package prober

import (
	"bytes"
	"errors"
	"fmt"
	"os/exec"
	"regexp"
	"strconv"
	"strings"

	"git.faercol.me/faercol/http-boot-config/config/logger"
)

var efiBootmgrRegexp = regexp.MustCompile(`Boot(?P<id>\d+)\* (?P<name>[\w ]+)\t(HD\(.+,.+,(?P<disk_id>[0-9a-f-]+),.+,.+\))/File\((?P<filepath>.+)\)`)
var activeRegexp = regexp.MustCompile(`BootCurrent: (\d+)`)

type EfiApp struct {
	ID     int
	Name   string
	Path   string
	DiskID string
	Active bool
}

func efiAppFromBootMgrOutput(rawVal string, activeId int) (app EfiApp, ok bool) {
	match := efiBootmgrRegexp.FindStringSubmatch(rawVal)
	if len(match) == 0 {
		return
	}
	result := make(map[string]string)
	for i, name := range efiBootmgrRegexp.SubexpNames() {
		if i != 0 && name != "" {
			result[name] = match[i]
		}
	}
	id, ok := result["id"]
	if !ok {
		return
	}
	idInt, err := strconv.Atoi(id)
	if err != nil {
		return app, false
	}
	name, ok := result["name"]
	if !ok {
		return
	}
	filepath, ok := result["filepath"]
	if !ok {
		return
	}
	disk_id, ok := result["disk_id"]
	if !ok {
		return
	}
	return EfiApp{
		ID:     idInt,
		Name:   strings.TrimSpace(name),
		Path:   strings.TrimSpace(filepath),
		Active: idInt == activeId,
		DiskID: disk_id,
	}, true
}

func getActiveEFIApp(output string) (int, error) {
	match := activeRegexp.FindStringSubmatch(output)
	if len(match) == 0 {
		return -1, errors.New("no active boot image found")
	}
	strId := match[1]
	id, err := strconv.Atoi(strId)
	if err != nil {
		return -1, err
	}
	return id, nil
}

func GetEFIApps(log *logger.SimpleLogger) (apps []EfiApp, err error) {
	cmd := exec.Command("/usr/bin/efibootmgr")
	var out bytes.Buffer
	cmd.Stdout = &out

	err = cmd.Run()
	if err != nil {
		return
	}
	if cmd.ProcessState.ExitCode() != 0 {
		return nil, fmt.Errorf("error running efibootmgr, returncode %d", cmd.ProcessState.ExitCode())
	}

	outStr := out.String()
	activeBootID, err := getActiveEFIApp(outStr)
	if err != nil {
		return
	}

	for _, l := range strings.Split(outStr, "\n") {
		log.Debugf("Parsing line %q", l)
		app, ok := efiAppFromBootMgrOutput(l, activeBootID)
		if !ok {
			log.Debug("Line is not a valid EFI application")
			continue
		}
		apps = append(apps, app)
	}
	return
}