package main

import (
	"bytes"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
)

// goEnv is the environment every build and test runs with: no cgo, no
// enclosing go.work, the plugin's vendor folder.
func goEnv(goos, goarch string) []string {
	env := append(os.Environ(), "CGO_ENABLED=0", "GOWORK=off")
	if goos != "" {
		env = append(env, "GOOS="+goos, "GOARCH="+goarch)
	}
	return env
}

// goRun runs a go command in dir and returns its combined output.
func goRun(dir string, env []string, args ...string) (string, error) {
	cmd := exec.Command("go", args...)
	cmd.Dir = dir
	cmd.Env = env
	var out bytes.Buffer
	cmd.Stdout = &out
	cmd.Stderr = &out
	err := cmd.Run()
	return out.String(), err
}

// buildWorker builds ./cmd/worker for this machine into a temporary folder.
func buildWorker(dir string) (string, func(), error) {
	tmp, err := os.MkdirTemp("", "cletus-plugin-")
	if err != nil {
		return "", nil, err
	}
	cleanup := func() { os.RemoveAll(tmp) }
	name := "worker"
	if runtime.GOOS == "windows" {
		name += ".exe"
	}
	bin := filepath.Join(tmp, name)
	if out, err := goRun(dir, goEnv("", ""), "build", "-trimpath", "-o", bin, "./cmd/worker"); err != nil {
		cleanup()
		return "", nil, fmt.Errorf("the worker doesn't build:\n%s", out)
	}
	return bin, cleanup, nil
}