/*
Copyright 2016 The Kubernetes Authors 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 dm

import (
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"net/url"
	"os"
	fancypath "path"
	"path/filepath"
	"strings"
	"time"

	"github.com/kubernetes/deployment-manager/pkg/common"
)

// The default HTTP timeout
var DefaultHTTPTimeout = time.Second * 10

// The default HTTP Protocol
var DefaultHTTPProtocol = "http"

// Client is a DM client.
type Client struct {
	// Timeout on HTTP connections.
	HTTPTimeout time.Duration
	// The remote host
	Host string
	// The protocol. Currently only http and https are supported.
	Protocol string
	// Transport
	Transport http.RoundTripper
	// Debug enables http logging
	Debug bool

	// Base URL for remote service
	baseURL *url.URL
}

// NewClient creates a new DM client. Host name is required.
func NewClient(host string) *Client {
	url, _ := DefaultServerURL(host)

	return &Client{
		HTTPTimeout: DefaultHTTPTimeout,
		baseURL:     url,
		Transport:   http.DefaultTransport,
	}
}

// SetDebug enables debug mode which logs http
func (c *Client) SetDebug(enable bool) *Client {
	c.Debug = enable
	return c
}

// transport wraps client transport if debug is enabled
func (c *Client) transport() http.RoundTripper {
	if c.Debug {
		return NewDebugTransport(c.Transport)
	}
	return c.Transport
}

// SetTransport sets a custom Transport. Defaults to http.DefaultTransport
func (c *Client) SetTransport(tr http.RoundTripper) *Client {
	c.Transport = tr
	return c
}

// SetTimeout sets a timeout for http connections
func (c *Client) SetTimeout(seconds int) *Client {
	c.HTTPTimeout = time.Duration(time.Duration(seconds) * time.Second)
	return c
}

// url constructs the URL.
func (c *Client) url(rawurl string) (string, error) {
	u, err := url.Parse(rawurl)
	if err != nil {
		return "", err
	}
	return c.baseURL.ResolveReference(u).String(), nil
}

func (c *Client) agent() string {
	return fmt.Sprintf("helm/%s", "0.0.1")
}

// CallService is a low-level function for making an API call.
//
// This calls the service and then unmarshals the returned data into dest.
func (c *Client) CallService(path, method, action string, dest interface{}, reader io.ReadCloser) error {
	u, err := c.url(path)
	if err != nil {
		return err
	}

	resp, err := c.callHTTP(u, method, action, reader)
	if err != nil {
		return err
	}
	if err := json.Unmarshal([]byte(resp), dest); err != nil {
		return fmt.Errorf("Failed to parse JSON response from service: %s", resp)
	}
	return nil
}

// callHTTP is  a low-level primitive for executing HTTP operations.
func (c *Client) callHTTP(path, method, action string, reader io.ReadCloser) (string, error) {
	request, err := http.NewRequest(method, path, reader)

	// TODO: dynamically set version
	request.Header.Set("User-Agent", c.agent())
	request.Header.Add("Content-Type", "application/json")

	client := &http.Client{
		Timeout:   c.HTTPTimeout,
		Transport: c.transport(),
	}

	response, err := client.Do(request)
	if err != nil {
		return "", err
	}

	defer response.Body.Close()
	body, err := ioutil.ReadAll(response.Body)
	if err != nil {
		return "", err
	}

	s := response.StatusCode
	if s < http.StatusOK || s >= http.StatusMultipleChoices {
		return "", &HTTPError{StatusCode: s, Message: string(body), URL: request.URL}
	}

	return string(body), nil
}

// DefaultServerURL converts a host, host:port, or URL string to the default base server API path
// to use with a Client
func DefaultServerURL(host string) (*url.URL, error) {
	if host == "" {
		return nil, fmt.Errorf("host must be a URL or a host:port pair")
	}
	base := host
	hostURL, err := url.Parse(base)
	if err != nil {
		return nil, err
	}
	if hostURL.Scheme == "" {
		hostURL, err = url.Parse(DefaultHTTPProtocol + "://" + base)
		if err != nil {
			return nil, err
		}
	}
	if len(hostURL.Path) > 0 && !strings.HasSuffix(hostURL.Path, "/") {
		hostURL.Path = hostURL.Path + "/"
	}

	return hostURL, nil
}

// ListDeployments lists the deployments in DM.
func (c *Client) ListDeployments() ([]string, error) {
	var l []string
	if err := c.CallService("deployments", "GET", "list deployments", &l, nil); err != nil {
		return nil, err
	}

	return l, nil
}

// PostChart sends a chart to DM for deploying.
//
// This returns the location for the new chart, typically of the form
// `helm:repo/bucket/name-version.tgz`.
func (c *Client) PostChart(filename, deployname string) (string, error) {
	f, err := os.Open(filename)
	if err != nil {
		return "", err
	}

	u, err := c.url("/v2/charts")
	request, err := http.NewRequest("POST", u, f)
	if err != nil {
		f.Close()
		return "", err
	}

	// There is an argument to be made for using the legacy x-octet-stream for
	// this. But since we control both sides, we should use the standard one.
	// Also, gzip (x-compress) is usually treated as a content encoding. In this
	// case it probably is not, but it makes more sense to follow the standard,
	// even though we don't assume the remote server will strip it off.
	request.Header.Add("Content-Type", "application/x-tar")
	request.Header.Add("Content-Encoding", "gzip")
	request.Header.Add("X-Deployment-Name", deployname)
	request.Header.Add("X-Chart-Name", filepath.Base(filename))
	request.Header.Set("User-Agent", c.agent())

	client := &http.Client{
		Timeout:   c.HTTPTimeout,
		Transport: c.transport(),
	}

	response, err := client.Do(request)
	if err != nil {
		return "", err
	}

	// We only want 201 CREATED. Admittedly, we could accept 200 and 202.
	if response.StatusCode != http.StatusCreated {
		body, err := ioutil.ReadAll(response.Body)
		response.Body.Close()
		if err != nil {
			return "", err
		}
		return "", &HTTPError{StatusCode: response.StatusCode, Message: string(body), URL: request.URL}
	}

	loc := response.Header.Get("Location")
	return loc, nil
}

// HTTPError is an error caused by an unexpected HTTP status code.
//
// The StatusCode will not necessarily be a 4xx or 5xx. Any unexpected code
// may be returned.
type HTTPError struct {
	StatusCode int
	Message    string
	URL        *url.URL
}

// Error implements the error interface.
func (e *HTTPError) Error() string {
	return e.Message
}

// String implmenets the io.Stringer interface.
func (e *HTTPError) String() string {
	return e.Error()
}

// GetDeployment retrieves the supplied deployment
func (c *Client) GetDeployment(name string) (*common.Deployment, error) {
	var deployment *common.Deployment
	if err := c.CallService(fancypath.Join("deployments", name), "GET", "get deployment", &deployment, nil); err != nil {
		return nil, err
	}
	return deployment, nil
}

// DeleteDeployment deletes the supplied deployment
func (c *Client) DeleteDeployment(name string) (*common.Deployment, error) {
	var deployment *common.Deployment
	if err := c.CallService(filepath.Join("deployments", name), "DELETE", "delete deployment", &deployment, nil); err != nil {
		return nil, err
	}
	return deployment, nil
}

// PostDeployment posts a deployment objec to the manager service.
func (c *Client) PostDeployment(cfg *common.Configuration) error {
	return c.CallService("/deployments", "POST", "post deployment", cfg, nil)
}