package main

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

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

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

func triggerBuild(cfg *config, log *syslog.Writer, trigger *buildTrigger) error {
	env := make(map[string]string)
	branch := trigger.ref

	if trigger.changeId != "" && trigger.patchset != "" {
		env["GERRIT_CHANGE_ID"] = trigger.changeId
		env["GERRIT_CHANGE_URL"] = trigger.changeUrl
		env["GERRIT_PATCHSET"] = trigger.patchset

		branch = fmt.Sprintf("cl/%v", strings.Split(trigger.ref, "/")[3])
	}

	b := Build{
		Commit: trigger.commit,
		Branch: branch,
		Env:    env,
	}

	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
}

func postCommand(cfg *config) {
	changeId := os.Getenv("GERRIT_CHANGE_ID")
	patchSet := os.Getenv("GERRIT_PATCHSET")

	if changeId == "" || patchSet == "" {
		fmt.Println("nothing to do")
		return
	}

	// our build stage has the label :hammer:
	if os.Getenv("BUILDKITE_LABEL") != ":hammer:" {
		return
	}

	var vote int
	var verb string
	var notify string

	if os.Getenv("BUILDKITE_COMMAND_EXIT_STATUS") == "0" {
		vote = 1
		verb = "passed"
		notify = "NONE"
	} else {
		vote = -1
		verb = "failed"
		notify = "OWNER"
	}

	msg := fmt.Sprintf("Build of patchset %s %s: %s", patchSet, verb, os.Getenv("BUILDKITE_BUILD_URL"))
	review := reviewInput{
		Message:                        msg,
		OmitDuplicateComments:          true,
		IgnoreDefaultAttentionSetRules: vote == 1,
		Tag:                            "autogenerated:buildkite~result",
		Notify:                         notify,
		Labels: map[string]int{
			"Verified": vote,
		},
	}

	updateGerrit(cfg, review, changeId, patchSet)
}