Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/platform/services/slackimport/converters.go

@@ -0,0 +1,150 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package slackimport
+
+import (
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/mattermost/mattermost-server/v6/server/platform/shared/mlog"
+)
+
+func slackConvertTimeStamp(ts string) int64 {
+	timeString := strings.SplitN(ts, ".", 2)[0]
+
+	timeStamp, err := strconv.ParseInt(timeString, 10, 64)
+	if err != nil {
+		mlog.Warn("Slack Import: Bad timestamp detected.")
+		return 1
+	}
+	return timeStamp * 1000 // Convert to milliseconds
+}
+
+func slackConvertChannelName(channelName string, channelId string) string {
+	newName := strings.Trim(channelName, "_-")
+	if len(newName) == 1 {
+		return "slack-channel-" + newName
+	}
+
+	if isValidChannelNameCharacters(newName) {
+		return newName
+	}
+	return strings.ToLower(channelId)
+}
+
+func slackConvertUserMentions(users []slackUser, posts map[string][]slackPost) map[string][]slackPost {
+	var regexes = make(map[string]*regexp.Regexp, len(users))
+	for _, user := range users {
+		r, err := regexp.Compile("<@" + user.Id + `(\|` + user.Username + ")?>")
+		if err != nil {
+			mlog.Warn("Slack Import: Unable to compile the @mention, matching regular expression for the Slack user.", mlog.String("user_name", user.Username), mlog.String("user_id", user.Id))
+			continue
+		}
+		regexes["@"+user.Username] = r
+	}
+
+	// Special cases.
+	regexes["@here"], _ = regexp.Compile(`<!here\|@here>`)
+	regexes["@channel"], _ = regexp.Compile("<!channel>")
+	regexes["@all"], _ = regexp.Compile("<!everyone>")
+
+	for channelName, channelPosts := range posts {
+		for postIdx, post := range channelPosts {
+			for mention, r := range regexes {
+				post.Text = r.ReplaceAllString(post.Text, mention)
+				posts[channelName][postIdx] = post
+			}
+		}
+	}
+
+	return posts
+}
+
+func slackConvertChannelMentions(channels []slackChannel, posts map[string][]slackPost) map[string][]slackPost {
+	var regexes = make(map[string]*regexp.Regexp, len(channels))
+	for _, channel := range channels {
+		r, err := regexp.Compile("<#" + channel.Id + `(\|` + channel.Name + ")?>")
+		if err != nil {
+			mlog.Warn("Slack Import: Unable to compile the !channel, matching regular expression for the Slack channel.", mlog.String("channel_id", channel.Id), mlog.String("channel_name", channel.Name))
+			continue
+		}
+		regexes["~"+channel.Name] = r
+	}
+
+	for channelName, channelPosts := range posts {
+		for postIdx, post := range channelPosts {
+			for channelReplace, r := range regexes {
+				post.Text = r.ReplaceAllString(post.Text, channelReplace)
+				posts[channelName][postIdx] = post
+			}
+		}
+	}
+
+	return posts
+}
+
+func slackConvertPostsMarkup(posts map[string][]slackPost) map[string][]slackPost {
+	regexReplaceAllString := []struct {
+		regex *regexp.Regexp
+		rpl   string
+	}{
+		// URL
+		{
+			regexp.MustCompile(`<([^|<>]+)\|([^|<>]+)>`),
+			"[$2]($1)",
+		},
+		// bold
+		{
+			regexp.MustCompile(`(^|[\s.;,])\*(\S[^*\n]+)\*`),
+			"$1**$2**",
+		},
+		// strikethrough
+		{
+			regexp.MustCompile(`(^|[\s.;,])\~(\S[^~\n]+)\~`),
+			"$1~~$2~~",
+		},
+		// single paragraph blockquote
+		// Slack converts > character to &gt;
+		{
+			regexp.MustCompile(`(?sm)^&gt;`),
+			">",
+		},
+	}
+
+	regexReplaceAllStringFunc := []struct {
+		regex *regexp.Regexp
+		fn    func(string) string
+	}{
+		// multiple paragraphs blockquotes
+		{
+			regexp.MustCompile(`(?sm)^>&gt;&gt;(.+)$`),
+			func(src string) string {
+				// remove >>> prefix, might have leading \n
+				prefixRegexp := regexp.MustCompile(`^([\n])?>&gt;&gt;(.*)`)
+				src = prefixRegexp.ReplaceAllString(src, "$1$2")
+				// append > to start of line
+				appendRegexp := regexp.MustCompile(`(?m)^`)
+				return appendRegexp.ReplaceAllString(src, ">$0")
+			},
+		},
+	}
+
+	for channelName, channelPosts := range posts {
+		for postIdx, post := range channelPosts {
+			result := post.Text
+
+			for _, rule := range regexReplaceAllString {
+				result = rule.regex.ReplaceAllString(result, rule.rpl)
+			}
+
+			for _, rule := range regexReplaceAllStringFunc {
+				result = rule.regex.ReplaceAllStringFunc(result, rule.fn)
+			}
+			posts[channelName][postIdx].Text = result
+		}
+	}
+
+	return posts
+}