using System.Text.Json;

namespace HrynCo.NotificationService.DAL.Abstract.Templates;

public static class PushTemplateActionValidation
{
    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
    {
        PropertyNameCaseInsensitive = false
    };

    public static PushTemplateActions Parse(string json)
    {
        if (string.IsNullOrWhiteSpace(json))
            throw new EmailTemplateWriteException("Actions JSON is required. Use {} for no actions.", false);
        try
        {
            var actions = JsonSerializer.Deserialize<PushTemplateActions>(json, JsonOptions)
                ?? throw new JsonException();
            Validate(actions);
            return actions;
        }
        catch (JsonException)
        {
            throw new EmailTemplateWriteException("Invalid actions JSON. Use defaultAction and buttons with action and label.", false);
        }
    }

    public static void Validate(PushTemplateActions actions)
    {
        if (actions.DefaultAction is not null) ValidateKey(actions.DefaultAction);
        if (actions.Buttons is null || actions.Buttons.Count > 3)
            throw new EmailTemplateWriteException("Configure up to three push buttons.", false);
        var keys = new HashSet<string>(StringComparer.Ordinal);
        foreach (var button in actions.Buttons)
        {
            if (button is null) throw new EmailTemplateWriteException("A button needs an action and label.", false);
            ValidateKey(button.Action);
            if (!keys.Add(button.Action) || string.IsNullOrWhiteSpace(button.Label) || button.Label.Length > 100)
                throw new EmailTemplateWriteException("Button actions must be unique and labels must contain 1–100 characters.", false);
        }
    }

    private static void ValidateKey(string key)
    {
        if (string.IsNullOrWhiteSpace(key) || key.Length > 100 || key.Any(c => !char.IsAsciiLetterOrDigit(c) && c is not '_' and not '-' and not '.'))
            throw new EmailTemplateWriteException("Action keys need 1–100 letters, digits, dots, underscores or hyphens.", false);
    }
}