PLT-6965 jira integration (plus plugin scaffolding) (#6918)

* plugin scaffolding / jira integration

* add vendored testify packages

* webhook fix

* don't change i18n ids

* support configuration watching

* add basic jira plugin configuration to admin console

* fix eslint errors

* fix another eslint warning

* polish

* undo unintentional config.json commit >:(

* test fix

* add jira plugin diagnostics, remove dm support, add bot tag, generate web-safe secrets

* rebase, implement requested changes

* requested changes

* remove tests and minimize makefile change

* add missing license headers

* add missing comma

* remove bad line from Makefile

app/plugin/jira/webhook.go

@@ -0,0 +1,168 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package jira
+
+import (
+	"bytes"
+	"net/url"
+	"strings"
+	"text/template"
+
+	"github.com/mattermost/platform/model"
+)
+
+type Webhook struct {
+	WebhookEvent string
+	Issue        struct {
+		Self   string
+		Key    string
+		Fields struct {
+			Assignee *struct {
+				DisplayName string
+				Name        string
+			}
+			Summary     string
+			Description string
+			Priority    *struct {
+				Id   string
+				Name string
+			}
+			IssueType struct {
+				Name    string
+				IconURL string
+			}
+			Resolution *struct {
+				Id string
+			}
+			Status struct {
+				Id string
+			}
+		}
+	}
+	User struct {
+		Name        string
+		AvatarUrls  map[string]string
+		DisplayName string
+	}
+	Comment struct {
+		Body string
+	}
+	ChangeLog struct {
+		Items []struct {
+			FromString string
+			ToString   string
+			Field      string
+		}
+	}
+}
+
+// Returns the text to be placed in the resulting post or an empty string if nothing should be
+// posted.
+func (w *Webhook) SlackAttachment() (*model.SlackAttachment, error) {
+	switch w.WebhookEvent {
+	case "jira:issue_created":
+	case "jira:issue_updated":
+		isResolutionChange := false
+		for _, change := range w.ChangeLog.Items {
+			if change.Field == "resolution" {
+				isResolutionChange = (change.FromString == "") != (change.ToString == "")
+				break
+			}
+		}
+		if !isResolutionChange {
+			return nil, nil
+		}
+	case "jira:issue_deleted":
+		if w.Issue.Fields.Resolution != nil {
+			return nil, nil
+		}
+	default:
+		return nil, nil
+	}
+
+	pretext, err := w.renderText("" +
+		"{{.User.DisplayName}} {{.Verb}} {{.Issue.Fields.IssueType.Name}} " +
+		"[{{.Issue.Key}}]({{.JIRAURL}}/browse/{{.Issue.Key}})" +
+		"")
+	if err != nil {
+		return nil, err
+	}
+
+	text, err := w.renderText("" +
+		"[{{.Issue.Fields.Summary}}]({{.JIRAURL}}/browse/{{.Issue.Key}})" +
+		"{{if eq .WebhookEvent \"jira:issue_created\"}}{{if ne .Issue.Fields.Description \"\"}}" +
+		"\n\n{{.Issue.Fields.Description}}" +
+		"{{end}}{{end}}" +
+		"")
+	if err != nil {
+		return nil, err
+	}
+
+	var fields []*model.SlackAttachmentField
+	if w.WebhookEvent == "jira:issue_created" {
+		if w.Issue.Fields.Assignee != nil {
+			fields = append(fields, &model.SlackAttachmentField{
+				Title: "Assignee",
+				Value: w.Issue.Fields.Assignee.DisplayName,
+				Short: true,
+			})
+		}
+		if w.Issue.Fields.Priority != nil {
+			fields = append(fields, &model.SlackAttachmentField{
+				Title: "Priority",
+				Value: w.Issue.Fields.Priority.Name,
+				Short: true,
+			})
+		}
+	}
+
+	return &model.SlackAttachment{
+		Fallback: pretext,
+		Color:    "#95b7d0",
+		Pretext:  pretext,
+		Text:     text,
+		Fields:   fields,
+	}, nil
+}
+
+func (w *Webhook) renderText(tplBody string) (string, error) {
+	issueSelf, err := url.Parse(w.Issue.Self)
+	if err != nil {
+		return "", err
+	}
+	jiraURL := strings.TrimRight(issueSelf.ResolveReference(&url.URL{Path: "/"}).String(), "/")
+	verb := strings.TrimPrefix(w.WebhookEvent, "jira:issue_")
+
+	if w.WebhookEvent == "jira:issue_updated" {
+		for _, change := range w.ChangeLog.Items {
+			if change.Field == "resolution" {
+				if change.ToString == "" && change.FromString != "" {
+					verb = "reopened"
+				} else if change.ToString != "" && change.FromString == "" {
+					verb = "resolved"
+				}
+				break
+			}
+		}
+	}
+
+	tpl, err := template.New("post").Parse(tplBody)
+	if err != nil {
+		return "", err
+	}
+
+	var buf bytes.Buffer
+	if err := tpl.Execute(&buf, struct {
+		*Webhook
+		JIRAURL string
+		Verb    string
+	}{
+		Webhook: w,
+		JIRAURL: jiraURL,
+		Verb:    verb,
+	}); err != nil {
+		return "", err
+	}
+	return buf.String(), nil
+}