package main

import (
	"bufio"
	"bytes"
	"context"
	"fmt"
	"io"
	"log"
	"mime/multipart"
	"net/http"
	"os"
	"time"

	"gitea.teamortix.com/team-ortix/coverage/cover"
)

const (
	profilePath = "/go/coverage.out"
)

func main() {
	event := os.Getenv("DRONE_BUILD_EVENT")
	if event != "push" && event != "pull_request" {
		log.Printf("DRONE_BUILD EVENT of '%s' skipped. Expecting 'push' or 'pull_request'", event)
		return
	}

	namespace := os.Getenv("DRONE_REPO_NAMESPACE")
	if namespace == "" {
		log.Fatalln("could not find DRONE_REPO_NAMESPACE")
	}

	project := os.Getenv("DRONE_REPO_NAME")
	if project == "" {
		log.Fatalln("could not find DRONE_REPO_NAME")
	}

	switch event {
	case "push":
		branch := os.Getenv("DRONE_BRANCH")
		if branch == "" {
			log.Fatalln("could not find DRONE_BRANCH")
		}
		handlePush(namespace, project, branch)
	case "pull_request":
		pull := os.Getenv("DRONE_PULL_REQUEST")
		if pull == "" {
			log.Fatalln("could not find DRONE_PULL_REQUEST")
		}
		handlePullRequest(namespace, project, pull)
	default:
		log.Fatalf("invalid branch name: %s\n", event)
	}
}

const urlFormat = "https://coverage.teamortix.com/upload/%s/%s/%s/%s"

func handlePush(namespace, project, branch string) {
	tmpl, percentage := getCoverageData()
	url := fmt.Sprintf(urlFormat, "branch", namespace, project, branch)
	err := request(url, percentage, tmpl)
	if err != nil {
		log.Fatalf("could not make request: %v\n", err)
	}
	log.Printf("Successfully made request to %s.\n", url)
}

func handlePullRequest(namespace, project, pull string) {
	tmpl, percentage := getCoverageData()

	url := fmt.Sprintf(urlFormat, "pulls", namespace, project, pull)
	err := request(url, percentage, tmpl)
	if err != nil {
		log.Fatalf("could not make request: %v\n", err)
	}
	log.Printf("Successfully made request to %s.\n", url)
}

// getCoverageData uses `go tool cover` to get the coverage profile.
// It expects coverage file `coverage.out` to be present in `/go`.
func getCoverageData() (cover.TemplateData, float64) {
	file, err := os.Open(profilePath)
	if err != nil {
		log.Fatalf("could not open cover profiles: %v\n", err)
	}
	profiles, err := cover.ParseProfiles(bufio.NewReader(file))
	if err != nil {
		log.Fatalf("could not parse cover profiles: %v\n", err)
	}
	tmpl, err := cover.Template(profiles)
	if err != nil {
		log.Fatalf("could not parse cover profiles: %v\n", err)
	}
	coverage := percentCovered(profiles)
	return tmpl, coverage
}

// percentCovered returns, as a percentage, the fraction of the statements in
// the profile covered by the test run.
// In effect, it reports the coverage of a given source file.
func percentCovered(ps []*cover.Profile) float64 {
	var total, covered int64
	for _, p := range ps {
		for _, b := range p.Blocks {
			total += int64(b.NumStmt)
			if b.Count > 0 {
				covered += int64(b.NumStmt)
			}
		}
		if total == 0 {
			return 0
		}
	}

	return float64(covered) / float64(total)
}

func request(url string, coverage float64, tmpl cover.TemplateData) error {
	client := &http.Client{Timeout: time.Second * 5}

	body := &bytes.Buffer{}
	writer := multipart.NewWriter(body)

	fw, err := writer.CreateFormFile("report", "report.html")
	if err != nil {
		return err
	}
	err = render(fw, tmpl)
	if err != nil {
		return err
	}
	fw, err = writer.CreateFormField("coverage")
	if err != nil {
		return err
	}
	if _, err = fmt.Fprintf(fw, "%.03f", coverage); err != nil {
		return err
	}
	fw, err = writer.CreateFormField("secret")
	if err != nil {
		return err
	}
	if _, err = fw.Write([]byte(os.Getenv("COVERAGE_SECRET"))); err != nil {
		return err
	}

	if err = writer.Close(); err != nil {
		return err
	}

	req, err := http.NewRequestWithContext(context.Background(), "POST", url, body)
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", writer.FormDataContentType())
	res, err := client.Do(req)
	if err != nil {
		return err
	}

	resBody, err := io.ReadAll(res.Body)
	if err != nil {
		return err
	}
	fmt.Printf("Response from coverage server: %s", resBody)

	if err = res.Body.Close(); err != nil {
		return err
	}

	if res.StatusCode != http.StatusOK {
		return fmt.Errorf("request did not succeed: (code %d): %s", res.StatusCode, resBody)
	}
	return nil
}