using EnvelopeGenerator.Application.Configurations;
using EnvelopeGenerator.Application.Contracts;
using Microsoft.Extensions.Options;
using System.Text;

namespace EnvelopeGenerator.Application.Services
{
    public class CodeGenerator : ICodeGenerator
    {
        public static Lazy<CodeGenerator> LazyStatic => new(() => new CodeGenerator(Options.Create<CodeGeneratorConfig>(new())));

        public static CodeGenerator Static => LazyStatic.Value;

        private readonly string _charPool = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

        public CodeGenerator(IOptions<CodeGeneratorConfig> options)
        {
            _charPool = options.Value.CharPool;
        }

        public string GenerateCode(int length)
        {
            //TODO: Inject Random as a singleton to support multithreading to improve performance.
            Random random = new();

            if (length <= 0)
                throw new ArgumentException("Password length must be greater than 0.");

            var passwordBuilder = new StringBuilder(length);

            for (int i = 0; i < length; i++)
                passwordBuilder.Append(_charPool[random.Next(_charPool.Length)]);

            return passwordBuilder.ToString();
        }
    }
}