using System;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using GB5Shared.DTO.Framework.CacheLogin;
using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using static GB5Shared.GB5Constant.Constant;

namespace GB5Shared.DaprCache
{
    public class CacheKeyGeneration
    {
        // ── Performance: static options — constructing JsonSerializerOptions is expensive.
        // A single shared instance is safe here because CacheLoginDTO / CriteriaDTO
        // have no custom converters that carry mutable state.
        private static readonly JsonSerializerOptions _jsonOptions = new()
        {
            WriteIndented            = false,
            PropertyNamingPolicy     = null,   // preserve exact property names
            DefaultIgnoreCondition   = System.Text.Json.Serialization.JsonIgnoreCondition.Never
        };

        public string KeyGeneration(
            object ObjectId, int ObjectTypeId, int CachingKeyLevel,
            LoginDTO LoginDTO, CriteriaDTO? CriteriaDTO = null)
        {
            if (CachingKeyLevel == CacheKeyLevel.NOT_REQUIRED)
                return "Null";

            var CacheLoginDTO = new CacheLoginDTO();

            if (CachingKeyLevel == CacheKeyLevel.OVERALL)
            {
                CacheLoginDTO.ServerId        = -1;
                CacheLoginDTO.ClientId        = -1;
                CacheLoginDTO.ServerConfigId  = -1;
                CacheLoginDTO.UserId          = -1;
                CacheLoginDTO.RoleId          = -1;
                CacheLoginDTO.LoginEventLogId = -1;
                CacheLoginDTO.LanguageId      = LoginDTO.LanguageId;
            }
            else if (CachingKeyLevel == CacheKeyLevel.DB_SERVER)
            {
                CacheLoginDTO.ServerId        = LoginDTO.ServerId;
                CacheLoginDTO.ClientId        = -1;
                CacheLoginDTO.ServerConfigId  = -1;
                CacheLoginDTO.UserId          = -1;
                CacheLoginDTO.RoleId          = -1;
                CacheLoginDTO.LoginEventLogId = -1;
                CacheLoginDTO.LanguageId      = LoginDTO.LanguageId;
            }
            else if (CachingKeyLevel == CacheKeyLevel.CLIENT_LEVEL)
            {
                CacheLoginDTO.ServerId        = LoginDTO.ServerId;
                CacheLoginDTO.ServerConfigId  = LoginDTO.ServerConfigId;
                CacheLoginDTO.ClientId        = LoginDTO.ClientId;
                CacheLoginDTO.UserId          = -1;
                CacheLoginDTO.RoleId          = -1;
                CacheLoginDTO.LoginEventLogId = -1;
                CacheLoginDTO.LanguageId      = LoginDTO.LanguageId;
            }
            else if (CachingKeyLevel == CacheKeyLevel.ROLE_LEVEL)
            {
                CacheLoginDTO.ServerId        = LoginDTO.ServerId;
                CacheLoginDTO.ClientId        = LoginDTO.ClientId;
                CacheLoginDTO.ServerConfigId  = LoginDTO.ServerConfigId;
                CacheLoginDTO.RoleId          = LoginDTO.RoleId;
                CacheLoginDTO.UserId          = -1;
                CacheLoginDTO.LoginEventLogId = -1;
                CacheLoginDTO.LanguageId      = LoginDTO.LanguageId;
            }
            else if (CachingKeyLevel == CacheKeyLevel.USER_LEVEL)
            {
                CacheLoginDTO.ServerId        = LoginDTO.ServerId;
                CacheLoginDTO.ClientId        = LoginDTO.ClientId;
                CacheLoginDTO.ServerConfigId  = LoginDTO.ServerConfigId;
                CacheLoginDTO.RoleId          = LoginDTO.RoleId;
                CacheLoginDTO.UserId          = LoginDTO.UserId;
                CacheLoginDTO.LoginEventLogId = -1;
                CacheLoginDTO.LanguageId      = LoginDTO.LanguageId;
            }
            else if (CachingKeyLevel == CacheKeyLevel.SESSION_LEVEL)
            {
                CacheLoginDTO.ServerId        = LoginDTO.ServerId;
                CacheLoginDTO.ClientId        = LoginDTO.ClientId;
                CacheLoginDTO.ServerConfigId  = LoginDTO.ServerConfigId;
                CacheLoginDTO.RoleId          = LoginDTO.RoleId;
                CacheLoginDTO.UserId          = LoginDTO.UserId;
                CacheLoginDTO.LoginEventLogId = LoginDTO.LoginEventLogId;
                CacheLoginDTO.LanguageId      = LoginDTO.LanguageId;
            }

            // System.Text.Json — no reflection overhead per call (options are shared static)
            string loginJson = JsonSerializer.Serialize(CacheLoginDTO, _jsonOptions);
            string dataToHash = CriteriaDTO is null
                ? $"{ObjectId}:{ObjectTypeId}:{loginJson}"
                : $"{ObjectId}:{ObjectTypeId}:{loginJson}:{JsonSerializer.Serialize(CriteriaDTO, _jsonOptions)}";

            // SHA256.HashData — static method, allocates no SHA256 instance
            byte[] hashBytes = SHA256.HashData(Encoding.UTF8.GetBytes(dataToHash));
            return Convert.ToBase64String(hashBytes);
        }
    }
}