package notify

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"

	"github.com/drone/drone/shared/model"
)

const (
	slackEndpoint       = "https://%s.slack.com/services/hooks/incoming-webhook?token=%s"
	slackStartedMessage = "*Building* %s, commit <%s|%s>, author %s"
	slackSuccessMessage = "*Success* %s, commit <%s|%s>, author %s"
	slackFailureMessage = "*Failed* %s, commit <%s|%s>, author %s"
)

type Slack struct {
	Team     string `yaml:"team,omitempty"`
	Channel  string `yaml:"channel,omitempty"`
	Username string `yaml:"username,omitempty"`
	Token    string `yaml:"token,omitempty"`
	Started  bool   `yaml:"on_started,omitempty"`
	Success  bool   `yaml:"on_success,omitempty"`
	Failure  bool   `yaml:"on_failure,omitempty"`
}

func (s *Slack) Send(context *model.Request) error {
	switch {
	case context.Commit.Status == "Started" && s.Started:
		return s.sendStarted(context)
	case context.Commit.Status == "Success" && s.Success:
		return s.sendSuccess(context)
	case context.Commit.Status == "Failure" && s.Failure:
		return s.sendFailure(context)
	}

	return nil
}

func getBuildUrl(context *model.Request) string {
	return fmt.Sprintf("%s/%s/%s/%s/%s/%s", context.Host, context.Repo.Host, context.Repo.Owner, context.Repo.Name, context.Commit.Branch, context.Commit.Sha)
}

func getMessage(context *model.Request, message string) string {
	url := getBuildUrl(context)
	return fmt.Sprintf(message, context.Repo.Name, url, context.Commit.ShaShort(), context.Commit.Author)
}

func (s *Slack) sendStarted(context *model.Request) error {
	return s.send(getMessage(context, slackStartedMessage))
}

func (s *Slack) sendSuccess(context *model.Request) error {
	return s.send(getMessage(context, slackSuccessMessage))
}

func (s *Slack) sendFailure(context *model.Request) error {
	return s.send(getMessage(context, slackFailureMessage))
}

// helper function to send HTTP requests
func (s *Slack) send(msg string) error {
	// data will get posted in this format
	data := struct {
		Channel  string `json:"channel"`
		Username string `json:"username"`
		Text     string `json:"text"`
	}{s.Channel, s.Username, msg}

	// data json encoded
	payload, err := json.Marshal(data)
	if err != nil {
		return err
	}

	// send payload
	url := fmt.Sprintf(slackEndpoint, s.Team, s.Token)
	go sendJson(url, payload)

	return nil
}

// helper fuction to sent HTTP Post requests
// with JSON data as the payload.
func sendJson(url string, payload []byte) {
	buf := bytes.NewBuffer(payload)
	resp, err := http.Post(url, "application/json", buf)
	if err != nil {
		return
	}
	resp.Body.Close()
}