Refactor webhook payload convertion (#12310)

* Refactor webhook payload convertion

* Fix lint

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/webhook/payloader.go

@@ -0,0 +1,56 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package webhook
+
+import (
+	"code.gitea.io/gitea/models"
+	api "code.gitea.io/gitea/modules/structs"
+)
+
+// PayloadConvertor defines the interface to convert system webhook payload to external payload
+type PayloadConvertor interface {
+	api.Payloader
+	Create(*api.CreatePayload) (api.Payloader, error)
+	Delete(*api.DeletePayload) (api.Payloader, error)
+	Fork(*api.ForkPayload) (api.Payloader, error)
+	Issue(*api.IssuePayload) (api.Payloader, error)
+	IssueComment(*api.IssueCommentPayload) (api.Payloader, error)
+	Push(*api.PushPayload) (api.Payloader, error)
+	PullRequest(*api.PullRequestPayload) (api.Payloader, error)
+	Review(*api.PullRequestPayload, models.HookEventType) (api.Payloader, error)
+	Repository(*api.RepositoryPayload) (api.Payloader, error)
+	Release(*api.ReleasePayload) (api.Payloader, error)
+}
+
+func convertPayloader(s PayloadConvertor, p api.Payloader, event models.HookEventType) (api.Payloader, error) {
+	switch event {
+	case models.HookEventCreate:
+		return s.Create(p.(*api.CreatePayload))
+	case models.HookEventDelete:
+		return s.Delete(p.(*api.DeletePayload))
+	case models.HookEventFork:
+		return s.Fork(p.(*api.ForkPayload))
+	case models.HookEventIssues, models.HookEventIssueAssign, models.HookEventIssueLabel, models.HookEventIssueMilestone:
+		return s.Issue(p.(*api.IssuePayload))
+	case models.HookEventIssueComment, models.HookEventPullRequestComment:
+		pl, ok := p.(*api.IssueCommentPayload)
+		if ok {
+			return s.IssueComment(pl)
+		}
+		return s.PullRequest(p.(*api.PullRequestPayload))
+	case models.HookEventPush:
+		return s.Push(p.(*api.PushPayload))
+	case models.HookEventPullRequest, models.HookEventPullRequestAssign, models.HookEventPullRequestLabel,
+		models.HookEventPullRequestMilestone, models.HookEventPullRequestSync:
+		return s.PullRequest(p.(*api.PullRequestPayload))
+	case models.HookEventPullRequestReviewApproved, models.HookEventPullRequestReviewRejected, models.HookEventPullRequestReviewComment:
+		return s.Review(p.(*api.PullRequestPayload), event)
+	case models.HookEventRepository:
+		return s.Repository(p.(*api.RepositoryPayload))
+	case models.HookEventRelease:
+		return s.Release(p.(*api.ReleasePayload))
+	}
+	return s, nil
+}