package client

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"net/url"
	"strconv"

	"github.com/drone/drone/model"
	"github.com/drone/drone/queue"
	"golang.org/x/net/context"
	"golang.org/x/net/context/ctxhttp"
	"golang.org/x/oauth2"
)

const (
	pathPull   = "%s/api/queue/pull"
	pathWait   = "%s/api/queue/wait/%d"
	pathStream = "%s/api/queue/stream/%d"
	pathPush   = "%s/api/queue/status/%d"
)

type client struct {
	client *http.Client
	base   string // base url
}

// NewClient returns a client at the specified url.
func NewClient(uri string) Client {
	return &client{http.DefaultClient, uri}
}

// NewClientToken returns a client at the specified url that
// authenticates all outbound requests with the given token.
func NewClientToken(uri, token string) Client {
	config := new(oauth2.Config)
	auther := config.Client(oauth2.NoContext, &oauth2.Token{AccessToken: token})
	return &client{auther, uri}
}

// Pull pulls work from the server queue.
func (c *client) Pull() (*queue.Work, error) {
	out := new(queue.Work)
	uri := fmt.Sprintf(pathPull, c.base)
	err := c.post(uri, nil, out)
	return out, err
}

// Push pushes an update to the server.
func (c *client) Push(p *queue.Work) error {
	uri := fmt.Sprintf(pathPush, c.base, p.Job.ID)
	err := c.post(uri, p, nil)
	return err
}

// Stream streams the build logs to the server.
func (c *client) Stream(id int64, rc io.ReadCloser) error {
	uri := fmt.Sprintf(pathStream, c.base, id)
	err := c.post(uri, rc, nil)
	return err
}

// Wait watches and waits for the build to cancel or finish.
func (c *client) Wait(id int64) *Wait {
	ctx, cancel := context.WithCancel(context.Background())
	return &Wait{id, c, ctx, cancel}
}

type Wait struct {
	id     int64
	client *client

	ctx    context.Context
	cancel context.CancelFunc
}

func (w *Wait) Done() (*model.Job, error) {
	uri := fmt.Sprintf(pathWait, w.client.base, w.id)
	req, err := w.client.createRequest(uri, "POST", nil)
	if err != nil {
		return nil, err
	}

	res, err := ctxhttp.Do(w.ctx, w.client.client, req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()
	job := &model.Job{}
	err = json.NewDecoder(res.Body).Decode(&job)
	if err != nil {
		return nil, err
	}
	return job, nil
}

func (w *Wait) Cancel() {
	w.cancel()
}

//
// http request helper functions
//

// helper function for making an http GET request.
func (c *client) get(rawurl string, out interface{}) error {
	return c.do(rawurl, "GET", nil, out)
}

// helper function for making an http POST request.
func (c *client) post(rawurl string, in, out interface{}) error {
	return c.do(rawurl, "POST", in, out)
}

// helper function for making an http PUT request.
func (c *client) put(rawurl string, in, out interface{}) error {
	return c.do(rawurl, "PUT", in, out)
}

// helper function for making an http PATCH request.
func (c *client) patch(rawurl string, in, out interface{}) error {
	return c.do(rawurl, "PATCH", in, out)
}

// helper function for making an http DELETE request.
func (c *client) delete(rawurl string) error {
	return c.do(rawurl, "DELETE", nil, nil)
}

// helper function to make an http request
func (c *client) do(rawurl, method string, in, out interface{}) error {
	// executes the http request and returns the body as
	// and io.ReadCloser
	body, err := c.open(rawurl, method, in, out)
	if err != nil {
		return err
	}
	defer body.Close()

	// if a json response is expected, parse and return
	// the json response.
	if out != nil {
		return json.NewDecoder(body).Decode(out)
	}
	return nil
}

// helper function to open an http request
func (c *client) open(rawurl, method string, in, out interface{}) (io.ReadCloser, error) {
	uri, err := url.Parse(rawurl)
	if err != nil {
		return nil, err
	}

	// creates a new http request to bitbucket.
	req, err := http.NewRequest(method, uri.String(), nil)
	if err != nil {
		return nil, err
	}

	// if we are posting or putting data, we need to
	// write it to the body of the request.
	if in != nil {
		rc, ok := in.(io.ReadCloser)
		if ok {
			req.Body = rc
			req.Header.Set("Content-Type", "plain/text")
		} else {
			inJson, err := json.Marshal(in)
			if err != nil {
				return nil, err
			}

			buf := bytes.NewBuffer(inJson)
			req.Body = ioutil.NopCloser(buf)

			req.ContentLength = int64(len(inJson))
			req.Header.Set("Content-Length", strconv.Itoa(len(inJson)))
			req.Header.Set("Content-Type", "application/json")
		}
	}
	resp, err := c.client.Do(req)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode > http.StatusPartialContent {
		defer resp.Body.Close()
		out, _ := ioutil.ReadAll(resp.Body)
		return nil, fmt.Errorf(string(out))
	}
	return resp.Body, nil
}

// createRequest is a helper function that builds an http.Request.
func (c *client) createRequest(rawurl, method string, in interface{}) (*http.Request, error) {
	uri, err := url.Parse(rawurl)
	if err != nil {
		return nil, err
	}

	// if we are posting or putting data, we need to
	// write it to the body of the request.
	var buf io.ReadWriter
	if in != nil {
		buf = new(bytes.Buffer)
		err := json.NewEncoder(buf).Encode(in)
		if err != nil {
			return nil, err
		}
	}

	// creates a new http request to bitbucket.
	req, err := http.NewRequest(method, uri.String(), buf)
	if err != nil {
		return nil, err
	}
	if in != nil {
		req.Header.Set("Content-Type", "application/json")
	}
	return req, nil
}