feat(recurring-tasks): implement recurring tasks service with timezone support and notifications

- Added a new service for managing recurring tasks, allowing configuration of task schedules with timezone support.
- Introduced job queues for processing recurring tasks and handling task creation in bulk.
- Implemented notification system to alert users about newly created recurring tasks, including email and in-app notifications.
- Enhanced database schema with new tables for notifications and audit logs to track recurring task operations.
- Updated frontend components to support timezone selection and manage excluded dates for recurring tasks.
- Refactored existing code to integrate new features and improve overall task management experience.

worklenz-backend/src/utils/recurring-tasks-audit-logger.ts

@@ -0,0 +1,189 @@
+import db from "../config/db";
+import { log_error } from "../shared/utils";
+
+export enum RecurringTaskOperationType {
+  CRON_JOB_RUN = "cron_job_run",
+  CRON_JOB_ERROR = "cron_job_error",
+  TEMPLATE_CREATED = "template_created",
+  TEMPLATE_UPDATED = "template_updated",
+  TEMPLATE_DELETED = "template_deleted",
+  SCHEDULE_CREATED = "schedule_created",
+  SCHEDULE_UPDATED = "schedule_updated",
+  SCHEDULE_DELETED = "schedule_deleted",
+  TASKS_CREATED = "tasks_created",
+  TASKS_CREATION_FAILED = "tasks_creation_failed",
+  MANUAL_TRIGGER = "manual_trigger",
+  BULK_OPERATION = "bulk_operation"
+}
+
+export interface AuditLogEntry {
+  operationType: RecurringTaskOperationType;
+  templateId?: string;
+  scheduleId?: string;
+  taskId?: string;
+  templateName?: string;
+  success?: boolean;
+  errorMessage?: string;
+  details?: any;
+  createdTasksCount?: number;
+  failedTasksCount?: number;
+  executionTimeMs?: number;
+  createdBy?: string;
+}
+
+export class RecurringTasksAuditLogger {
+  private static startTime: number;
+
+  /**
+   * Start timing an operation
+   */
+  static startTimer(): void {
+    this.startTime = Date.now();
+  }
+
+  /**
+   * Get elapsed time since timer started
+   */
+  static getElapsedTime(): number {
+    return this.startTime ? Date.now() - this.startTime : 0;
+  }
+
+  /**
+   * Log a recurring task operation
+   */
+  static async log(entry: AuditLogEntry): Promise<void> {
+    try {
+      const query = `SELECT log_recurring_task_operation($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12);`;
+      
+      await db.query(query, [
+        entry.operationType,
+        entry.templateId || null,
+        entry.scheduleId || null,
+        entry.taskId || null,
+        entry.templateName || null,
+        entry.success !== false, // Default to true
+        entry.errorMessage || null,
+        entry.details ? JSON.stringify(entry.details) : null,
+        entry.createdTasksCount || 0,
+        entry.failedTasksCount || 0,
+        entry.executionTimeMs || this.getElapsedTime(),
+        entry.createdBy || null
+      ]);
+    } catch (error) {
+      // Don't let audit logging failures break the main flow
+      log_error("Failed to log recurring task audit entry:", error);
+    }
+  }
+
+  /**
+   * Log cron job execution
+   */
+  static async logCronJobRun(
+    totalTemplates: number,
+    createdTasksCount: number,
+    errors: any[] = []
+  ): Promise<void> {
+    await this.log({
+      operationType: RecurringTaskOperationType.CRON_JOB_RUN,
+      success: errors.length === 0,
+      errorMessage: errors.length > 0 ? `${errors.length} errors occurred` : undefined,
+      details: {
+        totalTemplates,
+        errors: errors.map(e => e.message || e.toString())
+      },
+      createdTasksCount,
+      executionTimeMs: this.getElapsedTime()
+    });
+  }
+
+  /**
+   * Log template processing
+   */
+  static async logTemplateProcessing(
+    templateId: string,
+    templateName: string,
+    scheduleId: string,
+    createdCount: number,
+    failedCount: number,
+    details?: any
+  ): Promise<void> {
+    await this.log({
+      operationType: RecurringTaskOperationType.TASKS_CREATED,
+      templateId,
+      scheduleId,
+      templateName,
+      success: failedCount === 0,
+      createdTasksCount: createdCount,
+      failedTasksCount: failedCount,
+      details
+    });
+  }
+
+  /**
+   * Log schedule changes
+   */
+  static async logScheduleChange(
+    operationType: RecurringTaskOperationType,
+    scheduleId: string,
+    templateId?: string,
+    userId?: string,
+    details?: any
+  ): Promise<void> {
+    await this.log({
+      operationType,
+      scheduleId,
+      templateId,
+      createdBy: userId,
+      details
+    });
+  }
+
+  /**
+   * Get audit log summary
+   */
+  static async getAuditSummary(days: number = 7): Promise<any> {
+    try {
+      const query = `
+        SELECT 
+          operation_type,
+          COUNT(*) as count,
+          SUM(CASE WHEN success THEN 1 ELSE 0 END) as success_count,
+          SUM(CASE WHEN NOT success THEN 1 ELSE 0 END) as failure_count,
+          SUM(created_tasks_count) as total_tasks_created,
+          SUM(failed_tasks_count) as total_tasks_failed,
+          AVG(execution_time_ms) as avg_execution_time_ms
+        FROM recurring_tasks_audit_log
+        WHERE created_at >= CURRENT_TIMESTAMP - INTERVAL '${days} days'
+        GROUP BY operation_type
+        ORDER BY count DESC;
+      `;
+      
+      const result = await db.query(query);
+      return result.rows;
+    } catch (error) {
+      log_error("Failed to get audit summary:", error);
+      return [];
+    }
+  }
+
+  /**
+   * Get recent errors
+   */
+  static async getRecentErrors(limit: number = 10): Promise<any[]> {
+    try {
+      const query = `
+        SELECT *
+        FROM v_recent_recurring_tasks_audit
+        WHERE NOT success
+        ORDER BY created_at DESC
+        LIMIT $1;
+      `;
+      
+      const result = await db.query(query, [limit]);
+      return result.rows;
+    } catch (error) {
+      log_error("Failed to get recent errors:", error);
+      return [];
+    }
+  }
+}