Pull request review/approval and comment on code (#3748)

* Initial ui components for pull request review

* Add Review
Add IssueComment types

Signed-off-by: Jonas Franz <info@jonasfranz.software>

(cherry picked from commit 2b4daab)
Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Replace ReviewComment with Content

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add load functions
Add ReviewID to findComments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add create review comment implementation
Add migration for review
Other small changes

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Simplified create and find functions for review

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Moved "Pending" to first position

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add GetCurrentReview to simplify fetching current review

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Preview for listing comments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Move new comment form to its own file

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Implement Review form
Show Review comments on comment stream

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add support for single comments
Showing buttons in context

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add pending tag to pending review comments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add unit tests for Review

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fetch all review ids at once
Add unit tests

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* gofmt

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Improved comment rendering in "Files" view by adding Comments to DiffLine

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add support for invalidating comments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Switched back to code.gitea.io/git

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Moved review migration from v64 to v65

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Rebuild css

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* gofmt

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Improve translations

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix unit tests by updating fixtures and updating outdated test

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Comments will be shown at the right place now

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add support for deleting CodeComments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix problems caused by files in subdirectories

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add support for showing code comments of reviews in conversation

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add support for "Show/Hide outdated"

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update code.gitea.io/git

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add support for new webhooks

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update comparison

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Resolve conflicts

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Minor UI improvements

* update code.gitea.io/git

* Fix ui bug reported by @lunny causing wrong position of add button
Add functionality to "Cancel" button
Add scale effects to add button
Hide "Cancel" button for existing comments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Prepare solving conflicts

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Show add button only if no comments already exist for the line

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add missing vendor files

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Check if reviewer is nil

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Show forms only to users who are logged in

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Revert "Show forms only to users who are logged in"

This reverts commit c083682

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Save patch in comment
Render patch for code comments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add link to comment in code

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add reply form to comment list
Show forms only to signed in users

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add 'Reply' as translatable
Add CODE_COMMENT_LINES setting

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* gofmt

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix problems introduced by checking for singed in user

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add v70

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update generated stylesheet

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix preview
Beginn with new review comment patch system

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add new algo to generate diff for line range
Remove old algo used for cutting big diffs (it was very buggy)

* Add documentation and example for CutDiffAroundLine

* Fix example of CutDiffAroundLine

* Fix some comment UI rendering bugs

* Add code comment edit mode

* Send notifications / actions to users until review gets published
Fix diff generation bug
Fix wrong hashtag

* Fix vet errors

* Send notifications also for single comments

* Fix some notification bugs, fix link

* Fix: add comment icon is only shown on code lines

* Add lint comment

* Add unit tests for git diff

* Add more error messages

* Regenerated css

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* fmt

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Regenerated CSS with latest less version

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix test by updating comment type to new ID

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Introducing CodeComments as type for map[string]map[int64][]*Comment
Other minor code improvements

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix data-tab issues

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Remove unnecessary change

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* refactored checkForInvalidation

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Append comments instead of setting

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Use HeadRepo instead of BaseRepo

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update migration

Signed-off-by: Jonas Franz <info@jonasfranz.de>

* Regenerated CSS

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add copyright

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update index.css

Signed-off-by: Jonas Franz <info@jonasfranz.software>

13 files changed, 1131 insertions, 35 deletions

diff --git a/models/error.go b/models/error.go
index 029c33aba4..b079f06d84 100644
--- a/models/error.go
+++ b/models/error.go
@@ -1344,3 +1344,25 @@ func IsErrUnknownDependencyType(err error) bool {
 func (err ErrUnknownDependencyType) Error() string {
 	return fmt.Sprintf("unknown dependency type [type: %d]", err.Type)
 }
+
+//  __________            .__
+//  \______   \ _______  _|__| ______  _  __
+//  |       _// __ \  \/ /  |/ __ \ \/ \/ /
+//  |    |   \  ___/\   /|  \  ___/\     /
+//  |____|_  /\___  >\_/ |__|\___  >\/\_/
+//  \/     \/             \/
+
+// ErrReviewNotExist represents a "ReviewNotExist" kind of error.
+type ErrReviewNotExist struct {
+	ID int64
+}
+
+// IsErrReviewNotExist checks if an error is a ErrReviewNotExist.
+func IsErrReviewNotExist(err error) bool {
+	_, ok := err.(ErrReviewNotExist)
+	return ok
+}
+
+func (err ErrReviewNotExist) Error() string {
+	return fmt.Sprintf("review does not exist [id: %d]", err.ID)
+}
diff --git a/models/fixtures/comment.yml b/models/fixtures/comment.yml
index 34df02d28c..6d4812f096 100644
--- a/models/fixtures/comment.yml
+++ b/models/fixtures/comment.yml
@@ -20,3 +20,24 @@
   issue_id: 1 # in repo_id 1
   content: "meh..."
   created_unix: 946684812
+-
+  id: 4
+  type: 21 # code comment
+  poster_id: 1
+  issue_id: 2
+  content: "meh..."
+  review_id: 4
+  line: 4
+  tree_path: "README.md"
+  created_unix: 946684812
+  invalidated: false
+-
+  id: 5
+  type: 21 # code comment
+  poster_id: 1
+  issue_id: 2
+  content: "meh..."
+  line: -4
+  tree_path: "README.md"
+  created_unix: 946684812
+  invalidated: false
diff --git a/models/fixtures/review.yml b/models/fixtures/review.yml
new file mode 100644
index 0000000000..17defd1b3a
--- /dev/null
+++ b/models/fixtures/review.yml
@@ -0,0 +1,32 @@
+-
+  id: 1
+  type: 1
+  reviewer_id: 1
+  issue_id: 2
+  content: "Demo Review"
+  updated_unix: 946684810
+  created_unix: 946684810
+-
+  id: 2
+  type: 1
+  reviewer_id: 534543
+  issue_id: 534543
+  content: "Invalid Review #1"
+  updated_unix: 946684810
+  created_unix: 946684810
+-
+  id: 3
+  type: 1
+  reviewer_id: 1
+  issue_id: 343545
+  content: "Invalid Review #2"
+  updated_unix: 946684810
+  created_unix: 946684810
+-
+  id: 4
+  type: 0 # Pending review
+  reviewer_id: 1
+  issue_id: 2
+  content: "Pending Review"
+  updated_unix: 946684810
+  created_unix: 946684810
diff --git a/models/git_diff.go b/models/git_diff.go
index 7b0b672ff1..006238cd06 100644
--- a/models/git_diff.go
+++ b/models/git_diff.go
@@ -14,6 +14,8 @@ import (
 	"io/ioutil"
 	"os"
 	"os/exec"
+	"regexp"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -57,6 +59,7 @@ type DiffLine struct {
 	RightIdx int
 	Type     DiffLineType
 	Content  string
+	Comments []*Comment
 }
 
 // GetType returns the type of a DiffLine.
@@ -64,6 +67,19 @@ func (d *DiffLine) GetType() int {
 	return int(d.Type)
 }
 
+// CanComment returns whether or not a line can get commented
+func (d *DiffLine) CanComment() bool {
+	return len(d.Comments) == 0 && d.Type != DiffLineSection
+}
+
+// GetCommentSide returns the comment side of the first comment, if not set returns empty string
+func (d *DiffLine) GetCommentSide() string {
+	if len(d.Comments) == 0 {
+		return ""
+	}
+	return d.Comments[0].DiffSide()
+}
+
 // DiffSection represents a section of a DiffFile.
 type DiffSection struct {
 	Name  string
@@ -225,11 +241,167 @@ type Diff struct {
 	IsIncomplete                 bool
 }
 
+// LoadComments loads comments into each line
+func (diff *Diff) LoadComments(issue *Issue, currentUser *User) error {
+	allComments, err := FetchCodeComments(issue, currentUser)
+	if err != nil {
+		return err
+	}
+	for _, file := range diff.Files {
+		if lineCommits, ok := allComments[file.Name]; ok {
+			for _, section := range file.Sections {
+				for _, line := range section.Lines {
+					if comments, ok := lineCommits[int64(line.LeftIdx*-1)]; ok {
+						line.Comments = append(line.Comments, comments...)
+					}
+					if comments, ok := lineCommits[int64(line.RightIdx)]; ok {
+						line.Comments = append(line.Comments, comments...)
+					}
+					sort.SliceStable(line.Comments, func(i, j int) bool {
+						return line.Comments[i].CreatedUnix < line.Comments[j].CreatedUnix
+					})
+				}
+			}
+		}
+	}
+	return nil
+}
+
 // NumFiles returns number of files changes in a diff.
 func (diff *Diff) NumFiles() int {
 	return len(diff.Files)
 }
 
+// Example: @@ -1,8 +1,9 @@ => [..., 1, 8, 1, 9]
+var hunkRegex = regexp.MustCompile(`^@@ -([0-9]+),([0-9]+) \+([0-9]+),([0-9]+) @@`)
+
+func isHeader(lof string) bool {
+	return strings.HasPrefix(lof, cmdDiffHead) || strings.HasPrefix(lof, "---") || strings.HasPrefix(lof, "+++")
+}
+
+// CutDiffAroundLine cuts a diff of a file in way that only the given line + numberOfLine above it will be shown
+// it also recalculates hunks and adds the appropriate headers to the new diff.
+// Warning: Only one-file diffs are allowed.
+func CutDiffAroundLine(originalDiff io.Reader, line int64, old bool, numbersOfLine int) string {
+	if line == 0 || numbersOfLine == 0 {
+		// no line or num of lines => no diff
+		return ""
+	}
+	scanner := bufio.NewScanner(originalDiff)
+	hunk := make([]string, 0)
+	// begin is the start of the hunk containing searched line
+	// end is the end of the hunk ...
+	// currentLine is the line number on the side of the searched line (differentiated by old)
+	// otherLine is the line number on the opposite side of the searched line (differentiated by old)
+	var begin, end, currentLine, otherLine int64
+	var headerLines int
+	for scanner.Scan() {
+		lof := scanner.Text()
+		// Add header to enable parsing
+		if isHeader(lof) {
+			hunk = append(hunk, lof)
+			headerLines++
+		}
+		if currentLine > line {
+			break
+		}
+		// Detect "hunk" with contains commented lof
+		if strings.HasPrefix(lof, "@@") {
+			// Already got our hunk. End of hunk detected!
+			if len(hunk) > headerLines {
+				break
+			}
+			groups := hunkRegex.FindStringSubmatch(lof)
+			if old {
+				begin = com.StrTo(groups[1]).MustInt64()
+				end = com.StrTo(groups[2]).MustInt64()
+				// init otherLine with begin of opposite side
+				otherLine = com.StrTo(groups[3]).MustInt64()
+			} else {
+				begin = com.StrTo(groups[3]).MustInt64()
+				end = com.StrTo(groups[4]).MustInt64()
+				// init otherLine with begin of opposite side
+				otherLine = com.StrTo(groups[1]).MustInt64()
+			}
+			end += begin // end is for real only the number of lines in hunk
+			// lof is between begin and end
+			if begin <= line && end >= line {
+				hunk = append(hunk, lof)
+				currentLine = begin
+				continue
+			}
+		} else if len(hunk) > headerLines {
+			hunk = append(hunk, lof)
+			// Count lines in context
+			switch lof[0] {
+			case '+':
+				if !old {
+					currentLine++
+				} else {
+					otherLine++
+				}
+			case '-':
+				if old {
+					currentLine++
+				} else {
+					otherLine++
+				}
+			default:
+				currentLine++
+				otherLine++
+			}
+		}
+	}
+
+	// No hunk found
+	if currentLine == 0 {
+		return ""
+	}
+	// headerLines + hunkLine (1) = totalNonCodeLines
+	if len(hunk)-headerLines-1 <= numbersOfLine {
+		// No need to cut the hunk => return existing hunk
+		return strings.Join(hunk, "\n")
+	}
+	var oldBegin, oldNumOfLines, newBegin, newNumOfLines int64
+	if old {
+		oldBegin = currentLine
+		newBegin = otherLine
+	} else {
+		oldBegin = otherLine
+		newBegin = currentLine
+	}
+	// headers + hunk header
+	newHunk := make([]string, headerLines)
+	// transfer existing headers
+	for idx, lof := range hunk[:headerLines] {
+		newHunk[idx] = lof
+	}
+	// transfer last n lines
+	for _, lof := range hunk[len(hunk)-numbersOfLine-1:] {
+		newHunk = append(newHunk, lof)
+	}
+	// calculate newBegin, ... by counting lines
+	for i := len(hunk) - 1; i >= len(hunk)-numbersOfLine; i-- {
+		switch hunk[i][0] {
+		case '+':
+			newBegin--
+			newNumOfLines++
+		case '-':
+			oldBegin--
+			oldNumOfLines++
+		default:
+			oldBegin--
+			newBegin--
+			newNumOfLines++
+			oldNumOfLines++
+		}
+	}
+	// construct the new hunk header
+	newHunk[headerLines] = fmt.Sprintf("@@ -%d,%d +%d,%d @@",
+		oldBegin, oldNumOfLines, newBegin, newNumOfLines)
+	return strings.Join(newHunk, "\n")
+}
+
 const cmdDiffHead = "diff --git "
 
 // ParsePatch builds a Diff object from a io.Reader and some
@@ -307,7 +479,6 @@ func ParsePatch(maxLines, maxLineCharacters, maxFiles int, reader io.Reader) (*D
 		if curFileLinesCount >= maxLines {
 			curFile.IsIncomplete = true
 		}
-
 		switch {
 		case line[0] == ' ':
 			diffLine := &DiffLine{Type: DiffLinePlain, Content: line, LeftIdx: leftLine, RightIdx: rightLine}
@@ -524,32 +695,46 @@ const (
 // GetRawDiff dumps diff results of repository in given commit ID to io.Writer.
 // TODO: move this function to gogits/git-module
 func GetRawDiff(repoPath, commitID string, diffType RawDiffType, writer io.Writer) error {
+	return GetRawDiffForFile(repoPath, "", commitID, diffType, "", writer)
+}
+
+// GetRawDiffForFile dumps diff results of file in given commit ID to io.Writer.
+// TODO: move this function to gogits/git-module
+func GetRawDiffForFile(repoPath, startCommit, endCommit string, diffType RawDiffType, file string, writer io.Writer) error {
 	repo, err := git.OpenRepository(repoPath)
 	if err != nil {
 		return fmt.Errorf("OpenRepository: %v", err)
 	}
 
-	commit, err := repo.GetCommit(commitID)
+	commit, err := repo.GetCommit(endCommit)
 	if err != nil {
 		return fmt.Errorf("GetCommit: %v", err)
 	}
-
+	fileArgs := make([]string, 0)
+	if len(file) > 0 {
+		fileArgs = append(fileArgs, "--", file)
+	}
 	var cmd *exec.Cmd
 	switch diffType {
 	case RawDiffNormal:
-		if commit.ParentCount() == 0 {
-			cmd = exec.Command("git", "show", commitID)
+		if len(startCommit) != 0 {
+			cmd = exec.Command("git", append([]string{"diff", "-M", startCommit, endCommit}, fileArgs...)...)
+		} else if commit.ParentCount() == 0 {
+			cmd = exec.Command("git", append([]string{"show", endCommit}, fileArgs...)...)
 		} else {
 			c, _ := commit.Parent(0)
-			cmd = exec.Command("git", "diff", "-M", c.ID.String(), commitID)
+			cmd = exec.Command("git", append([]string{"diff", "-M", c.ID.String(), endCommit}, fileArgs...)...)
 		}
 	case RawDiffPatch:
-		if commit.ParentCount() == 0 {
-			cmd = exec.Command("git", "format-patch", "--no-signature", "--stdout", "--root", commitID)
+		if len(startCommit) != 0 {
+			query := fmt.Sprintf("%s...%s", endCommit, startCommit)
+			cmd = exec.Command("git", append([]string{"format-patch", "--no-signature", "--stdout", "--root", query}, fileArgs...)...)
+		} else if commit.ParentCount() == 0 {
+			cmd = exec.Command("git", append([]string{"format-patch", "--no-signature", "--stdout", "--root", endCommit}, fileArgs...)...)
 		} else {
 			c, _ := commit.Parent(0)
-			query := fmt.Sprintf("%s...%s", commitID, c.ID.String())
-			cmd = exec.Command("git", "format-patch", "--no-signature", "--stdout", query)
+			query := fmt.Sprintf("%s...%s", endCommit, c.ID.String())
+			cmd = exec.Command("git", append([]string{"format-patch", "--no-signature", "--stdout", query}, fileArgs...)...)
 		}
 	default:
 		return fmt.Errorf("invalid diffType: %s", diffType)
@@ -560,7 +745,6 @@ func GetRawDiff(repoPath, commitID string, diffType RawDiffType, writer io.Write
 	cmd.Dir = repoPath
 	cmd.Stdout = writer
 	cmd.Stderr = stderr
-
 	if err = cmd.Run(); err != nil {
 		return fmt.Errorf("Run: %v - %s", err, stderr)
 	}
diff --git a/models/git_diff_test.go b/models/git_diff_test.go
index a29830c7fa..ac64771226 100644
--- a/models/git_diff_test.go
+++ b/models/git_diff_test.go
@@ -2,9 +2,11 @@ package models
 
 import (
 	"html/template"
+	"strings"
 	"testing"
 
 	dmp "github.com/sergi/go-diff/diffmatchpatch"
+	"github.com/stretchr/testify/assert"
 )
 
 func assertEqual(t *testing.T, s1 string, s2 template.HTML) {
@@ -34,3 +36,106 @@ func TestDiffToHTML(t *testing.T) {
 		{Type: dmp.DiffEqual, Text: " biz"},
 	}, DiffLineDel))
 }
+
+const exampleDiff = `diff --git a/README.md b/README.md
+--- a/README.md
++++ b/README.md
+@@ -1,3 +1,6 @@
+ # gitea-github-migrator
++
++ Build Status
+- Latest Release
+ Docker Pulls
++ cut off
++ cut off`
+
+func TestCutDiffAroundLine(t *testing.T) {
+	result := CutDiffAroundLine(strings.NewReader(exampleDiff), 4, false, 3)
+	resultByLine := strings.Split(result, "\n")
+	assert.Len(t, resultByLine, 7)
+	// Check if headers got transferred
+	assert.Equal(t, "diff --git a/README.md b/README.md", resultByLine[0])
+	assert.Equal(t, "--- a/README.md", resultByLine[1])
+	assert.Equal(t, "+++ b/README.md", resultByLine[2])
+	// Check if hunk header is calculated correctly
+	assert.Equal(t, "@@ -2,2 +3,2 @@", resultByLine[3])
+	// Check if line got transferred
+	assert.Equal(t, "+ Build Status", resultByLine[4])
+
+	// Must be same result as before since old line 3 == new line 5
+	newResult := CutDiffAroundLine(strings.NewReader(exampleDiff), 3, true, 3)
+	assert.Equal(t, result, newResult, "Must be same result as before since old line 3 == new line 5")
+
+	newResult = CutDiffAroundLine(strings.NewReader(exampleDiff), 6, false, 300)
+	assert.Equal(t, exampleDiff, newResult)
+
+	emptyResult := CutDiffAroundLine(strings.NewReader(exampleDiff), 6, false, 0)
+	assert.Empty(t, emptyResult)
+
+	// Line is out of scope
+	emptyResult = CutDiffAroundLine(strings.NewReader(exampleDiff), 434, false, 0)
+	assert.Empty(t, emptyResult)
+}
+
+func BenchmarkCutDiffAroundLine(b *testing.B) {
+	for n := 0; n < b.N; n++ {
+		CutDiffAroundLine(strings.NewReader(exampleDiff), 3, true, 3)
+	}
+}
+
+func ExampleCutDiffAroundLine() {
+	const diff = `diff --git a/README.md b/README.md
+--- a/README.md
++++ b/README.md
+@@ -1,3 +1,6 @@
+ # gitea-github-migrator
++
++ Build Status
+- Latest Release
+ Docker Pulls
++ cut off
++ cut off`
+	result := CutDiffAroundLine(strings.NewReader(diff), 4, false, 3)
+	println(result)
+}
+
+func setupDefaultDiff() *Diff {
+	return &Diff{
+		Files: []*DiffFile{
+			{
+				Name: "README.md",
+				Sections: []*DiffSection{
+					{
+						Lines: []*DiffLine{
+							{
+								LeftIdx:  4,
+								RightIdx: 4,
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+}
+func TestDiff_LoadComments(t *testing.T) {
+	issue := AssertExistsAndLoadBean(t, &Issue{ID: 2}).(*Issue)
+	user := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+	diff := setupDefaultDiff()
+	assert.NoError(t, PrepareTestDatabase())
+	assert.NoError(t, diff.LoadComments(issue, user))
+	assert.Len(t, diff.Files[0].Sections[0].Lines[0].Comments, 2)
+}
+
+func TestDiffLine_CanComment(t *testing.T) {
+	assert.False(t, (&DiffLine{Type: DiffLineSection}).CanComment())
+	assert.False(t, (&DiffLine{Type: DiffLineAdd, Comments: []*Comment{{Content: "bla"}}}).CanComment())
+	assert.True(t, (&DiffLine{Type: DiffLineAdd}).CanComment())
+	assert.True(t, (&DiffLine{Type: DiffLineDel}).CanComment())
+	assert.True(t, (&DiffLine{Type: DiffLinePlain}).CanComment())
+}
+
+func TestDiffLine_GetCommentSide(t *testing.T) {
+	assert.Equal(t, "previous", (&DiffLine{Comments: []*Comment{{Line: -3}}}).GetCommentSide())
+	assert.Equal(t, "proposed", (&DiffLine{Comments: []*Comment{{Line: 3}}}).GetCommentSide())
+}
diff --git a/models/issue_comment.go b/models/issue_comment.go
index ad276e61f9..8cbd9613a0 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -1,13 +1,19 @@
-// Copyright 2016 The Gogs Authors. All rights reserved.
+// Copyright 2018 The Gitea Authors.
+// Copyright 2016 The Gogs 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 (
+	"bytes"
 	"fmt"
 	"strings"
 
+	"code.gitea.io/git"
+	"code.gitea.io/gitea/modules/markup/markdown"
+	"code.gitea.io/gitea/modules/setting"
 	"github.com/Unknwon/com"
 	"github.com/go-xorm/builder"
 	"github.com/go-xorm/xorm"
@@ -70,6 +76,10 @@ const (
 	CommentTypeAddDependency
 	//Dependency removed
 	CommentTypeRemoveDependency
+	// Comment a line of code
+	CommentTypeCode
+	// Reviews a pull request by giving general feedback
+	CommentTypeReview
 )
 
 // CommentTag defines comment tag type
@@ -106,10 +116,14 @@ type Comment struct {
 	DependentIssue   *Issue `xorm:"-"`
 
 	CommitID        int64
-	Line            int64
+	Line            int64 // - previous line / + proposed line
+	TreePath        string
 	Content         string `xorm:"TEXT"`
 	RenderedContent string `xorm:"-"`
 
+	// Path represents the 4 lines of code cemented by this comment
+	Patch string `xorm:"TEXT"`
+
 	CreatedUnix util.TimeStamp `xorm:"INDEX created"`
 	UpdatedUnix util.TimeStamp `xorm:"INDEX updated"`
 
@@ -121,6 +135,10 @@ type Comment struct {
 
 	// For view issue page.
 	ShowTag CommentTag `xorm:"-"`
+
+	Review      *Review `xorm:"-"`
+	ReviewID    int64
+	Invalidated bool
 }
 
 // LoadIssue loads issue from database
@@ -171,6 +189,20 @@ func (c *Comment) HTMLURL() string {
 		log.Error(4, "LoadIssue(%d): %v", c.IssueID, err)
 		return ""
 	}
+	if c.Type == CommentTypeCode {
+		if c.ReviewID == 0 {
+			return fmt.Sprintf("%s/files#%s", c.Issue.HTMLURL(), c.HashTag())
+		}
+		if c.Review == nil {
+			if err := c.LoadReview(); err != nil {
+				log.Warn("LoadReview(%d): %v", c.ReviewID, err)
+				return fmt.Sprintf("%s/files#%s", c.Issue.HTMLURL(), c.HashTag())
+			}
+		}
+		if c.Review.Type <= ReviewTypePending {
+			return fmt.Sprintf("%s/files#%s", c.Issue.HTMLURL(), c.HashTag())
+		}
+	}
 	return fmt.Sprintf("%s#%s", c.Issue.HTMLURL(), c.HashTag())
 }
 
@@ -342,6 +374,89 @@ func (c *Comment) LoadReactions() error {
 	return c.loadReactions(x)
 }
 
+func (c *Comment) loadReview(e Engine) (err error) {
+	if c.Review, err = getReviewByID(e, c.ReviewID); err != nil {
+		return err
+	}
+	return nil
+}
+
+// LoadReview loads the associated review
+func (c *Comment) LoadReview() error {
+	return c.loadReview(x)
+}
+
+func (c *Comment) checkInvalidation(e Engine, doer *User, repo *git.Repository, branch string) error {
+	// FIXME differentiate between previous and proposed line
+	commit, err := repo.LineBlame(branch, repo.Path, c.TreePath, uint(c.UnsignedLine()))
+	if err != nil {
+		return err
+	}
+	if c.CommitSHA != commit.ID.String() {
+		c.Invalidated = true
+		return UpdateComment(doer, c, "")
+	}
+	return nil
+}
+
+// CheckInvalidation checks if the line of code comment got changed by another commit.
+// If the line got changed the comment is going to be invalidated.
+func (c *Comment) CheckInvalidation(repo *git.Repository, doer *User, branch string) error {
+	return c.checkInvalidation(x, doer, repo, branch)
+}
+
+// DiffSide returns "previous" if Comment.Line is a LOC of the previous changes and "proposed" if it is a LOC of the proposed changes.
+func (c *Comment) DiffSide() string {
+	if c.Line < 0 {
+		return "previous"
+	}
+	return "proposed"
+}
+
+// UnsignedLine returns the LOC of the code comment without + or -
+func (c *Comment) UnsignedLine() uint64 {
+	if c.Line < 0 {
+		return uint64(c.Line * -1)
+	}
+	return uint64(c.Line)
+}
+
+// AsDiff returns c.Patch as *Diff
+func (c *Comment) AsDiff() (*Diff, error) {
+	diff, err := ParsePatch(setting.Git.MaxGitDiffLines,
+		setting.Git.MaxGitDiffLineCharacters, setting.Git.MaxGitDiffFiles, strings.NewReader(c.Patch))
+	if err != nil {
+		return nil, err
+	}
+	if len(diff.Files) == 0 {
+		return nil, fmt.Errorf("no file found for comment ID: %d", c.ID)
+	}
+	secs := diff.Files[0].Sections
+	if len(secs) == 0 {
+		return nil, fmt.Errorf("no sections found for comment ID: %d", c.ID)
+	}
+	return diff, nil
+}
+
+// MustAsDiff executes AsDiff and logs the error instead of returning
+func (c *Comment) MustAsDiff() *Diff {
+	diff, err := c.AsDiff()
+	if err != nil {
+		log.Warn("MustAsDiff: %v", err)
+	}
+	return diff
+}
+
+// CodeCommentURL returns the url to a comment in code
+func (c *Comment) CodeCommentURL() string {
+	err := c.LoadIssue()
+	if err != nil { // Silently dropping errors :unamused:
+		log.Error(4, "LoadIssue(%d): %v", c.IssueID, err)
+		return ""
+	}
+	return fmt.Sprintf("%s/files#%s", c.Issue.HTMLURL(), c.HashTag())
+}
+
 func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err error) {
 	var LabelID int64
 	if opts.Label != nil {
@@ -365,6 +480,9 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 		OldTitle:         opts.OldTitle,
 		NewTitle:         opts.NewTitle,
 		DependentIssueID: opts.DependentIssueID,
+		TreePath:         opts.TreePath,
+		ReviewID:         opts.ReviewID,
+		Patch:            opts.Patch,
 	}
 	if _, err = e.Insert(comment); err != nil {
 		return nil, err
@@ -374,6 +492,14 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 		return nil, err
 	}
 
+	if err = sendCreateCommentAction(e, opts, comment); err != nil {
+		return nil, err
+	}
+
+	return comment, nil
+}
+
+func sendCreateCommentAction(e *xorm.Session, opts *CreateCommentOptions, comment *Comment) (err error) {
 	// Compose comment action, could be plain comment, close or reopen issue/pull request.
 	// This object will be used to notify watchers in the end of function.
 	act := &Action{
@@ -386,14 +512,25 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 		CommentID: comment.ID,
 		IsPrivate: opts.Repo.IsPrivate,
 	}
-
 	// Check comment type.
 	switch opts.Type {
+	case CommentTypeCode:
+		if comment.ReviewID != 0 {
+			if comment.Review == nil {
+				if err := comment.LoadReview(); err != nil {
+					return err
+				}
+			}
+			if comment.Review.Type <= ReviewTypePending {
+				return nil
+			}
+		}
+		fallthrough
 	case CommentTypeComment:
 		act.OpType = ActionCommentIssue
 
 		if _, err = e.Exec("UPDATE `issue` SET num_comments=num_comments+1 WHERE id=?", opts.Issue.ID); err != nil {
-			return nil, err
+			return err
 		}
 
 		// Check attachments
@@ -404,7 +541,7 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 				if IsErrAttachmentNotExist(err) {
 					continue
 				}
-				return nil, fmt.Errorf("getAttachmentByUUID [%s]: %v", uuid, err)
+				return fmt.Errorf("getAttachmentByUUID [%s]: %v", uuid, err)
 			}
 			attachments = append(attachments, attach)
 		}
@@ -414,7 +551,7 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 			attachments[i].CommentID = comment.ID
 			// No assign value could be 0, so ignore AllCols().
 			if _, err = e.ID(attachments[i].ID).Update(attachments[i]); err != nil {
-				return nil, fmt.Errorf("update attachment [%d]: %v", attachments[i].ID, err)
+				return fmt.Errorf("update attachment [%d]: %v", attachments[i].ID, err)
 			}
 		}
 
@@ -430,7 +567,7 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 			_, err = e.Exec("UPDATE `repository` SET num_closed_issues=num_closed_issues-1 WHERE id=?", opts.Repo.ID)
 		}
 		if err != nil {
-			return nil, err
+			return err
 		}
 
 	case CommentTypeClose:
@@ -445,15 +582,13 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 			_, err = e.Exec("UPDATE `repository` SET num_closed_issues=num_closed_issues+1 WHERE id=?", opts.Repo.ID)
 		}
 		if err != nil {
-			return nil, err
+			return err
 		}
 	}
-
 	// update the issue's updated_unix column
 	if err = updateIssueCols(e, opts.Issue, "updated_unix"); err != nil {
-		return nil, err
+		return err
 	}
-
 	// Notify watchers for whatever action comes in, ignore if no action type.
 	if act.OpType > 0 {
 		if err = notifyWatchers(e, act); err != nil {
@@ -463,8 +598,7 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 			log.Error(4, "MailParticipants: %v", err)
 		}
 	}
-
-	return comment, nil
+	return nil
 }
 
 func createStatusComment(e *xorm.Session, doer *User, repo *Repository, issue *Issue) (*Comment, error) {
@@ -616,7 +750,10 @@ type CreateCommentOptions struct {
 	NewTitle         string
 	CommitID         int64
 	CommitSHA        string
+	Patch            string
 	LineNum          int64
+	TreePath         string
+	ReviewID         int64
 	Content          string
 	Attachments      []string // UUIDs of attachments
 }
@@ -673,6 +810,58 @@ func CreateIssueComment(doer *User, repo *Repository, issue *Issue, content stri
 	return comment, nil
 }
 
+// CreateCodeComment creates a plain code comment at the specified line / path
+func CreateCodeComment(doer *User, repo *Repository, issue *Issue, content, treePath string, line, reviewID int64) (*Comment, error) {
+	var commitID, patch string
+	pr, err := GetPullRequestByIssueID(issue.ID)
+	if err != nil {
+		return nil, fmt.Errorf("GetPullRequestByIssueID: %v", err)
+	}
+	if err := pr.GetBaseRepo(); err != nil {
+		return nil, fmt.Errorf("GetHeadRepo: %v", err)
+	}
+	gitRepo, err := git.OpenRepository(pr.BaseRepo.RepoPath())
+	if err != nil {
+		return nil, fmt.Errorf("OpenRepository: %v", err)
+	}
+	// FIXME differentiate between previous and proposed line
+	var gitLine = line
+	if gitLine < 0 {
+		gitLine *= -1
+	}
+	// FIXME validate treePath
+	// Get latest commit referencing the commented line
+	commit, err := gitRepo.LineBlame(pr.GetGitRefName(), gitRepo.Path, treePath, uint(gitLine))
+	if err != nil {
+		return nil, fmt.Errorf("LineBlame[%s, %s, %s, %d]: %v", pr.GetGitRefName(), gitRepo.Path, treePath, gitLine, err)
+	}
+	// Only fetch diff if comment is review comment
+	if reviewID != 0 {
+		headCommitID, err := gitRepo.GetRefCommitID(pr.GetGitRefName())
+		if err != nil {
+			return nil, fmt.Errorf("GetRefCommitID[%s]: %v", pr.GetGitRefName(), err)
+		}
+		patchBuf := new(bytes.Buffer)
+		if err := GetRawDiffForFile(gitRepo.Path, pr.MergeBase, headCommitID, RawDiffNormal, treePath, patchBuf); err != nil {
+			return nil, fmt.Errorf("GetRawDiffForLine[%s, %s, %s, %s]: %v", err, gitRepo.Path, pr.MergeBase, headCommitID, treePath)
+		}
+		patch = CutDiffAroundLine(strings.NewReader(patchBuf.String()), int64((&Comment{Line: line}).UnsignedLine()), line < 0, setting.UI.CodeCommentLines)
+		commitID = commit.ID.String()
+	}
+	return CreateComment(&CreateCommentOptions{
+		Type:      CommentTypeCode,
+		Doer:      doer,
+		Repo:      repo,
+		Issue:     issue,
+		Content:   content,
+		LineNum:   line,
+		TreePath:  treePath,
+		CommitSHA: commitID,
+		ReviewID:  reviewID,
+		Patch:     patch,
+	})
+}
+
 // CreateRefComment creates a commit reference comment to issue.
 func CreateRefComment(doer *User, repo *Repository, issue *Issue, content, commitSHA string) error {
 	if len(commitSHA) == 0 {
@@ -716,10 +905,11 @@ func GetCommentByID(id int64) (*Comment, error) {
 
 // FindCommentsOptions describes the conditions to Find comments
 type FindCommentsOptions struct {
-	RepoID  int64
-	IssueID int64
-	Since   int64
-	Type    CommentType
+	RepoID   int64
+	IssueID  int64
+	ReviewID int64
+	Since    int64
+	Type     CommentType
 }
 
 func (opts *FindCommentsOptions) toConds() builder.Cond {
@@ -730,6 +920,9 @@ func (opts *FindCommentsOptions) toConds() builder.Cond {
 	if opts.IssueID > 0 {
 		cond = cond.And(builder.Eq{"comment.issue_id": opts.IssueID})
 	}
+	if opts.ReviewID > 0 {
+		cond = cond.And(builder.Eq{"comment.review_id": opts.ReviewID})
+	}
 	if opts.Since > 0 {
 		cond = cond.And(builder.Gte{"comment.updated_unix": opts.Since})
 	}
@@ -870,3 +1063,75 @@ func DeleteComment(doer *User, comment *Comment) error {
 
 	return nil
 }
+
+// CodeComments represents comments on code by using this structure: FILENAME -> LINE (+ == proposed; - == previous) -> COMMENTS
+type CodeComments map[string]map[int64][]*Comment
+
+func fetchCodeComments(e Engine, issue *Issue, currentUser *User) (CodeComments, error) {
+	return fetchCodeCommentsByReview(e, issue, currentUser, nil)
+}
+
+func fetchCodeCommentsByReview(e Engine, issue *Issue, currentUser *User, review *Review) (CodeComments, error) {
+	pathToLineToComment := make(CodeComments)
+	if review == nil {
+		review = &Review{ID: 0}
+	}
+	//Find comments
+	opts := FindCommentsOptions{
+		Type:     CommentTypeCode,
+		IssueID:  issue.ID,
+		ReviewID: review.ID,
+	}
+	conds := opts.toConds()
+	if review.ID == 0 {
+		conds.And(builder.Eq{"invalidated": false})
+	}
+
+	var comments []*Comment
+	if err := e.Where(conds).
+		Asc("comment.created_unix").
+		Asc("comment.id").
+		Find(&comments); err != nil {
+		return nil, err
+	}
+
+	if err := issue.loadRepo(e); err != nil {
+		return nil, err
+	}
+	// Find all reviews by ReviewID
+	reviews := make(map[int64]*Review)
+	var ids = make([]int64, 0, len(comments))
+	for _, comment := range comments {
+		if comment.ReviewID != 0 {
+			ids = append(ids, comment.ReviewID)
+		}
+	}
+	if err := e.In("id", ids).Find(&reviews); err != nil {
+		return nil, err
+	}
+	for _, comment := range comments {
+		if re, ok := reviews[comment.ReviewID]; ok && re != nil {
+			// If the review is pending only the author can see the comments (except the review is set)
+			if review.ID == 0 {
+				if re.Type == ReviewTypePending &&
+					(currentUser == nil || currentUser.ID != re.ReviewerID) {
+					continue
+				}
+			}
+			comment.Review = re
+		}
+
+		comment.RenderedContent = string(markdown.Render([]byte(comment.Content), issue.Repo.Link(),
+			issue.Repo.ComposeMetas()))
+		if pathToLineToComment[comment.TreePath] == nil {
+			pathToLineToComment[comment.TreePath] = make(map[int64][]*Comment)
+		}
+		pathToLineToComment[comment.TreePath][comment.Line] = append(pathToLineToComment[comment.TreePath][comment.Line], comment)
+	}
+	return pathToLineToComment, nil
+}
+
+// FetchCodeComments will return a 2d-map: ["Path"]["Line"] = Comments at line
+func FetchCodeComments(issue *Issue, currentUser *User) (CodeComments, error) {
+	return fetchCodeComments(x, issue, currentUser)
+}
diff --git a/models/issue_comment_test.go b/models/issue_comment_test.go
index f6a6fbce9b..91dd5c1732 100644
--- a/models/issue_comment_test.go
+++ b/models/issue_comment_test.go
@@ -39,3 +39,21 @@ func TestCreateComment(t *testing.T) {
 	updatedIssue := AssertExistsAndLoadBean(t, &Issue{ID: issue.ID}).(*Issue)
 	AssertInt64InRange(t, now, then, int64(updatedIssue.UpdatedUnix))
 }
+
+func TestFetchCodeComments(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	issue := AssertExistsAndLoadBean(t, &Issue{ID: 2}).(*Issue)
+	user := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+	res, err := FetchCodeComments(issue, user)
+	assert.NoError(t, err)
+	assert.Contains(t, res, "README.md")
+	assert.Contains(t, res["README.md"], int64(4))
+	assert.Len(t, res["README.md"][4], 1)
+	assert.Equal(t, int64(4), res["README.md"][4][0].ID)
+
+	user2 := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
+	res, err = FetchCodeComments(issue, user2)
+	assert.NoError(t, err)
+	assert.Len(t, res, 1)
+}
diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index b4e1a67187..15bb0723c0 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -194,8 +194,10 @@ var migrations = []Migration{
 	NewMigration("move team units to team_unit table", moveTeamUnitsToTeamUnitTable),
 	// v70 -> v71
 	NewMigration("add issue_dependencies", addIssueDependencies),
-	// v70 -> v71
+	// v71 -> v72
 	NewMigration("protect each scratch token", addScratchHash),
+	// v72 -> v73
+	NewMigration("add review", addReview),
 }
 
 // Migrate database to current version
diff --git a/models/migrations/v72.go b/models/migrations/v72.go
new file mode 100644
index 0000000000..4924b41ceb
--- /dev/null
+++ b/models/migrations/v72.go
@@ -0,0 +1,31 @@
+// Copyright 2018 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 migrations
+
+import (
+	"fmt"
+
+	"code.gitea.io/gitea/modules/util"
+
+	"github.com/go-xorm/xorm"
+)
+
+func addReview(x *xorm.Engine) error {
+	// Review see models/review.go
+	type Review struct {
+		ID          int64 `xorm:"pk autoincr"`
+		Type        string
+		ReviewerID  int64 `xorm:"index"`
+		IssueID     int64 `xorm:"index"`
+		Content     string
+		CreatedUnix util.TimeStamp `xorm:"INDEX created"`
+		UpdatedUnix util.TimeStamp `xorm:"INDEX updated"`
+	}
+
+	if err := x.Sync2(new(Review)); err != nil {
+		return fmt.Errorf("Sync2: %v", err)
+	}
+	return nil
+}
diff --git a/models/models.go b/models/models.go
index 9477b6950a..878e27e996 100644
--- a/models/models.go
+++ b/models/models.go
@@ -124,6 +124,7 @@ func init() {
 		new(IssueAssignees),
 		new(U2FRegistration),
 		new(TeamUnit),
+		new(Review),
 	)
 
 	gonicNames := []string{"SSL", "UID"}
diff --git a/models/pull.go b/models/pull.go
index 90b341907d..7faf1f1172 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -1075,10 +1075,7 @@ func (prs PullRequestList) loadAttributes(e Engine) error {
 	}
 
 	// Load issues.
-	issueIDs := make([]int64, 0, len(prs))
-	for i := range prs {
-		issueIDs = append(issueIDs, prs[i].IssueID)
-	}
+	issueIDs := prs.getIssueIDs()
 	issues := make([]*Issue, 0, len(issueIDs))
 	if err := e.
 		Where("id > 0").
@@ -1097,11 +1094,44 @@ func (prs PullRequestList) loadAttributes(e Engine) error {
 	return nil
 }
 
+func (prs PullRequestList) getIssueIDs() []int64 {
+	issueIDs := make([]int64, 0, len(prs))
+	for i := range prs {
+		issueIDs = append(issueIDs, prs[i].IssueID)
+	}
+	return issueIDs
+}
+
 // LoadAttributes load all the prs attributes
 func (prs PullRequestList) LoadAttributes() error {
 	return prs.loadAttributes(x)
 }
 
+func (prs PullRequestList) invalidateCodeComments(e Engine, doer *User, repo *git.Repository, branch string) error {
+	if len(prs) == 0 {
+		return nil
+	}
+	issueIDs := prs.getIssueIDs()
+	var codeComments []*Comment
+	if err := e.
+		Where("type = ? and invalidated = ?", CommentTypeCode, false).
+		In("issue_id", issueIDs).
+		Find(&codeComments); err != nil {
+		return fmt.Errorf("find code comments: %v", err)
+	}
+	for _, comment := range codeComments {
+		if err := comment.CheckInvalidation(repo, doer, branch); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// InvalidateCodeComments will lookup the prs for code comments which got invalidated by change
+func (prs PullRequestList) InvalidateCodeComments(doer *User, repo *git.Repository, branch string) error {
+	return prs.invalidateCodeComments(x, doer, repo, branch)
+}
+
 func addHeadRepoTasks(prs []*PullRequest) {
 	for _, pr := range prs {
 		log.Trace("addHeadRepoTasks[%d]: composing new test task", pr.ID)
@@ -1128,10 +1158,13 @@ func AddTestPullRequestTask(doer *User, repoID int64, branch string, isSync bool
 	}
 
 	if isSync {
-		if err = PullRequestList(prs).LoadAttributes(); err != nil {
+		requests := PullRequestList(prs)
+		if err = requests.LoadAttributes(); err != nil {
 			log.Error(4, "PullRequestList.LoadAttributes: %v", err)
 		}
-
+		if invalidationErr := checkForInvalidation(requests, repoID, doer, branch); invalidationErr != nil {
+			log.Error(4, "checkForInvalidation: %v", invalidationErr)
+		}
 		if err == nil {
 			for _, pr := range prs {
 				pr.Issue.PullRequest = pr
@@ -1152,6 +1185,7 @@ func AddTestPullRequestTask(doer *User, repoID int64, branch string, isSync bool
 				go HookQueue.Add(pr.Issue.Repo.ID)
 			}
 		}
+
 	}
 
 	addHeadRepoTasks(prs)
@@ -1167,6 +1201,24 @@ func AddTestPullRequestTask(doer *User, repoID int64, branch string, isSync bool
 	}
 }
 
+func checkForInvalidation(requests PullRequestList, repoID int64, doer *User, branch string) error {
+	repo, err := GetRepositoryByID(repoID)
+	if err != nil {
+		return fmt.Errorf("GetRepositoryByID: %v", err)
+	}
+	gitRepo, err := git.OpenRepository(repo.RepoPath())
+	if err != nil {
+		return fmt.Errorf("git.OpenRepository: %v", err)
+	}
+	go func() {
+		err := requests.InvalidateCodeComments(doer, gitRepo, branch)
+		if err != nil {
+			log.Error(4, "PullRequestList.InvalidateCodeComments: %v", err)
+		}
+	}()
+	return nil
+}
+
 // ChangeUsernameInPullRequests changes the name of head_user_name
 func ChangeUsernameInPullRequests(oldUserName, newUserName string) error {
 	pr := PullRequest{
diff --git a/models/review.go b/models/review.go
new file mode 100644
index 0000000000..3326ea0549
--- /dev/null
+++ b/models/review.go
@@ -0,0 +1,256 @@
+// Copyright 2018 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 (
+	"fmt"
+
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/util"
+	"github.com/go-xorm/xorm"
+
+	"github.com/go-xorm/builder"
+)
+
+// ReviewType defines the sort of feedback a review gives
+type ReviewType int
+
+// ReviewTypeUnknown unknown review type
+const ReviewTypeUnknown ReviewType = -1
+
+const (
+	// ReviewTypePending is a review which is not published yet
+	ReviewTypePending ReviewType = iota
+	// ReviewTypeApprove approves changes
+	ReviewTypeApprove
+	// ReviewTypeComment gives general feedback
+	ReviewTypeComment
+	// ReviewTypeReject gives feedback blocking merge
+	ReviewTypeReject
+)
+
+// Icon returns the corresponding icon for the review type
+func (rt ReviewType) Icon() string {
+	switch rt {
+	case ReviewTypeApprove:
+		return "eye"
+	case ReviewTypeReject:
+		return "x"
+	default:
+	case ReviewTypeComment:
+	case ReviewTypeUnknown:
+		return "comment"
+	}
+	return "comment"
+}
+
+// Review represents collection of code comments giving feedback for a PR
+type Review struct {
+	ID         int64 `xorm:"pk autoincr"`
+	Type       ReviewType
+	Reviewer   *User  `xorm:"-"`
+	ReviewerID int64  `xorm:"index"`
+	Issue      *Issue `xorm:"-"`
+	IssueID    int64  `xorm:"index"`
+	Content    string
+
+	CreatedUnix util.TimeStamp `xorm:"INDEX created"`
+	UpdatedUnix util.TimeStamp `xorm:"INDEX updated"`
+
+	// CodeComments are the initial code comments of the review
+	CodeComments CodeComments `xorm:"-"`
+}
+
+func (r *Review) loadCodeComments(e Engine) (err error) {
+	r.CodeComments, err = fetchCodeCommentsByReview(e, r.Issue, nil, r)
+	return
+}
+
+// LoadCodeComments loads CodeComments
+func (r *Review) LoadCodeComments() error {
+	return r.loadCodeComments(x)
+}
+
+func (r *Review) loadIssue(e Engine) (err error) {
+	r.Issue, err = getIssueByID(e, r.IssueID)
+	return
+}
+
+func (r *Review) loadReviewer(e Engine) (err error) {
+	if r.ReviewerID == 0 {
+		return nil
+	}
+	r.Reviewer, err = getUserByID(e, r.ReviewerID)
+	return
+}
+
+func (r *Review) loadAttributes(e Engine) (err error) {
+	if err = r.loadReviewer(e); err != nil {
+		return
+	}
+	if err = r.loadIssue(e); err != nil {
+		return
+	}
+	return
+}
+
+// LoadAttributes loads all attributes except CodeComments
+func (r *Review) LoadAttributes() error {
+	return r.loadAttributes(x)
+}
+
+// Publish will send notifications / actions to participants for all code comments; parts are concurrent
+func (r *Review) Publish() error {
+	return r.publish(x)
+}
+
+func (r *Review) publish(e *xorm.Engine) error {
+	if r.Type == ReviewTypePending || r.Type == ReviewTypeUnknown {
+		return fmt.Errorf("review cannot be published if type is pending or unknown")
+	}
+	if r.Issue == nil {
+		if err := r.loadIssue(e); err != nil {
+			return err
+		}
+	}
+	if err := r.Issue.loadRepo(e); err != nil {
+		return err
+	}
+	if len(r.CodeComments) == 0 {
+		if err := r.loadCodeComments(e); err != nil {
+			return err
+		}
+	}
+	for _, lines := range r.CodeComments {
+		for _, comments := range lines {
+			for _, comment := range comments {
+				go func(en *xorm.Engine, review *Review, comm *Comment) {
+					sess := en.NewSession()
+					defer sess.Close()
+					if err := sendCreateCommentAction(sess, &CreateCommentOptions{
+						Doer:    comm.Poster,
+						Issue:   review.Issue,
+						Repo:    review.Issue.Repo,
+						Type:    comm.Type,
+						Content: comm.Content,
+					}, comm); err != nil {
+						log.Warn("sendCreateCommentAction: %v", err)
+					}
+				}(e, r, comment)
+			}
+		}
+	}
+	return nil
+}
+
+func getReviewByID(e Engine, id int64) (*Review, error) {
+	review := new(Review)
+	if has, err := e.ID(id).Get(review); err != nil {
+		return nil, err
+	} else if !has {
+		return nil, ErrReviewNotExist{ID: id}
+	} else {
+		return review, nil
+	}
+}
+
+// GetReviewByID returns the review by the given ID
+func GetReviewByID(id int64) (*Review, error) {
+	return getReviewByID(x, id)
+}
+
+// FindReviewOptions represent possible filters to find reviews
+type FindReviewOptions struct {
+	Type       ReviewType
+	IssueID    int64
+	ReviewerID int64
+}
+
+func (opts *FindReviewOptions) toCond() builder.Cond {
+	var cond = builder.NewCond()
+	if opts.IssueID > 0 {
+		cond = cond.And(builder.Eq{"issue_id": opts.IssueID})
+	}
+	if opts.ReviewerID > 0 {
+		cond = cond.And(builder.Eq{"reviewer_id": opts.ReviewerID})
+	}
+	if opts.Type != ReviewTypeUnknown {
+		cond = cond.And(builder.Eq{"type": opts.Type})
+	}
+	return cond
+}
+
+func findReviews(e Engine, opts FindReviewOptions) ([]*Review, error) {
+	reviews := make([]*Review, 0, 10)
+	sess := e.Where(opts.toCond())
+	return reviews, sess.
+		Asc("created_unix").
+		Asc("id").
+		Find(&reviews)
+}
+
+// FindReviews returns reviews passing FindReviewOptions
+func FindReviews(opts FindReviewOptions) ([]*Review, error) {
+	return findReviews(x, opts)
+}
+
+// CreateReviewOptions represent the options to create a review. Type, Issue and Reviewer are required.
+type CreateReviewOptions struct {
+	Content  string
+	Type     ReviewType
+	Issue    *Issue
+	Reviewer *User
+}
+
+func createReview(e Engine, opts CreateReviewOptions) (*Review, error) {
+	review := &Review{
+		Type:       opts.Type,
+		Issue:      opts.Issue,
+		IssueID:    opts.Issue.ID,
+		Reviewer:   opts.Reviewer,
+		ReviewerID: opts.Reviewer.ID,
+		Content:    opts.Content,
+	}
+	if _, err := e.Insert(review); err != nil {
+		return nil, err
+	}
+	return review, nil
+}
+
+// CreateReview creates a new review based on opts
+func CreateReview(opts CreateReviewOptions) (*Review, error) {
+	return createReview(x, opts)
+}
+
+func getCurrentReview(e Engine, reviewer *User, issue *Issue) (*Review, error) {
+	if reviewer == nil {
+		return nil, nil
+	}
+	reviews, err := findReviews(e, FindReviewOptions{
+		Type:       ReviewTypePending,
+		IssueID:    issue.ID,
+		ReviewerID: reviewer.ID,
+	})
+	if err != nil {
+		return nil, err
+	}
+	if len(reviews) == 0 {
+		return nil, ErrReviewNotExist{}
+	}
+	return reviews[0], nil
+}
+
+// GetCurrentReview returns the current pending review of reviewer for given issue
+func GetCurrentReview(reviewer *User, issue *Issue) (*Review, error) {
+	return getCurrentReview(x, reviewer, issue)
+}
+
+// UpdateReview will update all cols of the given review in db
+func UpdateReview(r *Review) error {
+	if _, err := x.ID(r.ID).AllCols().Update(r); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/models/review_test.go b/models/review_test.go
new file mode 100644
index 0000000000..3c0444e7a3
--- /dev/null
+++ b/models/review_test.go
@@ -0,0 +1,107 @@
+package models
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetReviewByID(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+	review, err := GetReviewByID(1)
+	assert.NoError(t, err)
+	assert.Equal(t, "Demo Review", review.Content)
+	assert.Equal(t, ReviewTypeApprove, review.Type)
+
+	_, err = GetReviewByID(23892)
+	assert.Error(t, err)
+	assert.True(t, IsErrReviewNotExist(err), "IsErrReviewNotExist")
+}
+
+func TestReview_LoadAttributes(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+	review := AssertExistsAndLoadBean(t, &Review{ID: 1}).(*Review)
+	assert.NoError(t, review.LoadAttributes())
+	assert.NotNil(t, review.Issue)
+	assert.NotNil(t, review.Reviewer)
+
+	invalidReview1 := AssertExistsAndLoadBean(t, &Review{ID: 2}).(*Review)
+	assert.Error(t, invalidReview1.LoadAttributes())
+
+	invalidReview2 := AssertExistsAndLoadBean(t, &Review{ID: 3}).(*Review)
+	assert.Error(t, invalidReview2.LoadAttributes())
+
+}
+
+func TestReview_LoadCodeComments(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	review := AssertExistsAndLoadBean(t, &Review{ID: 4}).(*Review)
+	assert.NoError(t, review.LoadAttributes())
+	assert.NoError(t, review.LoadCodeComments())
+	assert.Len(t, review.CodeComments, 1)
+	assert.Equal(t, int64(4), review.CodeComments["README.md"][int64(4)][0].Line)
+}
+
+func TestReviewType_Icon(t *testing.T) {
+	assert.Equal(t, "eye", ReviewTypeApprove.Icon())
+	assert.Equal(t, "x", ReviewTypeReject.Icon())
+	assert.Equal(t, "comment", ReviewTypeComment.Icon())
+	assert.Equal(t, "comment", ReviewTypeUnknown.Icon())
+	assert.Equal(t, "comment", ReviewType(4).Icon())
+}
+
+func TestFindReviews(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+	reviews, err := FindReviews(FindReviewOptions{
+		Type:       ReviewTypeApprove,
+		IssueID:    2,
+		ReviewerID: 1,
+	})
+	assert.NoError(t, err)
+	assert.Len(t, reviews, 1)
+	assert.Equal(t, "Demo Review", reviews[0].Content)
+}
+
+func TestGetCurrentReview(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+	issue := AssertExistsAndLoadBean(t, &Issue{ID: 2}).(*Issue)
+	user := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+
+	review, err := GetCurrentReview(user, issue)
+	assert.NoError(t, err)
+	assert.NotNil(t, review)
+	assert.Equal(t, ReviewTypePending, review.Type)
+	assert.Equal(t, "Pending Review", review.Content)
+
+	user2 := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
+	review2, err := GetCurrentReview(user2, issue)
+	assert.Error(t, err)
+	assert.True(t, IsErrReviewNotExist(err))
+	assert.Nil(t, review2)
+}
+
+func TestCreateReview(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	issue := AssertExistsAndLoadBean(t, &Issue{ID: 2}).(*Issue)
+	user := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+
+	review, err := CreateReview(CreateReviewOptions{
+		Content:  "New Review",
+		Type:     ReviewTypePending,
+		Issue:    issue,
+		Reviewer: user,
+	})
+	assert.NoError(t, err)
+	assert.Equal(t, "New Review", review.Content)
+	AssertExistsAndLoadBean(t, &Review{Content: "New Review"})
+}
+
+func TestUpdateReview(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+	review := AssertExistsAndLoadBean(t, &Review{ID: 1}).(*Review)
+	review.Content = "Updated Review"
+	assert.NoError(t, UpdateReview(review))
+	AssertExistsAndLoadBean(t, &Review{ID: 1, Content: "Updated Review"})
+}