using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using NeonSprawl.Server.Game.Contracts;
using NeonSprawl.Server.Game.Factions;
using NeonSprawl.Server.Game.PositionState;
using NeonSprawl.Server.Game.Quests;
using NeonSprawl.Server.Tests;
using Xunit;

namespace NeonSprawl.Server.Tests.Game.Contracts;

public sealed class ContractGeneratorOperationsTests
{
    private const string PlayerId = "dev-local-1";
    private const string UnknownPlayerId = "unknown-player-xyz";
    private const string TemplateId = "prototype_contract_clear_combat_pocket";
    private const string EncounterId = "prototype_combat_pocket";
    private const string SeedBucket = "2026-06-22";
    private const string AlternateSeedBucket = "2026-06-23";
    private static readonly DateTimeOffset IssuedAt = new(2026, 6, 22, 10, 0, 0, TimeSpan.Zero);
    private static readonly DateTimeOffset CompletedAt = new(2026, 6, 22, 12, 0, 0, TimeSpan.Zero);

    [Fact]
    public void TryIssue_ShouldCreateActiveInstance_WhenTemplateEligible()
    {
        // Arrange
        var deps = CreateDependencies();
        var expectedInstanceId = ContractInstanceIds.MakeDeterministicInstanceId(
            PlayerId,
            TemplateId,
            SeedBucket);
        // Act
        var result = TryIssue(deps, templateId: TemplateId, seedBucket: SeedBucket);
        // Assert
        Assert.True(result.Success);
        Assert.Null(result.ReasonCode);
        Assert.NotNull(result.Snapshot);
        Assert.Equal(expectedInstanceId, result.Snapshot!.ContractInstanceId);
        Assert.Equal(TemplateId, result.Snapshot.TemplateId);
        Assert.Equal(PlayerId, result.Snapshot.PlayerId);
        Assert.Equal(ContractInstanceStatus.Active, result.Snapshot.Status);
        Assert.Equal(SeedBucket, result.Snapshot.SeedBucket);
        Assert.Equal(IssuedAt, result.Snapshot.IssuedAt);
        Assert.Equal(EncounterId, result.EncounterTemplateId);
        Assert.True(deps.InstanceStore.TryGetActiveForPlayer(PlayerId, out var active));
        Assert.Equal(expectedInstanceId, active.ContractInstanceId);
    }

    [Fact]
    public void TryIssue_ShouldAutoSelectTemplate_WhenTemplateIdOmitted()
    {
        // Arrange
        var deps = CreateDependencies();
        // Act
        var result = TryIssue(deps, templateId: null, seedBucket: SeedBucket);
        // Assert
        Assert.True(result.Success);
        Assert.Equal(TemplateId, result.Snapshot!.TemplateId);
        Assert.Equal(EncounterId, result.EncounterTemplateId);
    }

    [Fact]
    public void MakeDeterministicInstanceId_ShouldMatchForSameInputs_AndDifferForDifferentSeedBucket()
    {
        // Arrange
        var first = ContractInstanceIds.MakeDeterministicInstanceId(PlayerId, TemplateId, SeedBucket);
        var same = ContractInstanceIds.MakeDeterministicInstanceId(PlayerId, TemplateId, SeedBucket);
        var different = ContractInstanceIds.MakeDeterministicInstanceId(PlayerId, TemplateId, AlternateSeedBucket);
        // Act
        // Assert
        Assert.Equal(first, same);
        Assert.NotEqual(first, different);
        Assert.StartsWith("ci_", first, StringComparison.Ordinal);
    }

    [Fact]
    public void TryIssue_ShouldDenyActiveContractExists_WhenPlayerAlreadyHasActiveInstance()
    {
        // Arrange
        var deps = CreateDependencies();
        var first = TryIssue(deps, templateId: TemplateId, seedBucket: SeedBucket);
        Assert.True(first.Success);
        // Act
        var second = TryIssue(deps, templateId: TemplateId, seedBucket: AlternateSeedBucket);
        // Assert
        Assert.False(second.Success);
        Assert.Equal(ContractGeneratorReasonCodes.ActiveContractExists, second.ReasonCode);
        Assert.NotNull(second.Snapshot);
        Assert.Equal(first.Snapshot!.ContractInstanceId, second.Snapshot!.ContractInstanceId);
        Assert.Equal(ContractInstanceStatus.Active, second.Snapshot.Status);
        Assert.Null(second.EncounterTemplateId);
    }

    [Fact]
    public void TryIssue_ShouldAllowNewIssue_WhenPriorInstanceCompleted()
    {
        // Arrange
        var deps = CreateDependencies();
        var first = TryIssue(deps, templateId: TemplateId, seedBucket: SeedBucket);
        Assert.True(first.Success);
        Assert.True(deps.InstanceStore.TryMarkComplete(
            PlayerId,
            first.Snapshot!.ContractInstanceId,
            CompletedAt,
            out _));
        // Act
        var second = TryIssue(deps, templateId: TemplateId, seedBucket: AlternateSeedBucket);
        // Assert
        Assert.True(second.Success);
        Assert.NotEqual(first.Snapshot.ContractInstanceId, second.Snapshot!.ContractInstanceId);
        Assert.Equal(ContractInstanceStatus.Active, second.Snapshot.Status);
        Assert.Equal(EncounterId, second.EncounterTemplateId);
    }

    [Fact]
    public void TryIssue_ShouldDenyUnknownTemplate_WhenExplicitTemplateMissing()
    {
        // Arrange
        var deps = CreateDependencies();
        // Act
        var result = TryIssue(deps, templateId: "not_a_real_template", seedBucket: SeedBucket);
        // Assert
        Assert.False(result.Success);
        Assert.Equal(ContractGeneratorReasonCodes.UnknownTemplate, result.ReasonCode);
        Assert.Null(result.Snapshot);
        Assert.False(deps.InstanceStore.TryGetActiveForPlayer(PlayerId, out _));
    }

    [Fact]
    public void TryIssue_ShouldDenyNoEligibleTemplate_WhenBandMismatch()
    {
        // Arrange
        var deps = CreateDependencies();
        // Act
        var result = TryIssue(deps, templateId: TemplateId, seedBucket: SeedBucket, zoneDifficultyBand: 99);
        // Assert
        Assert.False(result.Success);
        Assert.Equal(ContractGeneratorReasonCodes.NoEligibleTemplate, result.ReasonCode);
        Assert.Null(result.Snapshot);
    }

    [Fact]
    public void TryIssue_ShouldDenyNoEligibleTemplate_WhenAutoSelectBandHasNoTemplates()
    {
        // Arrange
        var deps = CreateDependencies();
        // Act
        var result = TryIssue(deps, templateId: null, seedBucket: SeedBucket, zoneDifficultyBand: 99);
        // Assert
        Assert.False(result.Success);
        Assert.Equal(ContractGeneratorReasonCodes.NoEligibleTemplate, result.ReasonCode);
    }

    [Fact]
    public void TryIssue_ShouldDenyPlayerNotWritable_WhenPlayerUnknown()
    {
        // Arrange
        var deps = CreateDependencies();
        // Act
        var result = TryIssue(deps, playerId: UnknownPlayerId, templateId: TemplateId, seedBucket: SeedBucket);
        // Assert
        Assert.False(result.Success);
        Assert.Equal(ContractGeneratorReasonCodes.PlayerNotWritable, result.ReasonCode);
        Assert.Null(result.Snapshot);
    }

    [Fact]
    public void TryIssue_ShouldDenyInvalidIds_WhenPlayerIdEmpty()
    {
        // Arrange
        var deps = CreateDependencies();
        // Act
        var result = TryIssue(deps, playerId: "   ", templateId: TemplateId, seedBucket: SeedBucket);
        // Assert
        Assert.False(result.Success);
        Assert.Equal(ContractGeneratorReasonCodes.InvalidIds, result.ReasonCode);
    }

    [Fact]
    public void TryIssue_ShouldDenyInvalidIds_WhenSeedBucketEmpty()
    {
        // Arrange
        var deps = CreateDependencies();
        // Act
        var result = TryIssue(deps, templateId: TemplateId, seedBucket: " ");
        // Assert
        Assert.False(result.Success);
        Assert.Equal(ContractGeneratorReasonCodes.InvalidIds, result.ReasonCode);
    }

    private static ContractIssueOperationResult TryIssue(
        GeneratorTestDependencies deps,
        string? playerId = PlayerId,
        string? templateId = TemplateId,
        string seedBucket = SeedBucket,
        int? zoneDifficultyBand = null) =>
        ContractGeneratorOperations.TryIssue(
            playerId!,
            templateId,
            seedBucket,
            zoneDifficultyBand,
            deps.TemplateRegistry,
            deps.InstanceStore,
            deps.StandingStore,
            deps.TimeProvider);

    private static GeneratorTestDependencies CreateDependencies()
    {
        var template = PrototypeE7M4ContractCatalogRules.ExpectedTemplateFreeze[TemplateId];
        var rows = new Dictionary<string, ContractTemplateRow>(StringComparer.Ordinal)
        {
            [template.Id] = template,
        };
        var catalog = new ContractTemplateCatalog("/tmp/catalog", rows, catalogJsonFileCount: 1);
        var templateRegistry = new ContractTemplateRegistry(catalog);
        var positionOptions = Options.Create(new GamePositionOptions { DevPlayerId = PlayerId });
        var instanceStore = new InMemoryContractInstanceStore(positionOptions);
        var standingStore = CreateStandingStore();
        return new GeneratorTestDependencies(
            templateRegistry,
            instanceStore,
            standingStore,
            new FakeTimeProvider(IssuedAt));
    }

    private static InMemoryFactionStandingStore CreateStandingStore()
    {
        var gridFactionId = PrototypeE7M3QuestFactionRules.GridContractGateFactionId;
        var rustFactionId = "prototype_faction_rust_collective";
        var byId = new Dictionary<string, FactionDefRow>(StringComparer.Ordinal)
        {
            [gridFactionId] = PrototypeE7M3FactionCatalogRules.ExpectedFactionFreeze[gridFactionId],
            [rustFactionId] = PrototypeE7M3FactionCatalogRules.ExpectedFactionFreeze[rustFactionId],
        };
        var catalog = new FactionDefinitionCatalog("/tmp/catalog", byId, catalogJsonFileCount: 1);
        var registry = new FactionDefinitionRegistry(catalog);
        var options = Options.Create(new GamePositionOptions { DevPlayerId = PlayerId });
        return new InMemoryFactionStandingStore(options, registry);
    }

    private sealed class FakeTimeProvider(DateTimeOffset utcNow) : TimeProvider
    {
        public override DateTimeOffset GetUtcNow() => utcNow;
    }

    private readonly record struct GeneratorTestDependencies(
        IContractTemplateRegistry TemplateRegistry,
        IContractInstanceStore InstanceStore,
        IFactionStandingStore StandingStore,
        TimeProvider TimeProvider);
}