using System.Threading;
using BigRegister.Api.Data;
using BigRegister.Domain.Applications;
using BigRegister.Domain.Beoordeling;

namespace BigRegister.Tests.Builders;

/// <summary>Fixture identities test builders share across the suite.</summary>
public static class TestIdentities
{
  /// The default owner for a builder-made <see cref="Aanvraag"/> — matches
  /// <see cref="DocumentStore.DemoOwner"/> (the demo's only seeded user) so a fixture that
  /// doesn't care about identity gets a realistic, elfproef-valid BSN for free.
  public const string DemoBsn = DocumentStore.DemoOwner;
}

/// <summary>
/// Type-state test-data builder for <see cref="Aanvraag"/> (WP-70). "Build test data through the
/// same door production code uses" — a Concept can only ever become Submitted, and only a
/// Submitted aanvraag can be Decided, so the compiler refuses a fixture built through an illegal
/// path (e.g. deciding a still-Concept aanvraag) instead of that being a runtime assertion nobody
/// wrote. Start at <see cref="Given.Concept"/>.
///
/// ponytail: <see cref="Aanvraag"/> itself stays exactly what it always was — a mutable,
/// EF-backed bag with no invariants of its own (that's Data/ApplicationStore.cs's job in
/// production, via its own lock + <see cref="BeoordelingRules"/> checks). This builder does not
/// refactor it into an immutable aggregate; it's the one enforced DOOR through which TEST code
/// builds one, so the invariants a real request path enforces don't quietly go missing from a
/// fixture assembled by hand.
/// </summary>
public static class Given
{
  /// A fresh, unsubmitted wizard draft — step 0 of 0 until <see cref="ConceptAanvraag.AtStep"/>
  /// says otherwise, exactly what <c>ApplicationStore.CreateConcept</c> hands back.
  public static ConceptAanvraag Concept(string type = "registratie", string owner = TestIdentities.DemoBsn) =>
      new(type, owner);
}

/// <summary>A not-yet-submitted aanvraag. The only next step is <see cref="Submitted"/> — there
/// is deliberately no <c>Decided</c> here, since only a submitted aanvraag can be decided.</summary>
public sealed class ConceptAanvraag
{
  private readonly string _type;
  private readonly string _owner;
  private int _stepIndex;
  private int _stepCount;

  internal ConceptAanvraag(string type, string owner)
  {
    _type = type;
    _owner = owner;
  }

  /// The wizard's current position — step <paramref name="index"/> of <paramref name="of"/>.
  public ConceptAanvraag AtStep(int index, int of)
  {
    _stepIndex = index;
    _stepCount = of;
    return this;
  }

  /// Submits the draft — always assigns a Referentie AND SubmittedAt together (mirrors
  /// <c>ApplicationStore.Submit</c>), so <c>Aanvraag.StatusAt</c>'s <c>Referentie!</c> is honest
  /// for every fixture built this way, never a null-ref waiting to happen.
  public SubmittedAanvraag Submitted(bool autoApprovable = false) =>
      new(_type, _owner, _stepIndex, _stepCount, autoApprovable);

  public Aanvraag Build() => new()
  {
    Id = Guid.NewGuid().ToString(),
    Type = _type,
    Owner = _owner,
    StepIndex = _stepIndex,
    StepCount = _stepCount,
    CreatedAt = DateTimeOffset.UtcNow,
    UpdatedAt = DateTimeOffset.UtcNow,
  };
}

/// <summary>A submitted aanvraag, open for a behandelaar's decision. The only next step is
/// <see cref="Decided"/> — there is no way back to <c>ConceptAanvraag</c>.</summary>
public sealed class SubmittedAanvraag
{
  private static int _referentieSeq;

  private readonly string _type;
  private readonly string _owner;
  private readonly int _stepIndex;
  private readonly int _stepCount;
  private readonly bool _autoApprovable;
  private readonly string _referentie;
  private readonly DateTimeOffset _submittedAt;

  internal SubmittedAanvraag(string type, string owner, int stepIndex, int stepCount, bool autoApprovable)
  {
    _type = type;
    _owner = owner;
    _stepIndex = stepIndex;
    _stepCount = stepCount;
    _autoApprovable = autoApprovable;
    // A plausible reference in SubmissionRules.NewReference's shape ("BIG-2026-" + a number) —
    // sequential (not random) so a fixture's value is reproducible across a test run.
    _referentie = $"BIG-2026-{Interlocked.Increment(ref _referentieSeq)}";
    _submittedAt = DateTimeOffset.UtcNow;
  }

  /// <summary>Records a behandelaar's decision — reusing <see cref="BeoordelingRules.RequiresToelichting"/>,
  /// the SAME rule production's besluit endpoint runs, rather than restating it here where it
  /// could quietly drift. Throws <see cref="ArgumentException"/> for an Afwijzen/MeerInfoOpvragen
  /// with a null/blank <paramref name="toelichting"/> — exactly what that endpoint rejects with
  /// a 400, just caught here at fixture-build time instead.</summary>
  public DecidedAanvraag Decided(Besluit besluit, string? toelichting = null)
  {
    if (BeoordelingRules.RequiresToelichting(besluit) && string.IsNullOrWhiteSpace(toelichting))
      throw new ArgumentException($"{besluit} requires a toelichting.", nameof(toelichting));
    return new DecidedAanvraag(this, besluit, toelichting);
  }

  public Aanvraag Build() => new()
  {
    Id = Guid.NewGuid().ToString(),
    Type = _type,
    Owner = _owner,
    StepIndex = _stepIndex,
    StepCount = _stepCount,
    Submitted = true,
    Referentie = _referentie,
    AutoApprovable = _autoApprovable,
    SubmittedAt = _submittedAt,
    CreatedAt = _submittedAt,
    UpdatedAt = _submittedAt,
  };
}

/// <summary>A submitted aanvraag with a behandelaar's decision already recorded. Terminal in the
/// builder too — there's nothing past <see cref="Build"/>, matching Goedgekeurd/Afgewezen being
/// terminal in the domain (<see cref="BeoordelingRules.CanDecide"/>); a fixture that needs a
/// SECOND besluit (the MeerInfoGevraagd "still decidable" case) builds fresh from
/// <see cref="Given.Concept"/> again, exactly as a real second request would.</summary>
public sealed class DecidedAanvraag
{
  private readonly SubmittedAanvraag _submitted;
  private readonly Besluit _besluit;
  private readonly string? _toelichting;

  internal DecidedAanvraag(SubmittedAanvraag submitted, Besluit besluit, string? toelichting)
  {
    _submitted = submitted;
    _besluit = besluit;
    _toelichting = toelichting;
  }

  public Aanvraag Build()
  {
    var aanvraag = _submitted.Build();
    aanvraag.BesluitStatus = _besluit;
    aanvraag.BesluitToelichting = _toelichting;
    return aanvraag;
  }
}