid.NewGuid();
        db.WorkflowNodes.Add(new WorkflowNode
        {
            Id = nodeId,
            DefinitionId = definition.Id,
            NodeType = NodeType.Approval,
            Name = "Approval",
            PositionX = 50,
            PositionY = 50
        });
        await db.SaveChangesAsync();

        var handler = new UpdateNodeCommandHandler(db);
        var command = new UpdateNodeCommand(
            NodeId: nodeId,
            Name: "Approval",
            Config: null,
            PositionX: 50,
            PositionY: 50,
            FormDefinitionId: form.Id
        );

        // Act
        var result = await handler.Handle(command, CancellationToken.None);

        // Assert
        result.FormDefinitionId.Should().Be(form.Id);
        result.FormName.Should().Be("Approval Form");

        var entity = await db.WorkflowNodes.FindAsync(nodeId);
        entity.Should().NotBeNull();
        entity!.FormDefinitionId.Should().Be(form.Id);
    }

    [Fact]
    public async Task UpdateNode_WithMissingNode_ThrowsNotFoundException()
    {
        // Arrange
        await using var db = CreateDbContext();
        var handler = new UpdateNodeCommandHandler(db);
        var command = new UpdateNodeCommand(
            NodeId: Guid.NewGuid(),
            Name: "Ghost",
            Config: null,
            PositionX: 0,
            PositionY: 0,
            FormDefinitionId: null
        );

        // Act
        var act = () => handler.Handle(command, CancellationToken.None);

        // Assert
        await act.Should().ThrowAsync<NotFoundException>();
    }

    /// <summary>
    /// 不变量：已存在的 Condition 节点（NodeType 不可变）在更新时绑定表单必须被拒绝。
    /// 因 UpdateNodeCommand 不含 NodeType，校验需基于实体当前的 NodeType。
    /// </summary>
    [Fact]
    public async Task UpdateNode_ExistingConditionNodeWithForm_ThrowsBusinessException()
    {
        // Arrange
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);
        var form = await SeedFormDefinition(db);

        var nodeId = Guid.NewGuid();
        db.WorkflowNodes.Add(new WorkflowNode
        {
            Id = nodeId,
            DefinitionId = definition.Id,
            NodeType = NodeType.Condition,
            Name = "Branch",
            PositionX = 0,
            PositionY = 0
        });
        await db.SaveChangesAsync();

        var handler = new UpdateNodeCommandHandler(db);
        var command = new UpdateNodeCommand(
            NodeId: nodeId,
            Name: "Branch",
            Config: null,
            PositionX: 0,
            PositionY: 0,
            FormDefinitionId: form.Id
        );

        // Act
        var act = () => handler.Handle(command, CancellationToken.None);

        // Assert
        await act.Should().ThrowAsync<BusinessException>()
            .WithMessage("*表单*审批*抄送*");

        // 原有 FormDefinitionId 不得被篡改
        var entity = await db.WorkflowNodes.FindAsync(nodeId);
        entity.Should().NotBeNull();
        entity!.FormDefinitionId.Should().BeNull();
    }

    #endregion

    #region DeleteNode

    [Fact]
    public async Task DeleteNode_RemovesNode()
    {
        // Arrange
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);

        var nodeId = Guid.NewGuid();
        db.WorkflowNodes.Add(new WorkflowNode
        {
            Id = nodeId,
            DefinitionId = definition.Id,
            NodeType = NodeType.End,
            Name = "To Delete",
            PositionX = 0,
            PositionY = 0
        });
        await db.SaveChangesAsync();

        var handler = new DeleteNodeCommandHandler(db);
        var command = new DeleteNodeCommand(NodeId: nodeId);

        // Act
        await handler.Handle(command, CancellationToken.None);

        // Assert
        var nodes = await db.WorkflowNodes.ToListAsync();
        nodes.Should().BeEmpty();
    }

    [Fact]
    public async Task DeleteNode_RemovesConnectedEdges()
    {
        // Arrange
        await using var db = CreateDbContext();
        var definition = await SeedDefinition(db);

        var sourceNode = new WorkflowNode
        {
            Id = Guid.NewGuid(),
            DefinitionId = definition.Id,
            NodeType = NodeType.Approval,
            Name = "Source",
            PositionX = 0,
            PositionY = 0
        };
        var targetNode = new WorkflowNode
        {
            Id = Guid.NewGuid(),
            DefinitionId = definition.Id,
            NodeType = NodeType.End,
            Name = "Target",
            PositionX = 200,
            PositionY = 0
        };
        db.WorkflowNodes.AddRange(sourceNode, targetNode);
        db.WorkflowEdges.Add(new WorkflowEdge
        {
            Id = Guid.NewGuid(),
            DefinitionId = definition.Id,
            SourceNodeId = sourceNode.Id,
            TargetNodeId = targetNode.Id,
            EdgeType = EdgeType.Normal
        });
        await db.SaveChangesAsync();

        var handler = new DeleteNodeCommandHandler(db);

        // Act
        await handler.Handle(new DeleteNodeCommand(sourceNode.Id), CancellationToken.None);

        // Assert
        var edges = await db.WorkflowEdges.ToListAsync();
        edges.Should().BeEmpty();
    }

    [Fact]
    public async Task DeleteNode_WithMissingNode_ThrowsNotFoundException()
    {
        // Arrange
        await using var db = CreateDbContext();
        var handler = new DeleteNodeCommandHandler(db);
        var command = new DeleteNodeCommand(NodeId: Guid.NewGuid());

        // Act
        var act = () => handler.Handle(command, CancellationToken.None);

        // Assert
        await act.Should().ThrowAsync<NotFoundException>();
    }

    #endregion
}