Save and view issue/comment content history (#16909)

* issue content history

* Use timeutil.TimeStampNow() for content history time instead of issue/comment.UpdatedUnix (which are not updated in time)

* i18n for frontend

* refactor

* clean up

* fix refactor

* re-format

* temp refactor

* follow db refactor

* rename IssueContentHistory to ContentHistory, remove empty model tags

* fix html

* use avatar refactor to generate avatar url

* add unit test, keep at most 20 history revisions.

* re-format

* syntax nit

* Add issue content history table

* Update models/migrations/v197.go

Co-authored-by: 6543 <6543@obermui.de>

* fix merge

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lauris BH <lauris@nix.lv>

2 files changed, 214 insertions, 0 deletions

diff --git a/routers/web/repo/issue_content_history.go b/routers/web/repo/issue_content_history.go
new file mode 100644
index 0000000000..c0e958203d
--- /dev/null
+++ b/routers/web/repo/issue_content_history.go
@@ -0,0 +1,206 @@
+// Copyright 2021 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 repo
+
+import (
+	"bytes"
+	"fmt"
+	"html"
+	"net/http"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/models/db"
+	issuesModel "code.gitea.io/gitea/models/issues"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"github.com/sergi/go-diff/diffmatchpatch"
+	"github.com/unknwon/i18n"
+)
+
+// GetContentHistoryOverview get overview
+func GetContentHistoryOverview(ctx *context.Context) {
+	issue := GetActionIssue(ctx)
+	if issue == nil {
+		return
+	}
+
+	lang := ctx.Data["Lang"].(string)
+	editedHistoryCountMap, _ := issuesModel.QueryIssueContentHistoryEditedCountMap(db.DefaultContext, issue.ID)
+	ctx.JSON(http.StatusOK, map[string]interface{}{
+		"i18n": map[string]interface{}{
+			"textEdited":                   i18n.Tr(lang, "repo.issues.content_history.edited"),
+			"textDeleteFromHistory":        i18n.Tr(lang, "repo.issues.content_history.delete_from_history"),
+			"textDeleteFromHistoryConfirm": i18n.Tr(lang, "repo.issues.content_history.delete_from_history_confirm"),
+			"textOptions":                  i18n.Tr(lang, "repo.issues.content_history.options"),
+		},
+		"editedHistoryCountMap": editedHistoryCountMap,
+	})
+}
+
+// GetContentHistoryList  get list
+func GetContentHistoryList(ctx *context.Context) {
+	issue := GetActionIssue(ctx)
+	commentID := ctx.FormInt64("comment_id")
+	if issue == nil {
+		return
+	}
+
+	items, _ := issuesModel.FetchIssueContentHistoryList(db.DefaultContext, issue.ID, commentID)
+
+	// render history list to HTML for frontend dropdown items: (name, value)
+	// name is HTML of "avatar + userName + userAction + timeSince"
+	// value is historyId
+	lang := ctx.Data["Lang"].(string)
+	var results []map[string]interface{}
+	for _, item := range items {
+		var actionText string
+		if item.IsDeleted {
+			actionTextDeleted := i18n.Tr(lang, "repo.issues.content_history.deleted")
+			actionText = "<i data-history-is-deleted='1'>" + actionTextDeleted + "</i>"
+		} else if item.IsFirstCreated {
+			actionText = i18n.Tr(lang, "repo.issues.content_history.created")
+		} else {
+			actionText = i18n.Tr(lang, "repo.issues.content_history.edited")
+		}
+		timeSinceText := timeutil.TimeSinceUnix(item.EditedUnix, lang)
+		results = append(results, map[string]interface{}{
+			"name": fmt.Sprintf("<img class='ui avatar image' src='%s'><strong>%s</strong> %s %s",
+				html.EscapeString(item.UserAvatarLink), html.EscapeString(item.UserName), actionText, timeSinceText),
+			"value": item.HistoryID,
+		})
+	}
+
+	ctx.JSON(http.StatusOK, map[string]interface{}{
+		"results": results,
+	})
+}
+
+// canSoftDeleteContentHistory checks whether current user can soft-delete a history revision
+// Admins or owners can always delete history revisions. Normal users can only delete own history revisions.
+func canSoftDeleteContentHistory(ctx *context.Context, issue *models.Issue, comment *models.Comment,
+	history *issuesModel.ContentHistory) bool {
+
+	canSoftDelete := false
+	if ctx.Repo.IsOwner() {
+		canSoftDelete = true
+	} else if ctx.Repo.CanWrite(models.UnitTypeIssues) {
+		canSoftDelete = ctx.User.ID == history.PosterID
+		if comment == nil {
+			canSoftDelete = canSoftDelete && (ctx.User.ID == issue.PosterID)
+			canSoftDelete = canSoftDelete && (history.IssueID == issue.ID)
+		} else {
+			canSoftDelete = canSoftDelete && (ctx.User.ID == comment.PosterID)
+			canSoftDelete = canSoftDelete && (history.IssueID == issue.ID)
+			canSoftDelete = canSoftDelete && (history.CommentID == comment.ID)
+		}
+	}
+	return canSoftDelete
+}
+
+//GetContentHistoryDetail get detail
+func GetContentHistoryDetail(ctx *context.Context) {
+	issue := GetActionIssue(ctx)
+	if issue == nil {
+		return
+	}
+
+	historyID := ctx.FormInt64("history_id")
+	history, prevHistory, err := issuesModel.GetIssueContentHistoryAndPrev(db.DefaultContext, historyID)
+	if err != nil {
+		ctx.JSON(http.StatusNotFound, map[string]interface{}{
+			"message": "Can not find the content history",
+		})
+		return
+	}
+
+	// get the related comment if this history revision is for a comment, otherwise the history revision is for an issue.
+	var comment *models.Comment
+	if history.CommentID != 0 {
+		var err error
+		if comment, err = models.GetCommentByID(history.CommentID); err != nil {
+			log.Error("can not get comment for issue content history %v. err=%v", historyID, err)
+			return
+		}
+	}
+
+	// get the previous history revision (if exists)
+	var prevHistoryID int64
+	var prevHistoryContentText string
+	if prevHistory != nil {
+		prevHistoryID = prevHistory.ID
+		prevHistoryContentText = prevHistory.ContentText
+	}
+
+	// compare the current history revision with the previous one
+	dmp := diffmatchpatch.New()
+	diff := dmp.DiffMain(prevHistoryContentText, history.ContentText, true)
+	diff = dmp.DiffCleanupEfficiency(diff)
+
+	// use chroma to render the diff html
+	diffHTMLBuf := bytes.Buffer{}
+	diffHTMLBuf.WriteString("<pre class='chroma' style='tab-size: 4'>")
+	for _, it := range diff {
+		if it.Type == diffmatchpatch.DiffInsert {
+			diffHTMLBuf.WriteString("<span class='gi'>")
+			diffHTMLBuf.WriteString(html.EscapeString(it.Text))
+			diffHTMLBuf.WriteString("</span>")
+		} else if it.Type == diffmatchpatch.DiffDelete {
+			diffHTMLBuf.WriteString("<span class='gd'>")
+			diffHTMLBuf.WriteString(html.EscapeString(it.Text))
+			diffHTMLBuf.WriteString("</span>")
+		} else {
+			diffHTMLBuf.WriteString(html.EscapeString(it.Text))
+		}
+	}
+	diffHTMLBuf.WriteString("</pre>")
+
+	ctx.JSON(http.StatusOK, map[string]interface{}{
+		"canSoftDelete": canSoftDeleteContentHistory(ctx, issue, comment, history),
+		"historyId":     historyID,
+		"prevHistoryId": prevHistoryID,
+		"diffHtml":      diffHTMLBuf.String(),
+	})
+}
+
+//SoftDeleteContentHistory soft delete
+func SoftDeleteContentHistory(ctx *context.Context) {
+	issue := GetActionIssue(ctx)
+	if issue == nil {
+		return
+	}
+
+	commentID := ctx.FormInt64("comment_id")
+	historyID := ctx.FormInt64("history_id")
+
+	var comment *models.Comment
+	var history *issuesModel.ContentHistory
+	var err error
+	if commentID != 0 {
+		if comment, err = models.GetCommentByID(commentID); err != nil {
+			log.Error("can not get comment for issue content history %v. err=%v", historyID, err)
+			return
+		}
+	}
+	if history, err = issuesModel.GetIssueContentHistoryByID(db.DefaultContext, historyID); err != nil {
+		log.Error("can not get issue content history %v. err=%v", historyID, err)
+		return
+	}
+
+	canSoftDelete := canSoftDeleteContentHistory(ctx, issue, comment, history)
+	if !canSoftDelete {
+		ctx.JSON(http.StatusForbidden, map[string]interface{}{
+			"message": "Can not delete the content history",
+		})
+		return
+	}
+
+	err = issuesModel.SoftDeleteIssueContentHistory(db.DefaultContext, historyID)
+	log.Debug("soft delete issue content history. issue=%d, comment=%d, history=%d", issue.ID, commentID, historyID)
+	ctx.JSON(http.StatusOK, map[string]interface{}{
+		"ok": err == nil,
+	})
+}
diff --git a/routers/web/web.go b/routers/web/web.go
index b4103ccad3..caec067671 100644
--- a/routers/web/web.go
+++ b/routers/web/web.go
@@ -732,6 +732,9 @@ func RegisterRoutes(m *web.Route) {
 				m.Get("/attachments", repo.GetIssueAttachments)
 				m.Get("/attachments/{uuid}", repo.GetAttachment)
 			})
+			m.Group("/{index}", func() {
+				m.Post("/content-history/soft-delete", repo.SoftDeleteContentHistory)
+			})
 
 			m.Post("/labels", reqRepoIssuesOrPullsWriter, repo.UpdateIssueLabel)
 			m.Post("/milestone", reqRepoIssuesOrPullsWriter, repo.UpdateIssueMilestone)
@@ -853,6 +856,11 @@ func RegisterRoutes(m *web.Route) {
 		m.Group("", func() {
 			m.Get("/{type:issues|pulls}", repo.Issues)
 			m.Get("/{type:issues|pulls}/{index}", repo.ViewIssue)
+			m.Group("/{type:issues|pulls}/{index}/content-history", func() {
+				m.Get("/overview", repo.GetContentHistoryOverview)
+				m.Get("/list", repo.GetContentHistoryList)
+				m.Get("/detail", repo.GetContentHistoryDetail)
+			})
 			m.Get("/labels", reqRepoIssuesOrPullsReader, repo.RetrieveLabels, repo.Labels)
 			m.Get("/milestones", reqRepoIssuesOrPullsReader, repo.Milestones)
 		}, context.RepoRef())