// Copyright 2014 Manu Martinez-Almeida.  All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.

package gin

import (
	"encoding/base64"
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin/internal/bytesconv"
)

// AuthUserKey is the cookie name for user credential in basic auth.
const AuthUserKey = "user"

// Accounts defines a key/value for user/pass list of authorized logins.
type Accounts map[string]string

// authKVMap defines a key/value for Authorization token / user
type authKVMap map[string]string


func (a authKVMap) searchCredential(authValue string) (string, bool) {
	if authValue == "" {
		return "", false
	}
	user,ok:=a[authValue]
	if !ok{
		return "", false
	}
	return user,true
}


// BasicAuthForRealm returns a Basic HTTP Authorization middleware. It takes as arguments a map[string]string where
// the key is the user name and the value is the password, as well as the name of the Realm.
// If the realm is empty, "Authorization Required" will be used by default.
// (see http://tools.ietf.org/html/rfc2617#section-1.2)
func BasicAuthForRealm(accounts Accounts, realm string) HandlerFunc {
	if realm == "" {
		realm = "Authorization Required"
	}
	realm = "Basic realm=" + strconv.Quote(realm)
	pairMap := processAccounts(accounts)
	return func(c *Context) {
		// Search user in the slice of allowed credentials
		user, found := pairMap.searchCredential(c.requestHeader("Authorization"))
		if !found {
			// Credentials doesn't match, we return 401 and abort handlers chain.
			c.Header("WWW-Authenticate", realm)
			c.AbortWithStatus(http.StatusUnauthorized)
			return
		}

		// The user credentials was found, set user's id to key AuthUserKey in this context, the user's id can be read later using
		// c.MustGet(gin.AuthUserKey).
		c.Set(AuthUserKey, user)
	}
}

// BasicAuth returns a Basic HTTP Authorization middleware. It takes as argument a map[string]string where
// the key is the user name and the value is the password.
func BasicAuth(accounts Accounts) HandlerFunc {
	return BasicAuthForRealm(accounts, "")
}

func processAccounts(accounts Accounts) authKVMap {
	length := len(accounts)
	assert1(length > 0, "Empty list of authorized credentials")
	authMap := make(authKVMap)
	for user, password := range accounts {
		assert1(user != "", "User can not be empty")
		value := authorizationHeader(user, password)
		authMap[value]=user
	}
	return authMap
}

func authorizationHeader(user, password string) string {
	base := user + ":" + password
	return "Basic " + base64.StdEncoding.EncodeToString(bytesconv.StringToBytes(base))
}