resources: Address Dart Sass deprecation of global built-in functions

See https://github.com/sass/dart-sass/releases/tag/1.80.0

Fixes #12961

resources/resource_transformers/tocss/sass/helpers.go

@@ -0,0 +1,102 @@
+// Copyright 2024 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sass
+
+import (
+	"fmt"
+	"regexp"
+	"sort"
+	"strings"
+
+	"github.com/gohugoio/hugo/common/types/css"
+)
+
+const (
+	HugoVarsNamespace = "hugo:vars"
+	// Transpiler implementation can be controlled from the client by
+	// setting the 'transpiler' option.
+	// Default is currently 'libsass', but that may change.
+	TranspilerDart    = "dartsass"
+	TranspilerLibSass = "libsass"
+)
+
+func CreateVarsStyleSheet(transpiler string, vars map[string]any) string {
+	if vars == nil {
+		return ""
+	}
+	var varsStylesheet string
+
+	var varsSlice []string
+	for k, v := range vars {
+		var prefix string
+		if !strings.HasPrefix(k, "$") {
+			prefix = "$"
+		}
+
+		switch v.(type) {
+		case css.QuotedString:
+			// Marked by the user as a string that needs to be quoted.
+			varsSlice = append(varsSlice, fmt.Sprintf("%s%s: %q;", prefix, k, v))
+		default:
+			if isTypedCSSValue(v) {
+				// E.g. 24px, 1.5rem, 10%, hsl(0, 0%, 100%), calc(24px + 36px), #fff, #ffffff.
+				varsSlice = append(varsSlice, fmt.Sprintf("%s%s: %v;", prefix, k, v))
+			} else {
+				// unquote will preserve quotes around URLs etc. if needed.
+				if transpiler == TranspilerDart {
+					varsSlice = append(varsSlice, fmt.Sprintf("%s%s: string.unquote(%q);", prefix, k, v))
+				} else {
+					varsSlice = append(varsSlice, fmt.Sprintf("%s%s: unquote(%q);", prefix, k, v))
+				}
+			}
+		}
+	}
+	sort.Strings(varsSlice)
+
+	if transpiler == TranspilerDart {
+		varsStylesheet = `@use "sass:string";` + "\n" + strings.Join(varsSlice, "\n")
+	} else {
+		varsStylesheet = strings.Join(varsSlice, "\n")
+	}
+
+	return varsStylesheet
+}
+
+var (
+	isCSSColor = regexp.MustCompile(`^#[0-9a-fA-F]{3,6}$`)
+	isCSSFunc  = regexp.MustCompile(`^([a-zA-Z-]+)\(`)
+	isCSSUnit  = regexp.MustCompile(`^([0-9]+)(\.[0-9]+)?([a-zA-Z-%]+)$`)
+)
+
+// isTypedCSSValue returns true if the given string is a CSS value that
+// we should preserve the type of, as in: Not wrap it in quotes.
+func isTypedCSSValue(v any) bool {
+	switch s := v.(type) {
+	case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, float32, float64, css.UnquotedString:
+		return true
+	case string:
+		if isCSSColor.MatchString(s) {
+			return true
+		}
+		if isCSSFunc.MatchString(s) {
+			return true
+		}
+		if isCSSUnit.MatchString(s) {
+			return true
+		}
+
+	}
+
+	return false
+}