namespace New.Domain.ValueObjects;

/// <summary>
/// The decision on an application. Named <c>AssessmentOutcome</c> - never the
/// bare word "Status" - to keep it distinct from the case-framework's own
/// <c>ProcessStatus</c> and from the legacy `stat_cd` / `beoordRes` codes.
/// Also stands in for what the case-framework calls a "Decision" document.
/// </summary>
public enum AssessmentOutcome
{
    Approved,
    Rejected,
}

/// <summary>
/// A recorded assessment of a <see cref="RegistrationApplication"/>. Only ever
/// constructed through <see cref="Create"/>, which enforces every invariant
/// so the same validation applies whether the assessment is entered natively
/// through the owned path or reconstructed from legacy data during adoption.
/// </summary>
public sealed record Assessment
{
    private const int DefaultMinimumMotivationLength = 20;
    private const int OtherCategoryMinimumMotivationLength = 50;

    public AssessmentOutcome Outcome { get; }
    public string Motivation { get; }
    public IReadOnlyList<string> VerifiedItems { get; }
    public string? ExceptionReason { get; }
    public string? RejectionCategory { get; }
    public DateOnly DecidedOn { get; }

    private Assessment(
        AssessmentOutcome outcome,
        string motivation,
        IReadOnlyList<string> verifiedItems,
        string? exceptionReason,
        string? rejectionCategory,
        DateOnly decidedOn)
    {
        Outcome = outcome;
        Motivation = motivation;
        VerifiedItems = verifiedItems;
        ExceptionReason = exceptionReason;
        RejectionCategory = rejectionCategory;
        DecidedOn = decidedOn;
    }

    public static Assessment Create(
        AssessmentOutcome outcome,
        string motivation,
        IReadOnlyList<string>? verifiedItems,
        string? exceptionReason,
        string? rejectionCategory,
        DateOnly decidedOn)
    {
        var items = verifiedItems ?? Array.Empty<string>();

        // Recording an assessment requires either every diploma evidence item
        // to have been verified, or a recorded reason why verification was
        // skipped - never neither.
        if (items.Count == 0 && string.IsNullOrWhiteSpace(exceptionReason))
        {
            throw new DomainInvariantViolationException(
                "Assessment.VerificationRequired",
                "Recording an assessment requires either at least one verified item or a recorded exception reason.");
        }

        // rejectionCategory only makes sense - and is only carried - alongside
        // a Rejected outcome.
        var normalizedRejectionCategory = outcome == AssessmentOutcome.Rejected
            ? rejectionCategory
            : null;

        if (outcome == AssessmentOutcome.Rejected && string.IsNullOrWhiteSpace(normalizedRejectionCategory))
        {
            throw new DomainInvariantViolationException(
                "Assessment.RejectionCategoryRequired",
                "A rejection category is required when the outcome is Rejected.");
        }

        var minimumLength = IsOtherCategory(normalizedRejectionCategory)
            ? OtherCategoryMinimumMotivationLength
            : DefaultMinimumMotivationLength;

        if (string.IsNullOrWhiteSpace(motivation) || motivation.Trim().Length < minimumLength)
        {
            throw new DomainInvariantViolationException(
                "Assessment.MotivationTooShort",
                $"The motivation must be at least {minimumLength} characters long" +
                (IsOtherCategory(normalizedRejectionCategory) ? " when the rejection category is 'Other'." : "."));
        }

        return new Assessment(outcome, motivation, items, exceptionReason, normalizedRejectionCategory, decidedOn);
    }

    private static bool IsOtherCategory(string? rejectionCategory) =>
        rejectionCategory is not null &&
        (string.Equals(rejectionCategory, "Other", StringComparison.OrdinalIgnoreCase) ||
         string.Equals(rejectionCategory, "anders", StringComparison.OrdinalIgnoreCase));
}