using AcDream.Core.Net.Messages;
using AcDream.Headless.Hosting;
using AcDream.Runtime;
using AcDream.Runtime.Gameplay;

namespace AcDream.Headless.Tests;

/// <summary>
/// Campaign OP slice OP7 (2026-08-11), D8: the declared-vs-actual diff engine
/// (<see cref="HeadlessCharacterOptionsSeeder"/>) unit-tested against a fake
/// <see cref="IRuntimeCharacterCommands"/> so these tests never need a live
/// session, a wire, or a physics/collision fixture — only a bare
/// <see cref="GameRuntime"/> for its <c>CharacterOwner.Options</c> state and
/// <c>Generation</c> token. <see cref="RuntimeCharacterOptionsState.Replace"/>
/// stands in for "a PlayerDescription just landed" exactly like
/// <c>LiveSessionEventRouter</c>'s own <c>onCharacterOptions</c> wiring does.
/// </summary>
public sealed class HeadlessCharacterOptionsSeederTests
{
    // AutoRepeatAttack (0x00, Options1 0x00000002) is auto-save — sends
    // SetSingleOption (0x0005) immediately, per CharacterOptionTable.
    // IgnoreTradeRequests (0x03, Options1 0x00020000) is batched — dirties
    // the module; only SaveOptions flushes it. Both are exercised by name
    // throughout this file's tests.
    private const uint AutoSaveMask = 0x00000002u;

    [Fact]
    public void DeclaredEqualsActualSendsNothing()
    {
        using GameRuntime runtime = NewRuntime();
        runtime.CharacterOwner.Options.Replace(0u, 0u);
        var commands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var seeder = new HeadlessCharacterOptionsSeeder(
            new Dictionary<CharacterOptionId, bool>
            {
                [CharacterOptionId.AutoRepeatAttack] = false,
            },
            runtime,
            commands);

        seeder.NoteLoginCompleteSent();
        seeder.NoteOptionsSeeded();

        Assert.Empty(commands.CallOrder);
    }

    [Fact]
    public void AutoSaveDifferenceSendsExactlyOneSetSingleOption()
    {
        using GameRuntime runtime = NewRuntime();
        runtime.CharacterOwner.Options.Replace(0u, 0u);
        var commands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var seeder = new HeadlessCharacterOptionsSeeder(
            new Dictionary<CharacterOptionId, bool>
            {
                [CharacterOptionId.AutoRepeatAttack] = true,
            },
            runtime,
            commands);

        seeder.NoteLoginCompleteSent();
        seeder.NoteOptionsSeeded();

        var call = Assert.Single(commands.SingleOptionCalls);
        Assert.Equal((uint)CharacterOptionId.AutoRepeatAttack, call.OptionId);
        Assert.True(call.Value);
        Assert.Equal(0, commands.SaveOptionsCallCount);
        Assert.Equal(["set:0"], commands.CallOrder);
    }

    [Fact]
    public void BatchedDifferenceSendsSetSingleOptionThenExactlyOneSaveOptionsAtTheEnd()
    {
        using GameRuntime runtime = NewRuntime();
        runtime.CharacterOwner.Options.Replace(0u, 0u);
        var commands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var seeder = new HeadlessCharacterOptionsSeeder(
            new Dictionary<CharacterOptionId, bool>
            {
                [CharacterOptionId.IgnoreTradeRequests] = true,
            },
            runtime,
            commands);

        seeder.NoteLoginCompleteSent();
        seeder.NoteOptionsSeeded();

        var call = Assert.Single(commands.SingleOptionCalls);
        Assert.Equal((uint)CharacterOptionId.IgnoreTradeRequests, call.OptionId);
        Assert.True(call.Value);
        Assert.Equal(1, commands.SaveOptionsCallCount);
        Assert.Equal(["set:3", "save"], commands.CallOrder);
    }

    [Fact]
    public void MixedDeclarationOrdersAllSetsBeforeTheSingleFlush()
    {
        using GameRuntime runtime = NewRuntime();
        runtime.CharacterOwner.Options.Replace(0u, 0u);
        var commands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var seeder = new HeadlessCharacterOptionsSeeder(
            new Dictionary<CharacterOptionId, bool>
            {
                // Declared out of id order on purpose — the seeder sorts
                // id-ascending internally, so the batched id (0x03) is
                // expected AFTER the auto-save id (0x00) regardless of
                // declaration order, with the flush always last.
                [CharacterOptionId.IgnoreTradeRequests] = true,
                [CharacterOptionId.AutoRepeatAttack] = true,
            },
            runtime,
            commands);

        seeder.NoteLoginCompleteSent();
        seeder.NoteOptionsSeeded();

        Assert.Equal(2, commands.SingleOptionCalls.Count);
        Assert.Equal(1, commands.SaveOptionsCallCount);
        Assert.Equal(["set:0", "set:3", "save"], commands.CallOrder);
    }

    [Fact]
    public void NeitherPreconditionAloneSendsAnything()
    {
        using GameRuntime runtime = NewRuntime();
        var commands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var seeder = new HeadlessCharacterOptionsSeeder(
            new Dictionary<CharacterOptionId, bool>
            {
                [CharacterOptionId.AutoRepeatAttack] = true,
            },
            runtime,
            commands);

        // Login-complete alone: HasServerSeed is still false (no Replace
        // ever ran), so the diff cannot trust live state yet.
        seeder.NoteLoginCompleteSent();
        Assert.Empty(commands.CallOrder);

        // Now the seed lands — both preconditions are satisfied and the
        // deferred diff runs from THIS call.
        runtime.CharacterOwner.Options.Replace(0u, 0u);
        seeder.NoteOptionsSeeded();

        Assert.Single(commands.SingleOptionCalls);
    }

    [Fact]
    public void OptionsSeededBeforeLoginCompleteDefersUntilLoginCompleteArrives()
    {
        using GameRuntime runtime = NewRuntime();
        runtime.CharacterOwner.Options.Replace(0u, 0u);
        var commands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var seeder = new HeadlessCharacterOptionsSeeder(
            new Dictionary<CharacterOptionId, bool>
            {
                [CharacterOptionId.AutoRepeatAttack] = true,
            },
            runtime,
            commands);

        seeder.NoteOptionsSeeded();
        Assert.Empty(commands.CallOrder);

        seeder.NoteLoginCompleteSent();
        Assert.Single(commands.SingleOptionCalls);
    }

    [Fact]
    public void EmptyDeclarationNeverSendsRegardlessOfBothSignals()
    {
        using GameRuntime runtime = NewRuntime();
        runtime.CharacterOwner.Options.Replace(0xFFFFFFFFu, 0xFFFFFFFFu);
        var commands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var seeder = new HeadlessCharacterOptionsSeeder(
            new Dictionary<CharacterOptionId, bool>(),
            runtime,
            commands);

        Assert.False(seeder.HasDeclaredOptions);
        seeder.NoteLoginCompleteSent();
        seeder.NoteOptionsSeeded();

        Assert.Empty(commands.CallOrder);
    }

    /// <summary>
    /// D8 idempotence — the acceptance bar is "by construction", not a
    /// special-cased dedupe: a fresh, second seeder instance (mirroring the
    /// fresh instance <c>HeadlessSessionHost.CreateEventRoute</c> constructs
    /// per reconnect) diffs against the SAME declared dictionary but against
    /// live state that already reflects what the first seeder sent — the
    /// second diff simply finds nothing to do.
    /// </summary>
    [Fact]
    public void ReconnectWithSameDeclarationsAgainstServerThatNowAgreesSendsNothing()
    {
        using GameRuntime runtime = NewRuntime();
        var declared = new Dictionary<CharacterOptionId, bool>
        {
            [CharacterOptionId.AutoRepeatAttack] = true,
        };

        // First connect: server has the option OFF; the bot's declared
        // value differs, so it sends once.
        runtime.CharacterOwner.Options.Replace(0u, 0u);
        var firstCommands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var firstSeeder = new HeadlessCharacterOptionsSeeder(
            declared, runtime, firstCommands);
        firstSeeder.NoteLoginCompleteSent();
        firstSeeder.NoteOptionsSeeded();
        Assert.Single(firstCommands.SingleOptionCalls);

        // Reconnect: a fresh seeder instance (per CreateEventRoute's own
        // per-route construction), and the server's fresh PlayerDescription
        // now echoes what the bot itself set last time.
        runtime.CharacterOwner.Options.ResetSession();
        runtime.CharacterOwner.Options.Replace(AutoSaveMask, 0u);
        var secondCommands = new FakeCharacterCommands(runtime.CharacterOwner.Options);
        var secondSeeder = new HeadlessCharacterOptionsSeeder(
            declared, runtime, secondCommands);
        secondSeeder.NoteLoginCompleteSent();
        secondSeeder.NoteOptionsSeeded();

        Assert.Empty(secondCommands.CallOrder);
    }

    private static GameRuntime NewRuntime()
    {
        var gameplay = new HeadlessGameplayOperations();
        var runtime = new GameRuntime(new GameRuntimeDependencies(
            gameplay,
            gameplay,
            gameplay,
            gameplay));
        gameplay.Bind(runtime, catalog: null, () => "account");
        return runtime;
    }

    /// <summary>
    /// Writes the bit into <paramref name="options"/> as part of
    /// <see cref="SetSingleOption"/>, mirroring the REAL
    /// <c>DirectGameRuntimeCommandAdapter.SetSingleOption</c> →
    /// <c>RuntimeCharacterOptionsState.TrySetOption</c> contract: the local
    /// copy updates synchronously, in the same call, before the method
    /// returns. Without this, a fake that only records the call (never
    /// mutating live state) would make a SECOND diff pass — e.g. a
    /// legitimate redundant <c>NoteLoginCompleteSent</c>/<c>NoteOptionsSeeded</c>
    /// pairing — re-find the same already-handled mismatch and re-send it,
    /// which is a fidelity gap in the fake, not a real defect: production's
    /// idempotence depends on exactly this synchronous local write.
    /// </summary>
    private sealed class FakeCharacterCommands(
        RuntimeCharacterOptionsState options) : IRuntimeCharacterCommands
    {
        internal List<(uint OptionId, bool Value)> SingleOptionCalls { get; } = [];
        internal int SaveOptionsCallCount { get; private set; }
        internal List<string> CallOrder { get; } = [];

        public RuntimeCommandResult Advance(
            RuntimeGenerationToken expectedGeneration,
            in RuntimeAdvancementCommand command) =>
            throw new NotSupportedException(
                "HeadlessCharacterOptionsSeeder never calls Advance.");

        public RuntimeCommandResult SetSingleOption(
            RuntimeGenerationToken expectedGeneration,
            uint optionId,
            bool value)
        {
            SingleOptionCalls.Add((optionId, value));
            CallOrder.Add($"set:{optionId}");
            options.SetOptionBit(optionId, value);
            return new RuntimeCommandResult(
                RuntimeCommandStatus.Accepted,
                expectedGeneration);
        }

        public RuntimeCommandResult SaveOptions(
            RuntimeGenerationToken expectedGeneration)
        {
            SaveOptionsCallCount++;
            CallOrder.Add("save");
            return new RuntimeCommandResult(
                RuntimeCommandStatus.Accepted,
                expectedGeneration);
        }
    }
}