From 1af1ea9505c058bb64e7e791a73df74f20c0ca93 Mon Sep 17 00:00:00 2001
From: Derrick Hammer <derrick@derrickhammer.com>
Date: Sun, 28 Jan 2024 16:23:38 -0500
Subject: [PATCH] feat: create a cron job abstraction with a RetryableTask
 method, RetryableTaskParams struct, CronJob struct, and CreateJob method

---
 cron/cron.go | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/cron/cron.go b/cron/cron.go
index 3847f16..8c9d403 100644
--- a/cron/cron.go
+++ b/cron/cron.go
@@ -2,8 +2,10 @@ package cron
 
 import (
 	"context"
+	"github.com/google/uuid"
 	"go.uber.org/fx"
 	"go.uber.org/zap"
+	"time"
 
 	"github.com/go-co-op/gocron/v2"
 )
@@ -36,6 +38,22 @@ type CronServiceImpl struct {
 	logger    *zap.Logger
 }
 
+type RetryableTaskParams struct {
+	Name     string
+	Function any
+	Args     []any
+	Attempt  uint
+	Limit    uint
+	After    func(jobID uuid.UUID, jobName string)
+	Error    func(jobID uuid.UUID, jobName string, err error)
+}
+
+type CronJob struct {
+	Job     gocron.JobDefinition
+	Task    gocron.Task
+	Options []gocron.JobOption
+}
+
 func (c *CronServiceImpl) Scheduler() gocron.Scheduler {
 	return c.scheduler
 }
@@ -71,3 +89,59 @@ func (c *CronServiceImpl) start() error {
 func (c *CronServiceImpl) RegisterService(service CronableService) {
 	c.services = append(c.services, service)
 }
+
+func (c *CronServiceImpl) RetryableTask(params RetryableTaskParams) CronJob {
+	job := gocron.OneTimeJob(gocron.OneTimeJobStartImmediately())
+
+	if params.Attempt > 0 {
+		job = gocron.OneTimeJob(gocron.OneTimeJobStartDateTime(time.Now().Add(time.Duration(params.Attempt) * time.Minute)))
+	}
+
+	task := gocron.NewTask(params.Function, params.Args...)
+
+	afterFunc := params.After
+	if afterFunc == nil {
+		afterFunc = func(jobID uuid.UUID, jobName string) {}
+	}
+
+	errorFunc := params.Error
+	if errorFunc == nil {
+		errorFunc = func(jobID uuid.UUID, jobName string, err error) {}
+	}
+
+	listeners := gocron.WithEventListeners(gocron.AfterJobRunsWithError(func(jobID uuid.UUID, jobName string, err error) {
+		params.Error(jobID, jobName, err)
+
+		if params.Attempt >= params.Limit {
+			c.logger.Error("Retryable task limit reached", zap.String("jobName", jobName), zap.String("jobID", jobID.String()))
+			return
+		}
+
+		taskRetry := params
+		taskRetry.Attempt++
+
+		retryTask := c.RetryableTask(taskRetry)
+
+		_, err = c.CreateJob(retryTask)
+		if err != nil {
+			c.logger.Error("Failed to create retry job", zap.Error(err))
+		}
+	}), gocron.AfterJobRuns(params.After))
+
+	name := gocron.WithName(params.Name)
+
+	return CronJob{
+		Job:     job,
+		Task:    task,
+		Options: []gocron.JobOption{listeners, name},
+	}
+}
+
+func (c *CronServiceImpl) CreateJob(job CronJob) (gocron.Job, error) {
+	ret, err := c.Scheduler().NewJob(job.Job, job.Task, job.Options...)
+	if err != nil {
+		return nil, err
+	}
+
+	return ret, nil
+}