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)
}