validation.go

/*
 *  validation.go is part of github.com/mwmahlberg/swagger-ui project.
 *
 *  Copyright 2023 Markus W Mahlberg
 *
 *  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 swaggerui

import (
	"encoding/json"
	"regexp"
	"strings"

	"github.com/asaskevich/govalidator"
	"gopkg.in/yaml.v3"
)

var (
	// RegexValidFilename matches a valid filename for a swagger spec file.
	RegexValidFilename = regexp.MustCompile(`(?i)\.(y[a]?ml|json)$`)
)

func init() {
	govalidator.CustomTypeTagMap.Set("isYaml", isYaml)
	govalidator.CustomTypeTagMap.Set("correctContent", isCorrectContent)
	govalidator.CustomTypeTagMap.Set("acceptedFileName", isAcceptedFileName)
}

// isYaml checks if i is valid JSON data.
// It also explcitly checks that i is not JSON data, since JSON parses as YAML.
func isYaml(i interface{}, _ interface{}) bool {
	var tmp = make(map[string]interface{})
	var data []byte
	switch v := i.(type) {
	case []byte:
		data = v
	case string:
		data = []byte(v)
	default:
		return false
	}
	return yaml.Unmarshal(data, &tmp) == nil && !json.Valid(data)

}

func isAcceptedFileName(i interface{}, _ interface{}) bool {
	v, isString := i.(string)
	if !isString {
		return false
	}
	return RegexValidFilename.MatchString(v)
}

func isCorrectContent(i, o interface{}) bool {

	h, isHandler := o.(SwaggerUi)

	if !isHandler {
		return false
	}

	var foo string
	switch v := i.(type) {
	case string:
		foo = v
	case []byte:
		foo = string(v)
	default:
		return false
	}

	switch {
	case strings.HasSuffix(strings.ToLower(h.specFilename), ".yaml"):
		return isYaml(i, o)
	case strings.HasSuffix(strings.ToLower(h.specFilename), ".json"):
		return govalidator.IsJSON(foo)
	default:
		return false
	}

}