import { createLogger } from "@link-stack/logger";

const logger = createLogger('formstack-field-mapping');

/**
 * Field mapping configuration for Formstack to Zammad integration
 *
 * This configuration is completely flexible - you define your own internal field names
 * and map them to both Formstack source fields and Zammad custom fields.
 */
export interface FieldMappingConfig {
  /**
   * Map internal field keys to Formstack field names
   *
   * Required keys (system):
   * - formId: The Formstack Form ID field
   * - uniqueId: The Formstack submission unique ID field
   *
   * Optional keys with special behavior:
   * - email: Used for user lookup/creation (if provided)
   * - phone: Used for user lookup/creation (if provided)
   * - signalAccount: Used for Signal-based user lookup (tried first before phone)
   * - name: User's full name (can be nested object with first/last, used in user creation)
   * - organization: Used in ticket title template placeholder {organization}
   * - typeOfSupport: Used in ticket title template placeholder {typeOfSupport}
   * - descriptionOfIssue: Used as article subject (defaults to "Support Request" if not provided)
   *
   * All other keys are completely arbitrary and defined by your form.
   */
  sourceFields: Record<string, string>;

  /**
   * Map Zammad custom field names to internal field keys (from sourceFields)
   *
   * Example:
   * {
   *   "us_state": "state",        // Zammad field "us_state" gets value from sourceFields["state"]
   *   "zip_code": "zipCode",      // Zammad field "zip_code" gets value from sourceFields["zipCode"]
   *   "custom_field": "myField"   // Any custom field mapping
   * }
   *
   * The values in this object must correspond to keys in sourceFields.
   */
  zammadFields: Record<string, string>;

  /**
   * Configuration for ticket creation
   */
  ticket: {
    /** Zammad group name to assign tickets to */
    group: string;

    /** Article type name (e.g., "note", "cdr_signal", "email") */
    defaultArticleType: string;

    /**
     * Template for ticket title
     * Supports placeholders: {name}, {organization}, {typeOfSupport}
     * Placeholders reference internal field keys from sourceFields
     */
    titleTemplate?: string;
  };

  /**
   * Configuration for extracting nested field values
   */
  nestedFields?: {
    /**
     * How to extract first/last name from a nested Name field
     * Example: { firstNamePath: "first", lastNamePath: "last" }
     * for a field like { "Name": { "first": "John", "last": "Doe" } }
     */
    name?: {
      firstNamePath?: string;
      lastNamePath?: string;
    };
  };
}

let cachedMapping: FieldMappingConfig | null = null;

/**
 * Load field mapping configuration from environment variable (REQUIRED)
 */
export function loadFieldMapping(): FieldMappingConfig {
  if (cachedMapping) {
    return cachedMapping;
  }

  const configJson = process.env.FORMSTACK_FIELD_MAPPING;

  if (!configJson) {
    throw new Error(
      'FORMSTACK_FIELD_MAPPING environment variable is required. ' +
      'Please set it to a JSON string containing your field mapping configuration.'
    );
  }

  logger.info('Loading Formstack field mapping from environment variable');

  try {
    const config = JSON.parse(configJson) as FieldMappingConfig;

    // Validate required sections exist
    if (!config.sourceFields || typeof config.sourceFields !== 'object') {
      throw new Error('Invalid field mapping configuration: sourceFields must be an object');
    }

    if (!config.zammadFields || typeof config.zammadFields !== 'object') {
      throw new Error('Invalid field mapping configuration: zammadFields must be an object');
    }

    if (!config.ticket || typeof config.ticket !== 'object') {
      throw new Error('Invalid field mapping configuration: ticket must be an object');
    }

    // Validate required ticket fields
    if (!config.ticket.group) {
      throw new Error('Invalid field mapping configuration: ticket.group is required');
    }

    if (!config.ticket.defaultArticleType) {
      throw new Error('Invalid field mapping configuration: ticket.defaultArticleType is required');
    }

    // Validate required source fields
    const systemRequiredFields = ['formId', 'uniqueId'];
    for (const field of systemRequiredFields) {
      if (!config.sourceFields[field]) {
        throw new Error(`Invalid field mapping configuration: sourceFields.${field} is required (system field)`);
      }
    }

    // Validate zammadFields reference valid sourceFields
    for (const [zammadField, sourceKey] of Object.entries(config.zammadFields)) {
      if (!config.sourceFields[sourceKey]) {
        logger.warn(
          { zammadField, sourceKey },
          'Zammad field maps to non-existent source field key'
        );
      }
    }

    logger.info('Successfully loaded Formstack field mapping configuration');
    cachedMapping = config;
    return cachedMapping;

  } catch (error) {
    logger.error({
      error: error instanceof Error ? error.message : error,
      jsonLength: configJson.length
    }, 'Failed to parse field mapping configuration');

    throw new Error(
      `Failed to parse Formstack field mapping JSON: ${error instanceof Error ? error.message : error}`
    );
  }
}

/**
 * Get a field value from formData using the source field name mapping
 */
export function getFieldValue(
  formData: any,
  internalFieldKey: string,
  mapping?: FieldMappingConfig
): any {
  const config = mapping || loadFieldMapping();
  const sourceFieldName = config.sourceFields[internalFieldKey];
  if (!sourceFieldName) {
    return undefined;
  }
  return formData[sourceFieldName];
}

/**
 * Get a nested field value (e.g., Name.first)
 */
export function getNestedFieldValue(
  fieldValue: any,
  path: string | undefined
): any {
  if (!path || !fieldValue) {
    return undefined;
  }

  const parts = path.split('.');
  let current = fieldValue;

  for (const part of parts) {
    if (current && typeof current === 'object') {
      current = current[part];
    } else {
      return undefined;
    }
  }

  return current;
}

/**
 * Format field value (handle arrays, objects, etc.)
 */
export function formatFieldValue(value: any): string | undefined {
  if (value === null || value === undefined || value === '') {
    return undefined;
  }
  if (Array.isArray(value)) {
    return value.join(', ');
  }
  if (typeof value === 'object') {
    return JSON.stringify(value);
  }
  return String(value);
}

/**
 * Build ticket title from template and data
 * Replaces placeholders like {name}, {organization}, {typeOfSupport} with provided values
 */
export function buildTicketTitle(
  mapping: FieldMappingConfig,
  data: Record<string, string | undefined>
): string {
  const template = mapping.ticket.titleTemplate || '{name}';

  let title = template;

  // Replace all placeholders in the template
  for (const [key, value] of Object.entries(data)) {
    const placeholder = `{${key}}`;
    if (title.includes(placeholder)) {
      if (value) {
        title = title.replace(placeholder, value);
      } else {
        // Remove empty placeholder and surrounding separators
        title = title.replace(` - ${placeholder}`, '').replace(`${placeholder} - `, '').replace(placeholder, '');
      }
    }
  }

  return title.trim();
}

/**
 * Get all Zammad field values from form data using the mapping
 * Returns an object with Zammad field names as keys and formatted values
 */
export function getZammadFieldValues(
  formData: any,
  mapping?: FieldMappingConfig
): Record<string, string> {
  const config = mapping || loadFieldMapping();
  const result: Record<string, string> = {};

  for (const [zammadFieldName, sourceKey] of Object.entries(config.zammadFields)) {
    const value = getFieldValue(formData, sourceKey, config);
    const formatted = formatFieldValue(value);
    if (formatted !== undefined) {
      result[zammadFieldName] = formatted;
    }
  }

  return result;
}

/**
 * Reset cached mapping (useful for testing)
 */
export function resetMappingCache(): void {
  cachedMapping = null;
}