using System;
using System.IO;
using System.Linq;
using System.Reflection;

namespace GmRelay.Bot.Tests.Discord;

/// <summary>
/// Source-level structural smoke tests for the Discord wizard
/// interaction module. The NetCord component-interaction service
/// uses dispatch-by-attribute (no public registry), so a runtime
/// instantiation test would need to spin up the full NetCord host —
/// overkill for a smoke gate. Instead we assert on the source shape
/// (custom-id formats, handler method signatures, dispatcher wiring)
/// so the existing wizard tests catch regressions in the platform-
/// neutral state machine while this file catches regressions in the
/// Discord adapter shell.
/// </summary>
public sealed class DiscordWizardInteractionModuleSourceTests
{
    private static string GetRepoRoot()
    {
        var dir = AppContext.BaseDirectory;
        while (!string.IsNullOrEmpty(dir) && !File.Exists(Path.Combine(dir, "Directory.Build.props")))
        {
            dir = Directory.GetParent(dir)?.FullName;
        }

        return dir ?? throw new InvalidOperationException("Could not find repo root");
    }

    private static string ReadSource(string relativePath)
    {
        var repoRoot = GetRepoRoot();
        var fullPath = Path.Combine(repoRoot, relativePath);
        Assert.True(File.Exists(fullPath), $"Source file {relativePath} should exist.");
        return File.ReadAllText(fullPath);
    }

    [Fact]
    public void Module_ShouldExist()
    {
        var path = "src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs";
        var source = ReadSource(path);
        Assert.Contains("public sealed class DiscordWizardButtonModule", source, StringComparison.Ordinal);
        Assert.Contains("public sealed class DiscordWizardStringMenuModule", source, StringComparison.Ordinal);
        Assert.Contains("public sealed class DiscordWizardModalModule", source, StringComparison.Ordinal);
        Assert.Contains("public sealed class WizardInteractionDispatcher", source, StringComparison.Ordinal);
    }

    [Fact]
    public void Modules_ShouldBeDerivedFromComponentInteractionModule()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        // The dispatching modules are thin shells that inherit from
        // NetCord's ComponentInteractionModule<TContext> for each
        // supported component type.
        Assert.Contains("ComponentInteractionModule<ButtonInteractionContext>", source, StringComparison.Ordinal);
        Assert.Contains("ComponentInteractionModule<StringMenuInteractionContext>", source, StringComparison.Ordinal);
        Assert.Contains("ComponentInteractionModule<ModalInteractionContext>", source, StringComparison.Ordinal);
    }

    [Fact]
    public void Modules_ShouldRegisterWizardComponentInteraction()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        // All three modules use the [ComponentInteraction("wizard")]
        // prefix registration; the args string carries the rest of
        // the custom-id (e.g. "btn:choice:Type:single" or
        // "select:Visibility" or "modal:Title").
        var count = CountOccurrences(source, "[ComponentInteraction(\"wizard\")]");
        Assert.Equal(3, count);
    }

    [Fact]
    public void Dispatcher_ShouldHandleButtonSelectAndModal()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        Assert.Contains("public async Task HandleButtonAsync", source, StringComparison.Ordinal);
        Assert.Contains("public async Task HandleStringMenuAsync", source, StringComparison.Ordinal);
        Assert.Contains("public async Task HandleModalAsync", source, StringComparison.Ordinal);
    }

    [Fact]
    public void Dispatcher_ShouldParseAllWizardActionKinds()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        // The button handler must dispatch on the five action kinds
        // the wizard's callback data format emits: choice, back,
        // cancel, create. The resume flow is a wizard-internal control
        // emitted by the slash command's "Continue / Start over" row.
        Assert.Contains("\"choice\"", source, StringComparison.Ordinal);
        Assert.Contains("\"back\"", source, StringComparison.Ordinal);
        Assert.Contains("\"cancel\"", source, StringComparison.Ordinal);
        Assert.Contains("\"create\"", source, StringComparison.Ordinal);
        Assert.Contains("\"resume\"", source, StringComparison.Ordinal);
    }

    [Fact]
    public void Dispatcher_ShouldWireWizardStateMachine()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        // The dispatcher must call the shared GameCreationWizard's
        // HandleInteractionAsync, which is the same entry point the
        // Telegram bot uses. This is the core invariant of the
        // platform-neutral refactor.
        Assert.Contains("GameCreationWizard", source, StringComparison.Ordinal);
        Assert.Contains("HandleInteractionAsync", source, StringComparison.Ordinal);
    }

    [Fact]
    public void Dispatcher_ShouldInvokeSubmitterOnCreate()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        // The "create" callback must delegate to DiscordWizardSubmitter
        // (the 3-retry finalize loop) rather than call the wizard's
        // render path.
        Assert.Contains("SubmitAsync", source, StringComparison.Ordinal);
    }

    [Fact]
    public void Program_ShouldRegisterAllThreeComponentServices()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Program.cs");
        // NetCord requires AddComponentInteractions<TInteraction, TContext>
        // per supported interaction type. The wizard needs all three:
        // buttons, StringSelectMenus, and modal submits.
        Assert.Contains("AddComponentInteractions<ButtonInteraction, ButtonInteractionContext>", source, StringComparison.Ordinal);
        Assert.Contains("AddComponentInteractions<StringMenuInteraction, StringMenuInteractionContext>", source, StringComparison.Ordinal);
        Assert.Contains("AddComponentInteractions<ModalInteraction, ModalInteractionContext>", source, StringComparison.Ordinal);
    }

    [Fact]
    public void Program_ShouldRegisterWizardModuleClasses()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Program.cs");
        // The wizard module classes have constructor dependencies
        // (the dispatcher + shared services) that DI must resolve.
        // AddComponentInteractions only registers the IComponentInteractionService,
        // not the module classes themselves.
        Assert.Contains("WizardInteractionDispatcher", source, StringComparison.Ordinal);
        Assert.Contains("DiscordWizardButtonModule", source, StringComparison.Ordinal);
        Assert.Contains("DiscordWizardStringMenuModule", source, StringComparison.Ordinal);
        Assert.Contains("DiscordWizardModalModule", source, StringComparison.Ordinal);
    }

    [Fact]
    public void Dispatcher_ShouldLookupDraftByOwner()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        // All three handlers must look up the active draft by
        // (platform="Discord", ownerId=userId) — the wizard's
        // invariant is "one active draft per owner", not
        // "draft-id-in-custom-id".
        Assert.Contains("GetActiveAsync(\"Discord\"", source, StringComparison.Ordinal);
    }

    [Fact]
    public void ModalHandler_ShouldExtractTextFromLabel()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        // The wizard's modals wrap a single TextInput in a Label. The
        // handler must walk Components[0] (Label) → .Component (TextInput)
        // → .Value to retrieve the user's text. If this drifts the
        // modal submit silently becomes a no-op.
        Assert.Contains("Components[0]", source, StringComparison.Ordinal);
        Assert.Contains("TextInput", source, StringComparison.Ordinal);
        Assert.Contains(".Value", source, StringComparison.Ordinal);
    }

    [Fact]
    public void StringMenuHandler_ShouldReadSelectedValues()
    {
        var source = ReadSource("src/GmRelay.DiscordBot/Features/Sessions/Wizard/DiscordWizardInteractionModule.cs");
        // StringSelectMenu interactions expose SelectedValues[0]
        // for our MaxValues=1 menus.
        Assert.Contains("SelectedValues[0]", source, StringComparison.Ordinal);
    }

    private static int CountOccurrences(string haystack, string needle)
    {
        if (string.IsNullOrEmpty(needle)) return 0;
        var count = 0;
        var idx = 0;
        while ((idx = haystack.IndexOf(needle, idx, StringComparison.Ordinal)) >= 0)
        {
            count++;
            idx += needle.Length;
        }
        return count;
    }
}