/*
Copyright (c) 2014-2017 VMware, Inc. All Rights Reserved.

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 soap

import (
	"bufio"
	"bytes"
	"context"
	"crypto/sha1"
	"crypto/tls"
	"crypto/x509"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"net/http/cookiejar"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"
	"time"

	"github.com/vmware/govmomi/vim25/progress"
	"github.com/vmware/govmomi/vim25/types"
	"github.com/vmware/govmomi/vim25/xml"
)

type HasFault interface {
	Fault() *Fault
}

type RoundTripper interface {
	RoundTrip(ctx context.Context, req, res HasFault) error
}

const (
	DefaultVimNamespace  = "urn:vim25"
	DefaultVimVersion    = "6.5"
	DefaultMinVimVersion = "5.5"
)

type header struct {
	Cookie string `xml:"vcSessionCookie,omitempty"`
}

type Client struct {
	http.Client

	u *url.URL
	k bool // Named after curl's -k flag
	d *debugContainer
	t *http.Transport
	p *url.URL

	hostsMu sync.Mutex
	hosts   map[string]string

	Namespace string // Vim namespace
	Version   string // Vim version
	UserAgent string

	header *header
}

var schemeMatch = regexp.MustCompile(`^\w+://`)

// ParseURL is wrapper around url.Parse, where Scheme defaults to "https" and Path defaults to "/sdk"
func ParseURL(s string) (*url.URL, error) {
	var err error
	var u *url.URL

	if s != "" {
		// Default the scheme to https
		if !schemeMatch.MatchString(s) {
			s = "https://" + s
		}

		u, err = url.Parse(s)
		if err != nil {
			return nil, err
		}

		// Default the path to /sdk
		if u.Path == "" {
			u.Path = "/sdk"
		}

		if u.User == nil {
			u.User = url.UserPassword("", "")
		}
	}

	return u, nil
}

func NewClient(u *url.URL, insecure bool) *Client {
	c := Client{
		u: u,
		k: insecure,
		d: newDebug(),
	}

	// Initialize http.RoundTripper on client, so we can customize it below
	if t, ok := http.DefaultTransport.(*http.Transport); ok {
		c.t = &http.Transport{
			Proxy:                 t.Proxy,
			DialContext:           t.DialContext,
			MaxIdleConns:          t.MaxIdleConns,
			IdleConnTimeout:       t.IdleConnTimeout,
			TLSHandshakeTimeout:   t.TLSHandshakeTimeout,
			ExpectContinueTimeout: t.ExpectContinueTimeout,
		}
	} else {
		c.t = new(http.Transport)
	}

	c.hosts = make(map[string]string)
	c.t.TLSClientConfig = &tls.Config{InsecureSkipVerify: c.k}
	// Don't bother setting DialTLS if InsecureSkipVerify=true
	if !c.k {
		c.t.DialTLS = c.dialTLS
	}

	c.Client.Transport = c.t
	c.Client.Jar, _ = cookiejar.New(nil)

	// Remove user information from a copy of the URL
	c.u = c.URL()
	c.u.User = nil

	c.Namespace = DefaultVimNamespace
	c.Version = DefaultVimVersion

	return &c
}

// NewServiceClient creates a NewClient with the given URL.Path and namespace.
func (c *Client) NewServiceClient(path string, namespace string) *Client {
	u := c.URL()
	u.Path = path

	client := NewClient(u, c.k)

	client.Namespace = namespace

	// Copy the cookies
	client.Client.Jar.SetCookies(u, c.Client.Jar.Cookies(u))

	// Set SOAP Header cookie
	for _, cookie := range client.Jar.Cookies(u) {
		if cookie.Name == "vmware_soap_session" {
			client.header = &header{
				Cookie: cookie.Value,
			}

			break
		}
	}

	return client
}

// SetRootCAs defines the set of root certificate authorities
// that clients use when verifying server certificates.
// By default TLS uses the host's root CA set.
//
// See: http.Client.Transport.TLSClientConfig.RootCAs
func (c *Client) SetRootCAs(file string) error {
	pool := x509.NewCertPool()

	for _, name := range filepath.SplitList(file) {
		pem, err := ioutil.ReadFile(name)
		if err != nil {
			return err
		}

		pool.AppendCertsFromPEM(pem)
	}

	c.t.TLSClientConfig.RootCAs = pool

	return nil
}

// Add default https port if missing
func hostAddr(addr string) string {
	_, port := splitHostPort(addr)
	if port == "" {
		return addr + ":443"
	}
	return addr
}

// SetThumbprint sets the known certificate thumbprint for the given host.
// A custom DialTLS function is used to support thumbprint based verification.
// We first try tls.Dial with the default tls.Config, only falling back to thumbprint verification
// if it fails with an x509.UnknownAuthorityError or x509.HostnameError
//
// See: http.Client.Transport.DialTLS
func (c *Client) SetThumbprint(host string, thumbprint string) {
	host = hostAddr(host)

	c.hostsMu.Lock()
	if thumbprint == "" {
		delete(c.hosts, host)
	} else {
		c.hosts[host] = thumbprint
	}
	c.hostsMu.Unlock()
}

// Thumbprint returns the certificate thumbprint for the given host if known to this client.
func (c *Client) Thumbprint(host string) string {
	host = hostAddr(host)
	c.hostsMu.Lock()
	defer c.hostsMu.Unlock()
	return c.hosts[host]
}

// LoadThumbprints from file with the give name.
// If name is empty or name does not exist this function will return nil.
func (c *Client) LoadThumbprints(file string) error {
	if file == "" {
		return nil
	}

	for _, name := range filepath.SplitList(file) {
		err := c.loadThumbprints(name)
		if err != nil {
			return err
		}
	}

	return nil
}

func (c *Client) loadThumbprints(name string) error {
	f, err := os.Open(name)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}

	scanner := bufio.NewScanner(f)

	for scanner.Scan() {
		e := strings.SplitN(scanner.Text(), " ", 2)
		if len(e) != 2 {
			continue
		}

		c.SetThumbprint(e[0], e[1])
	}

	_ = f.Close()

	return scanner.Err()
}

// ThumbprintSHA1 returns the thumbprint of the given cert in the same format used by the SDK and Client.SetThumbprint.
//
// See: SSLVerifyFault.Thumbprint, SessionManagerGenericServiceTicket.Thumbprint, HostConnectSpec.SslThumbprint
func ThumbprintSHA1(cert *x509.Certificate) string {
	sum := sha1.Sum(cert.Raw)
	hex := make([]string, len(sum))
	for i, b := range sum {
		hex[i] = fmt.Sprintf("%02X", b)
	}
	return strings.Join(hex, ":")
}

func (c *Client) dialTLS(network string, addr string) (net.Conn, error) {
	// Would be nice if there was a tls.Config.Verify func,
	// see tls.clientHandshakeState.doFullHandshake

	conn, err := tls.Dial(network, addr, c.t.TLSClientConfig)

	if err == nil {
		return conn, nil
	}

	switch err.(type) {
	case x509.UnknownAuthorityError:
	case x509.HostnameError:
	default:
		return nil, err
	}

	thumbprint := c.Thumbprint(addr)
	if thumbprint == "" {
		return nil, err
	}

	config := &tls.Config{InsecureSkipVerify: true}
	conn, err = tls.Dial(network, addr, config)
	if err != nil {
		return nil, err
	}

	cert := conn.ConnectionState().PeerCertificates[0]
	peer := ThumbprintSHA1(cert)
	if thumbprint != peer {
		_ = conn.Close()

		return nil, fmt.Errorf("Host %q thumbprint does not match %q", addr, thumbprint)
	}

	return conn, nil
}

// splitHostPort is similar to net.SplitHostPort,
// but rather than return error if there isn't a ':port',
// return an empty string for the port.
func splitHostPort(host string) (string, string) {
	ix := strings.LastIndex(host, ":")

	if ix <= strings.LastIndex(host, "]") {
		return host, ""
	}

	name := host[:ix]
	port := host[ix+1:]

	return name, port
}

const sdkTunnel = "sdkTunnel:8089"

func (c *Client) SetCertificate(cert tls.Certificate) {
	t := c.Client.Transport.(*http.Transport)

	// Extension certificate
	t.TLSClientConfig.Certificates = []tls.Certificate{cert}

	// Proxy to vCenter host on port 80
	host, _ := splitHostPort(c.u.Host)

	// Should be no reason to change the default port other than testing
	key := "GOVMOMI_TUNNEL_PROXY_PORT"

	port := c.URL().Query().Get(key)
	if port == "" {
		port = os.Getenv(key)
	}

	if port != "" {
		host += ":" + port
	}

	c.p = &url.URL{
		Scheme: "http",
		Host:   host,
	}
	t.Proxy = func(r *http.Request) (*url.URL, error) {
		// Only sdk requests should be proxied
		if r.URL.Path == "/sdk" {
			return c.p, nil
		}
		return http.ProxyFromEnvironment(r)
	}

	// Rewrite url Host to use the sdk tunnel, required for a certificate request.
	c.u.Host = sdkTunnel
}

func (c *Client) URL() *url.URL {
	urlCopy := *c.u
	return &urlCopy
}

type marshaledClient struct {
	Cookies  []*http.Cookie
	URL      *url.URL
	Insecure bool
}

func (c *Client) MarshalJSON() ([]byte, error) {
	m := marshaledClient{
		Cookies:  c.Jar.Cookies(c.u),
		URL:      c.u,
		Insecure: c.k,
	}

	return json.Marshal(m)
}

func (c *Client) UnmarshalJSON(b []byte) error {
	var m marshaledClient

	err := json.Unmarshal(b, &m)
	if err != nil {
		return err
	}

	*c = *NewClient(m.URL, m.Insecure)
	c.Jar.SetCookies(m.URL, m.Cookies)

	return nil
}

func (c *Client) do(ctx context.Context, req *http.Request) (*http.Response, error) {
	if nil == ctx || nil == ctx.Done() { // ctx.Done() is for ctx
		return c.Client.Do(req)
	}

	return c.Client.Do(req.WithContext(ctx))
}

func (c *Client) RoundTrip(ctx context.Context, reqBody, resBody HasFault) error {
	var err error

	reqEnv := Envelope{Body: reqBody}
	resEnv := Envelope{Body: resBody}

	reqEnv.Header = c.header

	// Create debugging context for this round trip
	d := c.d.newRoundTrip()
	if d.enabled() {
		defer d.done()
	}

	b, err := xml.Marshal(reqEnv)
	if err != nil {
		panic(err)
	}

	rawReqBody := io.MultiReader(strings.NewReader(xml.Header), bytes.NewReader(b))
	req, err := http.NewRequest("POST", c.u.String(), rawReqBody)
	if err != nil {
		panic(err)
	}

	req.Header.Set(`Content-Type`, `text/xml; charset="utf-8"`)
	soapAction := fmt.Sprintf("%s/%s", c.Namespace, c.Version)
	req.Header.Set(`SOAPAction`, soapAction)
	if c.UserAgent != "" {
		req.Header.Set(`User-Agent`, c.UserAgent)
	}

	if d.enabled() {
		d.debugRequest(req)
	}

	tstart := time.Now()
	res, err := c.do(ctx, req)
	tstop := time.Now()

	if d.enabled() {
		d.logf("%6dms (%T)", tstop.Sub(tstart)/time.Millisecond, resBody)
	}

	if err != nil {
		return err
	}

	if d.enabled() {
		d.debugResponse(res)
	}

	// Close response regardless of what happens next
	defer res.Body.Close()

	switch res.StatusCode {
	case http.StatusOK:
		// OK
	case http.StatusInternalServerError:
		// Error, but typically includes a body explaining the error
	default:
		return errors.New(res.Status)
	}

	dec := xml.NewDecoder(res.Body)
	dec.TypeFunc = types.TypeFunc()
	err = dec.Decode(&resEnv)
	if err != nil {
		return err
	}

	if f := resBody.Fault(); f != nil {
		return WrapSoapFault(f)
	}

	return err
}

func (c *Client) CloseIdleConnections() {
	c.t.CloseIdleConnections()
}

// ParseURL wraps url.Parse to rewrite the URL.Host field
// In the case of VM guest uploads or NFC lease URLs, a Host
// field with a value of "*" is rewritten to the Client's URL.Host.
func (c *Client) ParseURL(urlStr string) (*url.URL, error) {
	u, err := url.Parse(urlStr)
	if err != nil {
		return nil, err
	}

	host, _ := splitHostPort(u.Host)
	if host == "*" {
		// Also use Client's port, to support port forwarding
		u.Host = c.URL().Host
	}

	return u, nil
}

type Upload struct {
	Type          string
	Method        string
	ContentLength int64
	Headers       map[string]string
	Ticket        *http.Cookie
	Progress      progress.Sinker
}

var DefaultUpload = Upload{
	Type:   "application/octet-stream",
	Method: "PUT",
}

// Upload PUTs the local file to the given URL
func (c *Client) Upload(f io.Reader, u *url.URL, param *Upload) error {
	var err error

	if param.Progress != nil {
		pr := progress.NewReader(param.Progress, f, param.ContentLength)
		f = pr

		// Mark progress reader as done when returning from this function.
		defer func() {
			pr.Done(err)
		}()
	}

	req, err := http.NewRequest(param.Method, u.String(), f)
	if err != nil {
		return err
	}

	req.ContentLength = param.ContentLength
	req.Header.Set("Content-Type", param.Type)

	for k, v := range param.Headers {
		req.Header.Add(k, v)
	}

	if param.Ticket != nil {
		req.AddCookie(param.Ticket)
	}

	res, err := c.Client.Do(req)
	if err != nil {
		return err
	}

	switch res.StatusCode {
	case http.StatusOK:
	case http.StatusCreated:
	default:
		err = errors.New(res.Status)
	}

	return err
}

// UploadFile PUTs the local file to the given URL
func (c *Client) UploadFile(file string, u *url.URL, param *Upload) error {
	if param == nil {
		p := DefaultUpload // Copy since we set ContentLength
		param = &p
	}

	s, err := os.Stat(file)
	if err != nil {
		return err
	}

	f, err := os.Open(file)
	if err != nil {
		return err
	}
	defer f.Close()

	param.ContentLength = s.Size()

	return c.Upload(f, u, param)
}

type Download struct {
	Method   string
	Headers  map[string]string
	Ticket   *http.Cookie
	Progress progress.Sinker
}

var DefaultDownload = Download{
	Method: "GET",
}

// DownloadRequest wraps http.Client.Do, returning the http.Response without checking its StatusCode
func (c *Client) DownloadRequest(u *url.URL, param *Download) (*http.Response, error) {
	req, err := http.NewRequest(param.Method, u.String(), nil)
	if err != nil {
		return nil, err
	}

	for k, v := range param.Headers {
		req.Header.Add(k, v)
	}

	if param.Ticket != nil {
		req.AddCookie(param.Ticket)
	}

	return c.Client.Do(req)
}

// directoryReader wraps an io.ReadCloser to support streaming download
// of a guest directory, stops reading once it sees the stream trailer.
// This is only useful when guest tools is the Go toolbox.
// The trailer is required since TransferFromGuest requires a Content-Length,
// which toolbox doesn't know ahead of time as the gzip'd tarball never touches the disk.
// We opted to wrap this here for now rather than guest.FileManager so
// DownloadFile can be also be used as-is to handle this use case.
type directoryReader struct {
	io.ReadCloser
}

var (
	gzipHeader    = []byte{0x1f, 0x8b, 0x08} // rfc1952 {ID1, ID2, CM}
	gzipHeaderLen = len(gzipHeader)
)

func (r *directoryReader) Read(buf []byte) (int, error) {
	nr, err := r.ReadCloser.Read(buf)

	// Stop reading if the last N bytes are the gzipTrailer
	if nr >= gzipHeaderLen {
		if bytes.Equal(buf[nr-gzipHeaderLen:nr], gzipHeader) {
			nr -= gzipHeaderLen
			err = io.EOF
		}
	}

	return nr, err
}

// Download GETs the remote file from the given URL
func (c *Client) Download(u *url.URL, param *Download) (io.ReadCloser, int64, error) {
	res, err := c.DownloadRequest(u, param)
	if err != nil {
		return nil, 0, err
	}

	switch res.StatusCode {
	case http.StatusOK:
	default:
		err = errors.New(res.Status)
	}

	if err != nil {
		return nil, 0, err
	}

	r := res.Body

	if strings.HasSuffix(u.Path, "/") {
		r = &directoryReader{ReadCloser: r}
	}

	return r, res.ContentLength, nil
}

// DownloadFile GETs the given URL to a local file
func (c *Client) DownloadFile(file string, u *url.URL, param *Download) error {
	var err error
	if param == nil {
		param = &DefaultDownload
	}

	rc, contentLength, err := c.Download(u, param)
	if err != nil {
		return err
	}
	defer rc.Close()

	var r io.Reader = rc

	fh, err := os.Create(file)
	if err != nil {
		return err
	}
	defer fh.Close()

	if param.Progress != nil {
		pr := progress.NewReader(param.Progress, r, contentLength)
		r = pr

		// Mark progress reader as done when returning from this function.
		defer func() {
			pr.Done(err)
		}()
	}

	_, err = io.Copy(fh, r)
	if err != nil {
		return err
	}

	// Assign error before returning so that it gets picked up by the deferred
	// function marking the progress reader as done.
	err = fh.Close()
	if err != nil {
		return err
	}

	return nil
}
