namespace StellaOps.DependencyInjection.Validation;

public abstract partial class OptionsValidatorBase<TOptions>
    where TOptions : class
{
    /// <summary>
    /// Provides a fluent interface for collecting validation errors.
    /// </summary>
    protected sealed partial class ValidationContext
    {
        private readonly List<string> _errors = new();
        private readonly string _sectionPrefix;

        internal ValidationContext(string sectionPrefix)
        {
            _sectionPrefix = sectionPrefix;
        }

        /// <summary>
        /// Gets the collected errors.
        /// </summary>
        public IReadOnlyList<string> Errors => _errors;

        /// <summary>
        /// Returns true if any errors have been added.
        /// </summary>
        public bool HasErrors => _errors.Count > 0;

        /// <summary>
        /// Adds a validation error for a specific property.
        /// </summary>
        /// <param name="propertyName">The property name (e.g., "MaxRetries").</param>
        /// <param name="message">The error message.</param>
        /// <returns>This context for chaining.</returns>
        public ValidationContext AddError(string propertyName, string message)
        {
            _errors.Add($"{_sectionPrefix}:{propertyName} {message}");
            return this;
        }

        /// <summary>
        /// Adds a validation error for a nested property.
        /// </summary>
        /// <param name="parentProperty">The parent property name.</param>
        /// <param name="childProperty">The child property name.</param>
        /// <param name="message">The error message.</param>
        /// <returns>This context for chaining.</returns>
        public ValidationContext AddError(string parentProperty, string childProperty, string message)
        {
            _errors.Add($"{_sectionPrefix}:{parentProperty}:{childProperty} {message}");
            return this;
        }

        /// <summary>
        /// Adds a general validation error.
        /// </summary>
        /// <param name="message">The error message.</param>
        /// <returns>This context for chaining.</returns>
        public ValidationContext AddGeneralError(string message)
        {
            _errors.Add($"{_sectionPrefix}: {message}");
            return this;
        }

        /// <summary>
        /// Conditionally adds an error if the condition is true.
        /// </summary>
        /// <param name="condition">The condition to check.</param>
        /// <param name="propertyName">The property name.</param>
        /// <param name="message">The error message.</param>
        /// <returns>This context for chaining.</returns>
        public ValidationContext AddErrorIf(bool condition, string propertyName, string message)
        {
            if (condition)
            {
                AddError(propertyName, message);
            }

            return this;
        }
    }
}