using System.Text.Json.Nodes;
using w4c_workflows.Models.Nodes;
using w4c_workflows.Services.Nodes;
using Xunit;

namespace w4c_workflows.Tests;

public class NodeGraphCompilerTests
{
    private const string BranchYaml = """
        name: branch-demo
        tasks:
          - id: prepare
            node: { type: core.set }
            parameters:
              mode: manual
              fields:
                - name: status
                  value: ready
            next: decide
          - id: decide
            node: { type: core.if }
            parameters:
              left: "={{ $json.status }}"
              operator: equals
              right: ready
            edges:
              - { output: 0, to: ok }
              - { output: 1, to: nope }
          - id: ok
            node: { type: core.noop }
          - id: nope
            node: { type: core.noop }
        """;

    [Fact]
    public void Compiles_a_node_workflow_and_lowers_next_into_an_edge()
    {
        var definition = NodeTestData.Parse(BranchYaml);
        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(definition);

        Assert.True(result.Success, string.Join("\n", result.Errors));
        var graph = result.Graph!;

        Assert.Equal(4, graph.Nodes.Count);
        Assert.Equal("prepare", graph.EntryNodeId);

        Assert.Contains(
            graph.Edges,
            e => e.FromNodeId == "prepare" && e.FromOutput == 0 && e.ToNodeId == "decide");

        Assert.Contains(graph.Edges, e => e.FromNodeId == "decide" && e.FromOutput == 0 && e.ToNodeId == "ok");
        Assert.Contains(graph.Edges, e => e.FromNodeId == "decide" && e.FromOutput == 1 && e.ToNodeId == "nope");
    }

    [Fact]
    public void Parameters_keep_yaml_types_including_nested_mappings()
    {
        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(BranchYaml));
        var prepare = result.Graph!.Find("prepare")!;

        Assert.Equal("manual", prepare.Parameters["mode"]!.GetValue<string>());

        var fields = prepare.Parameters["fields"]!.AsArray();
        Assert.Single(fields);
        Assert.Equal("status", fields[0]!["name"]!.GetValue<string>());
        Assert.Equal("ready", fields[0]!["value"]!.GetValue<string>());

        var decide = result.Graph!.Find("decide")!;
        Assert.Equal("={{ $json.status }}", decide.Parameters["left"]!.GetValue<string>());
        Assert.Equal("equals", decide.Parameters["operator"]!.GetValue<string>());
    }

    [Fact]
    public void Unknown_node_type_is_reported()
    {
        var yaml = """
            name: unknown
            tasks:
              - id: a
                node: { type: does.not.exist }
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.False(result.Success);
        Assert.Contains(result.Errors, e => e.Contains("unknown node type 'does.not.exist'"));
    }

    [Fact]
    public void Unknown_parameter_is_reported()
    {
        var yaml = """
            name: bad-param
            tasks:
              - id: a
                node: { type: core.set }
                parameters:
                  nope: 1
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.False(result.Success);
        Assert.Contains(result.Errors, e => e.Contains("has no parameter 'nope'"));
    }

    [Fact]
    public void Out_of_range_option_value_is_reported()
    {
        var yaml = """
            name: bad-option
            tasks:
              - id: a
                node: { type: core.set }
                parameters:
                  mode: nope
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.False(result.Success);
        Assert.Contains(result.Errors, e => e.Contains("parameter 'mode' has unsupported value"));
    }

    [Fact]
    public void Expression_parameter_values_skip_static_option_checks()
    {
        var yaml = """
            name: expr-option
            tasks:
              - id: a
                node: { type: core.set }
                parameters:
                  mode: "={{ $json.mode }}"
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.True(result.Success, string.Join("\n", result.Errors));
    }

    [Fact]
    public void A_cycle_is_rejected()
    {
        var yaml = """
            name: cycle
            tasks:
              - id: a
                node: { type: core.noop }
                next: b
              - id: b
                node: { type: core.noop }
                next: a
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.False(result.Success);
        Assert.Contains(result.Errors, e => e.Contains("no entry node") || e.Contains("cycle"));
    }

    [Fact]
    public void A_cycle_through_a_loop_node_is_allowed_and_marked_loop_back()
    {
        var yaml = """
            name: loop-ok
            tasks:
              - id: loop
                node: { type: core.splitInBatches }
                parameters: { batchSize: 2 }
                edges:
                  - { output: 0, to: body }
              - id: body
                node: { type: core.noop }
                edges:
                  - { output: 0, to: loop }
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.True(result.Success, string.Join("\n", result.Errors));
        var backEdge = Assert.Single(result.Graph!.Edges.Where(e => e.IsLoopBack));
        Assert.Equal("body", backEdge.FromNodeId);
        Assert.Equal("loop", backEdge.ToNodeId);
        Assert.Equal("loop", result.Graph!.EntryNodeId);
    }

    /// <summary>
    /// P1-2: loop-back classification must not depend on task declaration order.
    /// Declaring the body before the loop node previously made the DFS classify
    /// the forward edge (loop → body) as the back edge and reject a valid loop.
    /// </summary>
    [Fact]
    public void Loop_back_classification_is_order_independent()
    {
        var yaml = """
            name: loop-order
            tasks:
              - id: body
                node: { type: core.noop }
                edges:
                  - { output: 0, to: loop }
              - id: loop
                node: { type: core.splitInBatches }
                parameters: { batchSize: 2 }
                edges:
                  - { output: 0, to: body }
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.True(result.Success, string.Join("\n", result.Errors));
        var backEdge = Assert.Single(result.Graph!.Edges.Where(e => e.IsLoopBack));
        Assert.Equal("body", backEdge.FromNodeId);
        Assert.Equal("loop", backEdge.ToNodeId);
        Assert.Equal("loop", result.Graph!.EntryNodeId);
    }

    [Fact]
    public void Multiple_entry_nodes_are_rejected()
    {
        var yaml = """
            name: two-roots
            tasks:
              - id: a
                node: { type: core.noop }
              - id: b
                node: { type: core.noop }
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.False(result.Success);
        Assert.Contains(result.Errors, e => e.Contains("multiple entry nodes"));
    }

    [Fact]
    public void A_node_workflow_step_cannot_mix_node_and_entry()
    {
        var yaml = """
            name: mixed
            tasks:
              - id: a
                node: { type: core.noop }
                entry: { file: main.sh }
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.False(result.Success);
        Assert.Contains(result.Errors, e => e.Contains("mutually exclusive"));
    }

    [Fact]
    public void OnError_lowers_to_the_error_output_port()
    {
        var catalog = NodeTestData.Catalog(NodeTestData.NodeBlueprint(
            "test.fail",
            outputs: new List<NodePort> { NodePort.Main, NodePort.Error }));

        var yaml = """
            name: error-branch
            tasks:
              - id: work
                node: { type: test.fail }
                onError: recover
              - id: recover
                node: { type: core.noop }
            """;

        var result = new NodeGraphCompiler(catalog).Compile(NodeTestData.Parse(yaml));

        Assert.True(result.Success, string.Join("\n", result.Errors));
        Assert.Contains(
            result.Graph!.Edges,
            e => e.FromNodeId == "work" && e.FromOutput == 1 && e.ToNodeId == "recover");
    }

    [Fact]
    public void OnError_without_an_error_output_is_rejected()
    {
        var yaml = """
            name: bad-error-branch
            tasks:
              - id: work
                node: { type: core.noop }
                onError: recover
              - id: recover
                node: { type: core.noop }
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.False(result.Success);
        Assert.Contains(result.Errors, e => e.Contains("has no error output"));
    }

    [Fact]
    public void Pinned_version_resolves_to_that_blueprint()
    {
        var catalog = NodeTestData.Catalog(
            NodeTestData.NodeBlueprint("demo", 1),
            NodeTestData.NodeBlueprint("demo", 2));

        var yaml = """
            name: pinned
            tasks:
              - id: a
                node: { type: demo, version: 1 }
            """;

        var result = new NodeGraphCompiler(catalog).Compile(NodeTestData.Parse(yaml));

        Assert.True(result.Success, string.Join("\n", result.Errors));
        Assert.Equal(1, result.Graph!.Find("a")!.Blueprint.Version);
    }

    [Fact]
    public void IsNodeWorkflow_detects_node_mode()
    {
        Assert.True(NodeGraphCompiler.IsNodeWorkflow(NodeTestData.Parse(BranchYaml)));

        var legacy = NodeTestData.Parse("""
            name: legacy
            tasks:
              - id: a
                entry: { file: main.sh }
            """);
        Assert.False(NodeGraphCompiler.IsNodeWorkflow(legacy));
    }

    // Шаг 9 of the migration playbook: the Slack example YAML must compile and
    // keep its connector parameters + declared credential alias.
    [Fact]
    public void Compiles_the_slack_connector_example_yaml()
    {
        var yaml = """
            name: notify-on-order
            tasks:
              - id: notify
                node: { type: slack }
                credentials: { slack: my-bot }
                parameters:
                  operation: chat.postMessage
                  body:
                    channel: C08514ZPKB8
                    text: "test message"
                    link_names: true
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.True(result.Success, string.Join("\n", result.Errors));
        var notify = result.Graph!.Find("notify")!;
        Assert.Equal("chat.postMessage", notify.Parameters["operation"]!.GetValue<string>());
        Assert.Equal("C08514ZPKB8", notify.Parameters["body"]!["channel"]!.GetValue<string>());
        Assert.True(notify.Parameters["body"]!["link_names"]!.GetValue<bool>());
        Assert.Equal("my-bot", notify.CredentialRefs["slack"]);
    }

    [Fact]
    public void Slack_node_without_its_required_credential_is_reported()
    {
        var yaml = """
            name: notify-on-order
            tasks:
              - id: notify
                node: { type: slack }
                parameters:
                  operation: chat.postMessage
                  body: { channel: C1, text: hi }
            """;

        var result = new NodeGraphCompiler(NodeTestData.CoreCatalog()).Compile(NodeTestData.Parse(yaml));

        Assert.False(result.Success);
        Assert.Contains(result.Errors, e => e.Contains("requires credential 'slack'"));
    }
}