package process

import (
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"time"

	"github.com/autonomy/talos/internal/app/init/pkg/system/runner"
	processlogger "github.com/autonomy/talos/internal/app/init/pkg/system/runner/process/log"
	"github.com/autonomy/talos/internal/pkg/constants"
	"github.com/autonomy/talos/internal/pkg/userdata"
)

// Process is a runner.Runner that runs a process on the host.
type Process struct{}

// Run implements the Runner interface.
func (p *Process) Run(data *userdata.UserData, args *runner.Args, setters ...runner.Option) error {
	opts := runner.DefaultOptions()
	for _, setter := range setters {
		setter(opts)
	}

	switch opts.Type {
	case runner.Forever:
		if err := p.waitAndRestart(data, args, opts); err != nil {
			return err
		}
	case runner.Once:
		if err := p.waitForSuccess(data, args, opts); err != nil {
			return err
		}
	}

	return nil
}

func (p *Process) build(data *userdata.UserData, args *runner.Args, opts *runner.Options) (cmd *exec.Cmd, err error) {
	cmd = exec.Command(args.ProcessArgs[0], args.ProcessArgs[1:]...)

	// Set the environment for the service.
	cmd.Env = append([]string{fmt.Sprintf("PATH=%s", constants.PATH)}, opts.Env...)

	// Setup logging.
	w, err := processlogger.New(args.ID)
	if err != nil {
		err = fmt.Errorf("service log handler: %v", err)
		return
	}

	var writer io.Writer
	if data.Debug {
		writer = io.MultiWriter(w, os.Stdout)
	} else {
		writer = w
	}
	cmd.Stdout = writer
	cmd.Stderr = writer

	return cmd, nil
}

func (p *Process) waitAndRestart(data *userdata.UserData, args *runner.Args, opts *runner.Options) (err error) {
	cmd, err := p.build(data, args, opts)
	if err != nil {
		log.Printf("%v", err)
		time.Sleep(5 * time.Second)
		return p.waitAndRestart(data, args, opts)
	}
	if err = cmd.Start(); err != nil {
		log.Printf("%v", err)
		time.Sleep(5 * time.Second)
		return p.waitAndRestart(data, args, opts)
	}
	state, err := cmd.Process.Wait()
	if err != nil {
		log.Printf("%v", err)
		time.Sleep(5 * time.Second)
		return p.waitAndRestart(data, args, opts)
	}
	if state.Exited() {
		time.Sleep(5 * time.Second)
		return p.waitAndRestart(data, args, opts)
	}

	return nil
}

func (p *Process) waitForSuccess(data *userdata.UserData, args *runner.Args, opts *runner.Options) (err error) {
	cmd, err := p.build(data, args, opts)
	if err != nil {
		return
	}
	if err = cmd.Start(); err != nil {
		return
	}
	state, err := cmd.Process.Wait()
	if err != nil {
		return
	}
	if !state.Success() {
		time.Sleep(5 * time.Second)
		return p.waitForSuccess(data, args, opts)
	}

	return nil
}