7 files changed, 731 insertions, 16 deletions

diff --git a/app/import.go b/app/import.go
index c50c6d62d..1ca532902 100644
--- a/app/import.go
+++ b/app/import.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"io"
+	"net/http"
 	"regexp"
 	"strings"
 	"unicode/utf8"
@@ -15,7 +16,6 @@ import (
 	l4g "github.com/alecthomas/log4go"
 	"github.com/mattermost/platform/model"
 	"github.com/mattermost/platform/utils"
-	"net/http"
 )
 
 // Import Data Models
@@ -25,6 +25,7 @@ type LineImportData struct {
 	Team    *TeamImportData    `json:"team"`
 	Channel *ChannelImportData `json:"channel"`
 	User    *UserImportData    `json:"user"`
+	Post    *PostImportData    `json:"post"`
 	Version *int               `json:"version"`
 }
 
@@ -85,6 +86,15 @@ type UserChannelNotifyPropsImportData struct {
 	MarkUnread *string `json:"mark_unread"`
 }
 
+type PostImportData struct {
+	Team    *string `json:"team"`
+	Channel *string `json:"channel"`
+	User    *string `json:"user"`
+
+	Message  *string `json:"message"`
+	CreateAt *int64  `json:"create_at"`
+}
+
 //
 // -- Bulk Import Functions --
 // These functions import data directly into the database. Security and permission checks are bypassed but validity is
@@ -152,6 +162,12 @@ func ImportLine(line LineImportData, dryRun bool) *model.AppError {
 		} else {
 			return ImportUser(line.User, dryRun)
 		}
+	case line.Type == "post":
+		if line.Post == nil {
+			return model.NewAppError("BulkImport", "app.import.import_line.null_post.error", nil, "", http.StatusBadRequest)
+		} else {
+			return ImportPost(line.Post, dryRun)
+		}
 	default:
 		return model.NewLocAppError("BulkImport", "app.import.import_line.unknown_line_type.error", map[string]interface{}{"Type": line.Type}, "")
 	}
@@ -698,13 +714,112 @@ func validateUserChannelsImportData(data *[]UserChannelImportData) *model.AppErr
 	return nil
 }
 
+func ImportPost(data *PostImportData, dryRun bool) *model.AppError {
+	if err := validatePostImportData(data); err != nil {
+		return err
+	}
+
+	// If this is a Dry Run, do not continue any further.
+	if dryRun {
+		return nil
+	}
+
+	var team *model.Team
+	if result := <-Srv.Store.Team().GetByName(*data.Team); result.Err != nil {
+		return model.NewAppError("BulkImport", "app.import.import_post.team_not_found.error", map[string]interface{}{"TeamName": *data.Team}, "", http.StatusBadRequest)
+	} else {
+		team = result.Data.(*model.Team)
+	}
+
+	var channel *model.Channel
+	if result := <-Srv.Store.Channel().GetByName(team.Id, *data.Channel, false); result.Err != nil {
+		return model.NewAppError("BulkImport", "app.import.import_post.channel_not_found.error", map[string]interface{}{"ChannelName": *data.Channel}, "", http.StatusBadRequest)
+	} else {
+		channel = result.Data.(*model.Channel)
+	}
+
+	var user *model.User
+	if result := <-Srv.Store.User().GetByUsername(*data.User); result.Err != nil {
+		return model.NewAppError("BulkImport", "app.import.import_post.user_not_found.error", map[string]interface{}{"Username": *data.User}, "", http.StatusBadRequest)
+	} else {
+		user = result.Data.(*model.User)
+	}
+
+	// Check if this post already exists.
+	var posts []*model.Post
+	if result := <-Srv.Store.Post().GetPostsCreatedAt(channel.Id, *data.CreateAt); result.Err != nil {
+		return result.Err
+	} else {
+		posts = result.Data.([]*model.Post)
+	}
+
+	var post *model.Post
+	for _, p := range posts {
+		if p.Message == *data.Message {
+			post = p
+			break
+		}
+	}
+
+	if post == nil {
+		post = &model.Post{}
+	}
+
+	post.ChannelId = channel.Id
+	post.Message = *data.Message
+	post.UserId = user.Id
+	post.CreateAt = *data.CreateAt
+
+	post.Hashtags, _ = model.ParseHashtags(post.Message)
+
+	if post.Id == "" {
+		if result := <-Srv.Store.Post().Save(post); result.Err != nil {
+			return result.Err
+		}
+	} else {
+		if result := <-Srv.Store.Post().Overwrite(post); result.Err != nil {
+			return result.Err
+		}
+	}
+
+	return nil
+}
+
+func validatePostImportData(data *PostImportData) *model.AppError {
+	if data.Team == nil {
+		return model.NewAppError("BulkImport", "app.import.validate_post_import_data.team_missing.error", nil, "", http.StatusBadRequest)
+	}
+
+	if data.Channel == nil {
+		return model.NewAppError("BulkImport", "app.import.validate_post_import_data.channel_missing.error", nil, "", http.StatusBadRequest)
+	}
+
+	if data.User == nil {
+		return model.NewAppError("BulkImport", "app.import.validate_post_import_data.user_missing.error", nil, "", http.StatusBadRequest)
+	}
+
+	if data.Message == nil {
+		return model.NewAppError("BulkImport", "app.import.validate_post_import_data.message_missing.error", nil, "", http.StatusBadRequest)
+	} else if utf8.RuneCountInString(*data.Message) > model.POST_MESSAGE_MAX_RUNES {
+		return model.NewAppError("BulkImport", "app.import.validate_post_import_data.message_length.error", nil, "", http.StatusBadRequest)
+	}
+
+	if data.CreateAt == nil {
+		return model.NewAppError("BulkImport", "app.import.validate_post_import_data.create_at_missing.error", nil, "", http.StatusBadRequest)
+	} else if *data.CreateAt == 0 {
+		return model.NewAppError("BulkImport", "app.import.validate_post_import_data.create_at_zero.error", nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}
+
 //
 // -- Old SlackImport Functions --
 // Import functions are sutible for entering posts and users into the database without
 // some of the usual checks. (IsValid is still run)
 //
 
-func ImportPost(post *model.Post) {
+func OldImportPost(post *model.Post) {
 	// Workaround for empty messages, which may be the case if they are webhook posts.
 	firstIteration := true
 	for messageRuneCount := utf8.RuneCountInString(post.Message); messageRuneCount > 0 || firstIteration; messageRuneCount = utf8.RuneCountInString(post.Message) {
@@ -768,7 +883,7 @@ func OldImportChannel(channel *model.Channel) *model.Channel {
 	}
 }
 
-func ImportFile(file io.Reader, teamId string, channelId string, userId string, fileName string) (*model.FileInfo, error) {
+func OldImportFile(file io.Reader, teamId string, channelId string, userId string, fileName string) (*model.FileInfo, error) {
 	buf := bytes.NewBuffer(nil)
 	io.Copy(buf, file)
 	data := buf.Bytes()
@@ -787,7 +902,7 @@ func ImportFile(file io.Reader, teamId string, channelId string, userId string,
 	return fileInfo, nil
 }
 
-func ImportIncomingWebhookPost(post *model.Post, props model.StringInterface) {
+func OldImportIncomingWebhookPost(post *model.Post, props model.StringInterface) {
 	linkWithTextRegex := regexp.MustCompile(`<([^<\|]+)\|([^>]+)>`)
 	post.Message = linkWithTextRegex.ReplaceAllString(post.Message, "[${2}](${1})")
 
@@ -838,5 +953,5 @@ func ImportIncomingWebhookPost(post *model.Post, props model.StringInterface) {
 		}
 	}
 
-	ImportPost(post)
+	OldImportPost(post)
 }
diff --git a/app/import_test.go b/app/import_test.go
index ddcc2d06a..165c94875 100644
--- a/app/import_test.go
+++ b/app/import_test.go
@@ -6,6 +6,7 @@ package app
 import (
 	"github.com/mattermost/platform/model"
 	"github.com/mattermost/platform/utils"
+	"runtime/debug"
 	"strings"
 	"testing"
 )
@@ -454,6 +455,108 @@ func TestImportValidateUserChannelsImportData(t *testing.T) {
 	}
 }
 
+func TestImportValidatePostImportData(t *testing.T) {
+
+	// Test with minimum required valid properties.
+	data := PostImportData{
+		Team:     ptrStr("teamname"),
+		Channel:  ptrStr("channelname"),
+		User:     ptrStr("username"),
+		Message:  ptrStr("message"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := validatePostImportData(&data); err != nil {
+		t.Fatal("Validation failed but should have been valid.")
+	}
+
+	// Test with missing required properties.
+	data = PostImportData{
+		Channel:  ptrStr("channelname"),
+		User:     ptrStr("username"),
+		Message:  ptrStr("message"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := validatePostImportData(&data); err == nil {
+		t.Fatal("Should have failed due to missing required property.")
+	}
+
+	data = PostImportData{
+		Team:     ptrStr("teamname"),
+		User:     ptrStr("username"),
+		Message:  ptrStr("message"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := validatePostImportData(&data); err == nil {
+		t.Fatal("Should have failed due to missing required property.")
+	}
+
+	data = PostImportData{
+		Team:     ptrStr("teamname"),
+		Channel:  ptrStr("channelname"),
+		Message:  ptrStr("message"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := validatePostImportData(&data); err == nil {
+		t.Fatal("Should have failed due to missing required property.")
+	}
+
+	data = PostImportData{
+		Team:     ptrStr("teamname"),
+		Channel:  ptrStr("channelname"),
+		User:     ptrStr("username"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := validatePostImportData(&data); err == nil {
+		t.Fatal("Should have failed due to missing required property.")
+	}
+
+	data = PostImportData{
+		Team:    ptrStr("teamname"),
+		Channel: ptrStr("channelname"),
+		User:    ptrStr("username"),
+		Message: ptrStr("message"),
+	}
+	if err := validatePostImportData(&data); err == nil {
+		t.Fatal("Should have failed due to missing required property.")
+	}
+
+	// Test with invalid message.
+	data = PostImportData{
+		Team:     ptrStr("teamname"),
+		Channel:  ptrStr("channelname"),
+		User:     ptrStr("username"),
+		Message:  ptrStr(strings.Repeat("1234567890", 500)),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := validatePostImportData(&data); err == nil {
+		t.Fatal("Should have failed due to too long message.")
+	}
+
+	// Test with invalid CreateAt
+	data = PostImportData{
+		Team:     ptrStr("teamname"),
+		Channel:  ptrStr("channelname"),
+		User:     ptrStr("username"),
+		Message:  ptrStr("message"),
+		CreateAt: ptrInt64(0),
+	}
+	if err := validatePostImportData(&data); err == nil {
+		t.Fatal("Should have failed due to 0 create-at value.")
+	}
+
+	// Test with valid all optional parameters.
+	data = PostImportData{
+		Team:     ptrStr("teamname"),
+		Channel:  ptrStr("channelname"),
+		User:     ptrStr("username"),
+		Message:  ptrStr("message"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := validatePostImportData(&data); err != nil {
+		t.Fatal("Should have succeeded.")
+	}
+}
+
 func TestImportImportTeam(t *testing.T) {
 	_ = Setup()
 
@@ -1333,6 +1436,252 @@ func TestImportImportUser(t *testing.T) {
 	}
 }
 
+func AssertAllPostsCount(t *testing.T, initialCount int64, change int64, teamName string) {
+	if result := <-Srv.Store.Post().AnalyticsPostCount(teamName, false, false); result.Err != nil {
+		t.Fatal(result.Err)
+	} else {
+		if initialCount+change != result.Data.(int64) {
+			debug.PrintStack()
+			t.Fatalf("Did not find the expected number of posts.")
+		}
+	}
+}
+
+func TestImportImportPost(t *testing.T) {
+	_ = Setup()
+
+	// Create a Team.
+	teamName := model.NewId()
+	ImportTeam(&TeamImportData{
+		Name:        &teamName,
+		DisplayName: ptrStr("Display Name"),
+		Type:        ptrStr("O"),
+	}, false)
+	team, err := GetTeamByName(teamName)
+	if err != nil {
+		t.Fatalf("Failed to get team from database.")
+	}
+
+	// Create a Channel.
+	channelName := model.NewId()
+	ImportChannel(&ChannelImportData{
+		Team:        &teamName,
+		Name:        &channelName,
+		DisplayName: ptrStr("Display Name"),
+		Type:        ptrStr("O"),
+	}, false)
+	channel, err := GetChannelByName(channelName, team.Id)
+	if err != nil {
+		t.Fatalf("Failed to get channel from database.")
+	}
+
+	// Create a user.
+	username := model.NewId()
+	ImportUser(&UserImportData{
+		Username: &username,
+		Email:    ptrStr(model.NewId() + "@example.com"),
+	}, false)
+	user, err := GetUserByUsername(username)
+	if err != nil {
+		t.Fatalf("Failed to get user from database.")
+	}
+
+	// Count the number of posts in the testing team.
+	var initialPostCount int64
+	if result := <-Srv.Store.Post().AnalyticsPostCount(team.Id, false, false); result.Err != nil {
+		t.Fatal(result.Err)
+	} else {
+		initialPostCount = result.Data.(int64)
+	}
+
+	// Try adding an invalid post in dry run mode.
+	data := &PostImportData{
+		Team:    &teamName,
+		Channel: &channelName,
+		User:    &username,
+	}
+	if err := ImportPost(data, true); err == nil {
+		t.Fatalf("Expected error.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 0, team.Id)
+
+	// Try adding a valid post in dry run mode.
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  &channelName,
+		User:     &username,
+		Message:  ptrStr("Hello"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := ImportPost(data, true); err != nil {
+		t.Fatalf("Expected success.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 0, team.Id)
+
+	// Try adding an invalid post in apply mode.
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  &channelName,
+		User:     &username,
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := ImportPost(data, false); err == nil {
+		t.Fatalf("Expected error.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 0, team.Id)
+
+	// Try adding a valid post with invalid team in apply mode.
+	data = &PostImportData{
+		Team:     ptrStr(model.NewId()),
+		Channel:  &channelName,
+		User:     &username,
+		Message:  ptrStr("Message"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := ImportPost(data, false); err == nil {
+		t.Fatalf("Expected error.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 0, team.Id)
+
+	// Try adding a valid post with invalid channel in apply mode.
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  ptrStr(model.NewId()),
+		User:     &username,
+		Message:  ptrStr("Message"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := ImportPost(data, false); err == nil {
+		t.Fatalf("Expected error.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 0, team.Id)
+
+	// Try adding a valid post with invalid user in apply mode.
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  &channelName,
+		User:     ptrStr(model.NewId()),
+		Message:  ptrStr("Message"),
+		CreateAt: ptrInt64(model.GetMillis()),
+	}
+	if err := ImportPost(data, false); err == nil {
+		t.Fatalf("Expected error.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 0, team.Id)
+
+	// Try adding a valid post in apply mode.
+	time := model.GetMillis()
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  &channelName,
+		User:     &username,
+		Message:  ptrStr("Message"),
+		CreateAt: &time,
+	}
+	if err := ImportPost(data, false); err != nil {
+		t.Fatalf("Expected success.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 1, team.Id)
+
+	// Check the post values.
+	if result := <-Srv.Store.Post().GetPostsCreatedAt(channel.Id, time); result.Err != nil {
+		t.Fatal(result.Err.Error())
+	} else {
+		posts := result.Data.([]*model.Post)
+		if len(posts) != 1 {
+			t.Fatal("Unexpected number of posts found.")
+		}
+		post := posts[0]
+		if post.Message != *data.Message || post.CreateAt != *data.CreateAt || post.UserId != user.Id {
+			t.Fatal("Post properties not as expected")
+		}
+	}
+
+	// Update the post.
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  &channelName,
+		User:     &username,
+		Message:  ptrStr("Message"),
+		CreateAt: &time,
+	}
+	if err := ImportPost(data, false); err != nil {
+		t.Fatalf("Expected success.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 1, team.Id)
+
+	// Check the post values.
+	if result := <-Srv.Store.Post().GetPostsCreatedAt(channel.Id, time); result.Err != nil {
+		t.Fatal(result.Err.Error())
+	} else {
+		posts := result.Data.([]*model.Post)
+		if len(posts) != 1 {
+			t.Fatal("Unexpected number of posts found.")
+		}
+		post := posts[0]
+		if post.Message != *data.Message || post.CreateAt != *data.CreateAt || post.UserId != user.Id {
+			t.Fatal("Post properties not as expected")
+		}
+	}
+
+	// Save the post with a different time.
+	newTime := time + 1
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  &channelName,
+		User:     &username,
+		Message:  ptrStr("Message"),
+		CreateAt: &newTime,
+	}
+	if err := ImportPost(data, false); err != nil {
+		t.Fatalf("Expected success.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 2, team.Id)
+
+	// Save the post with a different message.
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  &channelName,
+		User:     &username,
+		Message:  ptrStr("Message 2"),
+		CreateAt: &time,
+	}
+	if err := ImportPost(data, false); err != nil {
+		t.Fatalf("Expected success.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 3, team.Id)
+
+	// Test with hashtags
+	hashtagTime := time + 2
+	data = &PostImportData{
+		Team:     &teamName,
+		Channel:  &channelName,
+		User:     &username,
+		Message:  ptrStr("Message 2 #hashtagmashupcity"),
+		CreateAt: &hashtagTime,
+	}
+	if err := ImportPost(data, false); err != nil {
+		t.Fatalf("Expected success.")
+	}
+	AssertAllPostsCount(t, initialPostCount, 4, team.Id)
+
+	if result := <-Srv.Store.Post().GetPostsCreatedAt(channel.Id, hashtagTime); result.Err != nil {
+		t.Fatal(result.Err.Error())
+	} else {
+		posts := result.Data.([]*model.Post)
+		if len(posts) != 1 {
+			t.Fatal("Unexpected number of posts found.")
+		}
+		post := posts[0]
+		if post.Message != *data.Message || post.CreateAt != *data.CreateAt || post.UserId != user.Id {
+			t.Fatal("Post properties not as expected")
+		}
+		if post.Hashtags != "#hashtagmashupcity" {
+			t.Fatalf("Hashtags not as expected: %s", post.Hashtags)
+		}
+	}
+}
+
 func TestImportImportLine(t *testing.T) {
 	_ = Setup()
 
@@ -1362,6 +1711,12 @@ func TestImportImportLine(t *testing.T) {
 	if err := ImportLine(line, false); err == nil {
 		t.Fatalf("Expected an error when importing a line with type uesr with a nil user.")
 	}
+
+	// Try import line with post type but nil post.
+	line.Type = "post"
+	if err := ImportLine(line, false); err == nil {
+		t.Fatalf("Expected an error when importing a line with type post with a nil post.")
+	}
 }
 
 func TestImportBulkImport(t *testing.T) {
@@ -1369,13 +1724,14 @@ func TestImportBulkImport(t *testing.T) {
 
 	teamName := model.NewId()
 	channelName := model.NewId()
+	username := model.NewId()
 
 	// Run bulk import with a valid 1 of everything.
 	data1 := `{"type": "version", "version": 1}
 {"type": "team", "team": {"type": "O", "display_name": "lskmw2d7a5ao7ppwqh5ljchvr4", "name": "` + teamName + `"}}
 {"type": "channel", "channel": {"type": "O", "display_name": "xr6m6udffngark2uekvr3hoeny", "team": "` + teamName + `", "name": "` + channelName + `"}}
-{"type": "user", "user": {"username": "kufjgnkxkrhhfgbrip6qxkfsaa", "email": "kufjgnkxkrhhfgbrip6qxkfsaa@example.com"}}
-{"type": "user", "user": {"username": "bwshaim6qnc2ne7oqkd5b2s2rq", "email": "bwshaim6qnc2ne7oqkd5b2s2rq@example.com", "teams": [{"name": "` + teamName + `", "channels": [{"name": "` + channelName + `"}]}]}}`
+{"type": "user", "user": {"username": "` + username + `", "email": "` + username + `@example.com", "teams": [{"name": "` + teamName + `", "channels": [{"name": "` + channelName + `"}]}]}}
+{"type": "post", "post": {"team": "` + teamName + `", "channel": "` + channelName + `", "user": "` + username + `", "message": "Hello World", "create_at": 123456789012}}`
 
 	if err, line := BulkImport(strings.NewReader(data1), false); err != nil || line != 0 {
 		t.Fatalf("BulkImport should have succeeded: %v, %v", err.Error(), line)
diff --git a/app/slackimport.go b/app/slackimport.go
index e54d0724b..c3d968907 100644
--- a/app/slackimport.go
+++ b/app/slackimport.go
@@ -242,7 +242,7 @@ func SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, use
 					newPost.Message = sPost.File.Title
 				}
 			}
-			ImportPost(&newPost)
+			OldImportPost(&newPost)
 			for _, fileId := range newPost.FileIds {
 				if result := <-Srv.Store.FileInfo().AttachToPost(fileId, newPost.Id); result.Err != nil {
 					l4g.Error(utils.T("api.slackimport.slack_add_posts.attach_files.error"), newPost.Id, newPost.FileIds, result.Err)
@@ -266,7 +266,7 @@ func SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, use
 				Message:   sPost.Comment.Comment,
 				CreateAt:  SlackConvertTimeStamp(sPost.TimeStamp),
 			}
-			ImportPost(&newPost)
+			OldImportPost(&newPost)
 		case sPost.Type == "message" && sPost.SubType == "bot_message":
 			if botUser == nil {
 				l4g.Warn(utils.T("api.slackimport.slack_add_posts.bot_user_no_exists.warn"))
@@ -298,7 +298,7 @@ func SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, use
 				Type:      model.POST_SLACK_ATTACHMENT,
 			}
 
-			ImportIncomingWebhookPost(post, props)
+			OldImportIncomingWebhookPost(post, props)
 		case sPost.Type == "message" && (sPost.SubType == "channel_join" || sPost.SubType == "channel_leave"):
 			if sPost.User == "" {
 				l4g.Debug(utils.T("api.slackimport.slack_add_posts.msg_no_usr.debug"))
@@ -325,7 +325,7 @@ func SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, use
 					"username": users[sPost.User].Username,
 				},
 			}
-			ImportPost(&newPost)
+			OldImportPost(&newPost)
 		case sPost.Type == "message" && sPost.SubType == "me_message":
 			if sPost.User == "" {
 				l4g.Debug(utils.T("api.slackimport.slack_add_posts.without_user.debug"))
@@ -340,7 +340,7 @@ func SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, use
 				Message:   "*" + sPost.Text + "*",
 				CreateAt:  SlackConvertTimeStamp(sPost.TimeStamp),
 			}
-			ImportPost(&newPost)
+			OldImportPost(&newPost)
 		case sPost.Type == "message" && sPost.SubType == "channel_topic":
 			if sPost.User == "" {
 				l4g.Debug(utils.T("api.slackimport.slack_add_posts.msg_no_usr.debug"))
@@ -356,7 +356,7 @@ func SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, use
 				CreateAt:  SlackConvertTimeStamp(sPost.TimeStamp),
 				Type:      model.POST_HEADER_CHANGE,
 			}
-			ImportPost(&newPost)
+			OldImportPost(&newPost)
 		case sPost.Type == "message" && sPost.SubType == "channel_purpose":
 			if sPost.User == "" {
 				l4g.Debug(utils.T("api.slackimport.slack_add_posts.msg_no_usr.debug"))
@@ -372,7 +372,7 @@ func SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, use
 				CreateAt:  SlackConvertTimeStamp(sPost.TimeStamp),
 				Type:      model.POST_PURPOSE_CHANGE,
 			}
-			ImportPost(&newPost)
+			OldImportPost(&newPost)
 		case sPost.Type == "message" && sPost.SubType == "channel_name":
 			if sPost.User == "" {
 				l4g.Debug(utils.T("api.slackimport.slack_add_posts.msg_no_usr.debug"))
@@ -388,7 +388,7 @@ func SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, use
 				CreateAt:  SlackConvertTimeStamp(sPost.TimeStamp),
 				Type:      model.POST_DISPLAYNAME_CHANGE,
 			}
-			ImportPost(&newPost)
+			OldImportPost(&newPost)
 		default:
 			l4g.Warn(utils.T("api.slackimport.slack_add_posts.unsupported.warn"), sPost.Type, sPost.SubType)
 		}
@@ -405,7 +405,7 @@ func SlackUploadFile(sPost SlackPost, uploads map[string]*zip.File, teamId strin
 			}
 			defer openFile.Close()
 
-			uploadedFile, err := ImportFile(openFile, teamId, channelId, userId, filepath.Base(file.Name))
+			uploadedFile, err := OldImportFile(openFile, teamId, channelId, userId, filepath.Base(file.Name))
 			if err != nil {
 				l4g.Warn(utils.T("api.slackimport.slack_add_posts.upload_file_upload_failed.warn", map[string]interface{}{"FileId": sPost.File.Id, "Error": err.Error()}))
 				return nil, false
diff --git a/i18n/en.json b/i18n/en.json
index d46812bd8..e6efcafda 100644
--- a/i18n/en.json
+++ b/i18n/en.json
@@ -2984,6 +2984,50 @@
     "translation": "Team name missing from User's Team Membership."
   },
   {
+    "id": "app.import.import_post.team_not_found.error",
+    "translation": "Error importing post. Team with name \"{{.TeamName}}\" could not be found."
+  },
+  {
+    "id": "app.import.import_post.channel_not_found.error",
+    "translation": "Error importing post. Channel with name \"{{.ChannelName}}\" could not be found."
+  },
+  {
+    "id": "app.import.import_post.user_not_found.error",
+    "translation": "Error importing post. User with username \"{{.Username}}\" could not be found."
+  },
+  {
+    "id": "app.import.validate_post_import_data.team_missing.error",
+    "translation": "Missing required Post property: Team."
+  },
+  {
+    "id": "app.import.validate_post_import_data.channel_missing.error",
+    "translation": "Missing required Post property: Channel."
+  },
+  {
+    "id": "app.import.validate_post_import_data.user_missing.error",
+    "translation": "Missing required Post property: User."
+  },
+  {
+    "id": "app.import.validate_post_import_data.message_missing.error",
+    "translation": "Missing required Post property: Message."
+  },
+  {
+    "id": "app.import.validate_post_import_data.create_at_missing.error",
+    "translation": "Missing required Post property: create_at."
+  },
+  {
+    "id": "app.import.validate_post_import_data.message_length.error",
+    "translation": "Post Message property is longer than the maximum permitted length."
+  },
+  {
+    "id": "app.import.validate_post_import_data.create_at_zero.error",
+    "translation": "Post CreateAt must not be zero if it is provided."
+  },
+  {
+    "id": "app.import.import_line.null_post.error",
+    "translation": "Import data line has type \"post\" but the post object is null."
+  },
+  {
     "id": "authentication.permissions.create_team_roles.description",
     "translation": "Ability to create new teams"
   },
@@ -4944,6 +4988,10 @@
     "translation": "We couldn't get the posts for the channel"
   },
   {
+    "id": "store.sql_post.get_posts_created_att.app_error",
+    "translation": "We couldn't get the posts for the channel"
+  },
+  {
     "id": "store.sql_post.get_posts_around.get_parent.app_error",
     "translation": "We couldn't get the parent posts for the channel"
   },
@@ -4992,6 +5040,10 @@
     "translation": "We couldn't update the Post"
   },
   {
+    "id": "store.sql_post.overwrite.app_error",
+    "translation": "We couldn't overwrite the Post"
+  },
+  {
     "id": "store.sql_preference.delete.app_error",
     "translation": "We encountered an error while deleting preferences"
   },
diff --git a/store/sql_post_store.go b/store/sql_post_store.go
index 060a3b1cf..e224f60bd 100644
--- a/store/sql_post_store.go
+++ b/store/sql_post_store.go
@@ -12,6 +12,7 @@ import (
 	"github.com/mattermost/platform/einterfaces"
 	"github.com/mattermost/platform/model"
 	"github.com/mattermost/platform/utils"
+	"net/http"
 )
 
 type SqlPostStore struct {
@@ -157,6 +158,33 @@ func (s SqlPostStore) Update(newPost *model.Post, oldPost *model.Post) StoreChan
 	return storeChannel
 }
 
+func (s SqlPostStore) Overwrite(post *model.Post) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		post.UpdateAt = model.GetMillis()
+
+		if result.Err = post.IsValid(); result.Err != nil {
+			storeChannel <- result
+			close(storeChannel)
+			return
+		}
+
+		if _, err := s.GetMaster().Update(post); err != nil {
+			result.Err = model.NewLocAppError("SqlPostStore.Overwrite", "store.sql_post.overwrite.app_error", nil, "id="+post.Id+", "+err.Error())
+		} else {
+			result.Data = post
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
+
 func (s SqlPostStore) GetFlaggedPosts(userId string, offset int, limit int) StoreChannel {
 	storeChannel := make(StoreChannel, 1)
 	go func() {
@@ -1132,3 +1160,27 @@ func (s SqlPostStore) AnalyticsPostCount(teamId string, mustHaveFile bool, mustH
 
 	return storeChannel
 }
+
+func (s SqlPostStore) GetPostsCreatedAt(channelId string, time int64) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		query := `SELECT * FROM Posts WHERE CreateAt = :CreateAt`
+
+		var posts []*model.Post
+		_, err := s.GetReplica().Select(&posts, query, map[string]interface{}{"CreateAt": time})
+
+		if err != nil {
+			result.Err = model.NewAppError("SqlPostStore.GetPostsCreatedAt", "store.sql_post.get_posts_created_att.app_error", nil, "channelId="+channelId+err.Error(), http.StatusInternalServerError)
+		} else {
+			result.Data = posts
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
diff --git a/store/sql_post_store_test.go b/store/sql_post_store_test.go
index 08fe1282e..82490fffd 100644
--- a/store/sql_post_store_test.go
+++ b/store/sql_post_store_test.go
@@ -1127,3 +1127,141 @@ func TestPostStoreGetFlaggedPosts(t *testing.T) {
 		t.Fatal("should have 2 posts")
 	}
 }
+
+func TestPostStoreGetPostsCreatedAt(t *testing.T) {
+	Setup()
+
+	createTime := model.GetMillis()
+
+	o0 := &model.Post{}
+	o0.ChannelId = model.NewId()
+	o0.UserId = model.NewId()
+	o0.Message = "a" + model.NewId() + "b"
+	o0.CreateAt = createTime
+	o0 = (<-store.Post().Save(o0)).Data.(*model.Post)
+
+	o1 := &model.Post{}
+	o1.ChannelId = o0.Id
+	o1.UserId = model.NewId()
+	o1.Message = "a" + model.NewId() + "b"
+	o0.CreateAt = createTime
+	o1 = (<-store.Post().Save(o1)).Data.(*model.Post)
+	time.Sleep(2 * time.Millisecond)
+
+	o2 := &model.Post{}
+	o2.ChannelId = o1.ChannelId
+	o2.UserId = model.NewId()
+	o2.Message = "a" + model.NewId() + "b"
+	o2.ParentId = o1.Id
+	o2.RootId = o1.Id
+	o2 = (<-store.Post().Save(o2)).Data.(*model.Post)
+	time.Sleep(2 * time.Millisecond)
+
+	o3 := &model.Post{}
+	o3.ChannelId = model.NewId()
+	o3.UserId = model.NewId()
+	o3.Message = "a" + model.NewId() + "b"
+	o3.CreateAt = createTime
+	o3 = (<-store.Post().Save(o3)).Data.(*model.Post)
+	time.Sleep(2 * time.Millisecond)
+
+	r1 := (<-store.Post().GetPostsCreatedAt(o1.ChannelId, createTime)).Data.([]*model.Post)
+
+	if len(r1) != 2 {
+		t.Fatalf("Got the wrong number of posts.")
+	}
+}
+
+func TestPostStoreOverwrite(t *testing.T) {
+	Setup()
+
+	o1 := &model.Post{}
+	o1.ChannelId = model.NewId()
+	o1.UserId = model.NewId()
+	o1.Message = "a" + model.NewId() + "AAAAAAAAAAA"
+	o1 = (<-store.Post().Save(o1)).Data.(*model.Post)
+
+	o2 := &model.Post{}
+	o2.ChannelId = o1.ChannelId
+	o2.UserId = model.NewId()
+	o2.Message = "a" + model.NewId() + "CCCCCCCCC"
+	o2.ParentId = o1.Id
+	o2.RootId = o1.Id
+	o2 = (<-store.Post().Save(o2)).Data.(*model.Post)
+
+	o3 := &model.Post{}
+	o3.ChannelId = o1.ChannelId
+	o3.UserId = model.NewId()
+	o3.Message = "a" + model.NewId() + "QQQQQQQQQQ"
+	o3 = (<-store.Post().Save(o3)).Data.(*model.Post)
+
+	ro1 := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o1.Id]
+	ro2 := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o2.Id]
+	ro3 := (<-store.Post().Get(o3.Id)).Data.(*model.PostList).Posts[o3.Id]
+
+	if ro1.Message != o1.Message {
+		t.Fatal("Failed to save/get")
+	}
+
+	o1a := &model.Post{}
+	*o1a = *ro1
+	o1a.Message = ro1.Message + "BBBBBBBBBB"
+	if result := <-store.Post().Overwrite(o1a); result.Err != nil {
+		t.Fatal(result.Err)
+	}
+
+	ro1a := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o1.Id]
+
+	if ro1a.Message != o1a.Message {
+		t.Fatal("Failed to overwrite/get")
+	}
+
+	o2a := &model.Post{}
+	*o2a = *ro2
+	o2a.Message = ro2.Message + "DDDDDDD"
+	if result := <-store.Post().Overwrite(o2a); result.Err != nil {
+		t.Fatal(result.Err)
+	}
+
+	ro2a := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o2.Id]
+
+	if ro2a.Message != o2a.Message {
+		t.Fatal("Failed to overwrite/get")
+	}
+
+	o3a := &model.Post{}
+	*o3a = *ro3
+	o3a.Message = ro3.Message + "WWWWWWW"
+	if result := <-store.Post().Overwrite(o3a); result.Err != nil {
+		t.Fatal(result.Err)
+	}
+
+	ro3a := (<-store.Post().Get(o3.Id)).Data.(*model.PostList).Posts[o3.Id]
+
+	if ro3a.Message != o3a.Message && ro3a.Hashtags != o3a.Hashtags {
+		t.Fatal("Failed to overwrite/get")
+	}
+
+	o4 := Must(store.Post().Save(&model.Post{
+		ChannelId: model.NewId(),
+		UserId:    model.NewId(),
+		Message:   model.NewId(),
+		Filenames: []string{"test"},
+	})).(*model.Post)
+
+	ro4 := (<-store.Post().Get(o4.Id)).Data.(*model.PostList).Posts[o4.Id]
+
+	o4a := &model.Post{}
+	*o4a = *ro4
+	o4a.Filenames = []string{}
+	o4a.FileIds = []string{model.NewId()}
+	if result := <-store.Post().Overwrite(o4a); result.Err != nil {
+		t.Fatal(result.Err)
+	}
+
+	if ro4a := Must(store.Post().Get(o4.Id)).(*model.PostList).Posts[o4.Id]; len(ro4a.Filenames) != 0 {
+		t.Fatal("Failed to clear Filenames")
+	} else if len(ro4a.FileIds) != 1 {
+		t.Fatal("Failed to set FileIds")
+	}
+}
diff --git a/store/store.go b/store/store.go
index 57741742c..a436f9ee7 100644
--- a/store/store.go
+++ b/store/store.go
@@ -152,6 +152,8 @@ type PostStore interface {
 	AnalyticsPostCountsByDay(teamId string) StoreChannel
 	AnalyticsPostCount(teamId string, mustHaveFile bool, mustHaveHashtag bool) StoreChannel
 	InvalidateLastPostTimeCache(channelId string)
+	GetPostsCreatedAt(channelId string, time int64) StoreChannel
+	Overwrite(post *model.Post) StoreChannel
 }
 
 type UserStore interface {