/*
 * Minimalist Object Storage, (C) 2014, 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 (
	"strings"

	"net/url"

	"github.com/minio-io/cli"
	"github.com/minio-io/minio/pkg/iodine"
)

// URLType defines supported storage protocols
type urlType int

const (
	urlUnknown       urlType = iota // Unknown type
	urlObjectStorage                // Minio and S3 compatible object storage
	urlFile                         // POSIX compatible file systems
)

// urlType detects the type of URL
func getURLType(urlStr string) (uType urlType, err error) {
	u, err := url.Parse(urlStr)
	if err != nil {
		return urlUnknown, iodine.New(err, nil)
	}
	switch u.Scheme {
	case "http":
		fallthrough
	case "https":
		return urlObjectStorage, nil
	case "file":
		fallthrough
	case "":
		return urlFile, nil
	default:
		return urlUnknown, nil
	}
}

// isValidURL checks the validity of supported URL types
func isValidURL(urlStr string) bool {
	u, e := getURLType(urlStr)
	if e != nil || u == urlUnknown {
		return false
	}
	return true
}

// isValidURL checks the validity of supported URL types
func isValidFileURL(urlStr string) bool {
	utype, e := getURLType(urlStr)
	if e != nil || utype != urlFile {
		return false
	}
	return true
}

// fixFileURL rewrites file URL to proper file:///path/to/ form.
func fixFileURL(urlStr string) (fixedURL string, err error) {
	if urlStr == "" {
		return "", iodine.New(errEmptyURL, nil)
	}

	utype, e := getURLType(urlStr)
	if e != nil || utype != urlFile {
		return "", iodine.New(e, nil)
	}

	u, e := url.Parse(urlStr)
	if e != nil {
		return "", iodine.New(e, nil)
	}

	// file:///path should always have empty host
	if u.Host != "" {
		// Not really a file URL. Host is not empty.
		return "", iodine.New(errInvalidURL, nil)
	}

	// fill missing scheme
	if u.Scheme == "" {
		// Set it to file
		u.Scheme = "file"
	}

	fixedURL = u.String()
	return fixedURL, nil

}

// url2Host extracts hostname from the URL.
func url2Host(urlStr string) (host string, err error) {
	if urlStr == "" {
		return "", iodine.New(errEmptyURL, nil)
	}

	utype, e := getURLType(urlStr)
	if e != nil || utype != urlFile {
		return "", iodine.New(e, nil)
	}

	u, e := url.Parse(urlStr)
	if e != nil {
		return "", iodine.New(e, nil)
	}

	return u.Host, nil
}

// url2Object converts URL to bucket and objectname
func url2Object(urlStr string) (bucketName, objectName string, err error) {
	u, err := url.Parse(urlStr)
	if u.Path == "" {
		// No bucket name passed. It is a valid case
		return "", "", nil
	}
	splits := strings.SplitN(u.Path, "/", 3)
	switch len(splits) {
	case 0, 1:
		bucketName = ""
		objectName = ""
	case 2:
		bucketName = splits[1]
		objectName = ""
	case 3:
		bucketName = splits[1]
		objectName = splits[2]
	}
	return bucketName, objectName, nil
}

// url2Bucket converts URL to bucket name
func url2Bucket(urlStr string) (bucketName string, err error) {
	bucketName, _, err = url2Object(urlStr)
	return bucketName, iodine.New(err, nil)
}

// parseURL extracts URL string from a single cmd-line argument
func parseURL(arg string) (urlStr string, err error) {
	urlStr = arg
	// Use default host if no argument is passed
	if urlStr == "" {
		// Load config file
		config, err := getMcConfig()
		if err != nil {
			return "", iodine.New(err, nil)
		}
		urlStr = config.DefaultHost
	}

	// Check and expand Alias
	urlStr, err = aliasExpand(urlStr)
	if err != nil {
		return "", iodine.New(err, nil)
	}

	if !isValidURL(urlStr) {
		return "", iodine.New(errUnsupportedScheme, nil)
	}

	// If it is a file URL, rewrite to file:///path/to form
	if isValidFileURL(urlStr) {
		return fixFileURL(urlStr)
	}
	return urlStr, nil
}

// parseURL extracts multiple URL strings from a single cmd-line argument
func parseURLs(c *cli.Context) (urlStr []string, err error) {
	for _, arg := range c.Args() {
		u, err := parseURL(arg)
		if err != nil {
			return nil, iodine.New(err, nil)
		}
		urlStr = append(urlStr, u)
	}
	return urlStr, iodine.New(err, nil)
}