/*
 * Minio Cloud Storage, (C) 2015, 2016 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 (
	"crypto/x509"
	"encoding/pem"
	"errors"
	"io/ioutil"
	"os"
	"path/filepath"
)

// createCertsPath create certs path.
func createCertsPath() error {
	certsPath, err := getCertsPath()
	if err != nil {
		return err
	}
	if err := os.MkdirAll(certsPath, 0700); err != nil {
		return err
	}
	rootCAsPath := filepath.Join(certsPath, globalMinioCertsCADir)
	return os.MkdirAll(rootCAsPath, 0700)
}

// getCertsPath get certs path.
func getCertsPath() (string, error) {
	var certsPath string
	configDir, err := getConfigPath()
	if err != nil {
		return "", err
	}
	certsPath = filepath.Join(configDir, globalMinioCertsDir)
	return certsPath, nil
}

// mustGetCertsPath must get certs path.
func mustGetCertsPath() string {
	certsPath, err := getCertsPath()
	fatalIf(err, "Failed to get certificate path.")
	return certsPath
}

// mustGetCertFile must get cert file.
func mustGetCertFile() string {
	return filepath.Join(mustGetCertsPath(), globalMinioCertFile)
}

// mustGetKeyFile must get key file.
func mustGetKeyFile() string {
	return filepath.Join(mustGetCertsPath(), globalMinioKeyFile)
}

// mustGetCAFiles must get the list of the CA certificates stored in minio config dir
func mustGetCAFiles() (caCerts []string) {
	CAsDir := filepath.Join(mustGetCertsPath(), globalMinioCertsCADir)
	caFiles, _ := ioutil.ReadDir(CAsDir)
	for _, cert := range caFiles {
		caCerts = append(caCerts, filepath.Join(CAsDir, cert.Name()))
	}
	return
}

// mustGetSystemCertPool returns empty cert pool in case of error (windows)
func mustGetSystemCertPool() *x509.CertPool {
	pool, err := x509.SystemCertPool()
	if err != nil {
		return x509.NewCertPool()
	}
	return pool
}

// isCertFileExists verifies if cert file exists, returns true if
// found, false otherwise.
func isCertFileExists() bool {
	st, e := os.Stat(filepath.Join(mustGetCertsPath(), globalMinioCertFile))
	// If file exists and is regular return true.
	if e == nil && st.Mode().IsRegular() {
		return true
	}
	return false
}

// isKeyFileExists verifies if key file exists, returns true if found,
// false otherwise.
func isKeyFileExists() bool {
	st, e := os.Stat(filepath.Join(mustGetCertsPath(), globalMinioKeyFile))
	// If file exists and is regular return true.
	if e == nil && st.Mode().IsRegular() {
		return true
	}
	return false
}

// isSSL - returns true with both cert and key exists.
func isSSL() bool {
	return isCertFileExists() && isKeyFileExists()
}

// Reads certificated file and returns a list of parsed certificates.
func readCertificateChain() ([]*x509.Certificate, error) {
	bytes, err := ioutil.ReadFile(mustGetCertFile())
	if err != nil {
		return nil, err
	}

	// Proceed to parse the certificates.
	return parseCertificateChain(bytes)
}

// Parses certificate chain, returns a list of parsed certificates.
func parseCertificateChain(bytes []byte) ([]*x509.Certificate, error) {
	var certs []*x509.Certificate
	var block *pem.Block
	current := bytes

	// Parse all certs in the chain.
	for len(current) > 0 {
		block, current = pem.Decode(current)
		if block == nil {
			return nil, errors.New("Could not PEM block")
		}
		// Parse the decoded certificate.
		cert, err := x509.ParseCertificate(block.Bytes)
		if err != nil {
			return nil, err
		}
		certs = append(certs, cert)

	}
	return certs, nil
}

// loadRootCAs fetches CA files provided in minio config and adds them to globalRootCAs
// Currently under Windows, there is no way to load system + user CAs at the same time
func loadRootCAs() {
	caFiles := mustGetCAFiles()
	if len(caFiles) == 0 {
		return
	}
	// Get system cert pool, and empty cert pool under Windows because it is not supported
	globalRootCAs = mustGetSystemCertPool()
	// Load custom root CAs for client requests
	for _, caFile := range caFiles {
		caCert, err := ioutil.ReadFile(caFile)
		if err != nil {
			fatalIf(err, "Unable to load a CA file")
		}
		globalRootCAs.AppendCertsFromPEM(caCert)
	}
}