using Campaign_Tracker.Server.LegacyData;

namespace Campaign_Tracker.Server.ExtensionData;

/// <summary>
/// Validates a <see cref="LegacyLinkReference"/> by resolving it through the
/// anti-corruption layer (<see cref="ILegacyDataAccess"/>).
/// Each link type maps to a unique primary-key lookup, guaranteeing no ambiguity (AC #2, AC #3).
/// </summary>
public sealed class LegacyLinkValidator : ILegacyLinkValidator
{
    private readonly ILegacyDataAccess _legacyData;

    public LegacyLinkValidator(ILegacyDataAccess legacyData)
    {
        _legacyData = legacyData;
    }

    public async Task<LegacyLinkValidationResult> ValidateAsync(
        LegacyLinkReference reference,
        CancellationToken cancellationToken = default)
    {
        return reference.Type switch
        {
            LegacyLinkType.JurisdictionJCode => await ValidateJurisdictionAsync(reference.Value, cancellationToken),
            LegacyLinkType.KitId             => await ValidateKitAsync(reference.Value, cancellationToken),
            LegacyLinkType.ContactId         => await ValidateContactAsync(reference.Value, cancellationToken),
            _ => LegacyLinkValidationResult.Failure($"Unknown legacy link type '{reference.Type}'."),
        };
    }

    private async Task<LegacyLinkValidationResult> ValidateJurisdictionAsync(
        string jCode, CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(jCode))
            return LegacyLinkValidationResult.Failure("JCode is required and cannot be blank.");

        var record = await _legacyData.GetJurisdictionAsync(jCode, cancellationToken);
        return record is null
            ? LegacyLinkValidationResult.Failure(
                $"No legacy jurisdiction found for JCode '{jCode}'. Verify the identifier and try again.")
            : LegacyLinkValidationResult.Success();
    }

    private async Task<LegacyLinkValidationResult> ValidateKitAsync(
        string rawId, CancellationToken cancellationToken)
    {
        if (!int.TryParse(rawId, System.Globalization.NumberStyles.Integer,
                System.Globalization.CultureInfo.InvariantCulture, out var id))
            return LegacyLinkValidationResult.Failure(
                $"Kit identifier '{rawId}' is not a valid integer ID.");

        if (id <= 0)
            return LegacyLinkValidationResult.Failure(
                $"Kit identifier '{rawId}' must be greater than zero.");

        var record = await _legacyData.GetKitByIdAsync(id, cancellationToken);
        return record is null
            ? LegacyLinkValidationResult.Failure(
                $"No legacy kit found for ID {id}. Verify the identifier and try again.")
            : LegacyLinkValidationResult.Success();
    }

    private async Task<LegacyLinkValidationResult> ValidateContactAsync(
        string rawId, CancellationToken cancellationToken)
    {
        if (!int.TryParse(rawId, System.Globalization.NumberStyles.Integer,
                System.Globalization.CultureInfo.InvariantCulture, out var id))
            return LegacyLinkValidationResult.Failure(
                $"Contact identifier '{rawId}' is not a valid integer ID.");

        if (id <= 0)
            return LegacyLinkValidationResult.Failure(
                $"Contact identifier '{rawId}' must be greater than zero.");

        var record = await _legacyData.GetContactByIdAsync(id, cancellationToken);
        return record is null
            ? LegacyLinkValidationResult.Failure(
                $"No legacy contact found for ID {id}. Verify the identifier and try again.")
            : LegacyLinkValidationResult.Success();
    }
}