Reference issues from pull requests and other issues (#8137)

* Update ref comment

* Generate comment on simple ref

* Make fmt + remove unneeded repo load

* Add TODO comments

* Add ref-check in issue creation; re-arrange template

* Make unit tests pass; rearrange code

* Make fmt

* Filter out xref comment if user can't see the referencing issue

* Add TODOs

* Add cross reference

* Rearrange code; add cross-repository references

* Striketrhough obsolete references

* Remove unnecesary TODO

* Add "not supported" note

* Support for edits and deletes, and issue title

* Revert changes to go.mod

* Fix fmt

* Add support for xref from API

* Add first integration test

* Add integration tests

* Correct formatting

* Fix add comment test

* Add migration

* Remove outdated comments; fix typo

* Some code refactoring and rearranging

* Rename findCrossReferences to createCrossReferences

* Delete xrefs when repository is deleted

* Corrections as suggested by @lafriks

* Prepare for merge

* Fix log for errors

1 files changed, 308 insertions, 0 deletions

diff --git a/models/issue_xref.go b/models/issue_xref.go
new file mode 100644
index 0000000000..3631bf3246
--- /dev/null
+++ b/models/issue_xref.go
@@ -0,0 +1,308 @@
+// Copyright 2019 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 models
+
+import (
+	"regexp"
+	"strconv"
+
+	"code.gitea.io/gitea/modules/log"
+
+	"github.com/go-xorm/xorm"
+	"github.com/unknwon/com"
+)
+
+var (
+	// TODO: Unify all regexp treatment of cross references in one place
+
+	// issueNumericPattern matches string that references to a numeric issue, e.g. #1287
+	issueNumericPattern = regexp.MustCompile(`(?:\s|^|\(|\[)(?:#)([0-9]+)(?:\s|$|\)|\]|:|\.(\s|$))`)
+	// crossReferenceIssueNumericPattern matches string that references a numeric issue in a different repository
+	// e.g. gogits/gogs#12345
+	crossReferenceIssueNumericPattern = regexp.MustCompile(`(?:\s|^|\(|\[)([0-9a-zA-Z-_\.]+)/([0-9a-zA-Z-_\.]+)#([0-9]+)(?:\s|$|\)|\]|\.(\s|$))`)
+)
+
+// XRefAction represents the kind of effect a cross reference has once is resolved
+type XRefAction int64
+
+const (
+	// XRefActionNone means the cross-reference is a mention (commit, etc.)
+	XRefActionNone XRefAction = iota // 0
+	// XRefActionCloses means the cross-reference should close an issue if it is resolved
+	XRefActionCloses // 1 - not implemented yet
+	// XRefActionReopens means the cross-reference should reopen an issue if it is resolved
+	XRefActionReopens // 2 - Not implemented yet
+	// XRefActionNeutered means the cross-reference will no longer affect the source
+	XRefActionNeutered // 3
+)
+
+type crossReference struct {
+	Issue  *Issue
+	Action XRefAction
+}
+
+// crossReferencesContext is context to pass along findCrossReference functions
+type crossReferencesContext struct {
+	Type        CommentType
+	Doer        *User
+	OrigIssue   *Issue
+	OrigComment *Comment
+}
+
+func newCrossReference(e *xorm.Session, ctx *crossReferencesContext, xref *crossReference) error {
+	var refCommentID int64
+	if ctx.OrigComment != nil {
+		refCommentID = ctx.OrigComment.ID
+	}
+	_, err := createComment(e, &CreateCommentOptions{
+		Type:         ctx.Type,
+		Doer:         ctx.Doer,
+		Repo:         xref.Issue.Repo,
+		Issue:        xref.Issue,
+		RefRepoID:    ctx.OrigIssue.RepoID,
+		RefIssueID:   ctx.OrigIssue.ID,
+		RefCommentID: refCommentID,
+		RefAction:    xref.Action,
+		RefIsPull:    xref.Issue.IsPull,
+	})
+	return err
+}
+
+func neuterCrossReferences(e Engine, issueID int64, commentID int64) error {
+	active := make([]*Comment, 0, 10)
+	sess := e.Where("`ref_action` IN (?, ?, ?)", XRefActionNone, XRefActionCloses, XRefActionReopens)
+	if issueID != 0 {
+		sess = sess.And("`ref_issue_id` = ?", issueID)
+	}
+	if commentID != 0 {
+		sess = sess.And("`ref_comment_id` = ?", commentID)
+	}
+	if err := sess.Find(&active); err != nil || len(active) == 0 {
+		return err
+	}
+	ids := make([]int64, len(active))
+	for i, c := range active {
+		ids[i] = c.ID
+	}
+	_, err := e.In("id", ids).Cols("`ref_action`").Update(&Comment{RefAction: XRefActionNeutered})
+	return err
+}
+
+// .___
+// |   | ______ ________ __   ____
+// |   |/  ___//  ___/  |  \_/ __ \
+// |   |\___ \ \___ \|  |  /\  ___/
+// |___/____  >____  >____/  \___  >
+//          \/     \/            \/
+//
+
+func (issue *Issue) addCrossReferences(e *xorm.Session, doer *User) error {
+	var commentType CommentType
+	if issue.IsPull {
+		commentType = CommentTypePullRef
+	} else {
+		commentType = CommentTypeIssueRef
+	}
+	ctx := &crossReferencesContext{
+		Type:      commentType,
+		Doer:      doer,
+		OrigIssue: issue,
+	}
+	return issue.createCrossReferences(e, ctx, issue.Title+"\n"+issue.Content)
+}
+
+func (issue *Issue) createCrossReferences(e *xorm.Session, ctx *crossReferencesContext, content string) error {
+	xreflist, err := ctx.OrigIssue.getCrossReferences(e, ctx, content)
+	if err != nil {
+		return err
+	}
+	for _, xref := range xreflist {
+		if err = newCrossReference(e, ctx, xref); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (issue *Issue) getCrossReferences(e *xorm.Session, ctx *crossReferencesContext, content string) ([]*crossReference, error) {
+	xreflist := make([]*crossReference, 0, 5)
+	var xref *crossReference
+
+	// Issues in the same repository
+	// FIXME: Should we support IssueNameStyleAlphanumeric?
+	matches := issueNumericPattern.FindAllStringSubmatch(content, -1)
+	for _, match := range matches {
+		if index, err := strconv.ParseInt(match[1], 10, 64); err == nil {
+			if err = ctx.OrigIssue.loadRepo(e); err != nil {
+				return nil, err
+			}
+			if xref, err = ctx.OrigIssue.isValidCommentReference(e, ctx, issue.Repo, index); err != nil {
+				return nil, err
+			}
+			if xref != nil {
+				xreflist = ctx.OrigIssue.updateCrossReferenceList(xreflist, xref)
+			}
+		}
+	}
+
+	// Issues in other repositories
+	matches = crossReferenceIssueNumericPattern.FindAllStringSubmatch(content, -1)
+	for _, match := range matches {
+		if index, err := strconv.ParseInt(match[3], 10, 64); err == nil {
+			repo, err := getRepositoryByOwnerAndName(e, match[1], match[2])
+			if err != nil {
+				if IsErrRepoNotExist(err) {
+					continue
+				}
+				return nil, err
+			}
+			if err = ctx.OrigIssue.loadRepo(e); err != nil {
+				return nil, err
+			}
+			if xref, err = issue.isValidCommentReference(e, ctx, repo, index); err != nil {
+				return nil, err
+			}
+			if xref != nil {
+				xreflist = issue.updateCrossReferenceList(xreflist, xref)
+			}
+		}
+	}
+
+	return xreflist, nil
+}
+
+func (issue *Issue) updateCrossReferenceList(list []*crossReference, xref *crossReference) []*crossReference {
+	if xref.Issue.ID == issue.ID {
+		return list
+	}
+	for i, r := range list {
+		if r.Issue.ID == xref.Issue.ID {
+			if xref.Action != XRefActionNone {
+				list[i].Action = xref.Action
+			}
+			return list
+		}
+	}
+	return append(list, xref)
+}
+
+func (issue *Issue) isValidCommentReference(e Engine, ctx *crossReferencesContext, repo *Repository, index int64) (*crossReference, error) {
+	refIssue := &Issue{RepoID: repo.ID, Index: index}
+	if has, _ := e.Get(refIssue); !has {
+		return nil, nil
+	}
+	if err := refIssue.loadRepo(e); err != nil {
+		return nil, err
+	}
+	// Check user permissions
+	if refIssue.Repo.ID != ctx.OrigIssue.Repo.ID {
+		perm, err := getUserRepoPermission(e, refIssue.Repo, ctx.Doer)
+		if err != nil {
+			return nil, err
+		}
+		if !perm.CanReadIssuesOrPulls(refIssue.IsPull) {
+			return nil, nil
+		}
+	}
+	return &crossReference{
+		Issue:  refIssue,
+		Action: XRefActionNone,
+	}, nil
+}
+
+func (issue *Issue) neuterCrossReferences(e Engine) error {
+	return neuterCrossReferences(e, issue.ID, 0)
+}
+
+// _________                                       __
+// \_   ___ \  ____   _____   _____   ____   _____/  |_
+// /    \  \/ /  _ \ /     \ /     \_/ __ \ /    \   __\
+// \     \___(  <_> )  Y Y  \  Y Y  \  ___/|   |  \  |
+//  \______  /\____/|__|_|  /__|_|  /\___  >___|  /__|
+//         \/             \/      \/     \/     \/
+//
+
+func (comment *Comment) addCrossReferences(e *xorm.Session, doer *User) error {
+	if comment.Type != CommentTypeCode && comment.Type != CommentTypeComment {
+		return nil
+	}
+	if err := comment.loadIssue(e); err != nil {
+		return err
+	}
+	ctx := &crossReferencesContext{
+		Type:        CommentTypeCommentRef,
+		Doer:        doer,
+		OrigIssue:   comment.Issue,
+		OrigComment: comment,
+	}
+	return comment.Issue.createCrossReferences(e, ctx, comment.Content)
+}
+
+func (comment *Comment) neuterCrossReferences(e Engine) error {
+	return neuterCrossReferences(e, 0, comment.ID)
+}
+
+// LoadRefComment loads comment that created this reference from database
+func (comment *Comment) LoadRefComment() (err error) {
+	if comment.RefComment != nil {
+		return nil
+	}
+	comment.RefComment, err = GetCommentByID(comment.RefCommentID)
+	return
+}
+
+// LoadRefIssue loads comment that created this reference from database
+func (comment *Comment) LoadRefIssue() (err error) {
+	if comment.RefIssue != nil {
+		return nil
+	}
+	comment.RefIssue, err = GetIssueByID(comment.RefIssueID)
+	if err == nil {
+		err = comment.RefIssue.loadRepo(x)
+	}
+	return
+}
+
+// CommentTypeIsRef returns true if CommentType is a reference from another issue
+func CommentTypeIsRef(t CommentType) bool {
+	return t == CommentTypeCommentRef || t == CommentTypePullRef || t == CommentTypeIssueRef
+}
+
+// RefCommentHTMLURL returns the HTML URL for the comment that created this reference
+func (comment *Comment) RefCommentHTMLURL() string {
+	if err := comment.LoadRefComment(); err != nil { // Silently dropping errors :unamused:
+		log.Error("LoadRefComment(%d): %v", comment.RefCommentID, err)
+		return ""
+	}
+	return comment.RefComment.HTMLURL()
+}
+
+// RefIssueHTMLURL returns the HTML URL of the issue where this reference was created
+func (comment *Comment) RefIssueHTMLURL() string {
+	if err := comment.LoadRefIssue(); err != nil { // Silently dropping errors :unamused:
+		log.Error("LoadRefIssue(%d): %v", comment.RefCommentID, err)
+		return ""
+	}
+	return comment.RefIssue.HTMLURL()
+}
+
+// RefIssueTitle returns the title of the issue where this reference was created
+func (comment *Comment) RefIssueTitle() string {
+	if err := comment.LoadRefIssue(); err != nil { // Silently dropping errors :unamused:
+		log.Error("LoadRefIssue(%d): %v", comment.RefCommentID, err)
+		return ""
+	}
+	return comment.RefIssue.Title
+}
+
+// RefIssueIdent returns the user friendly identity (e.g. "#1234") of the issue where this reference was created
+func (comment *Comment) RefIssueIdent() string {
+	if err := comment.LoadRefIssue(); err != nil { // Silently dropping errors :unamused:
+		log.Error("LoadRefIssue(%d): %v", comment.RefCommentID, err)
+		return ""
+	}
+	// FIXME: check this name for cross-repository references (#7901 if it gets merged)
+	return "#" + com.ToStr(comment.RefIssue.Index)
+}