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

namespace w4c_workflows.Tests;

public class NodeParameterInterpolatorTests
{
    private readonly NodeParameterInterpolator _interpolator = new();

    private static InterpolationScope Scope(
        string itemJson = "{}",
        string parametersJson = "{}",
        string environmentJson = "{}",
        Func<string, IReadOnlyList<FlowItem>>? nodeItems = null) =>
        new()
        {
            Item = JsonNode.Parse(itemJson)!.AsObject(),
            Parameters = JsonNode.Parse(parametersJson)!.AsObject(),
            Environment = JsonNode.Parse(environmentJson)!.AsObject(),
            ItemIndex = 2,
            RunIndex = 1,
            NodeItems = nodeItems,
        };

    [Fact]
    public void Plain_string_is_a_literal()
    {
        var result = _interpolator.ResolveString("hello", Scope());
        Assert.Equal("hello", result!.GetValue<string>());
    }

    [Fact]
    public void Equals_without_braces_is_still_literal_text()
    {
        var result = _interpolator.ResolveString("=plain text", Scope());
        Assert.Equal("plain text", result!.GetValue<string>());
    }

    [Fact]
    public void Whole_value_expression_preserves_type_string()
    {
        var result = _interpolator.ResolveString("={{ $json.name }}", Scope("""{"name":"Alice"}"""));
        Assert.Equal("Alice", result!.GetValue<string>());
    }

    [Fact]
    public void Whole_value_expression_preserves_type_number()
    {
        var result = _interpolator.ResolveString("={{ $json.count }}", Scope("""{"count":3}"""));
        Assert.Equal("3", result!.ToJsonString());
    }

    [Fact]
    public void Whole_value_expression_preserves_type_boolean()
    {
        var result = _interpolator.ResolveString("={{ $json.ok }}", Scope("""{"ok":true}"""));
        Assert.Equal("true", result!.ToJsonString());
    }

    [Fact]
    public void Embedded_expression_produces_an_interpolated_string()
    {
        var result = _interpolator.ResolveString("=Hi {{ $json.name }}, #{{ $json.count }}", Scope("""{"name":"Alice","count":3}"""));
        Assert.Equal("Hi Alice, #3", result!.GetValue<string>());
    }

    [Fact]
    public void Nested_paths_and_array_indexes_resolve()
    {
        var result = _interpolator.ResolveString(
            "={{ $json.orders[0].id }}",
            Scope("""{"orders":[{"id":42}]}"""));
        Assert.Equal("42", result!.ToJsonString());
    }

    [Fact]
    public void Bracket_notation_resolves()
    {
        var result = _interpolator.ResolveString(
            """={{ $json["odd name"] }}""",
            Scope("""{"odd name":"value"}"""));
        Assert.Equal("value", result!.GetValue<string>());
    }

    [Fact]
    public void Parameter_and_environment_roots_resolve()
    {
        var scope = Scope(parametersJson: """{"mode":"manual"}""", environmentJson: """{"REGION":"eu"}""");

        Assert.Equal("manual", _interpolator.ResolveString("={{ $parameter.mode }}", scope)!.GetValue<string>());
        Assert.Equal("eu", _interpolator.ResolveString("={{ $env.REGION }}", scope)!.GetValue<string>());
    }

    [Fact]
    public void Index_roots_resolve()
    {
        var scope = Scope();
        Assert.Equal("2", _interpolator.ResolveString("={{ $itemIndex }}", scope)!.ToJsonString());
        Assert.Equal("1", _interpolator.ResolveString("={{ $runIndex }}", scope)!.ToJsonString());
    }

    [Fact]
    public void Node_reference_returns_the_first_item_json()
    {
        var scope = Scope(nodeItems: _ => new List<FlowItem>
        {
            FlowItem.FromJson(new JsonObject { ["id"] = 7 }),
        });

        Assert.Equal("7", _interpolator.ResolveString("""={{ $("Prep").id }}""", scope)!.ToJsonString());
    }

    [Fact]
    public void Items_reference_returns_an_array()
    {
        var scope = Scope(nodeItems: _ => new List<FlowItem>
        {
            FlowItem.FromJson(new JsonObject { ["id"] = 7 }),
            FlowItem.FromJson(new JsonObject { ["id"] = 8 }),
        });

        Assert.Equal("""[{"id":7},{"id":8}]""", _interpolator.ResolveString("""={{ $items("Prep") }}""", scope)!.ToJsonString());
    }

    [Fact]
    public void Object_parameters_are_resolved_recursively()
    {
        var parameters = JsonNode.Parse("""
        {
          "url": "https://x/{{ $json.id }}",
          "options": { "flag": "={{ $json.ok }}" },
          "list": ["={{ $json.id }}"]
        }
        """)!.AsObject();

        var resolved = _interpolator.ResolveObject(parameters, Scope("""{"id":"abc","ok":true}"""));

        Assert.Equal("https://x/abc", resolved["url"]!.GetValue<string>());
        Assert.Equal("true", resolved["options"]!["flag"]!.ToJsonString());
        Assert.Equal("abc", resolved["list"]![0]!.GetValue<string>());
    }

    [Fact]
    public void Unknown_accessor_throws()
    {
        Assert.Throws<NodeInterpolationException>(() =>
            _interpolator.ResolveString("={{ $nope.x }}", Scope()));
    }

    [Fact]
    public void Missing_path_resolves_to_null_without_throwing()
    {
        var result = _interpolator.ResolveString("={{ $json.missing.deep }}", Scope("""{"other":1}"""));
        Assert.Null(result);
    }

    [Fact]
    public void Case_sensitive_literal_stays_lowercase()
    {
        var result = _interpolator.ResolveString("={{ $json.name }}", Scope("""{"name":"aB"}"""));
        Assert.Equal("aB", result!.GetValue<string>());
    }
}