using System.Text.RegularExpressions;

namespace HrynCo.NotificationService.DAL.Abstract.Templates;

public static partial class PushTemplateValidation
{
    public static void Validate(PushTemplateDefinition definition)
    {
        EmailTemplateValidation.ValidateIdentity("Push", definition.Key);
        EmailTemplateValidation.ValidateVariables(definition.Variables);
        var names = definition.Variables.Select(v => v.Name).ToHashSet(StringComparer.Ordinal);
        foreach (var language in definition.Languages)
            ValidateTranslation(language, names);
        if (definition.Languages.Select(l => l.LanguageCode).Distinct(StringComparer.Ordinal).Count() != definition.Languages.Count)
            throw new EmailTemplateWriteException("Language codes must be unique within a template.", false);
    }

    private static void ValidateTranslation(PushTemplateTranslation translation, HashSet<string> names)
    {
        if (string.IsNullOrWhiteSpace(translation.LanguageCode) || translation.LanguageCode.Length > 10)
            throw new EmailTemplateWriteException("A valid language code is required.", false);
        if (string.IsNullOrWhiteSpace(translation.Title) || string.IsNullOrWhiteSpace(translation.Body))
            throw new EmailTemplateWriteException("Every populated push language needs both Title and Body.", false);
        ValidatePlaceholders(translation.Title, names);
        ValidatePlaceholders(translation.Body, names);
        var actions = PushTemplateActionValidation.Parse(translation.ActionsJson);
        foreach (var button in actions.Buttons) ValidatePlaceholders(button.Label, names);
    }

    private static void ValidatePlaceholders(string text, HashSet<string> names)
    {
        foreach (Match match in Placeholder().Matches(text))
            if (!names.Contains(match.Groups[1].Value))
                throw new EmailTemplateWriteException("Every placeholder must be declared in this channel's variables.", false);
        var remainder = Placeholder().Replace(text, "");
        if (remainder.Contains("{{", StringComparison.Ordinal) || remainder.Contains("}}", StringComparison.Ordinal))
            throw new EmailTemplateWriteException("Use complete placeholders in the form {{VariableName}}.", false);
    }

    [GeneratedRegex(@"\{\{([^{}]+)\}\}")]
    private static partial Regex Placeholder();
}