// Copyright 2014 go-dockerclient authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package docker provides a client for the Docker remote API.
//
// See http://goo.gl/mxyql for more details on the remote API.
package docker

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"github.com/fsouza/go-dockerclient/utils"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"net/http/httputil"
	"net/url"
	"reflect"
	"strconv"
	"strings"
	"sync"
)

const userAgent = "go-dockerclient"

var (
	// ErrInvalidEndpoint is returned when the endpoint is not a valid HTTP URL.
	ErrInvalidEndpoint = errors.New("invalid endpoint")

	// ErrConnectionRefused is returned when the client cannot connect to the given endpoint.
	ErrConnectionRefused = errors.New("cannot connect to Docker endpoint")
)

// Client is the basic type of this package. It provides methods for
// interaction with the API.
type Client struct {
	endpoint     string
	endpointURL  *url.URL
	eventMonitor *eventMonitoringState
	client       *http.Client
}

// NewClient returns a Client instance ready for communication with the
// given server endpoint.
func NewClient(endpoint string) (*Client, error) {
	u, err := parseEndpoint(endpoint)
	if err != nil {
		return nil, err
	}
	return &Client{
		endpoint:     endpoint,
		endpointURL:  u,
		client:       http.DefaultClient,
		eventMonitor: new(eventMonitoringState),
	}, nil
}

func (c *Client) do(method, path string, data interface{}) ([]byte, int, error) {
	var params io.Reader
	if data != nil {
		buf, err := json.Marshal(data)
		if err != nil {
			return nil, -1, err
		}
		params = bytes.NewBuffer(buf)
	}
	req, err := http.NewRequest(method, c.getURL(path), params)
	if err != nil {
		return nil, -1, err
	}
	req.Header.Set("User-Agent", userAgent)
	if data != nil {
		req.Header.Set("Content-Type", "application/json")
	} else if method == "POST" {
		req.Header.Set("Content-Type", "plain/text")
	}
	var resp *http.Response
	protocol := c.endpointURL.Scheme
	address := c.endpointURL.Path
	if protocol == "unix" {
		dial, err := net.Dial(protocol, address)
		if err != nil {
			return nil, -1, err
		}
		clientconn := httputil.NewClientConn(dial, nil)
		resp, err = clientconn.Do(req)
		defer clientconn.Close()
	} else {
		resp, err = c.client.Do(req)
	}
	if err != nil {
		if strings.Contains(err.Error(), "connection refused") {
			return nil, -1, ErrConnectionRefused
		}
		return nil, -1, err
	}
	defer resp.Body.Close()
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, -1, err
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
		return nil, resp.StatusCode, newError(resp.StatusCode, body)
	}
	return body, resp.StatusCode, nil
}

func (c *Client) stream(method, path string, headers map[string]string, in io.Reader, out io.Writer) error {
	if (method == "POST" || method == "PUT") && in == nil {
		in = bytes.NewReader(nil)
	}
	req, err := http.NewRequest(method, c.getURL(path), in)
	if err != nil {
		return err
	}
	req.Header.Set("User-Agent", userAgent)
	if method == "POST" {
		req.Header.Set("Content-Type", "plain/text")
	}
	for key, val := range headers {
		req.Header.Set(key, val)
	}
	var resp *http.Response
	protocol := c.endpointURL.Scheme
	address := c.endpointURL.Path
	if out == nil {
		out = ioutil.Discard
	}
	if protocol == "unix" {
		dial, err := net.Dial(protocol, address)
		if err != nil {
			return err
		}
		clientconn := httputil.NewClientConn(dial, nil)
		resp, err = clientconn.Do(req)
		defer clientconn.Close()
	} else {
		resp, err = c.client.Do(req)
	}
	if err != nil {
		if strings.Contains(err.Error(), "connection refused") {
			return ErrConnectionRefused
		}
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			return err
		}
		return newError(resp.StatusCode, body)
	}
	if resp.Header.Get("Content-Type") == "application/json" {
		dec := json.NewDecoder(resp.Body)
		for {
			var m jsonMessage
			if err := dec.Decode(&m); err == io.EOF {
				break
			} else if err != nil {
				return err
			}
			if m.Stream != "" {
				fmt.Fprint(out, m.Stream)
			} else if m.Progress != "" {
				fmt.Fprintf(out, "%s %s\r", m.Status, m.Progress)
			} else if m.Error != "" {
				return errors.New(m.Error)
			}
			if m.Status != "" {
				fmt.Fprintln(out, m.Status)
			}
		}
	} else {
		if _, err := io.Copy(out, resp.Body); err != nil {
			return err
		}
	}
	return nil
}

func (c *Client) hijack(method, path string, success chan struct{}, in io.Reader, errStream io.Writer, out io.Writer) error {
	req, err := http.NewRequest(method, c.getURL(path), nil)
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "plain/text")
	protocol := c.endpointURL.Scheme
	address := c.endpointURL.Path
	if protocol != "unix" {
		protocol = "tcp"
		address = c.endpointURL.Host
	}
	dial, err := net.Dial(protocol, address)
	if err != nil {
		return err
	}
	defer dial.Close()
	clientconn := httputil.NewClientConn(dial, nil)
	clientconn.Do(req)
	if success != nil {
		success <- struct{}{}
		<-success
	}
	rwc, br := clientconn.Hijack()
	var wg sync.WaitGroup
	wg.Add(2)
	errs := make(chan error, 2)
	go func() {
		var err error
		if in != nil {
			_, err = io.Copy(out, br)
		} else {
			_, err = utils.StdCopy(out, errStream, br)
		}
		errs <- err
		wg.Done()
	}()
	go func() {
		var err error
		if in != nil {
			_, err = io.Copy(rwc, in)
		}
		rwc.(interface {
			CloseWrite() error
		}).CloseWrite()
		errs <- err
		wg.Done()
	}()
	wg.Wait()
	close(errs)
	if err := <-errs; err != nil {
		return err
	}
	return nil
}

func (c *Client) getURL(path string) string {
	urlStr := strings.TrimRight(c.endpointURL.String(), "/")
	if c.endpointURL.Scheme == "unix" {
		urlStr = ""
	}
	return fmt.Sprintf("%s%s", urlStr, path)
}

type jsonMessage struct {
	Status   string `json:"status,omitempty"`
	Progress string `json:"progress,omitempty"`
	Error    string `json:"error,omitempty"`
	Stream   string `json:"stream,omitempty"`
}

func queryString(opts interface{}) string {
	if opts == nil {
		return ""
	}
	value := reflect.ValueOf(opts)
	if value.Kind() == reflect.Ptr {
		value = value.Elem()
	}
	if value.Kind() != reflect.Struct {
		return ""
	}
	items := url.Values(map[string][]string{})
	for i := 0; i < value.NumField(); i++ {
		field := value.Type().Field(i)
		if field.PkgPath != "" {
			continue
		}
		key := field.Tag.Get("qs")
		if key == "" {
			key = strings.ToLower(field.Name)
		} else if key == "-" {
			continue
		}
		v := value.Field(i)
		switch v.Kind() {
		case reflect.Bool:
			if v.Bool() {
				items.Add(key, "1")
			}
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
			if v.Int() > 0 {
				items.Add(key, strconv.FormatInt(v.Int(), 10))
			}
		case reflect.Float32, reflect.Float64:
			if v.Float() > 0 {
				items.Add(key, strconv.FormatFloat(v.Float(), 'f', -1, 64))
			}
		case reflect.String:
			if v.String() != "" {
				items.Add(key, v.String())
			}
		case reflect.Ptr:
			if !v.IsNil() {
				if b, err := json.Marshal(v.Interface()); err == nil {
					items.Add(key, string(b))
				}
			}
		}
	}
	return items.Encode()
}

// Error represents failures in the API. It represents a failure from the API.
type Error struct {
	Status  int
	Message string
}

func newError(status int, body []byte) *Error {
	return &Error{Status: status, Message: string(body)}
}

func (e *Error) Error() string {
	return fmt.Sprintf("API error (%d): %s", e.Status, e.Message)
}

func parseEndpoint(endpoint string) (*url.URL, error) {
	u, err := url.Parse(endpoint)
	if err != nil {
		return nil, ErrInvalidEndpoint
	}
	if u.Scheme == "tcp" {
		u.Scheme = "http"
	}
	if u.Scheme != "http" && u.Scheme != "https" && u.Scheme != "unix" {
		return nil, ErrInvalidEndpoint
	}
	if u.Scheme != "unix" {
		_, port, err := net.SplitHostPort(u.Host)
		if err != nil {
			if e, ok := err.(*net.AddrError); ok {
				if e.Err == "missing port in address" {
					return u, nil
				}
			}
			return nil, ErrInvalidEndpoint
		}
		number, err := strconv.ParseInt(port, 10, 64)
		if err == nil && number > 0 && number < 65536 {
			return u, nil
		}
	} else {
		return u, nil // we don't need port when using a unix socket
	}
	return nil, ErrInvalidEndpoint
}