package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log/syslog"
	"net/http"
	"time"
)

// https://buildkite.com/docs/apis/rest-api/builds#create-a-Build
type Build struct {
	Commit string `json:"commit"`
	Branch string `json:"branch"`
}

type buildResponse struct {
	WebUrl string `json:"web_url"`
}

func triggerBuild(cfg *config, log *syslog.Writer, trigger *buildTrigger) error {
	b := Build{
		Commit: trigger.commit,
		Branch: trigger.ref,
	}

	body, _ := json.Marshal(b)
	reader := ioutil.NopCloser(bytes.NewReader(body))

	bkUrl := fmt.Sprintf("https://api.buildkite.com/v2/organizations/%s/pipelines/%s/builds", cfg.BuildKiteOrganization, trigger.project)
	req, err := http.NewRequest("POST", bkUrl, reader)
	if err != nil {
		return fmt.Errorf("failed to create an HTTP request: %v", err)
	}

	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", cfg.BuildKiteToken))
	req.Header.Add("Content-Type", "application/json")

	// Let's budget this to 10 seconds maximum, this should be more
	// than enough, as we're only triggering the build, we're not
	// waiting on the status of the build
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	resp, err := http.DefaultClient.Do(req.WithContext(ctx))
	if err != nil {
		return fmt.Errorf("failed to send buildKite request: %v", err)
	}
	defer resp.Body.Close()

	respBody, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("failed to parse buildKite response: %v", err)
	}

	if resp.StatusCode != http.StatusCreated {
		return fmt.Errorf("received a non-success response from buildKite: %s (%v)", respBody, resp.Status)
	}

	var buildResp buildResponse
	err = json.Unmarshal(respBody, &buildResp)
	if err != nil {
		return fmt.Errorf("failed to unmarshal build response: %v", err)
	}

	// Report the status back to the Gerrit CL so that users can click
	// through to the running build.
	msg := fmt.Sprintf("started build for patchset #%s on: %s", trigger.patchset, buildResp.WebUrl)
	review := reviewInput{
		Message:                        msg,
		OmitDuplicateComments:          true,
		Tag:                            "autogenerated:buildkite~trigger",
		IgnoreDefaultAttentionSetRules: true,
		Notify:                         "NONE",
	}
	updateGerrit(cfg, review, trigger.changeId, trigger.patchset)
	return nil
}