import { EventsHandler, IEventHandler } from '@nestjs/cqrs';
import { DataSchedulingUpdatedEvent } from '../../entities/event/data-scheduling-updated.event';
import {
  DataSchedulingLogEntity,
  SCHEDULING_LOG_ACTION_ENUM,
  SCHEDULING_LOG_TYPE_ENUM,
} from '../../entities/data-scheduling.entity';
import {
  decryptionTotal,
  encryptionTotal,
} from '../../../infrastructure/helpers';
import { Logger } from '@nestjs/common';
import { DataSchedulingLogDataService } from '../../../data/services/data-scheduling-log-data.service';

@EventsHandler(DataSchedulingUpdatedEvent)
export class DataSchedulingUpdatedHandler
  implements IEventHandler<DataSchedulingUpdatedEvent>
{
  private readonly logger = new Logger(DataSchedulingUpdatedHandler.name);

  constructor(private service: DataSchedulingLogDataService) {}

  // Map for readable labels
  private readonly labelMap: { [key: string]: string } = {
    name: 'Name',
    indexing_key: 'Total Data',
    schedule_date_from: 'Start Date',
    schedule_date_to: 'End Date',
  };

  // Relevant keys for comparing changes
  private readonly keysToCompare: string[] = [
    'name',
    'indexing_key',
    'schedule_date_from',
    'schedule_date_to',
  ];

  async handle(event: DataSchedulingUpdatedEvent) {
    const oldData = event?.data?.old;
    // Decrypt oldData.indexing_key here before comparison
    if (oldData?.indexing_key !== undefined && oldData?.indexing_key !== null) {
      oldData.indexing_key = decryptionTotal(oldData.indexing_key);
    }

    const newData = event?.data?.data;
    // Decrypt newData.indexing_key here before comparison
    if (newData?.indexing_key !== undefined && newData?.indexing_key !== null) {
      newData.indexing_key = decryptionTotal(newData.indexing_key);
    }

    const changingData = this.getChangingData(oldData, newData);
    const description = this.generateDescription(
      oldData,
      newData,
      changingData,
    );

    const payload: DataSchedulingLogEntity = {
      type: SCHEDULING_LOG_TYPE_ENUM.DATA_SCHEDULING,
      action: SCHEDULING_LOG_ACTION_ENUM.UPDATE,
      log_created_at: new Date().getTime(),

      data_id: newData?.id,
      name: newData?.name,
      indexing_key: encryptionTotal(newData?.indexing_key),
      schedule_date_from: newData?.schedule_date_from,
      schedule_date_to: newData?.schedule_date_to,

      status: newData?.status,
      creator_id: newData?.creator_id,
      creator_name: newData?.creator_name,
      editor_id: newData?.editor_id,
      editor_name: newData?.editor_name,
      created_at: newData?.created_at,
      updated_at: newData?.updated_at,
      description: description,
    };

    await this.service.create(payload as any);
    this.logger.verbose(
      `[SCHEDULING LOG] Update data for ID: ${payload.data_id}`,
    );
  }

  /**
   * Compares old and new data to find changes.
   * @param oldData Data before the change.
   * @param newData Data after the change.
   * @returns An object containing the old and new changed data.
   */
  private getChangingData(oldData: any, newData: any): { old: any; new: any } {
    const changingData: { old: any; new: any } = { old: {}, new: {} };

    this.keysToCompare.forEach((key) => {
      // Ensure comparisons are made on decrypted values if decryption happens before this
      if (oldData?.[key] !== newData?.[key]) {
        changingData.old[key] = oldData?.[key];
        changingData.new[key] = newData?.[key];
      }
    });

    return changingData;
  }

  /**
   * Generates an HTML description string based on data changes.
   * Includes the name from oldData for identification.
   * @param oldData Old data, used to get the name of the item.
   * @param newData New data containing editor information.
   * @param changingData An object containing the changed data.
   * @returns The HTML string of the change description.
   */
  private generateDescription(
    oldData: any,
    newData: any,
    changingData: { old: any; new: any },
  ): string {
    const editorName = newData.editor_name || 'System';
    const itemName = oldData?.name || 'an item';

    let description = `<p><b>${editorName}</b> has updated schedule for <b>${itemName}</b>.`;

    if (Object.keys(changingData.old).length > 0) {
      description += ` Change details:<ul>`;
      for (const key in changingData.old) {
        if (Object.prototype.hasOwnProperty.call(changingData.old, key)) {
          const label = this.labelMap[key] || key;
          let oldValue = changingData.old[key] || 'empty';
          let newValue = changingData.new[key] || 'empty';

          // Add '%' suffix if the key is 'indexing_key'
          if (key === 'indexing_key') {
            oldValue = `${oldValue}%`;
            newValue = `${newValue}%`;
          }

          description += `<li><b>${label}</b> changed from <i>${oldValue}</i> to <i>${newValue}</i>.</li>`;
        }
      }
      description += `</ul></p>`;
    } else {
      description += ` No significant data detail changes.</p>`;
    }

    return description;
  }
}