using System.Configuration;

namespace XP.Common.License.Configs
{
    /// <summary>
    /// 授权配置加载器，从 App.config 读取授权相关配置项 | License configuration loader, reads license-related configuration from App.config
    /// </summary>
    public static class ConfigLoader
    {
        /// <summary>
        /// 配置键前缀 | Configuration key prefix
        /// </summary>
        private const string KeyPrefix = "License:";

        /// <summary>
        /// LicenseMode 有效值集合 | Valid values for LicenseMode
        /// </summary>
        private static readonly int[] ValidLicenseModes = { 0, 885 };

        /// <summary>
        /// LicenseState 有效值集合 | Valid values for LicenseState
        /// </summary>
        private static readonly int[] ValidLicenseStates = { 10, 20 };

        /// <summary>
        /// 从 App.config 加载授权配置 | Load license configuration from App.config
        /// </summary>
        /// <returns>授权配置实体，缺失或无效配置项使用默认值 | License configuration entity, uses default values for missing or invalid items</returns>
        public static LicenseConfig LoadLicenseConfig()
        {
            var config = new LicenseConfig();

            // 加载 LicenseMode | Load LicenseMode
            var licenseModeStr = ConfigurationManager.AppSettings[KeyPrefix + "LicenseMode"];
            if (int.TryParse(licenseModeStr, out var licenseMode) && IsValidLicenseMode(licenseMode))
            {
                config.LicenseMode = licenseMode;
            }

            // 加载 ModuleId | Load ModuleId
            var moduleIdStr = ConfigurationManager.AppSettings[KeyPrefix + "ModuleId"];
            if (ushort.TryParse(moduleIdStr, out var moduleId) && IsValidModuleId(moduleId))
            {
                config.ModuleId = moduleId;
            }

            // 加载 UseSma | Load UseSma
            var useSmaStr = ConfigurationManager.AppSettings[KeyPrefix + "UseSma"];
            if (bool.TryParse(useSmaStr, out var useSma))
            {
                config.UseSma = useSma;
            }

            // 加载 LicenseState | Load LicenseState
            var licenseStateStr = ConfigurationManager.AppSettings[KeyPrefix + "LicenseState"];
            if (int.TryParse(licenseStateStr, out var licenseState) && IsValidLicenseState(licenseState))
            {
                config.LicenseState = licenseState;
            }

            return config;
        }

        /// <summary>
        /// 验证 LicenseMode 值是否有效 | Validate whether LicenseMode value is valid
        /// </summary>
        /// <param name="value">待验证的值 | Value to validate</param>
        /// <returns>true 表示有效，false 表示无效 | true if valid, false if invalid</returns>
        private static bool IsValidLicenseMode(int value)
        {
            foreach (var valid in ValidLicenseModes)
            {
                if (value == valid) return true;
            }
            return false;
        }

        /// <summary>
        /// 验证 ModuleId 值是否在有效范围内 | Validate whether ModuleId value is within valid range
        /// </summary>
        /// <param name="value">待验证的值 | Value to validate</param>
        /// <returns>true 表示有效，false 表示无效 | true if valid, false if invalid</returns>
        private static bool IsValidModuleId(ushort value)
        {
            return value >= 1 && value <= 65535;
        }

        /// <summary>
        /// 验证 LicenseState 值是否有效 | Validate whether LicenseState value is valid
        /// </summary>
        /// <param name="value">待验证的值 | Value to validate</param>
        /// <returns>true 表示有效，false 表示无效 | true if valid, false if invalid</returns>
        private static bool IsValidLicenseState(int value)
        {
            foreach (var valid in ValidLicenseStates)
            {
                if (value == valid) return true;
            }
            return false;
        }
    }
}