1 files changed, 42 insertions, 2 deletions

diff --git a/model/preference.go b/model/preference.go
index 22858e043..779c41e50 100644
--- a/model/preference.go
+++ b/model/preference.go
@@ -6,6 +6,8 @@ package model
 import (
 	"encoding/json"
 	"io"
+	"regexp"
+	"strings"
 	"unicode/utf8"
 )
 
@@ -17,6 +19,9 @@ const (
 	PREFERENCE_CATEGORY_DISPLAY_SETTINGS = "display_settings"
 	PREFERENCE_NAME_COLLAPSE_SETTING     = "collapse_previews"
 
+	PREFERENCE_CATEGORY_THEME = "theme"
+	// the name for theme props is the team id
+
 	PREFERENCE_CATEGORY_LAST     = "last"
 	PREFERENCE_NAME_LAST_CHANNEL = "channel"
 )
@@ -57,13 +62,48 @@ func (o *Preference) IsValid() *AppError {
 		return NewLocAppError("Preference.IsValid", "model.preference.is_valid.category.app_error", nil, "category="+o.Category)
 	}
 
-	if len(o.Name) == 0 || len(o.Name) > 32 {
+	if len(o.Name) > 32 {
 		return NewLocAppError("Preference.IsValid", "model.preference.is_valid.name.app_error", nil, "name="+o.Name)
 	}
 
-	if utf8.RuneCountInString(o.Value) > 128 {
+	if utf8.RuneCountInString(o.Value) > 2000 {
 		return NewLocAppError("Preference.IsValid", "model.preference.is_valid.value.app_error", nil, "value="+o.Value)
 	}
 
+	if o.Category == PREFERENCE_CATEGORY_THEME {
+		var unused map[string]string
+		if err := json.NewDecoder(strings.NewReader(o.Value)).Decode(&unused); err != nil {
+			return NewLocAppError("Preference.IsValid", "model.preference.is_valid.theme.app_error", nil, "value="+o.Value)
+		}
+	}
+
 	return nil
 }
+
+func (o *Preference) PreUpdate() {
+	if o.Category == PREFERENCE_CATEGORY_THEME {
+		// decode the value of theme (a map of strings to string) and eliminate any invalid values
+		var props map[string]string
+		if err := json.NewDecoder(strings.NewReader(o.Value)).Decode(&props); err != nil {
+			// just continue, the invalid preference value should get caught by IsValid before saving
+			return
+		}
+
+		colorPattern := regexp.MustCompile(`^#[0-9a-fA-F]{3}([0-9a-fA-F]{3})?$`)
+
+		// blank out any invalid theme values
+		for name, value := range props {
+			if name == "image" || name == "type" || name == "codeTheme" {
+				continue
+			}
+
+			if !colorPattern.MatchString(value) {
+				props[name] = "#ffffff"
+			}
+		}
+
+		if b, err := json.Marshal(props); err == nil {
+			o.Value = string(b)
+		}
+	}
+}