/*
 * Minio Cloud Storage, (C) 2015, 2016, 2017 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 cmd

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"encoding/xml"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"strings"
	"time"

	humanize "github.com/dustin/go-humanize"
	"github.com/pkg/profile"
)

// make a copy of http.Header
func cloneHeader(h http.Header) http.Header {
	h2 := make(http.Header, len(h))
	for k, vv := range h {
		vv2 := make([]string, len(vv))
		copy(vv2, vv)
		h2[k] = vv2

	}
	return h2
}

// Convert url path into bucket and object name.
func urlPath2BucketObjectName(u *url.URL) (bucketName, objectName string) {
	if u == nil {
		// Empty url, return bucket and object names.
		return
	}

	// Trim any preceding slash separator.
	urlPath := strings.TrimPrefix(u.Path, slashSeparator)

	// Split urlpath using slash separator into a given number of
	// expected tokens.
	tokens := strings.SplitN(urlPath, slashSeparator, 2)
	bucketName = tokens[0]
	if len(tokens) == 2 {
		objectName = tokens[1]
	}

	// Success.
	return bucketName, objectName
}

// URI scheme constants.
const (
	httpScheme  = "http"
	httpsScheme = "https"
)

// xmlDecoder provide decoded value in xml.
func xmlDecoder(body io.Reader, v interface{}, size int64) error {
	var lbody io.Reader
	if size > 0 {
		lbody = io.LimitReader(body, size)
	} else {
		lbody = body
	}
	d := xml.NewDecoder(lbody)
	return d.Decode(v)
}

// checkValidMD5 - verify if valid md5, returns md5 in bytes.
func checkValidMD5(md5 string) ([]byte, error) {
	return base64.StdEncoding.DecodeString(strings.TrimSpace(md5))
}

/// http://docs.aws.amazon.com/AmazonS3/latest/dev/UploadingObjects.html
const (
	// Maximum object size per PUT request is 5TB.
	// This is a divergence from S3 limit on purpose to support
	// use cases where users are going to upload large files
	// using 'curl' and presigned URL.
	globalMaxObjectSize = 5 * humanize.TiByte

	// Minimum Part size for multipart upload is 5MiB
	globalMinPartSize = 5 * humanize.MiByte

	// Maximum Part size for multipart upload is 5GiB
	globalMaxPartSize = 5 * humanize.GiByte

	// Maximum Part ID for multipart upload is 10000
	// (Acceptable values range from 1 to 10000 inclusive)
	globalMaxPartID = 10000
)

// isMaxObjectSize - verify if max object size
func isMaxObjectSize(size int64) bool {
	return size > globalMaxObjectSize
}

// // Check if part size is more than maximum allowed size.
func isMaxAllowedPartSize(size int64) bool {
	return size > globalMaxPartSize
}

// Check if part size is more than or equal to minimum allowed size.
func isMinAllowedPartSize(size int64) bool {
	return size >= globalMinPartSize
}

// isMaxPartNumber - Check if part ID is greater than the maximum allowed ID.
func isMaxPartID(partID int) bool {
	return partID > globalMaxPartID
}

func contains(stringList []string, element string) bool {
	for _, e := range stringList {
		if e == element {
			return true
		}
	}
	return false
}

// Starts a profiler returns nil if profiler is not enabled, caller needs to handle this.
func startProfiler(profiler string) interface {
	Stop()
} {
	// Enable profiler if ``_MINIO_PROFILER`` is set. Supported options are [cpu, mem, block].
	switch profiler {
	case "cpu":
		return profile.Start(profile.CPUProfile, profile.NoShutdownHook)
	case "mem":
		return profile.Start(profile.MemProfile, profile.NoShutdownHook)
	case "block":
		return profile.Start(profile.BlockProfile, profile.NoShutdownHook)
	default:
		return nil
	}
}

// Global profiler to be used by service go-routine.
var globalProfiler interface {
	Stop()
}

// dump the request into a string in JSON format.
func dumpRequest(r *http.Request) string {
	header := cloneHeader(r.Header)
	header.Set("Host", r.Host)
	// Replace all '%' to '%%' so that printer format parser
	// to ignore URL encoded values.
	rawURI := strings.Replace(r.RequestURI, "%", "%%", -1)
	req := struct {
		Method     string      `json:"method"`
		RequestURI string      `json:"reqURI"`
		Header     http.Header `json:"header"`
	}{r.Method, rawURI, header}

	var buffer bytes.Buffer
	enc := json.NewEncoder(&buffer)
	enc.SetEscapeHTML(false)
	if err := enc.Encode(&req); err != nil {
		// Upon error just return Go-syntax representation of the value
		return fmt.Sprintf("%#v", req)
	}

	// Formatted string.
	return strings.TrimSpace(string(buffer.Bytes()))
}

// isFile - returns whether given path is a file or not.
func isFile(path string) bool {
	if fi, err := os.Stat(path); err == nil {
		return fi.Mode().IsRegular()
	}

	return false
}

// checkURL - checks if passed address correspond
func checkURL(urlStr string) (*url.URL, error) {
	if urlStr == "" {
		return nil, errors.New("Address cannot be empty")
	}
	u, err := url.Parse(urlStr)
	if err != nil {
		return nil, fmt.Errorf("`%s` invalid: %s", urlStr, err.Error())
	}
	return u, nil
}

// UTCNow - returns current UTC time.
func UTCNow() time.Time {
	return time.Now().UTC()
}

// genETag - generate UUID based ETag
func genETag() string {
	return toS3ETag(getMD5Hash([]byte(mustGetUUID())))
}

// toS3ETag - return checksum to ETag
func toS3ETag(etag string) string {
	etag = canonicalizeETag(etag)

	if !strings.HasSuffix(etag, "-1") {
		// Tools like s3cmd uses ETag as checksum of data to validate.
		// Append "-1" to indicate ETag is not a checksum.
		etag += "-1"
	}

	return etag
}