/*
 * Minio Client (C) 2015 Minio, Inc.
 *
 * 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 main

import (
	"os"
	"regexp"
	"strings"
	"unicode/utf8"
)

// validAliasName regex validation.
var validAliasName = regexp.MustCompile("^[a-zA-Z][a-zA-Z0-9-]+$")

// Check if it is an aliased URL.
func isValidAliasName(aliasName string) bool {
	return validAliasName.MatchString(aliasName)
}

// getAliasURL expands aliased (name/path) to full URL, used by url-parser.
func getAliasURL(aliasedURL string, aliases map[string]string) string {
	for aliasName, aliasValue := range aliases {
		if strings.HasPrefix(aliasedURL, aliasName) {
			// Match found. Expand it.
			splits := strings.SplitN(aliasedURL, aliasName, 2)
			if len(splits) == 1 {
				return aliasedURL // Not an aliased URL. Return as is.
			}
			if len(splits[0]) == 0 && len(splits[1]) == 0 {
				return aliasValue // exact match.
			}
			_, sepLen := utf8.DecodeRuneInString(splits[1])
			if sepLen == 1 && !os.IsPathSeparator(splits[1][0]) && splits[1] != recursiveSeparator {
				return aliasedURL // Do not expand for whole strings with alias prefix.
			}
			// Matched, but path needs to be joined.
			return urlJoinPath(aliasValue, splits[1])
		}
	}
	return aliasedURL // No matching alias found. Return as is.
}