using System.Text.Json;
using Agent.Core.Tools;

namespace Agent.Core.Tests;

public sealed class InternalToolTests
{
    [Fact]
    public void Catalog_exposes_exactly_five_strict_tool_groups()
    {
        Assert.Equal(["file_search", "file_read", "file_edit", "process_run", "task_update"], InternalToolCatalog.All.Select(x => x.Name));
        foreach (InternalToolDefinition tool in InternalToolCatalog.All) Assert.False(tool.Parameters.GetProperty("additionalProperties").GetBoolean());
    }

    [Theory]
    [InlineData("file_read", "{}")]
    [InlineData("file_read", "{\"path\":\"a\",\"mode\":\"whole\",\"unknown\":1}")]
    [InlineData("file_read", "{\"path\":\"a\",\"mode\":\"invalid\"}")]
    [InlineData("file_search", "{\"root\":\".\",\"mode\":\"text\",\"query\":\"x\",\"max_results\":1001}")]
    [InlineData("process_run", "{\"executable\":\"x\",\"args\":\"bad\",\"cwd\":\".\"}")]
    [InlineData("task_update", "{\"operation\":\"add\",\"description\":\"missing estimate\"}")]
    public void Malformed_arguments_are_rejected(string tool, string json)
    {
        using JsonDocument document = JsonDocument.Parse(json);
        Assert.Throws<ToolValidationException>(() => InternalToolValidator.Validate(tool, document.RootElement));
    }

    [Fact]
    public async Task Policy_deny_has_no_backend_side_effect()
    {
        FakeInternalToolBackend backend = new();
        InternalToolDispatcher dispatcher = new(new DenyByDefaultPolicy(), backend);
        using JsonDocument document = JsonDocument.Parse("""{"path":"x","operation":"overwrite","content":"changed"}""");

        ToolExecutionResult result = await dispatcher.DispatchAsync(Guid.NewGuid(), "file_edit", document.RootElement, TestContext.Current.CancellationToken);

        Assert.False(result.Success);
        Assert.False(result.ExternalEffect);
        Assert.Empty(backend.Calls);
    }

    [Fact]
    public async Task Allowed_call_reaches_fake_backend_only_after_validation_and_policy()
    {
        FakeInternalToolBackend backend = new();
        InternalToolDispatcher dispatcher = new(new DenyByDefaultPolicy(new HashSet<string>(["file_read"], StringComparer.Ordinal)), backend);
        using JsonDocument document = JsonDocument.Parse("""{"path":"x","mode":"whole"}""");

        ToolExecutionResult result = await dispatcher.DispatchAsync(Guid.NewGuid(), "file_read", document.RootElement, TestContext.Current.CancellationToken);

        Assert.True(result.Success);
        Assert.Single(backend.Calls);
    }

    [Fact]
    public void Guard_requires_effect_and_fails_on_fifth_identical_failure()
    {
        ToolUseGuard guard = new();
        for (int attempt = 1; attempt < 5; attempt++) Assert.Equal(ToolUseGuardDecision.Retry, guard.Evaluate(true, false, false, "same").Decision);
        ToolUseGuardResult fifth = guard.Evaluate(true, false, false, "same");
        Assert.Equal(ToolUseGuardDecision.Fail, fifth.Decision);
        Assert.Equal(5, fifth.IdenticalFailureCount);
    }

    [Fact]
    public void Guard_does_not_force_tools_for_pure_analysis()
    {
        Assert.Equal(ToolUseGuardDecision.Complete, new ToolUseGuard().Evaluate(false, false, false).Decision);
    }

    [Fact]
    public void Task_update_mutates_the_real_deterministic_graph_without_external_effect_evidence()
    {
        Guid scope = Guid.NewGuid();
        Guid node = Guid.NewGuid();
        var handler = new TaskGraphToolHandler();
        handler.BeginTask(scope);
        using JsonDocument add = JsonDocument.Parse($$"""{"operation":"add","task_id":"{{node}}","description":"Build fixture","depends_on":[],"budget_class":"1K","optimistic_tokens":10,"most_likely_tokens":20,"pessimistic_tokens":30}""");

        ToolExecutionResult result = handler.Execute(scope, add.RootElement);

        Assert.True(result.Success);
        Assert.False(result.ExternalEffect);
        Assert.Contains(node.ToString(), result.Output, StringComparison.OrdinalIgnoreCase);
        handler.EndTask(scope);
        Assert.Throws<InvalidOperationException>(() => handler.Execute(scope, add.RootElement));
    }
}