import * as snmp from 'npm:net-snmp@3.26.0';
import { Buffer } from 'node:buffer';
import type { IOidSet, ISnmpConfig, IUpsStatus, TUpsModel } from './types.ts';
import { UpsOidSets } from './oid-sets.ts';
import { SNMP } from '../constants.ts';
import { logger } from '../logger.ts';
import type { INupstAccessor } from '../interfaces/index.ts';

/**
 * Class for SNMP communication with UPS devices
 * Main entry point for SNMP functionality
 */
export class NupstSnmp {
  // Active OID set
  private activeOIDs: IOidSet;
  // Reference to the parent Nupst instance (uses interface to avoid circular dependency)
  private nupst: INupstAccessor | null = null;
  // Debug mode flag
  private debug: boolean = false;

  // Default SNMP configuration
  private readonly DEFAULT_CONFIG: ISnmpConfig = {
    host: '127.0.0.1', // Default to localhost
    port: SNMP.DEFAULT_PORT, // Default SNMP port
    community: 'public', // Default community string for v1/v2c
    version: 1, // SNMPv1
    timeout: SNMP.DEFAULT_TIMEOUT_MS, // 5 seconds timeout
    upsModel: 'cyberpower', // Default UPS model
  };

  /**
   * Create a new SNMP manager
   * @param debug Whether to enable debug mode
   */
  constructor(debug = false) {
    this.debug = debug;
    // Set default OID set
    this.activeOIDs = UpsOidSets.getOidSet('cyberpower');
  }

  /**
   * Set reference to the main Nupst instance
   * @param nupst Reference to the main Nupst instance
   */
  public setNupst(nupst: INupstAccessor): void {
    this.nupst = nupst;
  }

  /**
   * Get reference to the main Nupst instance
   */
  public getNupst(): INupstAccessor | null {
    return this.nupst;
  }

  /**
   * Enable debug mode
   */
  public enableDebug(): void {
    this.debug = true;
    logger.info('SNMP debug mode enabled - detailed logs will be shown');
  }

  /**
   * Set active OID set based on UPS model
   * @param config SNMP configuration
   */
  private setActiveOIDs(config: ISnmpConfig): void {
    // If custom OIDs are provided, use them
    if (config.upsModel === 'custom' && config.customOIDs) {
      this.activeOIDs = config.customOIDs;
      if (this.debug) {
        logger.dim(`Using custom OIDs: ${JSON.stringify(this.activeOIDs)}`);
      }
      return;
    }

    // Use OIDs for the specified UPS model or default to Cyberpower
    const model = config.upsModel || 'cyberpower';
    this.activeOIDs = UpsOidSets.getOidSet(model);

    if (this.debug) {
      logger.dim(`Using OIDs for UPS model: ${model}`);
    }
  }

  /**
   * Send an SNMP GET request using the net-snmp package
   * @param oid OID to query
   * @param config SNMP configuration
   * @param retryCount Current retry count (unused in this implementation)
   * @returns Promise resolving to the SNMP response value
   */
  public snmpGet(
    oid: string,
    config = this.DEFAULT_CONFIG,
    retryCount = 0,
  ): Promise<any> {
    return new Promise((resolve, reject) => {
      if (this.debug) {
        logger.dim(
          `Sending SNMP v${config.version} GET request for OID ${oid} to ${config.host}:${config.port}`,
        );
        logger.dim(`Using community: ${config.community}`);
      }

      // Create SNMP options based on configuration
      const options: any = {
        port: config.port,
        retries: SNMP.RETRIES, // Number of retries
        timeout: config.timeout,
        transport: 'udp4',
        idBitsSize: 32,
        context: config.context || '',
      };

      // Set version based on config
      if (config.version === 1) {
        options.version = snmp.Version1;
      } else if (config.version === 2) {
        options.version = snmp.Version2c;
      } else {
        options.version = snmp.Version3;
      }

      // Create appropriate session based on SNMP version
      let session;

      if (config.version === 3) {
        // For SNMPv3, we need to set up authentication and privacy
        // For SNMPv3, we need a valid security level
        const securityLevel = config.securityLevel || 'noAuthNoPriv';

        // Create the user object with required structure for net-snmp
        const user: any = {
          name: config.username || '',
        };

        // Set security level
        if (securityLevel === 'noAuthNoPriv') {
          user.level = snmp.SecurityLevel.noAuthNoPriv;
        } else if (securityLevel === 'authNoPriv') {
          user.level = snmp.SecurityLevel.authNoPriv;

          // Set auth protocol - must provide both protocol and key
          if (config.authProtocol && config.authKey) {
            if (config.authProtocol === 'MD5') {
              user.authProtocol = snmp.AuthProtocols.md5;
            } else if (config.authProtocol === 'SHA') {
              user.authProtocol = snmp.AuthProtocols.sha;
            }
            user.authKey = config.authKey;
          } else {
            // Fallback to noAuthNoPriv if auth details missing
            user.level = snmp.SecurityLevel.noAuthNoPriv;
            if (this.debug) {
              logger.warn('Missing authProtocol or authKey, falling back to noAuthNoPriv');
            }
          }
        } else if (securityLevel === 'authPriv') {
          user.level = snmp.SecurityLevel.authPriv;

          // Set auth protocol - must provide both protocol and key
          if (config.authProtocol && config.authKey) {
            if (config.authProtocol === 'MD5') {
              user.authProtocol = snmp.AuthProtocols.md5;
            } else if (config.authProtocol === 'SHA') {
              user.authProtocol = snmp.AuthProtocols.sha;
            }
            user.authKey = config.authKey;

            // Set privacy protocol - must provide both protocol and key
            if (config.privProtocol && config.privKey) {
              if (config.privProtocol === 'DES') {
                user.privProtocol = snmp.PrivProtocols.des;
              } else if (config.privProtocol === 'AES') {
                user.privProtocol = snmp.PrivProtocols.aes;
              }
              user.privKey = config.privKey;
            } else {
              // Fallback to authNoPriv if priv details missing
              user.level = snmp.SecurityLevel.authNoPriv;
              if (this.debug) {
                logger.warn('Missing privProtocol or privKey, falling back to authNoPriv');
              }
            }
          } else {
            // Fallback to noAuthNoPriv if auth details missing
            user.level = snmp.SecurityLevel.noAuthNoPriv;
            if (this.debug) {
              logger.warn('Missing authProtocol or authKey, falling back to noAuthNoPriv');
            }
          }
        }

        if (this.debug) {
          const levelName = Object.keys(snmp.SecurityLevel).find((key) =>
            snmp.SecurityLevel[key] === user.level
          );
          logger.dim(`SNMPv3 user configuration: name=${user.name}, level=${levelName}, authProtocol=${user.authProtocol ? 'Set' : 'Not Set'}, privProtocol=${user.privProtocol ? 'Set' : 'Not Set'}`);
        }

        session = snmp.createV3Session(config.host, user, options);
      } else {
        // For SNMPv1/v2c, we use the community string
        session = snmp.createSession(config.host, config.community || 'public', options);
      }

      // Convert the OID string to an array of OIDs if multiple OIDs are needed
      const oids = [oid];

      // Send the GET request
      session.get(oids, (error: any, varbinds: any[]) => {
        // Close the session to release resources
        session.close();

        if (error) {
          if (this.debug) {
            logger.error(`SNMP GET error: ${error}`);
          }
          reject(new Error(`SNMP GET error: ${error.message || error}`));
          return;
        }

        if (!varbinds || varbinds.length === 0) {
          if (this.debug) {
            logger.error('No varbinds returned in response');
          }
          reject(new Error('No varbinds returned in response'));
          return;
        }

        // Check for SNMP errors in the response
        if (
          varbinds[0].type === snmp.ObjectType.NoSuchObject ||
          varbinds[0].type === snmp.ObjectType.NoSuchInstance ||
          varbinds[0].type === snmp.ObjectType.EndOfMibView
        ) {
          if (this.debug) {
            logger.error(`SNMP error: ${snmp.ObjectType[varbinds[0].type]}`);
          }
          reject(new Error(`SNMP error: ${snmp.ObjectType[varbinds[0].type]}`));
          return;
        }

        // Process the response value based on its type
        let value = varbinds[0].value;

        // Handle specific types that might need conversion
        if (Buffer.isBuffer(value)) {
          // If value is a Buffer, try to convert it to a string if it's printable ASCII
          const isPrintableAscii = value.every((byte: number) => byte >= 32 && byte <= 126);
          if (isPrintableAscii) {
            value = value.toString();
          }
        } else if (typeof value === 'bigint') {
          // Convert BigInt to a normal number or string if needed
          value = Number(value);
        }

        if (this.debug) {
          logger.dim(`SNMP response: oid=${varbinds[0].oid}, type=${varbinds[0].type}, value=${value}`);
        }

        resolve(value);
      });
    });
  }

  /**
   * Get the current status of the UPS
   * @param config SNMP configuration
   * @returns Promise resolving to the UPS status
   */
  public async getUpsStatus(config = this.DEFAULT_CONFIG): Promise<IUpsStatus> {
    try {
      // Set active OID set based on UPS model in config
      this.setActiveOIDs(config);

      if (this.debug) {
        logger.dim('---------------------------------------');
        logger.dim('Getting UPS status with config:');
        logger.dim(`  Host: ${config.host}`);
        logger.dim(`  Port: ${config.port}`);
        logger.dim(`  Version: ${config.version}`);
        logger.dim(`  Timeout: ${config.timeout} ms`);
        logger.dim(`  UPS Model: ${config.upsModel || 'cyberpower'}`);
        if (config.version === 1 || config.version === 2) {
          logger.dim(`  Community: ${config.community}`);
        } else if (config.version === 3) {
          logger.dim(`  Security Level: ${config.securityLevel}`);
          logger.dim(`  Username: ${config.username}`);
          logger.dim(`  Auth Protocol: ${config.authProtocol || 'None'}`);
          logger.dim(`  Privacy Protocol: ${config.privProtocol || 'None'}`);
        }
        logger.dim('Using OIDs:');
        logger.dim(`  Power Status: ${this.activeOIDs.POWER_STATUS}`);
        logger.dim(`  Battery Capacity: ${this.activeOIDs.BATTERY_CAPACITY}`);
        logger.dim(`  Battery Runtime: ${this.activeOIDs.BATTERY_RUNTIME}`);
        logger.dim(`  Output Load: ${this.activeOIDs.OUTPUT_LOAD}`);
        logger.dim(`  Output Power: ${this.activeOIDs.OUTPUT_POWER}`);
        logger.dim(`  Output Voltage: ${this.activeOIDs.OUTPUT_VOLTAGE}`);
        logger.dim(`  Output Current: ${this.activeOIDs.OUTPUT_CURRENT}`);
        logger.dim('---------------------------------------');
      }

      // Get all values with independent retry logic
      const powerStatusValue = await this.getSNMPValueWithRetry(
        this.activeOIDs.POWER_STATUS,
        'power status',
        config,
      );
      const batteryCapacity = await this.getSNMPValueWithRetry(
        this.activeOIDs.BATTERY_CAPACITY,
        'battery capacity',
        config,
      ) || 0;
      const batteryRuntime = await this.getSNMPValueWithRetry(
        this.activeOIDs.BATTERY_RUNTIME,
        'battery runtime',
        config,
      ) || 0;

      // Get power draw metrics
      const outputLoad = await this.getSNMPValueWithRetry(
        this.activeOIDs.OUTPUT_LOAD,
        'output load',
        config,
      ) || 0;
      const outputPower = await this.getSNMPValueWithRetry(
        this.activeOIDs.OUTPUT_POWER,
        'output power',
        config,
      ) || 0;
      const outputVoltage = await this.getSNMPValueWithRetry(
        this.activeOIDs.OUTPUT_VOLTAGE,
        'output voltage',
        config,
      ) || 0;
      const outputCurrent = await this.getSNMPValueWithRetry(
        this.activeOIDs.OUTPUT_CURRENT,
        'output current',
        config,
      ) || 0;

      // Determine power status - handle different values for different UPS models
      const powerStatus = this.determinePowerStatus(config.upsModel, powerStatusValue);

      // Convert to minutes for UPS models with different time units
      const processedRuntime = this.processRuntimeValue(config.upsModel, batteryRuntime);

      // Process power metrics with vendor-specific scaling
      const processedVoltage = this.processVoltageValue(config.upsModel, outputVoltage);
      const processedCurrent = this.processCurrentValue(config.upsModel, outputCurrent);

      // Calculate power from voltage × current if not provided by UPS
      let processedPower = outputPower;
      if (outputPower === 0 && processedVoltage > 0 && processedCurrent > 0) {
        processedPower = Math.round(processedVoltage * processedCurrent);
        if (this.debug) {
          logger.dim(
            `Calculated power from V×I: ${processedVoltage}V × ${processedCurrent}A = ${processedPower}W`,
          );
        }
      }

      const result = {
        powerStatus,
        batteryCapacity,
        batteryRuntime: processedRuntime,
        outputLoad,
        outputPower: processedPower,
        outputVoltage: processedVoltage,
        outputCurrent: processedCurrent,
        raw: {
          powerStatus: powerStatusValue,
          batteryCapacity,
          batteryRuntime,
          outputLoad,
          outputPower,
          outputVoltage,
          outputCurrent,
        },
      };

      if (this.debug) {
        logger.dim('---------------------------------------');
        logger.dim('UPS status result:');
        logger.dim(`  Power Status: ${result.powerStatus}`);
        logger.dim(`  Battery Capacity: ${result.batteryCapacity}%`);
        logger.dim(`  Battery Runtime: ${result.batteryRuntime} minutes`);
        logger.dim(`  Output Load: ${result.outputLoad}%`);
        logger.dim(`  Output Power: ${result.outputPower} watts`);
        logger.dim(`  Output Voltage: ${result.outputVoltage} volts`);
        logger.dim(`  Output Current: ${result.outputCurrent} amps`);
        logger.dim('---------------------------------------');
      }

      return result;
    } catch (error) {
      if (this.debug) {
        logger.error('---------------------------------------');
        logger.error(
          `Error getting UPS status: ${error instanceof Error ? error.message : String(error)}`,
        );
        logger.error('---------------------------------------');
      }
      throw new Error(
        `Failed to get UPS status: ${error instanceof Error ? error.message : String(error)}`,
      );
    }
  }

  /**
   * Helper method to get SNMP value with retry and fallback logic
   * @param oid OID to query
   * @param description Description of the value for logging
   * @param config SNMP configuration
   * @returns Promise resolving to the SNMP value
   */
  private async getSNMPValueWithRetry(
    oid: string,
    description: string,
    config: ISnmpConfig,
  ): Promise<any> {
    if (oid === '') {
      if (this.debug) {
        logger.dim(`No OID provided for ${description}, skipping`);
      }
      return 0;
    }

    if (this.debug) {
      logger.dim(`Getting ${description} OID: ${oid}`);
    }

    try {
      const value = await this.snmpGet(oid, config);
      if (this.debug) {
        logger.dim(`${description} value: ${value}`);
      }
      return value;
    } catch (error) {
      if (this.debug) {
        logger.error(
          `Error getting ${description}: ${error instanceof Error ? error.message : String(error)}`,
        );
      }

      // If we're using SNMPv3, try with different security levels
      if (config.version === 3) {
        return await this.tryFallbackSecurityLevels(oid, description, config);
      }

      // Try with standard OIDs as fallback
      if (config.upsModel !== 'custom') {
        return await this.tryStandardOids(oid, description, config);
      }

      // Return a default value if all attempts fail
      if (this.debug) {
        logger.dim(`Using default value 0 for ${description}`);
      }
      return 0;
    }
  }

  /**
   * Try fallback security levels for SNMPv3
   * @param oid OID to query
   * @param description Description of the value for logging
   * @param config SNMP configuration
   * @returns Promise resolving to the SNMP value
   */
  private async tryFallbackSecurityLevels(
    oid: string,
    description: string,
    config: ISnmpConfig,
  ): Promise<any> {
    if (this.debug) {
      logger.dim(`Retrying ${description} with fallback security level...`);
    }

    // Try with authNoPriv if current level is authPriv
    if (config.securityLevel === 'authPriv') {
      const retryConfig = { ...config, securityLevel: 'authNoPriv' as 'authNoPriv' };
      try {
        if (this.debug) {
          logger.dim(`Retrying with authNoPriv security level`);
        }
        const value = await this.snmpGet(oid, retryConfig);
        if (this.debug) {
          logger.dim(`${description} retry value: ${value}`);
        }
        return value;
      } catch (retryError) {
        if (this.debug) {
          logger.error(
            `Retry failed for ${description}: ${retryError instanceof Error ? retryError.message : String(retryError)}`,
          );
        }
      }
    }

    // Try with noAuthNoPriv as a last resort
    if (config.securityLevel === 'authPriv' || config.securityLevel === 'authNoPriv') {
      const retryConfig = { ...config, securityLevel: 'noAuthNoPriv' as 'noAuthNoPriv' };
      try {
        if (this.debug) {
          logger.dim(`Retrying with noAuthNoPriv security level`);
        }
        const value = await this.snmpGet(oid, retryConfig);
        if (this.debug) {
          logger.dim(`${description} retry value: ${value}`);
        }
        return value;
      } catch (retryError) {
        if (this.debug) {
          logger.error(
            `Retry failed for ${description}: ${retryError instanceof Error ? retryError.message : String(retryError)}`,
          );
        }
      }
    }

    return 0;
  }

  /**
   * Try standard OIDs as fallback
   * @param oid OID to query
   * @param description Description of the value for logging
   * @param config SNMP configuration
   * @returns Promise resolving to the SNMP value
   */
  private async tryStandardOids(
    oid: string,
    description: string,
    config: ISnmpConfig,
  ): Promise<any> {
    try {
      // Try RFC 1628 standard UPS MIB OIDs
      const standardOIDs = UpsOidSets.getStandardOids();

      if (this.debug) {
        logger.dim(
          `Trying standard RFC 1628 OID for ${description}: ${standardOIDs[description]}`,
        );
      }

      const standardValue = await this.snmpGet(standardOIDs[description], config);
      if (this.debug) {
        logger.dim(`${description} standard OID value: ${standardValue}`);
      }
      return standardValue;
    } catch (stdError) {
      if (this.debug) {
        logger.error(
          `Standard OID retry failed for ${description}: ${stdError instanceof Error ? stdError.message : String(stdError)}`,
        );
      }
    }

    return 0;
  }

  /**
   * Determine power status based on UPS model and raw value
   * Uses the value mappings defined in the OID sets
   * @param upsModel UPS model
   * @param powerStatusValue Raw power status value
   * @returns Standardized power status
   */
  private determinePowerStatus(
    upsModel: TUpsModel | undefined,
    powerStatusValue: number,
  ): 'online' | 'onBattery' | 'unknown' {
    // Get the OID set for this UPS model
    if (upsModel && upsModel !== 'custom') {
      const oidSet = UpsOidSets.getOidSet(upsModel);

      // Use the value mappings if available
      if (oidSet.POWER_STATUS_VALUES) {
        if (powerStatusValue === oidSet.POWER_STATUS_VALUES.online) {
          return 'online';
        } else if (powerStatusValue === oidSet.POWER_STATUS_VALUES.onBattery) {
          return 'onBattery';
        }
      }
    }

    // Fallback for custom or undefined models (RFC 1628 standard)
    // upsOutputSource: 3=normal (mains), 5=battery
    if (powerStatusValue === 3) {
      return 'online';
    } else if (powerStatusValue === 5) {
      return 'onBattery';
    }

    return 'unknown';
  }

  /**
   * Process runtime value based on UPS model
   * @param upsModel UPS model
   * @param batteryRuntime Raw battery runtime value
   * @returns Processed runtime in minutes
   */
  private processRuntimeValue(
    upsModel: TUpsModel | undefined,
    batteryRuntime: number,
  ): number {
    if (this.debug) {
      logger.dim(`Raw runtime value: ${batteryRuntime}`);
    }

    if (upsModel === 'cyberpower' && batteryRuntime > 0) {
      // CyberPower: TimeTicks is in 1/100 seconds, convert to minutes
      const minutes = Math.floor(batteryRuntime / 6000); // 6000 ticks = 1 minute
      if (this.debug) {
        logger.dim(
          `Converting CyberPower runtime from ${batteryRuntime} ticks to ${minutes} minutes`,
        );
      }
      return minutes;
    } else if (upsModel === 'eaton' && batteryRuntime > 0) {
      // Eaton: Runtime is in seconds, convert to minutes
      const minutes = Math.floor(batteryRuntime / 60);
      if (this.debug) {
        logger.dim(
          `Converting Eaton runtime from ${batteryRuntime} seconds to ${minutes} minutes`,
        );
      }
      return minutes;
    } else if (batteryRuntime > 10000) {
      // Generic conversion for large tick values (likely TimeTicks)
      const minutes = Math.floor(batteryRuntime / 6000);
      if (this.debug) {
        logger.dim(`Converting ${batteryRuntime} ticks to ${minutes} minutes`);
      }
      return minutes;
    }

    return batteryRuntime;
  }

  /**
   * Process voltage value based on UPS model
   * @param upsModel UPS model
   * @param outputVoltage Raw output voltage value
   * @returns Processed voltage in volts
   */
  private processVoltageValue(
    upsModel: TUpsModel | undefined,
    outputVoltage: number,
  ): number {
    if (this.debug) {
      logger.dim(`Raw voltage value: ${outputVoltage}`);
    }

    if (upsModel === 'cyberpower' && outputVoltage > 0) {
      // CyberPower: Voltage is in 0.1V, convert to volts
      const volts = outputVoltage / 10;
      if (this.debug) {
        logger.dim(
          `Converting CyberPower voltage from ${outputVoltage} (0.1V) to ${volts} volts`,
        );
      }
      return volts;
    }

    return outputVoltage;
  }

  /**
   * Process current value based on UPS model
   * @param upsModel UPS model
   * @param outputCurrent Raw output current value
   * @returns Processed current in amps
   */
  private processCurrentValue(
    upsModel: TUpsModel | undefined,
    outputCurrent: number,
  ): number {
    if (this.debug) {
      logger.dim(`Raw current value: ${outputCurrent}`);
    }

    if (upsModel === 'cyberpower' && outputCurrent > 0) {
      // CyberPower: Current is in 0.1A, convert to amps
      const amps = outputCurrent / 10;
      if (this.debug) {
        logger.dim(
          `Converting CyberPower current from ${outputCurrent} (0.1A) to ${amps} amps`,
        );
      }
      return amps;
    } else if ((upsModel === 'tripplite' || upsModel === 'liebert') && outputCurrent > 0) {
      // RFC 1628 standard: Current is in 0.1A, convert to amps
      const amps = outputCurrent / 10;
      if (this.debug) {
        logger.dim(
          `Converting RFC 1628 current from ${outputCurrent} (0.1A) to ${amps} amps`,
        );
      }
      return amps;
    }

    // Eaton XUPS-MIB and APC PowerNet report current directly in RMS Amps (no scaling needed)
    if ((upsModel === 'eaton' || upsModel === 'apc') && this.debug && outputCurrent > 0) {
      logger.dim(`${upsModel.toUpperCase()} current already in RMS Amps: ${outputCurrent}A`);
    }

    return outputCurrent;
  }
}